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Title: Man and the Glacial Period

Author: G. Frederick Wright

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THE INTERNATIONAL SCIENTIFIC SERIES

MAN AND
THE GLACIAL PERIOD
BY

G. FREDERICK WRIGHT
D. D., LL. D., F. G. S. A.
PROFESSOR IN OBERLIN THEOLOGICAL SEMINARY

FORMERLY ASSISTANT ON THE UNITED STATES GEOLOGICAL SURVEY

AUTHOR OF THE ICE AGE IN NORTH AMERICA.

LOGIC OF CHRISTIAN EVIDENCES, ETC.

WITH AN APPENDIX ON TERTIARY MAN

By PROF. HENRY W. HAYNES

FULLY ILLUSTRATED
SECOND EDITION

NEW YORK
D. APPLETON AND COMPANY
1895

Copyright, 1892,
By D. APPLETON AND COMPANY.

Electrotyped and Printed
at the Appleton Press, U. S. A.

TO

JUDGE C. C. BALDWIN
PRESIDENT OF THE WESTERN RESERVE HISTORICAL SOCIETY
CLEVELAND
THIS VOLUME IS DEDICATED
IN RECOGNITION OF
HIS SAGACIOUS AND UNFAILING INTEREST IN
THE INVESTIGATIONS WHICH HAVE MADE IT POSSIBLE

PREFACE TO THE SECOND EDITION.
Since, as stated in the Introduction (page 1), the plan of this volume
permitted only “a concise presentation of the facts,” it was impossible to
introduce either full references to the illimitable literature of the subject or
detailed discussion of all disputed points. The facts selected, therefore, were
for the most part those upon which it was supposed there would be pretty
general agreement.
The discussion upon the subject of the continuity of the Glacial period
was, however, somewhat elaborate (see pages 106-121, 311, 324, 332), and
was presented with excessive respect for the authority of those who

maintain the opposite view; all that was claimed (page 110) being that one
might maintain the unity or continuity of the Glacial period “without
forfeiting his right to the respect of his fellow-geologists.” But it already
appears that there was no need of this extreme modesty of statement. On the
contrary, the vigorous discussion of the subject which has characterized the
last two years reveals a decided reaction against the theory that there has
been more than one Glacial epoch in Quaternary times; while there have
been brought to light many most important if not conclusive facts in favour
of the theory supported in the volume.
In America the continuity of the Glacial period has been maintained
during the past two years with important new evidence, among others by
authorities of no less eminence and special experience in glacial
investigations than Professor Dana,[A] Mr. Warren Upham,[B] and Professor
Edward H. Williams, Jr.[C] Professor Williams’s investigations on the
attenuated border of the glacial deposits in the Lehigh, the most important
upper tributary to the Delaware Valley, Pa., are of important significance,
since the area which he so carefully studied lies wholly south of the
terminal moraine of Lewis and Wright, and belongs to the portion of the
older drift which Professors Chamberlin and Salisbury have been most
positive in assigning to the first Glacial epoch, which they have maintained
was separated from the second epoch by a length of time sufficient for the
streams to erode rock gorges in the Delaware and Lehigh Rivers from two
hundred to three hundred feet in depth.[D] But Professor Williams has found
that the rock gorges of the Lehigh, and even of its southern tributaries, had
been worn down approximately to the present depth of that of the Delaware
before this earliest period of glaciation, and that the gorges were filled with
the earliest glacial débris.
[A] American Journal of Science, vol. xlvi, pp. 327, 330.
[B] American Journal of Science, vols, xlvi, pp. 114-121; xlvii, pp. 358-365;
American Geologist, vols, x, pp. 339-362, especially pp. 361, 362; xiii, pp. 114,
278; Bulletin of the Geological Society of America, vol. v, pp. 71-86, 87-100.
[C] Bulletin of the Geological Society of America, vol. v, pp. 13-16, 281-
296; American Journal of Science, vol. xlvii, pp. 33-36.
[D] See especially Chamberlin, in the American Journal of Science, vol. xlv,
p. 192; Salisbury, in the American Geologist, vol. xi, p. 18.

A similar relation of the glacial deposits of the attenuated border to the
preglacial erosion of the rock gorges of the Alleghany and upper Ohio
Rivers has been brought to light by the joint investigations of Mr. Frank
Leverett and myself in western Pennsylvania, in the vicinity of Warren, Pa.,
where, in an area which was affected by only the earliest glaciation, glacial
deposits are found filling the rock channels of old tributaries to the
Alleghany to a depth of from one hundred and seventy to two hundred and
fifty feet, and carrying the preglacial erosion at that point very closely, if
not quite, down to the present rock bottoms of all the streams. This removes
from Professor Chamberlin a most important part of the evidence of a long
interglacial period to which he had appealed; he having maintained[E] that
“the higher glacial gravels antedated those of the moraine-forming epoch by
the measure of the erosion of the channel through the old drift and the rock,
whose mean depth here is about three hundred feet, of which perhaps two
hundred and fifty feet may be said to be rock,” adding that the “excavation
that intervened between the two epochs in other portions of the Alleghany,
Monongahela, and upper Ohio valleys is closely comparable with this.”
[E] Bulletin 58 of the United States Geological Survey, p. 35; American
Journal of Science, vol. xlv, p. 195.

These observations of Mr. Leverett and myself seem to demonstrate the
position maintained in the volume (page 218), namely, that the inner
precipitous rock gorges of the upper Ohio and its tributaries are mainly
preglacial, rather than interglacial. The only way in which Professor
Chamberlin can in any degree break the force of this discovery is by
assuming that in preglacial times the present narrow rock gorges of the
Alleghany and the Ohio were not continuous, but that (as indicated in the
present volume on page 206) the drainage of various portions of that region
was by northern outlets to the Lake Erie basin, leaving, on this supposition,
the cols between two or three drainage areas to be lowered in glacial or
interglacial time.
On the theory of continuity the erosion of these cols would have been
rapidly effected by the reversed drainage consequent upon the arrival of the
ice-front at the southern shore of the Lake Erie basin. During all the time
elapsing thereafter, until the ice had reached its southern limit, the stream
was also augmented by the annual partial melting of the advancing glacier
which was constantly bringing into the valley the frozen precipitation of the

far north. The distance is from thirty to seventy miles, so that a moderately
slow advance of the ice at that stage would afford time for a great amount
of erosion before sufficient northern gravel had reached the region to begin
the filling of the gorge.[F]
[F] See an elaborate discussion of the subject in its new phases by
Chamberlin and Leverett, in the American Journal of Science, vol. xlvii, pp. 247-
283.

Mr. Leverett also presented an important paper before the Geological
Society of America at its meeting at Madison, Wis., in August, 1893,
adducing evidence which, he thinks, goes to prove that the post-glacial
erosion in the earlier drift in the region of Rock River, Ill., was seven or
eight times as much as that in the later drift farther north; while Mr. Oscar
H. Hershey arrives at nearly the same conclusions from a study of the
buried channels in northwestern Illinois.[G] But even if these estimates are
approximately correct—which is by no means certain—they only prove the
length of the Glacial period, and not necessarily its discontinuity.
[G] American Geologist, vol. xii, p. 314f. Other important evidence to a
similar effect is given by Mr. Leverett, in an article on The Glacial Succession in
Ohio, Journal of Geology, vol. i, pp. 129-146.

At the same time it should be said that these investigations in western
Pennsylvania somewhat modify a portion of the discussion in the present
volume concerning the effects of the Cincinnati ice-dam. It now appears
that the full extent of the gravel terraces of glacial origin in the Alleghany
River had not before been fully appreciated, since they are nearly
continuous on the two-hundred-foot rock shelf, and are often as much as
eighty feet thick. It seems probable, therefore, that the Alleghany and upper
Ohio gorge was filled with glacial gravel to a depth of about two hundred
and fifty or three hundred feet, as far down at least as Wheeling, W. Va. If
this was the case, it would obviate the necessity of bringing in the
Cincinnati ice-dam (as set forth in pages 212-216) to account directly for all
the phenomena in that region, except as this obstruction at Cincinnati would
greatly facilitate the silting up of the gorge. The simple accumulation of
glacial gravel in the Alleghany gorge would of itself dam up the
Monongahela at Pittsburg, so as to produce the results detailed by Professor
White on page 215.[H]

[H] For a full discussion of these topics, see paper by Professor B. C. Jillson,
Transactions of the Academy of Science and Art of Pittsburg, December 8, 1893;
G. F. Wright, American Journal of Science, vol. xlvii, pp. 161-187; especially pp.
177, 178; The Popular Science Monthly, vol. xlv, pp. 184-198.

Of European authorities who have recently favoured the theory of the
continuity of the Quaternary Glacial period, as maintained in the volume, it
is enough to mention the names of Prestwich,[I] Hughes,[J] Kendall,[K]
Lamplugh,[L] and Wallace,[M] of England; Falsan,[N] of France; Holst,[O] of
Sweden; Credner[P] and Diener,[Q] of Germany; and Nikitin[R] and
Kropotkin,[S] of Russia.[T] Among leading authorities still favouring a
succession of Glacial epochs are: Professor James Geikie,[U] of Scotland;
Baron de Geer,[V] of Sweden; and Professor Felix Wahnschaffe,[W] of
Germany.
[I] Quarterly Journal of the Geological Society for August, 1887.
[J] American Geologist, vol. viii, p. 241.
[K] Transactions of the Leeds Geological Association for February 10, 1893.
[L] Quarterly Journal of the Geological Society, August, 1891.
[M] Fortnightly Review, November, 1893, p. 633; reprinted in The Popular
Science Monthly, vol. xliv, p. 790.
[N] La Période glaciaire (Félix Alcan. Paris, 1889).
[O] American Geologist, vol. viii, p. 242.
[P] Ibid., p. 241.
[Q] Ibid., p. 242.
[R] Congrès International d’Archéologie, Moscow, 1892.
[S] Nineteenth Century, January, 1894, p. 151, note.
[T] The volume The Glacial Geology of Great Britain and Ireland, edited
from the unpublished MSS. of the late Henry Carvill Lewis (London, Longmans,
Green & Co., 1894), adds much important evidence in favour of the continuity of
the Glacial epoch; see especially pp. 187, 460, 461, 466.
[U] Transactions of the Royal Society of Edinburgh, vol. xxxvii, Part I, pp.
127-150.
[V] American Geologist, vol. viii, p. 246.
[W] Forschungen zur deutschen Landes und Volkskunde von Dr. A.
Kirchhoff. Bd. vi, Heft i.

When the first edition was issued, two years ago, there seemed to be a
general acceptance of all the facts detailed in it which directly connected
man with the Glacial period both in America and in Europe; and, indeed, I
had studiously limited myself to such facts as had been so long and so fully
before the public that there would seem to be no necessity for going again
into the details of evidence relating to them. It appears, however, that this
confidence was ill-founded; for the publication of the book seems to have
been the signal for a confident challenge, by Mr. W. H. Holmes, of all the
American evidence, with intimations that the European also was very likely
equally defective.[X] In particular Mr. Holmes denies the conclusiveness of
the evidence of glacial man adduced by Dr. Abbott and others at Trenton, N.
J.; Dr. Metz, at Madisonville, Ohio; Mr. Mills, at Newcomerstown, Ohio;
and Miss Babbitt, at Little Falls, Minn.
[X] Journal of Geology, vol. i, pp. 15-37, 147-163; American Geologist, vol.
xi, pp. 219-240.

The sum of Mr. Holmes’s effort amounts, however, to little more than
the statement that, with a limited amount of time and labour, neither he nor
his assistants had been able to find any implements in undisturbed gravel in
any of these places; and the suggestion of various ways in which he thinks
it possible that the observers mentioned may have been deceived as to the
original position of the implements found. But, as had been amply and
repeatedly published,[Y] Professor J. D. Whitney, Professor Lucien Carr,
Professor N. S. Shaler, Professor F. W. Putnam, of Harvard University,
besides Dr. C. C. Abbott, all expressly and with minute detail describe
finding implements in the undisturbed gravel at Trenton, which no one
denies to be of glacial origin. In the face of such testimony, which had been
before the public and freely discussed for several years, it is an arduous
undertaking for Mr. Holmes to claim that none of the implements have been
found in place, because he and his assistants (whose opportunities for
observation had scarcely been one twentieth part as great as those of the
others) failed to find any. To see how carefully the original observations
were made, one has but to read the reports to Professor Putnam which have
from time to time appeared in the Proceedings of the Peabody Museum and
of the Boston Society of Natural History,, and which are partially summed
up in the thirty-second chapter of Dr. Abbott’s volume on Primitive
Industry.

[Y] Proceedings of the Boston Society of Natural History, vol. xxi, January
19, 1881; Report of the Peabody Museum, vol. ii, pp. 44-47; chap, xxxii of
Abbott’s Primitive Industry; American Geologist, vol. xi, pp. 180-184.

In the case of the discovery at Newcomerstown, Mr. Holmes is
peculiarly unfortunate in his efforts to present the facts, since, in
endeavouring to represent the conditions under which the implement was
found by Mr. Mills, he has relied upon an imaginary drawing of his own, in
which an utterly impossible state of things is pictured. The claim of Mr.
Holmes in this case, as in the other, is that possibly the gravel in which the
implements were found had been disturbed. In some cases, as in Little Falls
and at Madison ville, he thinks the implements may have worked down to a
depth of several feet by the overturning of trees or by the decay of the tap-
root of trees. A sufficient answer to these suggestions is, that Mr. Holmes is
able to find no instance in which the overturning of trees has disturbed the
soil to a depth of more than three or four feet, while some of the
implements in these places had been found buried from eight to sixteen feet.
Even if, as Mr. Chamberlin suggests,[Z] fifty generations of trees have
decayed on the spot since the retreat of the ice, it is difficult to see how that
would help the matter, since the effect could not be cumulative, and fifty
upturnings of three or four feet would not produce the results of one
upturning of eight feet. Moreover, at Trenton, where the upturning of trees
and the decaying of tap-roots would have been as likely as anywhere to
bury implements, none of those of flint or jasper (which occur upon the
surface by tens of thousands) are buried more than a foot in depth; while the
argillite implements occur as low down as fifteen or twenty feet. This
limitation of flint and jasper implements to the surface is conclusively
shown not only by Dr. Abbott’s discoveries, but also by the extensive
excavations at Trenton of Mr. Ernest Volk, whose collections formed so
prominent a part of Professor Putnam’s Palæolithic exhibit at the
Columbian Exposition at Chicago. In the village sites explored by Mr. Volk,
argillite was the exclusive material of the implements found in the lower
strata of gravel. Similar results are indicated by the excavations of Mr. H. C.
Mercer at Point Pleasant, Pa., about twenty miles above Trenton, where, in
the lower strata, the argillite specimens are sixty-one times more numerous
than the jasper are.
[Z] American Geologist, vol. xi, p. 188.

To discredit the discoveries at Trenton and Newcomerstown, Mr.
Holmes relies largely upon the theory that portions of gravel from the
surface had slid down to the bottom of the terrace, carrying implements
with them, and forming a talus, which, he thinks, Mr. Mills, Dr. Abbott, and
the others have mistaken for undisturbed strata of gravel. In his drawings
Mr. Holmes has even represented the gravel at Newcomerstown as caving
down into a talus without disturbing the strata to any great extent, and at the
same time he speaks slightingly of the promise which I had made to publish
a photograph of the bank as it really was. In answer, it is sufficient to give,
first, the drawing made at the time by Mr. Mills, to show the general
situation of the gravel bank at Newcomerstown, in which the implement
figured on page 252 was found; and, secondly, an engraving from a
photograph of the bank, taken by Mr. Mills after the discovery of the
implement, but before the talus had obscured its face. The implement was
found by Mr. Mills with its point projecting from a fresh exposure of the
terrace, just after a mass, loosened by his own efforts, had fallen away. The
gravel is of such consistency that every sign of stratification disappears
when it falls down, and there could be no occasion for a mistake even by an
ordinary observer, while Mr. Mills was a well-trained geologist and
collector, making his notes upon the spot.[AA]
[AA] The Popular Science Monthly, vol. xliii, pp. 29-39.

3
Height of Terrace exposed, 25 feet. Palæolith was found 144 feet from surface.

Terrace in Newcomerstown, showing where W. C. Mills found the Palæolithic
implement.

I had thought at first that Mr. Holmes had made out a better case against
the late Miss Babbitt’s discoveries at Little Falls (referred to on page 254),
but in the American Geologist for May, 1894, page 363, Mr. Warren
Upham, after going over the evidence, expresses it as still his conviction
that Mr. Holmes’s criticism fails to shake the force of the original evidence,
so that I do not see any reason for modifying any of the statements made in
the body of the book concerning the implements supposed to have been
found in glacial deposits. Yet if I had expected such an avalanche of
criticism of the evidence as has been loosened, I should at the time have
fortified my statements by fuller references, and should possibly have
somewhat enlarged the discussion. But this seemed then the less necessary,
from the fact that Mr. McGee had, in most emphatic manner, indorsed
nearly every item of the evidence adduced by me, and much more, in an
article which appeared in The Popular Science Monthly four years before
the publication of the volume (November, 1888). In this article he had said:
“But it is in the aqueo-glacial gravels of the Delaware River at Trenton,
which were laid down contemporaneously with the terminal moraine one

hundred miles farther northward, and which have been so thoroughly
studied by Abbott, that the most conclusive proof of the existence of glacial
man is found" (p. 23). “Excluding all doubtful cases, there remains a fairly
consistent body of testimony indicating the existence of a widely distributed
human population upon the North. American continent during the later Ice
epoch” (p. 24). “However the doubtful cases may be neglected, the
testimony is cumulative, parts of it are unimpeachable, and the proof of the
existence of glacial man seems conclusive” (p. 25).
In view of the grossly erroneous statements made by Mr. McGee
concerning the Nampa image (described on pages 298, 299), it is necessary
for me to speak somewhat more fully of this important discovery. The
details concerning the evidence were drawn out by me at length in two
communications to the Boston Society of Natural History (referred to on
page 297), which fill more than thirty pages of closely printed matter, while
two or three years before the appearance of the volume the facts had been
widely published in the New York Independent, the Scientific American,
The Nation, Scribner’s Magazine, and the Atlantic Monthly, and in
Washington at a meeting of the Geological Society of America in 1890. In
the second communication to the Boston Society of Natural History an
account was given of a personal visit to the Snake River Valley, largely for
the purpose of further investigation of the evidence brought to my notice by
Mr. Charles Francis Adams, and of the conditions under which the figurine
was found. Among the most important results of this investigation was the
discovery of numerous shells under the lava deposits, which Mr. Dall, of the
United States Geological Survey, identified for me as either post-Tertiary or
late Pliocene; thus throwing the superficial lava deposits of the region into
the Quaternary period, and removing from the evidence the antecedent
improbability which would bear so heavily against it if we were compelled
to suppose that the lava of the Snake River region was all of Tertiary or
even of early Quaternary age. Furthermore, the evidence of the occurrence
of a great débâcle in the Snake River Valley during the Glacial period,
incident upon the bursting of the banks of Lake Bonneville, goes far to
remove antecedent presumptions against the occurrence of human
implements in such conditions as those existing at Nampa (see below, pp.
233-237).

Mr. McGee’s misunderstanding of the evidence on one point is so gross,
that I must make special reference to it. He says[AB] that this image “is
alleged to have been pounded out of volcanic tuff by a heavy drill, ... under
a thick Tertiary lava bed.” The statement of facts on page 298 bears no
resemblance to this representation. It is there stated that there were but
fifteen feet of lava, and that near the surface; that below this there was
nothing but alternating beds of clay and quicksand, and that the lava is post-
Tertiary. The sand-pump I should perhaps have described more fully in the
book, as I had already done in the communication to the Boston Society of
Natural History. It was a tube eight feet long, with a valve at the bottom
three and a half inches in diameter on the inside. Through this it was the
easiest thing in the world for the object, which is only one inch and a half
long, to be brought up in the quicksand without injury.
[AB] Literary Northwest, vol. ii, p. 275.

The baseless assertions of Mr. McGee, involving the honesty of Messrs.
Kurtz and Duffes, are even less fortunate and far more reprehensible. “It is
a fact,” says Mr. McGee, “hat one of the best-known geologists of the world
chanced to visit Nampa while the boring was in progress, and the figurine
and the pretty fiction were laid before him. He recognized the figurine as a
toy such as the neighbouring Indians give their children, and laughed at the
story; whereupon the owner of the object enjoined secrecy, pleading: ‘Don’t
give me away; I’ve fooled a lot of fellows already, and I’d like to fool some
more.’”[AC] This well-known geologist, on being challenged by Professor
Claypole[AD] to give “a full, exact, and certified statement of the
conversation” above referred to, proved to be Major Powell, who responded
with the following statement: “In the fall of 1889 the writer visited Boise
City, in Idaho [twenty miles from Nampa]. While stopping at a hotel, some
gentlemen called on him to show him a figurine which they said they had
found in sinking an artesian well in the neighbourhood, at a depth, if I
remember rightly, of more than three hundred feet.... When this story was
told the writer, he simply jested with those who claimed to have found it.
He had known the Indians that live in the neighbourhood, had seen their
children play with just such figurines, and had no doubt that the little image
had lately belonged to some Indian child, and said the same. While stopping
at the hotel different persons spoke about it, and it was always passed off as
a jest; and various comments were made about it by various people, some

of them claiming that it had given them much sport, and that a good many
tenderfeet had looked at it, and believed it to be genuine; and they seemed
rather pleased that I had detected the hoax.”[AE]
[AC] American Anthropologist, vol. vi, p. 94: repeated by Mr. McGee in the
Literary Northwest, vol. ii, p. 276.
[AD] The Popular Science Monthly, vol. xlii, p. 773.
[AE] Ibid., vol. xliii, pp. 322, 323.

Thus it appears that Major Powell has made no such statement, at least
in public, as Mr. McGee attributes to him. It should be said, also, that Major
Powell’s memory is very much at fault when he affirms that there is a close
resemblance between this figurine and some of the children’s playthings
among the Pocatello Indians. On the contrary, it would have been even
more of a surprise to find it in the hands of these children than to find it
among the prehistoric deposits on the Pacific coast.
To most well-informed people it is sufficient to know that no less high
authorities than Mr. Charles Francis Adams and Mr. G. M. Gumming,
General Manager for the Union Pacific line for that district, carefully
investigated the evidence at the time of the discovery, and, knowing the
parties, were entirely satisfied with its sufficiency. It was also subjected to
careful examination by Professor F. W. Putnam, who discerned, in a deposit
of an oxide of iron on various parts of the image, indubitable evidence that
it was a relic which had lain for a long time in some such condition as was
assigned to it in the bottom of the well—all of which is detailed in the
papers referred to below, on page 297.
Finally, the discovery, both in its character and conditions, is in so many
respects analogous to those made under Table Mountain, near Sonora, Cal.
(described on pages 294-297), that the evidence of one locality adds
cumulative force to that of the other. The strata underneath the lava in
which these objects were found are all indirectly, but pretty certainly,
connected with the Glacial period.[AF] No student of glacial archæology,
therefore, can hereafter afford to disregard these facts from the Pacific
coast.
[AF] See below, p. 349.

Oberlin, Ohio, June 2, 1894.

PREFACE TO THE FIRST EDITION.
The wide interest manifested in my treatise upon The Ice Age in North
America and its Bearing upon the Antiquity of Man (of which a third
edition was issued a year ago), seemed to indicate the desirability of
providing for the public a smaller volume discussing the broader question
of man’s entire relation to the Glacial period in Europe as well as in
America. When the demand for such a volume became evident, I set about
preparing for the task by spending, first, a season in special study of the
lava-beds of the Pacific coast, whose relations to the Glacial period and to
man’s antiquity are of such great interest; and, secondly, a summer in
Europe, to enable me to compare the facts bearing upon the subject on both
continents.
Of course, the chapters of the present volume relating to America cover
much of the same ground gone over in the previous treatise; but the matter
has been entirely rewritten and very much condensed, so as to give due
proportions to all parts of the subject. It will interest some to know that
most of the new material in this volume was first wrought over in my
second course of Lowell Institute Lectures, given in Boston during the
month of March last.
I am under great obligations to Mr. Charles Francis Adams for his aid in
prosecuting investigations upon the Pacific coast of America; and also to
Dr. H. W. Crosskey, of Birmingham, England, and to Mr. G. W. Lamplugh,
of Bridlington, as well as to Mr. C. E. De Rance and Mr. Clement Reid, of
the British Geological Survey, besides many others in England who have
facilitated my investigations; but pre-eminently to Prof. Percy F. Kendall, of
Stockport, who consented to prepare for me the portion of Chapter VI
which relates to the glacial phenomena of the British Isles. I have no doubt
of the general correctness of the views maintained by him, and little doubt,
also, that his clear and forcible presentation of the facts will bring about
what is scarcely less than a revolution in the views generally prevalent
relating to the subject of which he treats.

For the glacial facts relating to France and Switzerland I am indebted
largely to M. Falsan’s valuable compendium, La Période Glaciaire.
It goes without saying, also, that I am under the deepest obligation to
the works of Prof. James Geikie upon The Great Ice Age and upon
Prehistoric Europe, and to the remarkable volume of the late Mr. James
Croll upon Climate and Time, as well as to the recent comprehensive
geological treatises of Sir Archibald Geikie and Prof. Prestwich. Finally, I
would express my gratitude for the great courtesy of Prof. Fraipont, of
Liége, in assisting me to an appreciation of the facts relating to the late
remarkable discovery of two entire skeletons of Paleolithic man in the
grotto of Spy.
Comparative completeness is also given to the volume by the appendix
on the question of man’s existence during the Tertiary period, prepared by
the competent hand of Prof. Henry W. Haynes, of Boston.
I trust this brief treatise will be useful not only in interesting the general
public, but in giving a clear view of the present state of progress in one
department of the inquiries concerning man’s antiquity. If the conclusions
reached are not as positive as could be wished, still it is both desirable and
important to see what degree of indefiniteness rests upon the subject, in
order that rash speculations may be avoided and future investigations
directed in profitable lines.
G. Frederick Wright.

Oberlin, Ohio, May 1, 1892.

CONTENTS.
PAGES

CHAPTER I.
Introductory 1-8
CHAPTER II.
Existing Glaciers 9-42

In Europe; in Asia; in Oceanica; in South America; on the
Antarctic Continent; in North America.
CHAPTER III.
Glacial Motion 43-50
CHAPTER IV.
Signs of Past Glaciation 51-65
CHAPTER V.
66-
Ancient Glaciers in the Western Hemisphere
128
New England; New York, New Jersey, and Pennsylvania; the
Mississippi Basin; west of the Rocky Mountains.
CHAPTER VI.
129-
Ancient Glaciers in the Eastern Hemisphere
192
Central and Southern Europe; the British Isles—the Preglacial
Level of the Land, the Great Glacial Centres, the Confluent
Glaciers, the East Anglian Glacier, the so-called Great
Submergence; Northern Europe; Asia; Africa.
CHAPTER VII.
193-
Drainage Systems in the Glacial Period
241
In America—Preglacial Erosion, Buried Outlets and Channels,
Ice-dams, Ancient River Terraces; in Europe.
CHAPTER VIII.
242-
Relics of Man in the Glacial Period
301
In Glacial Terraces of the United States; in Glacial Terraces of
Europe; in Cave Deposits in the British Isles; in Cave Deposits
on the Continent; Extinct Animals associated with Man; Earliest
Man on the Pacific Coast of North America.
CHAPTER IX.

302-
The Cause of the Glacial Period
331
CHAPTER X.
332-
The Date of the Glacial Period
364
365-
Appendix on the Tertiary Man
374
375-
Index
385

LIST OF ILLUSTRATIONS.
FIG. PAGE
1. Zermatt Glacier 2
2. Formation of veined structure 3
3, 4. Formation of marginal fissures and veins 4
5. Fissures and seracs 4
6. Section across glacial valley, showing old lateral moraines 5
7. Mont Blanc glacier region 10
8. Svartisen Glacier 13
9. Floating berg 18
10. Iceberg in the Antarctic Ocean 20
11. Map of southeastern Alaska 22
12. Map of Glacier Bay, Alaska 25
13. Front of Muir Glacier 26
14. Map of glaciers in the St. Elias Alps 31
15. Map of Greenland 33
16. Diagram showing the character of glacial motion 43
17. Line of most rapid glacial motion 45
18. Diagram showing retardation of the bottom of a glacier 46
19. Bed-rock scored with glacial marks 52
20. Scratched stone from the till of Boston 54

21. Typical section of till in Seattle, Wash. 55
22. Ideal section showing how the till overlies the stratified rocks 56
23. Vessel Rock, a glacial boulder 56
24. Map of Rhône Glacier 58
25. Conglomerate boulder found in Boone County, Ky. 63
26. Mohegan Rock 72
27. Drumlins in Goffstown, N. H. 73
28. Map of drumlins in the vicinity of Boston 75
29. Section of kame 77
30. Map of kames in Andover, Mass. 78
31. Longitudinal kames near Hingham, Mass. 79
Map showing the kames of Maine and southeastern New
32. 81
Hampshire
33. Western face of the Kettle Moraine near Eagle, Wis. 99
34. Section of the east-and-west glacial furrows on Kelly’s Island 103
35. Same as the preceding 105
36. Section of till near Germantown, Ohio 108
37. Moraines of Grape Creek, Col. 123
38. Map of North America in the Ice period 127
39. Quartzite boulder on Mont Lachat 128
40. Map showing glaciated areas in North America and Europe 130
Maps showing lines of débris extending from the Alps into the
41. 134
plains of the Po
42. Section of the Cefn Cave 148
43. Map showing moraine between Speeton and Flamborough 156
44. Diagram-section near Cromer 166
45. Section through the westerly chalk bluff at Trimingham, Norfolk 162
46. Section across Wales 172
47. Section of cliff at Flamborough Head 176
Enlarged section of the shelly sand and surrounding clay at B in
48. 177
preceding figure
49. Map showing the glaciated area of Europe 184
50. Map showing old channel and mouth of the Hudson 195
51. New York Harbor in preglacial times 197

52. Section across the valley of the Cuyahoga River 200
53. Map of Mississippi River from Fort Snelling to Minneapolis 209
54. Map showing the effect of the glacial dam at Cincinnati 213
55. Map of Lake Erie-Ontario 219
56. Map of Cuyahoga Lake 221
57. Section of the lake ridges near Sandusky, Ohio 223
58. Map showing stages of recession of the ice in Minnesota 225
59. Glacial terrace on Raccoon Creek, in Ohio 227
60. Ideal section across a river-bed in drift region 229
61. Map of Lakes Bonneville and Lahontan 234
62. Parallel roads of Glen Roy 239
Map showing glacial terraces on the Delaware and Schuylkill
63. 243
Rivers
64. Palæolith found by Abbott in New Jersey 244
65. Section across the Delaware River at Trenton, N. J. 245
66. Section of the Trenton gravel 246
Face view of argillite implement found by Dr. C. C. Abbott in
67. 247
1876.
68. Argillite implement found by Dr. C. C. Abbott, March, 1879 248
Chipped pebble of black chert found by Dr. C. L. Metz, October,
69. 249
1885
70. Map showing glaciated area in Ohio 250
71. Palæoliths from Newcomerstown and Amiens (face view) 252
72. Edge view of the preceding 253
73. Section across the Mississippi Valley at Little Falls, Minn. 254
Quartz implement found by Miss F. E. Babbitt, 1878, at Little
74. 255
Falls, Minn
75. Argillite implement found by H. T. Cresson, 1887 259
76. General view of Baltimore and Ohio Railroad cut, Claymont, Del. 260
77. Section across valley of the Somme 262
78. Mouth of Kent’s Hole 268
79. Engis skull (reduced) 274
80. Comparison of forms of skulls 276
81. Skull of the Man of Spy 277

82. Tooth of Machairodus neogæus 281
83. Perfect tooth of an Elephas 281
84. Skull of Hyena spelæa 282
85. Celebrated skeleton of mammoth in St. Petersburg Museum 283
86. Molar tooth of mammoth 284
87. Tooth of Mastodon Americanus 284
88. Skeleton of Mastodon Americanus 286
89. Skeleton of Rhinoceros tichorhinus 287
90. Skull of cave-bear 287
91. Skeleton of the Irish elk 288
92. Musk-sheep 289
93. Reindeer 290
94. Section across Table Mountain, Tuolumne County, Cal. 294
95. Calaveras skull 295
96. Three views of Nampa image, drawn to scale 298
97. Map showing Pocatello, Nampa, and the valley of Snake River 299
98. Section across the channel of the Stanislaus River 300
99. Diagram showing effect of precession 308
100. Map showing course of currents in the Atlantic Ocean 314
101. Map showing how the land clusters about the north pole 319
Diagram showing oscillations of land-surface and ice-surface
102. 323
during the Glacial epoch
103. Diagram of eccentricity and precession 333
104. Map of the Niagara River below the Falls 334
105. Section of strata along the Niagara Gorge 336
106. Map showing the recession of the Horseshoe Falls since 1842 338
107. Section of kettle-hole near Pomp’s Pond, Andover, Mass. 345
108. Flint-flakes collected by Abbé Bourgeois 368

MAPS.
TO FACE PAGE
Contour and glacial map of the British Isles Frontispiece.
Map showing the glacial geology of the United States 66

Map of glacial movements in France and Switzerland 132

MAN AND THE GLACIAL
PERIOD.

CHAPTER I.

INTRODUCTORY.
That glaciers now exist in the Alps, in the Scandinavian range, in
Iceland, in the Himalayas, in New Zealand, in Patagonia, and in the
mountains of Washington, British Columbia, and southeastern Alaska, and
that a vast ice-sheet envelops Greenland and the Antarctic Continent, are
statements which can be verified by any one who will take the trouble to
visit those regions. That, at a comparatively recent date, these glaciers
extended far beyond their present limits, and that others existed upon the
highlands of Scotland and British America, and at one time covered a large
part of the British Isles, the whole of British America, and a considerable

area in the northern part of the United States, are inferences drawn from
phenomena which are open to every one’s observations. That man was in
existence and occupied both Europe and America during this great
expansion of the northern glaciers is proved by evidence which is now
beyond dispute. It is the object of the present volume to make a concise
presentation of the facts which have been rapidly accumulating during the
past few years relating to the Glacial period and to its connection with
human history.
Before speaking of the number and present extent of existing glaciers, it
will be profitable, however, to devote a little attention to the definition of
terms.

Fig. 1.—Zermatt Glacier (Agassiz).

A glacier is a mass of ice so situated and of such size as to have motion
in itself. The conditions determining the character and rate of this motion
will come up for statement and discussion later. It is sufficient here to say
that ice has a capacity of movement similar to that possessed by such plastic
substances as cold molasses, wax, tar, or cooling lava.
The limit of a glacier’s motion is determined by the forces which fix the
point at which its final melting takes place. This will therefore depend upon

both the warmth of the weather and upon the amount of ice. If the ice is
abundant, it will move farther into the region of warm temperature than it
will if it is limited in supply.
Upon ascending a glacier far enough, one reaches a comparatively
motionless part corresponding to the lake out of which a river often flows.
Technically this is called the névé.
Glacial ice is formed from snow where the annual fall is in excess of
the melting power of the sun at that point. Through the influence of
pressure, such as a boy applies to a snow-ball (but which in the névé-field
arises from the weight of the accumulating mass), the lower strata of the
névé are gradually transformed into ice. This process, is also assisted by the
moisture which percolates through the snowy mass, and which is furnished
both by the melting of the surface snow and by occasional rains.
The division between the névé and the glacier proper is not always
easily determined. The beginnings of the glacial movement—that is, of the
movement of the ice-stream flowing out of the névé-field—are somewhat
like the beginnings of the movement of the water from a great lake into its
outlet. The névé is the reservoir from which the glacier gets both its supply
of ice and the impulse which gives it its first movement. There can not be a
glacier without a névé-field, as there can not be a river without a drainage
basin. But there may be a névé-field without a glacier—that is, a basin may
be partially filled with snow which never melts completely away, while the
equilibrium of forces is such that the ice barely reaches to the outlet from
which the tongue-like projection (to which the name glacier would be
applied) fails to emerge only because of the lack of material.
A glacier is characterised by both veins and
fissures. The veins give it a banded or stratified
appearance, blue alternating with lighter-coloured
portions of ice. As these bands are not arranged with
any apparent uniformity in the glacier, their
explanation has given rise to much discussion.
Sometimes the veins are horizontal, sometimes
Fig. 2.—Illustrates the vertical, and at other times at an angle with the line of
formation of veined motion. On close investigation, however, it is found
structure by pressure at

the junction of two that the veins are always at right angles to the line of
branches.
greatest pressure. This leads to the conclusion that
pressure is the cause of the banded structure. The blue
strata in the ice are those from which the particles of air have been expelled
by pressure; the lighter portions are those in which the particles are less
thoroughly compacted. Snow is but pulverized ice, and differs in colour
from the compact mass for the same reason that almost all rocks and
minerals change their colour when ground into a powder.
The fissures, which, when of large size,
are called crevasses, are formed in those
portions of a glacier where, from some cause,
the ice is subjected to slight tension. This
occurs especially where, through
irregularities in the bottom, the slope of the
descent is increased. The ice, then, instead of
Figs. 3, 4.—Illustrate the formation
of marginal fissures and veins. moving in a continuous stream at the top,
cracks open along the line of tension, and
wedge-shaped fissures are formed
extending from the top down to a
greater or less distance, according to
the degree of tension. Usually,
however, the ice remains continuous
in the lower strata, and when the slope
is diminished the pressure reunites the
Fig. 5.—c, c, show fissures and seracs where faces of the fissure, and the surface
the glacier moves down the steeper portion of becomes again comparatively smooth.
its incline; s, s, show the vertical structure
produced by pressure on the gentler slopes. Where there are extensive areas of
tension, the surface of the ice
sometimes becomes exceedingly
broken, presenting a tangled mass of towers, domes, and pinnacles of ice
called seracs.
Like running water, moving ice is a powerful agent in transporting
rocks and earthy débris of all grades of fineness; but, owing to the different
consistencies of ice and water, there are great differences in the mode and
result of transportation by them. While water can hold in suspension only
the very finest material, ice can bear upon its surface rocks of the greatest

magnitude, and can roll or shove along
under it boulders and pebbles which would
be Unaffected except by torrential currents
of water. We find, therefore, a great
amount of earthy material of all sizes upon
the top of a glacier, which has reached it
very much as débris reaches the bed of a Fig. 6.—Section across Glacial Valley,
river, namely, by falling down upon it from showing old Lateral Moraines.
overhanging cliffs, or by land-slides of
greater or less extent. Such material
coming into a river would either disappear beneath its surface, or would
form a line of débris along the banks; in both cases awaiting the gradual
erosion and transportation which running water is able to effect. But, in case
of a glacier, the material rests upon the surface of the ice, and at once begins
to partake of its motion, while successive accessions of material keep up the
supply at any one point, so as to form a train of boulders and other débris,
extending below the point as far as the glacial motion continues.
Such a line of débris is called a moraine. When it forms along the edge
of the ice, it is called a lateral moraine. It is easy to see that, where glaciers
come out from two valleys which are tributary to a larger valley, their inner
sides must coalesce below the separating promontory, and the two lateral
moraines will become united and will move onward in the middle of the
surface of the glacier. Such lines of débris are called medial moraines.
These are characteristic of all extensive glaciers formed by the union of
tributaries. There is no limit to the number of medial moraines, except in
the number of tributaries.
A medial moraine, when of sufficient thickness, protects the ice
underneath it from melting; so that the moraine will often appear to be
much larger than it really is: what seems to be a ridge of earthy material
being in reality a long ridge of ice, thinly covered with earthy débris,
sliding down the slanting sides as the ice slowly wastes away Large blocks
of stone in the same manner protect the ice from melting underneath, and
are found standing on pedestals of ice, often several feet in height. An
interesting feature of these blocks is that, when the pedestal fails, the block
uniformly falls towards the sun, since that is the side on which the melting
has proceeded most rapidly.

If the meteorological forces are so balanced that the foot of a glacier
remains at the same place for any great length of time, there must be a great
accumulation of earthy débris at the stationary point, since the motion of
the ice is constantly bearing its lines of lateral and medial moraine
downwards to be deposited, year by year, at the melting line along the front.
Such accumulations are called terminal moraines, and the process of
their formation may be seen at the foot of almost any large glacier. The pile
of material thus confusedly heaped up in front of some of the larger glaciers
of the world is enormous.
The melting away of the lower part of a glacier gives rise also to several
other characteristic phenomena. Where the foot of a glacier chances to be
on comparatively level land, the terminal moraine often covers a great
extent of ice, and protects it from melting for an indefinite period of time.
When the ice finally melts away and removes the support from the
overlying morainic débris, this settles down in a very irregular manner,
leaving enclosed depressions to which there is no natural outlet. These
depressions, from their resemblance to a familiar domestic utensil, are
technically known as kettle-holes. The terminal moraines of ancient glaciers
may often be traced by the relative abundance of these kettle-holes.
The streams of water arising both from the rainfall and from the melting
of the ice also produce a peculiar effect about the foot of an extensive
glacier. Sometimes these streams cut long, open channels near the end of
the glacier, and sweep into it vast quantities of morainic material, which is
pushed along by the torrential current, and, after being abraded, rolled, and
sorted, is deposited in a delta about its mouth, or left stranded in long lines
between the ice-walls which have determined its course. At other times the
stream has disappeared far back in the glacier, and plunged into a crevasse
(technically called a moulin), whence it flows onwards as a subglacial
stream. But in this case the deposits might closely resemble those of the
previous description. In both cases, when the ice has finally melted away,
peculiar ridge-like deposits of sorted material remain, to mark the
temporary line of drainage. These exist abundantly in most regions which
have been covered with glacial ice, and are referred to in Scotland as kames,
in Ireland as eskers, and in Sweden as osars. In this volume we shall call

them kames, and the deltas spread out in front of them will be referred to as
kame-plains.
With this preliminary description of glacial phenomena, we will proceed
to give, first, a brief enumeration and description of the ice-fields which are
still existing in the world; second, the evidences of the former existence of
far more extensive ice-fields; and, third, the relation of the Glacial period to
some of the vicissitudes which have attended the life of man in the world.
The geological period of which we shall treat is variously designated by
different writers. By some it is simply called the “post-Tertiary,” or
“Quaternary”; by others the term “post-Pliocene” is used, to indicate more
sharply its distinction from the latter portion of the Tertiary period; by
others this nicety of distinction is expressed by the term “Pleistocene.” But,
since the whole epoch was peculiarly characterised by the presence of
glaciers, which have not even yet wholly disappeared, we may properly
refer to it altogether under the descriptive name of “Glacial” period.

CHAPTER II.

EXISTING GLACIERS.
In Europe.—Our specific account of existing glaciers naturally begins
with those of the Alps, where Hugi, Charpentier, Agassiz, Forbes, and
Guyot, before the middle of this century, first brought clearly to light the
reality and nature of glacial motion.
According to Professor Heim, of Zürich, the total area covered by the
glaciers and ice-fields of the Alps is upwards of three thousand square
kilometres (about eleven hundred square miles). The Swiss Alps alone
contain nearly two-thirds of this area. Professor Heim enumerates 1,155
distinct glaciers in the region. Of these, 144 are in France, 78 in Italy, 471 in
Switzerland, and 462 in Austria.

Desor describes fourteen principal glacial districts in the Alps, the
westernmost of which is that of Mont Pelvoux, in Dauphiny, and the
easternmost that in the vicinity of the Gross Glockner, in Carinthia. The
most important of the Alpine systems are those which are grouped around
Mont Blanc, Monte Rosa, and the Finsteraarhorn, the two former peaks
being upwards of fifteen thousand feet in height, and the latter upwards of
fourteen thousand. The area covered by glaciers and snow-fields in the
Bernese Oberland, of which Finsteraarhorn is the culminating point, is
about three hundred and fifty square kilometres (a hundred square miles),
and contains the Aletsch Glacier, which is the longest in Europe, extending
twenty-one kilometres (about fourteen miles) from the névé-field to its foot.
The Mer de Glace, which descends from Mont Blanc to the valley of
Chamounix, has a length of about eight miles below the névé-field. In all,
there are estimated to be twenty-four glaciers in the Alps which are upwards
of four miles long, and six which are upwards of eight miles in length. The
principal of these are the Mer de Glace, of Chamounix, on Mont Blanc; the
Gorner Glacier, near Zermatt, on Monte Rosa; the lower glacier of the Aar,
in the Bernese Oberland; and the Aletsch Glacier and Glacier of the Rhône,
in Vallais; and the Pasterzen, in Carinthia.

Fig. 7.—Mount Blanc Glacier Region: m, Mer de Glace; g, Du Géant; l, Leschaux; t, Taléfre; B,
Bionassay; b, Bosson.

These glaciers adjust themselves to the width of the valleys down which
they flow, in some places being a mile or more in width, and at others
contracting into much narrower compass. The greatest depth which Agassiz
was able directly to measure in the Aar Glacier was two hundred and sixty
metres (five hundred and twenty-eight feet), but at another point the depth
was estimated by him to be four hundred and sixty metres (or fifteen
hundred and eighty-four feet).
The glaciers of the Alps are mostly confined to the northern side and to
the higher portions of the mountain-chain, none of them descending below
the level of four thousand feet, and all of them varying slightly in extent,
from year to year, according as there are changes in the temperature and in
the amount of snow-fall.
The Pyrenees, also, still maintain a glacial system, but it is of
insignificant importance. This is partly because the altitude is much less
than that of the Alps, the culminating point being scarcely more than eleven
thousand feet in height. Doubtless, also, it is partly due to the narrowness of
the range, which does not provide gathering-places for the snow sufficiently
extensive to produce large glaciers. The snow-fall also is less upon the
Pyrenees than upon the Alps. As a consequence of all these conditions, the
glaciers of the Pyrenees are scarcely more than stationary névé-fields
lingering upon the north side of the range. The largest of these is near
Bagnères de Luchon, and sends down a short, river-like glacier.
In Scandinavia the height of the mountains is also much less than that of
the Alps, but the moister climate and the more northern latitude favours the
growth of glaciers at a much lower level North of the sixty-second degree
of latitude, the plateaus over five thousand feet above the sea pretty
generally are gathering-places for glaciers. From the Justedal a snow-field,
covering five hundred and eighty square miles, in latitude 62°, twenty-four
glaciers push outwards towards the German Sea, the largest of which is five
miles long and three-quarters of a mile wide. The Fondalen snow-field,
between latitudes 66° and 67°, covers an area about equal to that of the
Justedal; but, on account of its more northern position, its glaciers descend
through the valleys quite to the ocean-level. The Folgofon snow-field is still

farther south, but, though occupying an area of only one hundred square
miles, it sends down as many as three glaciers to the sea-level. The total
area of the Scandinavian snow-fields is about five thousand square miles.
In Sweden Dr. Svenonius estimates that there are, between latitudes 67°
1
and 682°, twenty distinct groups of glaciers, covering an area of four
hundred square kilometres (one hundred and forty-four square miles), and
he numbers upwards of one hundred distinct glaciers of small size.
As is to be expected, the large islands in the Polar Sea north of Europe
and Asia are, to a great extent, covered with névé-fields, and numerous
glaciers push out from them to the sea in all directions, discharging their
surplus ice as bergs, which float away and cumber the waters with their
presence in many distant places.

Fig. 8.—The Svartisen Glacier on the west coast of Norway,
just within the Arctic circle, at the head of a fiord ten miles
from the ocean. The foot of the Glacier is one mile wide, and a
quarter of a mile back from the water. Terminal moraine in
front. (Photographed by Dr. L. C. Warner.)

The island of Spitzbergen, in latitude 76° to 81°, is favourably situated
for the production of glaciers, by reason both of its high northern latitude,
and of its relation to the Gulf Stream, which conveys around to it an
excessive amount of moisture, thus ensuring an exceptionally large snow-

fall over the island. The mountainous character of the island also favours
the concentration of the ice-movement into glaciers of vast size and power.
Still, even here, much of the land is free from snow and ice in summer. But
upon the northern portion of the island there is an extensive table-land,
upwards of two thousand feet above the sea, over which the ice-field is
continuous. Four great glaciers here descend to tide-water in Magdalena
Bay. The largest of these presents at the front a wall of ice seven thousand
feet across and three hundred feet high; but, as the depth of the water is not
great, few icebergs of large size break off and float away from it.
Nova Zembla, though not in quite so high latitude, has a lower mean
temperature upon the coasts than Spitzbergen. Owing to the absence of high
lands and mountains, however, it is not covered with perpetual snow, much
less with glacial ice, but its level portions are “carpeted with grasses and
flowers,” and sustain extensive forests of stunted trees.
Franz-Josef Land, to the north of Nova Zembla, both contains high
mountains and supports glaciers of great size. Mr. Payer conducted a sledge
party into this land in 1874, and reported that a precipitous wall of glacial
ice, “of more than a hundred feet in height, formed the usual edge of the
coast.” But the motion of the ice is very slow, and the ice coarse-grained in
structure, and it bears a small amount only of morainic material. So low is
here the line of perpetual snow, that the smaller islands “are covered with
caps of ice, so that a cross-section would exhibit a regular flat segment of
ice.” It is interesting to note, also, that “many ice-streams, descending from
the high névé plateau, spread themselves out over the mountain-slopes,”
and are not, as in the Alps, confined to definite valleys.
Iceland seems to have been properly named, since a single one of the
snow-fields—that of Vatnajoküll, with an extreme elevation of only six
thousand feet—is estimated by Helland to cover one hundred and fifty
Norwegian square miles (about seven thousand English square miles),
while five other ice-fields (the Langjoküll, the Hofsjoküll, the
Myrdalsjoküll, the Drangajoküll, and the Glamujoküll) have a combined
area of ninety-two Norwegian or about four thousand five hundred English
square miles. The glaciers are supposed by Whitney to have been rapidly
advancing for some time past.

In Asia.—Notwithstanding its lofty mountains and its great extent of
territory lying in high latitudes, glaciers are for two reasons relatively
infrequent: 1. The land in the more northern latitudes is low. 2. The dryness
of the atmosphere in the interior of the continent is such that it unduly limits
the snow-fall. Long before they reach the central plateau of Asia, the
currents of air which sweep over the continent from the Indian Ocean have
parted with their burdens of moisture, having left them in a snowy mantle
upon the southern flanks of the Himalayas. As a result, we have the
extensive deserts of the interior, where, on account of the clear atmosphere,
there is not snow enough to resist continuously the intense activity of the
unobstructed rays of the sun.
In spite of their high latitude and considerable elevation above the sea-
level, glaciers are absent from the Ural Mountains, for the range is too
narrow to afford névé-fields of sufficient size to produce glaciers of large
extent.
The Caucasus Mountains present more favourable conditions, and for a
distance of one hundred and twenty miles near their central portion have an
average height of 12,000 feet, with individual peaks rising to a height of
16,000 feet or more; but, owing to their low latitude, the line of perpetual
snow scarcely reaches down to the 11,000-foot level. So great are the snow-
fields, however, above this height that many glaciers push their way down
through the narrow mountain-gorges as far as the 6,000-foot level.
The Himalaya Mountains present many favourable conditions for the
development of glaciers of large size. The range is of great extent and
height, thus affording ample gathering-places for the snows, while the
relation of the mountains to the moisture-laden winds from the Indian
Ocean is such that they enjoy the first harvest of the clouds where the
interior of Asia gets only the gleanings. As is to be expected, therefore, all
the great rivers which course through the plains of Hindustan have their rise
in large glaciers far up towards the summits of the northern mountains. The
Indus and the Ganges are both glacial streams in their origin, as are their
larger tributary branches—the Basha, the Shigar, and the Sutlej. Many of
the glaciers in the higher levels of the Himalaya Mountains where these
streams rise have a length of from twenty-five to forty miles, and some of
them are as much as a mile and a half in width and extend for a long

distance, with an inclination as small as one degree and a half or one
hundred and thirty-eight feet to a mile.
In the Mustagh range of the western Himalayas there are two adjoining
glaciers whose united length is sixty-five miles, and another not far away
which is twenty-one miles long and from one to two miles wide in its upper
portion. Its lower portion terminates at an altitude of 16,000 feet above tide,
where it is three miles wide and two hundred and fifty feet thick.
Oceanica.—-Passing eastward to the islands of the Pacific Ocean, New
Zealand is the only one capable of supporting glaciers. Their existence on
this island seems the more remarkable because of its low latitude (42° to
45°); but a grand range of mountains rises abruptly from the water on the
western coast of the southern island, culminating in Mount Cook, 13,000
feet above the sea, and extending for a distance of about one hundred miles.
The extent and height of this chain, coupled with the moisture of the winds,
which sweep without obstruction over so many leagues of the tropical
Pacific, are specially favourable to the production of ice-fields of great
extent. Consequently we find glaciers in abundance, some of which are not
inferior in extent to the larger ones of the Alps. The Tasman Glacier,
described by Haas, is ten miles long and nearly two miles broad at its
termination, “the lower portion for a distance of three miles being covered
with morainic detritus.” The Mueller Glacier is about seven miles long and
one mile broad in its lower portion.
South America.—In America, existing glaciers are chiefly confined to
three principal centres, namely, to the Andes, south of the equator; to the
Cordilleras, north of central California; and to Greenland.
In South America, however, the high mountains of Ecuador sustain a
few glaciers above the twelve-thousand-foot level. The largest of these are
upon the eastern slope of the mountains, giving rise to some of the branches
of the Amazon—indeed, on the flanks of Cotopaxi, Chimborazo, and
Illinissa there are some glaciers in close proximity to the equator which are
fairly comparable in size to those of the Alps.
In Chili, at about latitude 35°, glaciers begin to appear at lower levels,
descending beyond the six-thousand-foot line, while south of this both the
increasing moisture of the winds and the decreasing average temperature

favour the increase of ice-fields and glaciers. Consequently, as Darwin long
ago observed, the line of perpetual snow here descends to an increasingly
lower level, and glaciers extend down farther and farther towards the sea,
until, in Tierra del Fuego, at about latitude 45°, they begin to discharge their
frozen contents directly into the tidal inlets. Darwin’s party surveyed a
glacier entering the Gulf of Penas in latitude 46° 50’, which was fifteen
miles long, and, in one part, seven broad. At Eyre’s Sound, also, in about
latitude 48°, they found immense glaciers coming clown to the sea and
discharging icebergs of great size, one of which, as they encountered it
floating outwards, was estimated to be “at least one hundred and sixty-eight
feet in total height.”
In Tierra del Fuego, where the mountains are only from three thousand
to four thousand feet in height and in latitude less than 55°, Darwin reports
that "every valley is filled with streams of ice descending to the sea-coast,"
and that the inlets penetrated by his party presented miniature likenesses of
the polar sea.

Fig. 9.—Floating berg, showing the
proportions above and under the water. About
seven feet under water to one above.

Antarctic Continent.—Of the so-called Antarctic Continent little is
known; but icebergs of great size are frequently encountered up to 58°
south latitude, in the direction of Cape Horn, and as far as latitude 33° in the

direction of Cape of Good Hope. Nearly all that is known about this
continent was discovered by Sir J. C. Ross during the period extending
from 1839 to 1843, when, between the parallels of 70° and 78° south
latitude, he encountered in his explorations a precipitous mountain coast,
rising from seven thousand to ten thousand feet above tide. Through the
valleys intervening between the mountain-ranges huge glaciers descended,
and “projected in many places several miles into the sea and terminated in
lofty, perpendicular cliffs. In a few places the rocks broke through their icy
covering, by which alone we could be assured that land formed the nucleus
of this, to appearance, enormous iceberg.”[AG]
[AG] Quoted by Whitney in Climatic Changes, p. 314.

Again, speaking of the region in the vicinity of the lofty volcanoes
Terror and Erebus, between ten thousand and twelve thousand feet high, the
same navigator says:
“We perceived a low, white line extending from its extreme eastern
point, as far as the eye could discern, to the eastward. It presented an
extraordinary appearance, gradually increasing in height as we got nearer to
it, and proving at length to be a perpendicular cliff of ice, between one
hundred and fifty and two hundred feet above the level of the sea, perfectly
flat and level at the top, and without any fissures or promontories on its
even, seaward face. What was beyond it we could not imagine; for, being
much higher than our mast-head, we could not see anything except the
summit of a lofty range of mountains extending to the southward as far as
the seventy-ninth degree of latitude. These mountains, being the
southernmost land hitherto discovered, I felt great satisfaction in naming
after Sir Edward Parry.... Whether Parry Mountains again take an easterly
trending and form the base to which this extraordinary mass of ice is
attached, must be left for future navigators to determine. If there be land to
the southward it must be very remote, or of much less elevation than any
other part of the coast we have seen, or it would have appeared above the
barrier.”
This ice-cliff or barrier was followed by Captain Ross as far as 198°
west longitude, and found to preserve very much the same character during
the whole of that distance. On the lithographic view of this great ice-sheet
given in Ross’s work it is described as “part of the South Polar Barrier, one

hundred and eighty feet above the sea-level, one thousand feet thick, and
four hundred and fifty miles in length.”
A similar vertical wall of ice was seen by D’Urville, off the coast of
Adelie Land. He thus describes it: “Its appearance was astonishing. We
perceived a cliff having a uniform elevation of from one hundred to one
hundred and fifty feet, forming a long line extending off to the west.... Thus
for more than twelve hours we had followed this wall of ice, and found its
sides everywhere perfectly vertical and its summit horizontal. Not the
smallest irregularity, not the most inconsiderable elevation, broke its
uniformity for the twenty leagues of distance which we followed it during
the day, although we passed it occasionally at a distance of only two or
three miles, so that we could make out with ease its smallest irregularities.
Some large pieces of ice were lying along the side of this frozen coast; but,
on the whole, there was open sea in the offing.” [AH]
[AH] Whitney’s Climatic Changes, pp. 315, 316.

Fig. 10.—Iceberg in the Antarctic Ocean.

North America.—In North America living glaciers begin to appear in
the Sierra Nevada Mountains, in the vicinity of the Yosemite Park, in
central California. Here the conditions necessary for the production of
glaciers are favourable, namely, a high altitude, snow-fields of considerable
extent, and unobstructed exposure to the moisture-laden currents of air from
the Pacific Ocean. Sixteen glaciers of small size have been noted among the
summits to the east of the Yosemite; but none of them descend much below
the eleven-thousand-foot line, and none of them are over a mile in length.

Indeed, they are so small, and their motion is so slight, that it is a question
whether or not they are to be classed with true glaciers.
Owing to the comparatively low elevation of the Sierra Nevada north of
Tuolumne County, California, no other living glaciers are found until
reaching Mount Shasta, in the extreme northern part of the State. This is a
volcanic peak, rising fourteen thousand five hundred feet above the sea, and
having no peaks within forty miles of it as high as ten thousand feet; yet so
abundant is the snow-fall that as many as five glaciers are found upon its
northern side, some of them being as much as three miles long and
extending as low down as the eight-thousand-foot level. Upon the southern
side glaciers are so completely absent that Professor Whitney ascended the
mountain and remained in perfect ignorance of its glacial system. In 1870
Mr. Clarence King first discovered and described them on the northern side.
North of California glaciers characterise the Cascade Range in
increasing numbers all the way to the Alaskan Peninsula. They are to be
found upon Diamond Peak, the Three Sisters, Mount Jefferson, and Mount
Hood, in Oregon, and appear in still larger proportions upon the flanks of
Mount Rainier (or Tacoma) and Mount Baker, in the State of Washington.
The glacier at the head of the White River Valley is upon the north side of
Rainier, and is the largest one upon that mountain, reaching down to within
five thousand feet of the sea-level, and being ten miles or more in length.
All the streams which descend the valleys upon this mountain are charged
with the milky-coloured water which betrays their glacial origin.

Fig. 11.—Map of Southeastern Alaska. The arrow-points mark
glaciers.

In British Columbia, Glacier Station, upon the Canadian Pacific
Railroad, in the Selkirk Mountains, is within half a mile of the handsome
Illicilliwaet Glacier, while others of larger size are found at no great
distance. The interior farther north is unexplored to so great an extent that

little can be definitely said concerning its glacial phenomena. The coast of
British Columbia is penetrated by numerous fiords, each of which receives
the drainage of a decaying glacier; but none are in sight of the tourist-
steamers which thread their way through the intricate network of channels
characterising this coast, until the Alaskan boundary is crossed and the
mouth of the Stickeen River is passed.
A few miles up from the mouth of the Stickeen, however, glaciers of
large size come down to the vicinity of the river, both from the north and
from the south, and the attention of tourists is always attracted by the
abundant glacial sediment borne into the tide-water by the river itself and
discolouring the surface for a long distance beyond the outlet. Northward
from this point the tourist is rarely out of sight of ice-fields. The Auk and
Patterson Glaciers are the first to come into view, but they do not descend to
the water-level. On nearing Holcomb Bay, however, small icebergs begin to
appear, heralding the first of the glaciers which descend beyond the water’s
edge. Taku Inlet, a little farther north, presents glaciers of great size coming
down to the sea-level, while the whole length of Lynn Canal, from Juneau
to Chilkat, a distance of eighty miles, is dotted on both sides by
conspicuous glaciers and ice-fields.
The Davidson Glacier, near the head of the canal, is one of the most
interesting for purposes of study. It comes down from an unknown distance
in the western interior, bearing two marked medial moraines upon its
surface. On nearing tide-level, the valley through which it flows is about
three-quarters of a mile in width; but, after emerging from the confinement
of the valley, the ice spreads out over a fan-shaped area until the width of its
front is nearly three miles. The supply of ice not being sufficient to push the
front of the glacier into deep water, equilibrium between the forces of heat
and cold is established near the water’s edge. Here, as from year to year the
ice melts and deposits its burdens of earthy débris, it has piled up a terminal
moraine which rises from two hundred to three hundred feet in height, and
is now covered with evergreen trees of considerable size. From Chilkat, at
the head of Lynn Canal, to the sources of the Yukon River, the distance is
only thirty-five miles, but the intervening mountain-chain is several
thousand feet in height and bears numerous glaciers upon its seaward side.

About forty miles west of Lynn Canal, and separated from it by a range
of mountains of moderate height, is Glacier Bay, at the head of one of
whose inlets is the Muir Glacier, which forms the chief attraction for the
great number of tourists that now visit the coast of southeastern Alaska
during the summer season. This glacier meets tide-water in latitude 58° 50’,
and longitude 136° 40’ west of Greenwich. It received its name from Mr.
John Muir, who, in company with Rev. Mr. Young, made a tour of the bay
and discovered the glacier in 1879. It was soon found that the bay could be
safely navigated by vessels of large size, and from that time on tourists in
increasing number have been attracted to the region. Commodious steamers
now regularly run close up to the ice-front, and lie-to for several hours, so
that the passengers may witness the “calving” of icebergs, and may climb
upon the sides of the icy stream and look into its deep crevasses and out
upon its corrugated and broken surface.

Fig. 12.—Map of Glacier Bay. Alaska, and its surroundings. Arrow-
points indicate glaciated area.

The first persons who found it in their way to pay more than a tourist’s
visit to this interesting object were Rev. J. L. Patton, Mr. Prentiss Baldwin,
and myself, who spent the entire month of August, 1886, encamped at the
foot of the glacier, conducting such observations upon it as weather and
equipment permitted. From that time till the summer of 1890 no one else
stopped off from the tourist steamers to bestow any special study upon it.
But during this latter season Mr. Muir returned to the scene of his
discovered wonder, and spent some weeks in exploring the interior of the
great ice-field. During the same season, also, Professors H. F. Reid and H.
Cushing, with a well-equipped party of young men, spent two months or
more in the same field, conducting observations and experiments, of
various kinds, relating to the extent, the motion, and the general behaviour
of the vast mass of moving ice.

Fig. 13.—Shows central part of the front of Muir Glacier one
half mile distant. Near the lower left hand corner the ice is
seen one mile distant resting for about one half mile on gravel
which it had overrun. The ice is now retreating in the channel.
(From photograph.)

The main body of the Muir Glacier occupies a vast amphitheatre, with
diameters ranging from thirty to forty miles, and covers an area of about
one thousand square miles. From one of the low mountains near its mouth I
could count twenty-six tributary glaciers which came together and became
confluent in the main stream of ice. Nine medial moraines marked the

continued course of as many main branches, which becoming united formed
the grand trunk of the glacier. Numerous rocky eminences also projected
above the surface of the ice, like islands in the sea, corresponding to what
are called “nunataks” in Greenland. The force of the ice against the upper
side of these rocky prominences is such as to push it in great masses above
the surrounding level, after the analogy of waves which dash themselves
into foam against similar obstructions. In front of the nunataks there is
uniformly a depression, like the eddies which appear in the current below
obstacles in running water.
Over some portions of the surface of the glacier there is a miniature
river system, consisting of a main stream, with numerous tributaries, but all
flowing in channels of deep blue ice. Before reaching the front of the
glacier, however, each one of these plunges down into a crevasse, or
moulin, to swell the larger current, which may be heard rushing along in an
impetuous course hundreds of feet beneath, and far out of sight. The portion
of the glacier in which there is the most rapid motion is characterised by
innumerable crags and domes and pinnacles of ice, projecting above the
general level, whose bases are separated by fissures, extending in many
cases more than a hundred feet below the general level. These irregularities
result from the combined effect of the differential motion (as illustrated in
the diagram on page 4), and the influence of sunshine and warm air in
irregularly melting the unprotected masses. The description given in our
introductory chapter of medial moraines and ice-pillars is amply illustrated
everywhere upon the surface of the Muir Glacier. I measured one block of
stone which was twenty feet square and about the same height, standing on
a pedestal of ice three or four feet high.
The mountains forming the periphery of this amphitheatre rise to a
height of several thousand feet; Mount Fairweather, upon the northwest,
from whose flanks probably a portion of the ice comes, being, in fact, more
than fifteen thousand feet high. The mouth of the amphitheatre is three
miles wide, in a line extending from shoulder to shoulder of the low
mountains which guard it. The actual water-front where the ice meets tide-
water is one mile and a half.[AI] Here the depth of the inlet is so great that
the front of the ice breaks off in icebergs of large size, which float away to
be dissolved at their leisure. At the water’s edge the ice presents a
perpendicular front of from two hundred and fifty to four hundred feet in

height, and the depth of the water in the middle of the inlet immediately in
front of the ice is upwards of seven hundred feet; thus giving a total height
to the precipitous front of a thousand feet.

[AI] These are the measurements of Professor Reid. In my former volume I have given
the dimensions as somewhat smaller.

The formation of icebergs can here be studied to admirable advantage. During the
month in which we encamped in the vicinity the process was going on continuously.
There was scarcely an interval of fifteen minutes during the whole time in which the
air was not rent with the significant boom connected with the “calving” of a berg.
Sometimes this was occasioned by the separation of a comparatively small mass of
ice from near the top of the precipitous wall, which would fall into the water below
with a loud splash. At other times I have seen a column of ice from top to bottom of
the precipice split off and fall over into the water, giving rise to great waves, which
would lash the shore with foam two miles below.
This manner of the production of icebergs differs from that which has been
ordinarily represented in the text-books, but it conforms to the law of glacial motion,
which we will describe a little later, namely, that the upper strata of ice move faster
than the lower. Hence the tendency is constantly to push the upper strata forwards, so
as to produce a perpendicular or even projecting front, after the analogy of the
formation of breakers on the shelving shore of a large body of water.
Evidently, however, these masses of ice which break off from above the water do
not reach the whole distance to the bottom of the glacier below the water; so that a
projecting foot of ice remains extending to an indefinite distance underneath the
surface. But at occasional intervals, as the superincumbent masses of ice above the
surface fall off and relieve the strata below of their weight, these submerged masses
suddenly rise, often shooting up considerably higher than they ultimately remain
when coming to rest. The bergs formed by this latter process often bear much earthy
material upon them, which is carried away with the floating ice, to be deposited
finally wherever the melting chances to take place.
Numerous opportunities are furnished about the front and foot of this vast glacier
to observe the manner of the formation of kames, kettle-holes, and various other
irregular forms into which glacial débris is accustomed to accumulate. Over portions
of the decaying foot of the glacier, which was deeply covered with morainic débris,
the supporting ice is being gradually removed through the influence of subglacial
streams or of abandoned tunnels, which permit the air to exert its melting power
underneath. In some places where old moulins had existed, the supporting ice is
melting away, so that the superincumbent mass of sand, gravel, and boulders is
slowly sliding into a common centre, like grain in a hopper. This must produce a
conical hill, to remain, after the ice has all melted away, a mute witness of the
impressive and complicated forces which have been so long in operation for its
production.

In other places I have witnessed the formation of a long ridge of gravel by the
gradual falling in of the roof of a tunnel which had been occupied by a subglacial
stream, and over which there was deposited a great amount of morainic material. As
the roof gave way, this was constantly falling to the bottom, where, being exempt
from further erosive agencies, it must remain as a gravel ridge or kame.
In other places, still, there were vast masses of ice covering many acres, and
buried beneath a great depth of morainic material which had been swept down upon it
while joined to the main glacier. In the retreat of the ice, however, these masses had
become isolated, and the sand, gravel, and boulders were sliding down the wasting
sides and forming long ridges of débris along the bottom, which, upon the final
melting of the ice, will be left as a complicated network of ridges and knolls of
gravel, enclosing an equally complicated nest of kettle-holes.
Beyond Cross Sound the Pacific coast is bounded for several hundred miles by
the magnificent semicircle of mountains known as the St. Elias Alps, with Mount
Crillon at the south, having an elevation of nearly sixteen thousand feet, and St. Elias
in the centre, rising to a greater height. Everywhere along this coast, as far as the
Alaskan Peninsula, vast glaciers come down from the mountain-sides, and in many
cases their precipitous fronts form the shore-line for many miles at a time. Icy Bay,
just to the south of Mount St, Elias, is fitly named, on account of the extent of the
glaciers emptying into it and the number of icebergs cumbering its waters.
In the summer of 1890 a party, under the lead of Mr. I. C. Russell, of the United
States Geological Survey, made an unsuccessful attempt to scale the heights of
Mount St. Elias; but the information brought back by them concerning the glaciers of
the region amply repaid them for their toil and expense, and consoled them for the
failure of their immediate object.

Fig. 14.—By the courtesy of the National Geographical
Society.

Leaving Yakutat Bay, and following the route indicated upon the accompanying
map, they travelled on glacial ice almost the entire distance to the foot of Mount St.
Elias. The numerous glaciers coming down from the summit of the mountain-ridge
become confluent nearer the shore, and spread out over an area of about a thousand
square miles. This is fitly named the Malaspina Glacier, after the Spanish explorer
who discovered it in 1792.
It is not necessary to add further particulars concerning the results of this
expedition, since they are so similar to those already detailed in connection with the
Muir Glacier. A feature, however, of special interest, pertains to the glacial lakes
which are held in place by the glacial ice at an elevation of thousands of feet above
the sea. One of considerable size is indicated upon the map just south of what was
called Blossom Island, which, however, is not an island, but simply a nunatak, the ice
here surrounding a considerable area of fertile land, which is covered with dense
forests and beautified by a brilliant assemblage of flowering plants. In other places
considerable vegetation was found upon the surface of moraines, which were
probably still in motion with the underlying ice.
Greenland.—The continental proportions of Greenland, and the extent to which
its area is covered by glacial ice, make it by far the most important accessible field
for glacial observations. The total area of Greenland can not be less than five hundred
thousand square miles—equal in extent to the portion of the United States east of the
Mississippi and north of the Ohio. It is now pretty evident that the whole of this area,
except a narrow border about the southern end, is covered by one continuous sheet of

moving ice, pressing outward on every side towards the open water of the
surrounding seas.
For a long time it was the belief of many that a large region in the interior of
Greenland was free from ice, and was perhaps inhabited. It was in part to solve this
problem that Baron Nordenskiöld set out upon his expedition of 1883. Ascending the
ice-sheet from Disco Bay, in latitude 69°, he proceeded eastward for eighteen days
across a continuous ice-field. Rivers were flowing in channels upon the surface like
those cut on land in horizontal strata of shale or sandstone, only that the pure deep
blue of the ice-walls was, by comparison, infinitely more beautiful. These rivers were
not, however, perfectly continuous. After flowing for a distance in channels on the
surface, they, one and all, plunged with deafening roar into some yawning crevasse,
to find their way to the sea through subglacial channels. Numerous lakes with shores
of ice were also encountered.

Fig. 15.—Map of Greenland. The arrow-points mark the margin of the ice-field.

“On bending down the ear to the ice,” says this explorer, “we could hear on every
side a peculiar subterranean hum, proceeding from rivers flowing within the ice; and
occasionally a loud, single report, like that of a cannon, gave notice of the formation
of a new glacier-cleft.... In the afternoon we saw at some distance from us a well-
defined pillar of mist, which, when we approached it, appeared to rise from a
bottomless abyss, into which a mighty glacier-river fell. The vast, roaring water-mass
had bored for itself a vertical hole, probably down to the rock, certainly more than
two thousand feet beneath, on which the glacier rested.”[AJ]

[AJ] Geological Magazine, vol. ix, pp. 393, 399.

At the end of the eighteen days Nordenskiöld found himself about a hundred and
fifty miles from his starting-point, and about five thousand feet above the sea. Here
the party rested, and sent two Eskimos forward on skidor—a kind of long wooden
skate, with which they could move rapidly over the ice, notwithstanding the
numerous small, circular holes which everywhere pitted the surface. These Eskimos
were gone fifty-seven hours, having slept only four hours of the period. It is
estimated that they made about a hundred and fifty miles, and attained an altitude of
six thousand feet. The ice is reported as rising in distinct terraces, and as seemingly
boundless beyond. If this is the case, two hundred miles from Disco Bay, there would
seem little hope of finding in Greenland an interior freed from ice. So we may pretty
confidently speak of that continental body of land as still enveloped in an ice-sheet.
Up to about latitude 75°, however, the continent is fringed by a border of islands,
over which there is no continuous covering of ice. In south Greenland the continuous
ice-sheet is reached about thirty miles back from the shore.
A summary of the results of Greenland exploration was given by Dr. Kink in
1886, from which it appears that since 1876 one thousand miles of the coast-line have
been carefully explored by entering every fiord and attempting to reach the inland
ice. According to this authority—
We are now able to demonstrate that a movement of ice from the central regions
of Greenland to the coast continually goes on, and must be supposed to act upon the
ground over which it is pushed so as to detach and transport fragments of it for such a
distance.... The plainest idea of the ice-formation here in question is given by
comparing it with an inundation.... Only the marginal parts show irregularity; towards
the interior the surface grows more and more level and passes into a plain very
slightly rising in the same direction. It has been proved that, ascending its extreme
verge, where it has spread like a lava-stream over the lower ground in front of it, the
irregularities are chiefly met with up to a height of 2,000 feet, but the distance from
1
the margin in which the height is reached varies much. While under 682° north
1
latitude it took twenty-four miles before this elevation was attained, in 722° the same
height was arrived at in half the distance....
A general movement of the whole mass from the central regions towards the sea
is still continued, but it concentrates its force to comparatively few points in the most
extraordinary degree. These points are represented by the ice-fiords, through which
the annual surplus ice is carried off in the shape of bergs.... In Danish Greenland are
found five of the first, four of the second, and eight of the third (or least productive)
class, besides a number of inlets which only receive insignificant fragments. Direct

measurements of the velocity have now been applied on three first-rate and one
second-rate fiords, all situated between 69° and 71° north latitude. The measurements
have been repeated during the coldest and the warmest season, and connected with
surveying and other investigations of the inlets and their environs. It is now proved
that the glacier branches which produce the bergs proceed incessantly at a rate of
thirty to fifty feet per diem, this movement being not at all influenced by the seasons.
...
In the ice-fiord of Jakobshavn, which spreads its enormous bergs over Disco Bay
and probably far into the Atlantic, the productive part of the glacier is 4,500 metres
1
(about 22 miles) broad. The movement along its middle line, which is quicker than on
the sides nearer the shores, can be rated at fifty feet per diem. The bulk of ice here
annually forced into the sea would, if taken on the shore, make a mountain two miles
long, two miles broad, and 1,000 feet high. The ice-fiord of Torsukatak receives four
or five branches of the glacier; the most productive of them is about 9,000 metres
broad (five miles), and moves between sixteen and thirty-two feet per diem. The large
Karajak Glacier, about 7,000 metres (four miles) broad, proceeds at a rate of from
twenty-two to thirty-eight feet per diem. Finally, a glacier branch dipping into the
fiord of Jtivdliarsuk, 5,800 metres broad (three miles), moved between twenty-four
and forty-six feet per diem.[AK]
[AK] See Transactions of the Edinburgh Geological Society for February 18, 1886, vol.
v, part ii, pp. 286-293.

The principal part of our information concerning the glaciers of Greenland north
of Melville Bay was obtained by Drs. Kane and Hayes, in 1853 and 1854, while
conducting an expedition in search of Sir John Franklin and his unfortunate crew. Dr.
Hayes conducted another expedition to the same desolate region in 1860, while other
explorers have to some extent supplemented their observations. The largest glacier
which they saw enters the sea between latitude 79° and 80°, where it presents a
precipitous discharging front more than sixty miles in width and hundreds of feet in
perpendicular height.
Dr. Kane gives his first impressions of this grand glacier in the following vivid
description:
“I will not attempt to do better by florid description. Men only rhapsodize about
Niagara and the ocean. My notes speak simply of the ‘long, ever-shining line of cliff
diminished to a well-pointed wedge in the perspective’; and, again, of ‘the face of
glistening ice, sweeping in a long curve from the low interior, the facets in front
intensely illuminated by the sun.’ But this line of cliff rose in a solid, glassy wall
three hundred feet above the water-level, with an unknown, unfathomable depth
below it; and its curved face, sixty miles in length from Cape Agassiz to Cape Forbes,

vanished into unknown space at not more than a single day’s railroad-travel from the
pole. The interior, with which it communicated and from which it issued, was an
unsurveyed mer de glace—an ice-ocean to the eye, of boundless dimensions.
“It was in full sight—the mighty crystal bridge which connects the two continents
of America and Greenland. I say continents, for Greenland, however insulated it may
ultimately prove to be, is in mass strictly continental. Its least possible axis, measured
from Cape Farewell to the line of this glacier, in the neighbourhood of the eightieth
parallel, gives a length of more than 1,200 miles, not materially less than that of
Australia from its northern to its southern cape.
“Imagine, now, the centre of such a continent, occupied through nearly its whole
extent by a deep, unbroken sea of ice that gathers perennial increase from the water-
shed of vast snow-covered mountains and all the precipitations of its atmosphere
upon its own surface. Imagine this, moving onwards like a great glacial river, seeking
outlets at every fiord and valley, rolling icy cataracts into the Atlantic and Greenland
seas; and, having at last reached the northern limit of the land that has borne it up,
pouring out a mighty frozen torrent into unknown arctic space!
“It is thus, and only thus, that we must form a just conception of a phenomenon
like this great glacier. I had looked in my own mind for such an appearance, should I
ever be fortunate enough to reach the northern coast of Greenland; but, now that it
was before me, I could hardly realize it. I had recognized, in my quiet library at
home, the beautiful analogies which Forbes and Studer have developed between the
glacier and the river. But I could not comprehend at first this complete substitution of
ice for water.
“It was slowly that the conviction dawned on me that I was looking upon the
counterpart of the great river-system of Arctic Asia and America. Yet here were no
water-feeders from the south. Every particle of moisture had its origin within the
polar circle and had been converted into ice. There were no vast alluvions, no forest
or animal traces borne down by liquid torrents. Here was a plastic, moving, semi-
solid mass, obliterating life, swallowing rocks and islands, and ploughing its way
with irresistible march through the crust of an investing sea.”[AL]
[AL] Arctic Explorations in the Years 1853, 1854, and 1855, vol. i, pp. 225-228.

Much less is known concerning the eastern coast of Greenland than about the
western coast. For a long time it was supposed that there might be a considerable
population in the lower latitudes along the eastern side. But that is now proved to be a
mistake. The whole coast is very inhospitable and difficult of approach. From latitude
65° to latitude 69° little or nothing is known of it. In 1822-’23 Scoresby, Cleavering,
and Sabine hastily explored the coast from latitude 69° to 76°, and reported numerous
glaciers descending to the sea-level through extensive fiords, from which immense

icebergs float out and render navigation dangerous. In 1869 and 1870 the second
North-German Expedition partly explored the coast between latitude 73° and 77°. Mr.
Payer, an experienced Alpine explorer, who accompanied the expedition, reports the
country as much broken, and the glaciers as “subordinated in position to the higher
peaks, and having their moraines, both lateral and terminal, like those of the Alpine
ranges, and on a still grander scale.” Petermann Peak, in latitude 73°, is reported as
13,000 feet high. Captain Koldewey, chief of the expedition, found extensive plateaus
on the mainland, in latitude 75°, to be “entirely clear of snow, although only sparsely
covered with vegetation.” The mountains in this vicinity, also, rising to a height of
more than 2,000 feet, were free from snow in the summer. Some of the fiords in this
vicinity penetrate the continent through several degrees of longitude.
An interesting episode of this expedition was the experience of the crew of the
ship Hansa, which was caught in the ice and destroyed. The crew, however, escaped
by encamping on the ice-floe which had crushed the ship. From this, as it slowly
floated towards the south through several degrees of latitude, they had opportunity to
make many important observations upon the continent itself. As viewed from this
unique position the coast had the appearance everywhere of being precipitous, with
mountains of considerable height rising in the background, from which numerous
small glaciers descended to the sea-level.
In 1888 Dr. F. Nansen, with Lieutenant Sverdrup and four others, was left by a
whaler on the ice-pack bordering the east of Greenland about latitude 65°, and in
sight of the coast. For twelve days the party was on the ice-pack floating south, and
so actually reached the coast only about latitude 64°. From this point they attempted
to cross the inland ice in a northwesterly direction towards Christianshaab. They soon
reached a height of 7,000 feet, and were compelled by severe northerly storms to
diverge from their course, taking a direction more to the west. The greatest height
attained was 9,500 feet, and the party arrived on the western coast at Ameralik Fiord,
a little south of Godhaab, about the same latitude at which they entered.
It thus appears that subsequent investigations have confirmed in a remarkable
manner the sagacious conclusions made by the eminent Scotch geologist and
glacialist Robert Brown in 1875, soon after his own expedition to the country. “I look
upon Greenland and its interior ice-field,” he writes, "in the light of a broad-lipped,
shallow vessel, but with chinks in the lips here and there, and the glacier like viscous
matter in it. As more is poured in, the viscous matter will run over the edges,
naturally taking the line of the chinks as its line of outflow. The broad lips of the
vessel are the outlying islands or ‘outskirts’; the viscous matter in the vessel the
inland ice, the additional matter continually being poured in in the form of the
enormous snow covering, which, winter after winter, for seven or eight months in the
year, falls almost continuously on it; the chinks are the fiords or valleys down which
the glaciers, representing the outflowing viscous matter, empty the surplus of the

vessel—in other words, the ice floats out in glaciers, overflows the land in fact, down
the valleys and fiords of Greenland by force of the superincumbent weight of snow,
just as does the grain on the floor of a barn (as admirably described by Mr. Jamieson)
when another sackful is emptied on the top of the mound already on the floor. ‘The
floor is flat, and therefore does not conduct the grain in any direction; the outward
motion is due to the pressure of the particles of grain on one another; and, given a
floor of infinite extension and a pile of sufficient amount, the mass would move
outward to any distance, and with a very slight pitch or slope it would slide forward
along the incline.’ To this let me add that if the floor on the margin of the heap of
grain was undulating the stream of grain would take the course of such undulations.
The want, therefore, of much slope in a country and the absence of any great
mountain-range are of very little moment to the movement of land-ice, provided we
have snow enough" On another page Dr. Brown had well said that “the country seems
only a circlet of islands separated from one another by deep fiords or straits, and
bound together on the landward side by the great ice covering which overlies the
whole interior.... No doubt under this ice there lies land, just as it lies under the sea;
but nowadays none can be seen, and as an insulating medium it might as well be
water.”
In his recently published volumes descriptive of the journey across the Greenland
ice-sheet, alluded to on page 39, Dr. Nansen sums up his inferences in very much the
same way: “The ice-sheet rises comparatively abruptly from the sea on both sides,
but more especially on the east coast, while its central portion is tolerably flat. On the
whole, the gradient decreases the farther one gets into the interior, and the mass thus
presents the form of a shield with a surface corrugated by gentle, almost
imperceptible, undulations lying more or less north and south, and with its highest
point not placed symmetrically, but very decidedly nearer the east coast than the
west.”
From this rapid glance at the existing glaciers of the world we see that a great ice
age is not altogether a strange thing in the world. The lands about the south pole and
Greenland are each continental in dimensions, and present at the present time
accumulations of land-ice so extensive, so deep, and so alive with motion as to
prepare our minds for almost anything that may be suggested concerning the
glaciated condition of other portions of the earth’s surface. The vera causa is
sufficient to accomplish anything of which glacialists have ever dreamed. It only
remains to enquire what the facts really are and over how great an extent of territory
the actual results of glacial action may be found. But we will first direct more
particular attention to some of the facts and theories concerning glacial motion.

CHAPTER III.

GLACIAL MOTION.
That glacial ice actually moves after the analogy of a semi-fluid has been
abundantly demonstrated by observation. In the year 1827 Professor Hugi, of
Soleure, built a hut far up upon the Aar Glacier in Switzerland, in order to determine
the rate of its motion. After three years he found that it had moved 330 feet; after nine
years, 2,354 feet; and after fourteen years Louis Agassiz found that its motion had
been 4,712 feet. In 1841 Agassiz began a more accurate series of observation upon
the same glacier. Boring holes in the ice, he set across it a row of stakes which, on
visiting in 1842, he found to be no longer in a straight line. All had moved
downwards with varying velocity, those near the centre having moved farther than
the others. The displacements of the stakes were in order, from side to side, as
follows: 160 feet, 225 feet, 269 feet, 245 feet, 210 feet, and 125 feet. Agassiz
followed up his observations for six years, and in 1847 published the results in his
celebrated work System Glacière.
But in August, 1841, the distinguished Swiss investigator had
invited Professor J. D. Forbes, of Edinburgh, to interest himself in
solving the problem of glacial motion. In response to this request,
Professor Forbes spent three weeks with Agassiz upon the Aar
Glacier. Stimulated by the interest of this visit, Forbes returned to
Switzerland in 1842 and began a series of independent
investigations upon the Mer de Glace. After a week’s observations
with accurate instruments, Forbes wrote to Professor Jameson, Fig. 16.
editor of the Edinburgh New Philosophical Journal, that he had
already made it certain that “the central part of the glacier moves
faster than the edges in a very considerable proportion, quite contrary to the opinion
generally maintained.” This letter was dated July 4, 1842, but was not published until
the October following, Agassiz’s results, so far as then determined, were, however,
published in Comptes Rendus of the 29th of August, 1842, two months before the
publication of Forbes’s letter. But Agassiz’s letter was dated twenty-seven days later
than that of Forbes. It becomes certain, therefore, that both Agassiz and Forbes,
independently and about the same time, discovered the fact that the central portion of
a glacier moves more rapidly than the sides.
In 1857 Professor Tyndall began his systematic and fruitful observations upon the
Mer de Glace and other Alpine glaciers. Professor Forbes had already demonstrated
that, with an accurate instrument of observation, the motion of a line of stakes might
be observed after the lapse of a single clay, or even of a few hours. As a result of

Tyndall’s observations, it was found that the most rapid daily motion in the Mer de
Glace in 1857 was about thirty-seven inches. This amount of motion was near the
lower end of the glacier On ascending the glacier, the rate was found in general to be
diminished; but the diminution was not uniform throughout the whole distance, being
affected both by the size and by the contour of the valley. The motion in the tributary
glaciers was also much less than that of the main glacier.
This diminution of movement in the tributary glaciers was somewhat
proportionate to their increase in width. For example, the combined width of the three
tributaries uniting to form the Mer de Glace is 2,597 yards; but a short distance below
the junction of these tributaries the total width of the Mer de Glace itself is only 893
yards, or one-third that of the tributaries combined. Yet, though the depth of the ice is
probably here much greater than in the tributaries, the rapidity of movement is
between two and three times as great as that of any one of the branches.[AM]
[AM] See Tyndall’s Forms of Water, pp. 78-82.

From Tyndall’s observations it appears also that the line of most rapid motion is
not exactly in the middle of the channel, but is pushed by its own momentum from
one side to the other of the middle, so as always to be nearer the concave side; in this
respect conforming, as far as its nature will permit, to the motion of water in a
tortuous channel.
It is easy to account for this differential motion upon the surface
of a glacier, since it is clear that the friction of the sides of the
channel must retard the motion of ice as it does that of water. It is
clear also that the friction of the bottom must retard the motion of ice
even more than it is known to do in the case of water. In the
formation of breakers, when the waves roll in upon a shallowing
beach, every one is familiar with the effect of the bottom upon the
moving mass. Here friction retards the lower strata of water, and the
upper strata slide over the lower, and, where the water is of sufficient
depth and the motion is sufficiently great, the crest breaks down in
foam before the ever-advancing tide. A similar phenomenon occurs
when dams give way and reservoirs suddenly pour their contents into
the restricted channels below. At such times the advancing water rolls Fig. 17.
onwards like the surf with a perpendicular front, varying in height
according to the extent of the flood.
Seasoning from these phenomena connected with moving water, it was naturally
suggested to Professor Tyndall that an analogous movement must take place in a
glacier. Choosing, therefore, a favourable place for observation on the Mer de Glace
where the ice emerged from a gorge, he found a perpendicular side about one
hundred and fifty feet in height from bottom to top. In this face he drove stakes in a

perpendicular line from top to bottom. Upon subsequently observing them, Tyndall
found, as he expected, that there was a differential motion among them as in the
stakes upon the surface. The retarding effect of friction upon the bottom was evident.
The stake near the top moved forwards about three times as fast as the one which was
only four feet from the bottom.
The most rapid motion (thirty-seven inches per
day) observed by Professor Tyndall upon the Alpine
glaciers occurred in midsummer. In winter the rate was
only about one-half as great; but in the year 1875 the
Norwegian geologist, Helland, reported a movement of
Fig. 18.
twenty metres (about sixty-five feet) per day in the
Jakobshavn Glacier which enters Disco Bay,
Greenland, about latitude 70°. For some time there was
a disposition on the part of many scientific men to doubt the correctness of Holland’s
calculations. Subsequent observations have shown, however, that from the
comparatively insignificant glaciers of the Alps they were not justified in drawing
inferences with respect to the motion of the vastly larger masses which come down to
the sea through the fiords of Greenland. The Jakobshavn Glacier was about two and a
half miles in width and its depth very likely more than a thousand feet, making a
cross-section of more than 1,400,000 square yards, whereas the cross-section of the
Mer de Glace at Montanvert is estimated to be but 190,000 square yards or only
about one-seventh the above estimate for the Greenland glacier. As the friction of the
sides would be no greater upon a large stream than upon a small one, while upon the
bottom it would be only in proportion to the area, it is evident that we cannot tell
beforehand how rapidly an increase in the volume of the ice might augment the
velocity of the glacier.
At any rate, all reasonable grounds for distrusting the accuracy of Helland’s
estimates seem to have been removed by later investigations. According to my own
observations in the summer of 1886 upon the Muir Glacier, Alaska, the central
portions, a mile back from the front of that vast ice-current, were moving from sixty-
five to seventy feet per day. These observations were taken with a sextant upon
pinnacles of ice recognizable from a baseline established upon the shore. It is fair to
add, however, that during the summer of 1890 Professor H. F. Reid attempted to
measure the motion of the same glacier by methods promising greater accuracy than
could be obtained by mine. He endeavoured to plant, after the method of Tyndall, a
line of stakes across the ice-current. But with his utmost efforts, working inwards
from both sides, he was unable to accomplish his purpose, and so left unmeasured a
quarter of a mile or more of the most rapidly-moving portion of the glacier. His
results, therefore, of ten feet per day in the most rapidly-moving portion observed
cannot discredit my own observations on a portion of the stream inaccessible by his

method. A quarter of a mile in width near the centre of so vast a glacier gives ample
opportunity for a much greater rate of motion than that observed by Professor Reid.
Especially may this be true in view of Tyndall’s suggestion that the contour of the
bottom over which the ice flows may greatly affect the rate in certain places. A
sudden deepening of the channel may affect the motion of ice in a glacier as much as
it does that of water in a river.
Other observations also amply sustain the conclusions of Helland. As already
stated, the Danish surveying party under Steenstrup, after several years’ work upon
the southwestern coast of Greenland, have ascertained that the numerous glaciers
coming down to the sea in that region and furnishing the icebergs incessantly floating
down Baffin’s Bay, move at a rate of from thirty to fifty feet per day, while
Lieutenants Ryder and Bloch, of the Danish Navy, who spent the year 1887 in
exploring the coast in the vicinity of Upernavik, about latitude 73°, found that the
great glacier entering the fiord east of the village had a velocity of ninety-nine feet
per day during the month of August.[AN]
[AN] Nature, December 29, 1887.

It is easier to establish the fact of glacial motion than to explain how the motion
takes place, for ice seems to be as brittle as glass. This, however, is true of it only
when compelled suddenly to change its form. When subjected to slow and long-
continued pressure it gradually yet readily yields, and takes on new forms. From this
capacity of ice, it has come to be regarded by some as a really viscous substance, like
tar or cooling lava, and upon that theory Professor Forbes endeavours to explain all
glacial movement.
The theory, however, seems to be contradicted by familiar facts; for the iceman,
after sawing a shallow groove across a piece of ice, can then split it as easily as he
would a piece of sandstone or wood. On the glaciers themselves, likewise, the
existence of innumerable crevasses would seem to contradict the plastic theory of
glacier motion; for, wherever the slope of the glacier’s bed increases, crevasses are
formed by the increased strain to which the ice is subjected. Crevasses are also
formed in rapidly-moving glaciers by the slight strain occasioned by the more rapid
motion of the middle portion. Still, in the words of Tyndall, “it is undoubted that the
glacier moves like a viscous body. The centre flows past the sides, the top flows over
the bottom, and the motion through a curved valley corresponds to fluid motion.”[AO]
[AO] Forms of Water, p. 163.

To explain this combination of the seemingly contradictory qualities of brittleness
and viscosity in ice, physicists have directed attention to the remarkable
transformations which take place in water at the freezing-point. Faraday discovered

in 1850 that "when two pieces of thawing ice are placed together they freeze together
at the point of contact.[AP]
[AP] Ibid., p. 164.

“Place a number of fragments of ice in a basin of water and cause them to touch
each other; they freeze together where they touch. You can form a chain of such
fragments; and then, by taking hold of one end of the chain, you can draw the whole
series after it. Chains of icebergs are sometimes formed in this way in the arctic
seas.”[AQ]
[AQ] Ibid., pp. 164, 165.

This is really what takes place when a hard snow-ball is made by pressure in the
hand. So, by subjecting fragments of ice to pressure it is first crumbled to powder,
and then, as the particles are pressed together in close contact, it resumes the nature
of ice again, though in a different form, taking now the shape of the mould in which
it has been pressed.
Thus it is supposed that, when the temperature of ice is near the melting-point, the
pressure of the superincumbent mass may produce at certain points insensible
disintegration, while, upon the removal of the pressure by change of position,
regulation instantly takes place, and thus the phenomena which simulate plasticity are
produced. As the freezing-point of water is, within a narrow range, determined by the
amount of pressure to which it is subjected, it is not difficult to see how these
changes may occur. Pressure slightly lowers the freezing-point, and so would liquefy
the portions of ice subjected to greatest pressure, wherever that might be in the mass
of the glacier, and thus permit a momentary movement of the particles, until they
should recongeal in adjusting themselves to spaces of less pressure.[AR] This is the
theory by which Professor James Thompson would account for the apparent plasticity
of glacial ice.
[AR] Forms of Water, p. 168.

CHAPTER IV.

SIGNS OF PAST GLACIATION.
The facts from which we draw the inference that vast areas of the earth’s surface
which are now free from glaciers were, at a comparatively recent time, covered with
them, are fourfold, and are everywhere open to inspection. These facts are: 1.

Scratches upon the rocks. 2. Extensive unstratified deposits of clay and sand
intermingled with scratched stones and loose fragments of rock. 3. Transported
boulders left in such positions and of such size as to preclude the sufficiency of
water-carriage to account for them. 4. Extensive gravel terraces bordering the valleys
which emerge from the glaciated areas. We will consider these in their order:
1. The scratches upon the rocks.
Almost anywhere in the region designated as having been covered with ice during
the Glacial period, the surface of the rocks when freshly uncovered will be found to
be peculiarly marked by grooves and scratches more or less fine, and such as could
not be produced by the action of water. But, when we consider the nature of a glacier,
these marks seem to be just what would be produced by the pushing or dragging
along of boulders, pebbles, gravel, and particles of sand underneath a moving mass of
ice.
Running water does indeed move gravel, pebbles, and boulders along with the
current, but these objects are not held by it in a firm grasp, such as is required to
make a groove or scratch in the rock. If, also, there are inequalities in the
compactness or hardness of the rock, the natural action of running water is to hollow
out the soft parts, and leave the harder parts projecting. But, in the phenomena which
we are attributing to glacial action, there has been a movement which has steadily
planed down the surface of the underlying rock; polishing it, indeed, but also
grooving it and scratching it in a manner which could be accomplished only by firmly
held graving-tools.

Fig. 19.—Bed-rock scored with glacial marks, near Amherst,
Ohio. (From a photograph by Chamberlin.)

This polishing and scratching can indeed be produced by various agencies; as, for
example, by the forces which fracture the earth’s crust, and shove one portion past
another, producing what is called a slicken-side. Or, again, avalanches or land-slides
might be competent to produce the results over limited and peculiarly situated areas.
Icebergs, also, and shore ice which is moved backwards and forwards by the waves,
would produce a certain amount of such grooving and scratching. But the phenomena
to which we refer are so extensive, and occur in such a variety of situations, that the
movement of glacial ice is alone sufficient to afford a satisfactory explanation.
Moreover, in Alaska, Greenland, Norway, and Switzerland, and wherever else there
are living glaciers, it is possible to follow up these grooved and striated surfaces till
they disappear underneath the existing glaciers which are now producing the
phenomena. Thus by its tracks we can, as it were, follow this monster to its lair with
as great certainty as we could any animal with whose footprints we had become
familiar.
2. The till, or boulder-clay.
A second sign of the former existence of glaciers over any area consists of an
unstratified deposit of earthy material, of greater or less depth, in which scratched
pebbles and fragments of rock occur without any definite arrangement.

Moving water is a most perfect sieve. During floods, a river shoves along over its
bed gravel and pebbles of considerable size, whereas in time of low-water the current
may be so gentle as to transport nothing but fine sand, and the clay will be carried
still farther onwards, to settle in the still water and form a delta about the river’s
mouth. The transporting capacity of running water is in direct ratio to the sixth power
of its velocity. Other things being equal, if the velocity be doubled, the size of the
grains of sand or gravel which it transports is increased sixty-four fold.[AS] So
frequent are the changes in the velocity of running water, that the stratification of its
deposits is almost necessary and universal. If large fragments of rocks or boulders are
found embedded in stratified clay, it is pretty surely a sign that they have been carried
to their position by floating ice. A small mountain stream with great velocity may
move a good-sized boulder, while the Amazon, with its mighty but slow-moving
current, would pass by it forever without stirring it from its position. But the vast area
which is marked in our map as having been covered with ice during the Glacial
period is characterised by deep and extensive deposits of loose material devoid of
stratification, and composed of soil and rock gathered in considerable part from other
localities, and mixed in an indiscriminate mass with material which has originated in
the disintegration of the underlying local strata.
[AS] Le Conte’s Geology, p. 19.

Fig. 20.—Scratched stone from the till of Boston. Natural size
about one foot and a half long by ten inches wide. (From
photograph.)

Fig. 21.—Typical section of till in Seattle. Washington
State, about two hundred feet above Puget Sound. This
is on the height between the sound and Lake
Washington.

Fig. 22.—Ideal section, showing how the till overlies the
stratified rocks.

Fig. 23.—Vessel Rock, a glacial boulder in Gilsum. N. H. (C.
H. Hitchcock.)

3. Transported boulders.
Where there is a current of water deep enough to float large masses of ice, there is
scarcely any limit to the size of boulders which may be transported upon them, or to
the distance to which the boulders may be carried and dropped upon the bottom. The
icebergs which break off from the glaciers of Greenland may bear their burdens of
rock far down into the Atlantic, depositing them finally amidst the calcareous ooze
and the fine sediment from the Gulf Stream which is slowly covering the area
between Northern America and Europe. Northern streams like the St. Lawrence,
which are deeply frozen over with ice in the winter, and are heavily flooded as the ice
breaks up in the spring, afford opportunity for much transportation of boulders in the
direction of their current. In attributing the transportation of a boulder to glacial ice, it
is necessary, therefore, to examine the contour of the country, so as to eliminate from
the problem the possibility of the effects having been produced by floating ice.
Another source of error against which one has to be on his guard arises from the
close resemblance of boulders resulting from disintegration to those which have been
transported by ice from distant places. Owing to the fact that large masses of rocks,
especially those which are crystalline, are seldom homogeneous in their structure, it
results that, under the slow action of disintegrating and erosive agencies, the softer
parts often are completely removed before the harder nodules are sensibly affected,
and these may remain as a collection of boulders dotting the surface. Such boulders
are frequent in the granitic regions of North Carolina and vicinity, where there has
been no glacial transportation. Several localities in Pennsylvania, also, south of the
line of glacial action as delineated by Professor Lewis and myself, had previously
been supposed to contain transported boulders of large size, but on examination they
proved in all cases to be resting upon undisturbed strata of the parent rock, and were
evidently the harder portions of the rock left in loco by the processes of erosion
spoken of. In New England, also, it is possible that some boulders heretofore
attributed to ice-action may be simply the results of these processes of disintegration

and erosion. Whether they are or not can usually be determined by their likeness or
unlikeness to the rocks on which they rest; but oftentimes, where a particular variety
of rock is exposed over a broad area, it is difficult to tell whether a boulder has
suffered any extensive transportation or not.
One of the most interesting and satisfactory
demonstrations of the distribution of boulders by
glacial ice was furnished by Guyot in Switzerland in
1845. His observations and argument will be most
readily understood by reference to the accompanying
map, taken from Lyell’s clear description.[AT] The
Jura Mountains are separated from the Alps by a
valley, about eighty miles in width, which constitutes
the main habitable portion of Switzerland, and they
rise upwards of two thousand feet above it. But large
Alpine boulders are found as high as two thousand
feet above the Lake Neufchâtel upon the flanks of the Fig. 24.—Map showing the outline and
Jura Mountains beyond Chasseron (at the point course of flow of the great Rhône
Glacier (after Lyell).
marked G on the map), and the whole valley is dotted Click on image to view larger sized.
with Alpine boulders. Upon comparing these with the
native rocks in the Alps, Guyot in many cases was
able to determine the exact centres from which they were distributed, and the
distribution is such as to demonstrate that glacial ice was the medium of distribution.
[AT] Antiquity of Man, p. 299.

For example, the dotted lines upon the map indicate the motion of the
transporting medium. On ascending the valley of the Rhône to A, the diminutive
representative of the ancient glacier is still found in existence, and is at work
transporting boulders and moraines according to the law of ice-movement. Following
down the valley from A, boulders from the head of the Rhône Valley are found
distributed as far as B at Martigny, where the valley turns at right angles towards the
north. It is evident that floating ice in a stream of water would by its momentum be
carried to the left bank, so that if icebergs were the medium of transportation we
should expect to find the boulders from the right-hand side of the Rhône Valley
distributed towards the left end of the great valley of Switzerland—that is, in the
direction of Geneva. But, instead, the boulders derived from C, D, and E, on the
Bernese Oberland side, instead of crossing the valley at B, continue to keep on the
right-hand side and are distributed over the main valley in the direction of the river
Aar.
As is to be expected also, the direct northward motion of the ice from B is
stronger than the lateral movement to the right and left after it emerges from the

mouth of the Rhône Valley, at F, and consequently it has pushed forwards in a straight
line, so as to raise the Alpine boulders to a greater height upon the Jura Mountains at
G than anywhere else, the upper limit of boulders at G being 1,500 feet higher than
the limits at I or K on the left and right, points distant about one hundred miles from
each other. All the boulders to the right of the line from B to G have been derived
from the right side of the Rhône, while all the boulders to the left of that line have
been derived from its left side.
A boulder of talcose granite containing 61,000 French cubic feet, measuring
about forty feet in one direction, came, according to Charpentier, from the point n,
near the head of the Rhône Valley, and must have travelled one hundred and fifty
miles to reach its present position.
It scarcely needs to be added that the grooves and scratches upon the rocks over
the floor of this great valley of Switzerland indicate a direction of the ice-movement
corresponding to that implied in the distribution of boulders. Thus, at K upon the map
referred to, Lyell reports that the abundant grooves and striæ upon the polished
marble all trend down the valley of the Aar.[AU]
[AU] Antiquity of Man, p. 305.

Similar facts concerning the transportation of boulders have been observed at
Trogen, in Appenzel, where boulders derived from Trons, one hundred miles distant,
are found to keep upon the left bank of the Rhine, however much the valley may
wind about; and in some places, as at Mayenfeld, it turns almost at right angles, as
did the Rhône at Martigny. Upon reaching the lower country at Lake Constance,
these granite blocks from the left side of the valley deploy out upon the same side and
do not cross over, as they would inevitably have done had they been borne along by
currents of water.
In America Ave do not have quite so easy a field as is presented in Switzerland
for the discovery of crucial instances showing that boulders have been transported by
glacial ice rather than by floating ice, for in Switzerland the glaciated area is
comparatively small and the diminutive remnants of former glaciers are still in
existence, furnishing a comprehensive object-lesson of great interest and convincing
power. Still, it is not difficult to find decisive instances of glacial transportation even
in the broad fields of America which now retain no living remnants of the great
continental ice-sheet.
As every one who resides in or who visits New England knows, boulders are
scattered freely over all parts of that region, but for a long time the theory suggested
to account for their distribution was that of floating ice during a period of
submergence. One of the most convincing evidences that the boulders were
distributed by glacial ice rather than by icebergs is found in Professor C. H.

Hitchcock’s discovery of boulders on the summit of Mount Washington (over 6,000
feet above the sea), which he was able to identify as derived from the ledges of light
grey Bethlehem gneiss, whose nearest outcrop is in Jefferson, several miles to the
northwest, and 3,000 or 4,000 feet lower than Mount Washington. However difficult
it may be to explain the movement of these boulders by glacial ice, it is not
impossible to do so, but the attempt to account for their transportation by floating ice
is utterly preposterous. No iceberg could pick up boulders so far beneath the surface
of the water, and even if it could advance thus far in its work it could not by any
possibility land them afterwards upon the summit of Mount Washington.
Among the most impressive instances of boulders evidently transported by glacial
ice, rather than by icebergs, were some which came to my notice when, in company
with the late Professor H. Carvill Lewis, I was tracing the glacial boundary across the
State of Pennsylvania. We had reached the elevated plateau (two thousand feet above
the sea) which extends westwards and southwards from the peak of Pocono
Mountain, in Monroe County. This plateau consists of level strata of sandstone, the
southern part of which is characterised by a thin sandy soil, such as is naturally
formed by the disintegration of the underlying rock, and there is no foreign material
to be found in it. But, on going northwards to the boundary of Tobyhanna township,
we at once struck a large line of accumulations, stretching from east to west, and
rising to a height of seventy or eighty feet. This was chiefly an accumulation of
transported boulders, resembling in its structure the terminal moraines which are
found at the front of glaciers in the Alps and in Alaska, and indeed wherever active
glaciers still remain. But here we were upon the summit of the mountain, where there
are no higher levels to the north of us, down which the ice could flow. Besides,
among these boulders we readily recognised many of granite, which must have come
either from the Adirondack Mountains, two hundred miles to the north, or from the
Canadian highlands, still farther away.
Limiting our observations simply to the boulders, we should indeed have been at
liberty to suppose that they had been transported across the valley of the Mohawk or
of the Great Lakes by floating ice during a period of submergence. But we were
forbidden to resort to this hypothesis by the abrupt marginal line, running east and
west, upon Pocono plateau, along which these northern boulders ceased. South of this
evident terminal moraine there was no barrier, and there were no northern boulders.
On the theory of submergence, there was no reason for the boundary-line so clearly
manifested. Ice which had floated so far would have floated farther.
Still further, on going a few miles east of the Pocono plateau, one descends into a
parallel valley, lying between Pocono Mountain and Blue Mountain, and one
thousand feet below their level. But our marginal southern boundary of transported
granite rocks did not extend much farther south in the valley than it did on the
plateau, except where we could trace the action of a running stream, evidently

corresponding to the subglacial rivers which pour forth from the front of every
extensive glacier. In these facts, therefore, we had a crucial test of the glacial
hypothesis, and, in view of them, could maintain, against all objectors, the theory of
the distant glacial transportation of boulders, even over vast areas of the North
American continent.
Since that experience, I have traced this limit of southern boulders for thousands
of miles across the continent, according to the delineation which may be seen in the
map in a later chapter. If necessary, I could indicate hundreds of places where the
proof of glacial transportation is almost as clear as that on the Pocono plateau in
Pennsylvania. One of the most interesting of these is on the hills in Kentucky, about
twelve miles south of the Ohio River, at Cincinnati, where I discovered boulders of a
conglomerate containing many pebbles of red jasper, which can be identified as from
a limited formation cropping out in Canada, to the north of Lake Huron, six hundred
or seven hundred miles distant. That this was transported by glacial ice, and not by
floating ice, is evident from the fact that here, too, there was no barrier to the south,
requiring deposits to cease at that point, and from the further fact that boulders of this
material are found in increasing frequency all the way from Kentucky to the parent
ledges in Canada. With reference to these boulders, as with reference to those found
on the summit of Mount Washington, we can reason, also, that any northerly
subsidence permitting a body of water to occupy the space between Kentucky and
Lake Superior, and deep enough to facilitate the movement across it of floating ice,
would render it impossible for the ice to have loaded itself with them.

Fig. 25.—Conglomerate boulder found in Boone County,
Kentucky. (See text.)

The same line of reasoning is conclusive respecting the innumerable boulders
which cover the northern portion of Ohio, where I have my residence. The whole
State of Ohio, and indeed almost the entire Mississippi basin between the

Appalachian and the Rocky Mountains, is completely covered, and to a great depth,
with stratified rocks which have been but slightly disturbed in the elevation of the
continent; yet, down to an irregular border-line running east and west, granitic
boulders everywhere occur in great numbers. In the locality spoken of in northern
Ohio the elevation of the country is from two hundred to five hundred feet above the
level of Lake Erie. The nearest outcrops of granitic rock occur about four hundred
miles to the north, in Canada. After the meeting of the American Association for the
Advancement of Science in Toronto in the summer of 1889, I had the privilege of
joining a company of geologists in an excursion, conducted by members of the
Canadian Survey, to visit the region beyond Lake Nipissing, north of Lake Huron,
where the ancient Laurentian and Huronian rocks are most typically developed. I
took advantage of the trip to collect specimens of a great variety of the granites and
gneisses and metamorphic schists and trap-rock of the region. On bringing them
home I turned them over to the professor of geology, who at once set his class at
work to see if they could match my fragments from Canada with corresponding
fragments from the boulders of the vicinity. To the great gratification, both of the
pupils and myself, they were able to do so in almost every case; and so they might
have done in any county or township to the south until reaching the limit of glacier
action which I had previously mapped. Here, at Oberlin, on the north side of the
water-shed, it is possible to imagine that we are on the southern border of an ancient
lake upon whose bosom floating ice had brought these objects from their distant
home in Canada. But this theory would not apply to the portion of the State which is
south of the water-shed and which slopes rapidly towards the Gulf of Mexico. Yet the
distribution of boulders is practically uniform over the glaciated area on both sides of
the water-shed, constituting thus an indisputable proof of the glacial theory.
4th. As the significance of the gravel terraces which mark the lines of outward
drainage from the glaciated area cannot well be indicated in a single paragraph, the
reader is referred for further information upon this point to the general statements
respecting them throughout the next chapter.

Click on map to view larger sized.

CHAPTER V.

ANCIENT GLACIERS IN THE WESTERN
HEMISPHERE.
New England.
In North America all the indubitable signs of glacial action are found over the
entire area of New England, the southern coast being bordered by a double line of
terminal moraines. The outermost of these appears in Nantucket, Martha’s Vineyard,
No Man’s Land, Block Island, and through the entire length of Long Island—from
Montauk Point, through the centre of the island, to Brooklyn, N. Y., and thence across
Staten Island to Perth Amboy in New Jersey. The interior line is nearly parallel with
the outer, and, beginning at the east end of Cape Cod, runs in a westerly direction to
Falmouth, and thence southwesterly through Wood’s Holl, and the Elizabeth Islands
—these being, indeed, but the unsubmerged portions of the moraine. On the mainland

this interior line reappears near Point Judith, on the south shore of Rhode Island, and,
running slightly south of west, serves to give character to the scenery at Watch Hill,
and thence crops out in the Sound as Fisher and Plum Islands, and farther west forms
the northern shore of Long Island to Port Jefferson.
In these accumulations bordering the southern shore of New England, the
characteristic marks of glacial action can readily be detected even by the casual
observer, and prolonged examination will amply confirm the first impression. The
material of which they are composed is, for the most part, foreign to the localities,
and can be traced to outcrops of rock at the north. The boulders scattered over the
surface of Long Island, for example, consist largely of granite, gneiss, hornblende,
mica slate, and red sandstone, which are easily recognised as fragments from well-
known quarries in Connecticut, Rhode Island, and Massachusetts; yet they have been
transported bodily across Long Island Sound, and deposited in a heterogeneous mass
through the entire length of the island. Not only do they lie upon the surface, but, in
digging into the lines of hills which constitute the backbone of Long Island, these
transported boulders are found often to make up a large part of the accumulation.
Almost any of the railroad excavations in the city of Brooklyn present an interesting
object-lesson respecting the composition of a terminal moraine.
All these things are true also of the lines of moraine farther east, as just described.
Professor Shaler has traced to its source a belt of boulders occurring extensively over
southern Rhode Island, and found that they have spread out pretty evenly over a
triangular area to the southward, in accordance with the natural course to be pursued
by an ice-movement. Nearly all of Plymouth County, in southeastern Massachusetts,
is composed of foreign material, much of which can be traced to the hills and
mountains to the north. Even Plymouth Rock is a boulder from the direction of
Boston, and the “rock-bound” shores upon which the Pilgrims are poetically
conceived to have landed are known, in scientific prose, as piles of glacial rubbish
dumped into the edge of the sea by the great continental ice-sheet.
The whole area of southeastern Massachusetts is dotted with conical knolls of
sand, gravel, and boulders, separated by circular masses of peat or ponds of water,
whose origin and arrangement can be accounted for only by the peculiar agency of a
decaying ice-front. Indeed, this whole line of moraines, from the end of Cape Cod to
Brooklyn, N. Y., consists of a reticulated network of ridges and knolls, so deposited
by the ice as to form innumerable kettle-holes which are filled with water where other
conditions are favourable. Those which are dry are so because of their elevation
above the general level, and of the looseness of the surrounding soil; while many
have been filled with a growth of peat, so that their original character as lakelets is
disguised.

As already described, these depressions, so characteristic of the glaciated region,
are, in the majority of cases, supposed to have originated by the deposition of a great
quantity of earthy material around and upon the masses of ice belonging to the
receding front of the glacier, so that, when at length the ice melted away, a permanent
depression in the soil was left, without any outlet.
To some extent, however, the kettle-holes may have been formed by the irregular
deposition of streams of water whose courses have crossed each other, or where
eddies of considerable force have been produced in any way. The ordinary formation
of kettle-holes can be observed in progress on the foot of almost any glacier, or,
indeed, on a small scale, during the melting away of almost any winter’s snow.
Where, from any cause, a stratum of dirt has accumulated upon a mass of compact
snow or ice, it will be found to settle down in an irregular manner; furrows will be
formed in various directions by currents of water, so that the melting will proceed
irregularly, and produce upon a miniature scale exactly what I have seen on a large
scale over whole square miles of the decaying foot of the great Muir Glacier in
Alaska. The effects of similar causes and conditions we can see on a most enormous
scale in the ten thousand lakes and ponds and peat-bogs of the whole glaciated area
both in North America and in Europe.
In addition to these two lines of evidence of glacial action in New England, we
should mention also the innumerable glacial grooves and scratches upon the rocks
which can be found on almost any freshly uncovered surface. In New England the
direction of these grooves is ordinarily a little east of south. Upon the east coast of
Massachusetts and New Hampshire the scratches trend much more to the east than
they do over most of the interior. This is as it should be on the glacial theory, since
the ice would naturally move outwards in the line of least resistance, which would, of
course, be towards the open sea wherever that is near. In the interior of New England
the scratches upon the rocks indicate a more southerly movement in the Connecticut
Valley than upon the mountains in the western part of Massachusetts. This also is as it
should be upon the glacial theory. The scratches upon the mountains were made when
the ice was at its greatest depth and when it moved over the country in comparative
disregard of minor irregularities of surface, while in the valleys, at least in the later
portion of the Ice age, the movement would be obstructed except in one direction. In
the interpretation of the glacial grooves and scratches it should be borne in mind that
they often represent the work done during the closing stages of the period. Just as the
last shove of the carpenter’s plane removes the marks of the previous work, so the
last rasping of a glacial movement wears away the surfaces which have been
previously polished and striated.
In various places of New England it is interesting as well as instructive to trace
the direction of the ice-movement by the distribution of boulders. My own attention
was early attracted to numerous fragments of gneiss in eastern Massachusetts

containing beautiful crystals of feldspar, which proved to be peculiar to the region of
Lake Winnepesaukee, a hundred miles to the north, and to a narrow belt stretching
thence to the southwestward. In ascending almost any of the lower summits of the
White Mountains one’s attention can scarcely fail of being directed to the difference
between the material of which the mountains are composed and that of the numerous
boulders which lie scattered over the surface. The local geologist readily recognises
these boulders as pilgrims that have wandered far from their homes to the northward.
Trains of boulders, such as those already described in Rhode Island, can
frequently be traced to some prominent outcrop of the rock in a hill or mountain-peak
from which they have been derived. One of the earliest of these to attract attention
occurs in the towns of Richmond, Lenox, and Stockbridge, in the western part of
Massachusetts. Here a belt of peculiar boulders about four hundred feet wide is found
to originate in the town of Lebanon, N. Y., and to run continuously to the southeast
for a distance of nine miles. West of Fry’s Hill, where the outcrop occurs, no boulders
of this variety of rock are to be found, while to the southeast the boulders gradually
diminish in size as their distance from the outcrop increases. Near the outcrop
boulders of thirty feet in diameter occur, while nine miles away two feet is the largest
diameter observed.
Sir Charles Lyell endeavoured to explain this train of boulders by the action of
icebergs during a period of submergence—supposing that, as icebergs floated past or
away from this hill in Lebanon, N. Y., they were the means of the regular distribution
described. It is needless to repeat the difficulties arising in connection with such a
theory, since now both by observation and experiment we have become more familiar
with the movement of glacial ice. What we have already said about the transportation
of boulders over Switzerland by the Alpine glaciers, and what is open to observation
at the present time upon the large glaciers of Alaska, closely agree with the facts
concerning this Richmond train of boulders, and we have no occasion to look further
for a cause.
Indeed, trains of boulders ought to appear almost everywhere over the glaciated
area; and so they do where all the circumstances are favourable. But, readily to
identify the train, requires that to furnish the boulders there should be in the line of
the ice-movement a projecting mass of rock hard enough to offer considerable
resistance to the abrading agency of the ice and characteristic enough in its
composition to be readily recognised. Ship Rock, in Peabody, Mass., weighing about
eleven hundred tons, and Mohegan Rock, in Montville, Conn., weighing about ten
thousand tons, have ordinarily been pointed to as boulders illustrating the power of
ice-action. Their glacial character, however, has been challenged from the fact that
the variety of granite to which they belong occurs in the neighbourhood, and indeed
constitutes the bed-rock upon which they rest.[AV] Some would therefore consider
them, like some of which we have already spoken, to be boulders which have

originated through the disintegration of great masses of rock, of which these were
harder nuclei that have longer resisted the ravages of the tooth of time. It must be
admitted that possibly this explanation is correct; but it is scarcely probable that, in a
region where there are so many other evidences of glacial action, these boulders
could have remained immovable in presence of the onward progress of the ice-
current that certainly passed over them.
[AV] Popular Science Monthly, vol. xxxvii, pp. 196-201.

However, as already seen, we are not left to doubt as to the movement of some
boulders of great size. That which now claims the reputation of being the largest in
New England is in Madison, N. H., and measures thirty by forty by seventy-five feet.
This can be traced to ledges of Conway granite, about two miles away.[AW] Many
boulders in the vicinity of New Haven, Conn., can be identified, as from well-known
trap-dykes, sixteen miles or more to the north. The so-called Judge’s Cave, on West
Rock, 365 feet above the adjoining valley and weighing a thousand tons, is one of
these. Professor Edward Orton[AX] describes a mass of Clinton limestone near
Freeport, Warren County, Ohio, as covering an area of three-fourths of an acre, and as
sixteen feet in thickness. It overlies glacial clays and gravels, and must have been
transported bodily from the elevations containing this rock several miles to the
northwest.
[AW] See W. 0. Crosby’s paper in Appalachia, vol. vi, pp. 59-70.
[AX] Geological Survey of Ohio, vol. iii, p. 385,

Fig. 26.—Mohegan Rock.

Portions of New England present the best illustrations anywhere afforded in
America of what are called “drumlins.” These are “lenticular-shaped” hills,
composed of till, and containing, interspersed through their mass, numerous
scratched stones of all sizes. They vary in length from a few hundred feet to a mile,
and are usually from half to two-thirds as wide as they are long. In height they vary
from twenty-five to two hundred feet.
But, according to the description of Mr. Upham, whatever may be their size and
height, they are singularly alike in outline and form, usually having steep sides, with
gently sloping, rounded tops, and presenting a very smooth and regular contour. From
this resemblance in shape to an elliptical convex lens, Professor Hitchcock has called
them lenticular hills to distinguish these deposits of till from the broadly flattened or
undulating sheets which are common throughout New England.

Fig. 27.—Drumlins in Goffstown, N. H. (Hitchcock).

The trend, or direction of the longer axis, of these lenticular hills is nearly the
same for all of them comprised within any limited area, and is approximately like the
course of the striæ or glacial furrows marked upon the neighbouring ledges. In
eastern Massachusetts and New Hampshire, within twenty-five miles of the coast, it
is quite uniformly to the southeast, or east-southeast. Farther inland, in both of these
States, it is generally from north to south, or a few degrees east of south; while in the
valley of the Connecticut River it is frequently a little to the west of south. In New
Hampshire, besides its accumulation in these hills, the till is frequently amassed in
slopes of similar lenticular form. These have their position almost invariably upon
either the south or north side of the ledgy hills against which they rest, showing a
considerable deflection towards the southeast and northwest in the east part of the
State. It cannot be doubted that the trend of the lenticular hills, and the direction
taken by these slopes, have been determined by the glacial current, which produced
the striæ with which they are parallel.[AY]
[AY] Proceedings of the Boston Society of Natural History, vol. xx, pp. 224, 225.

Drumlins are abundant in the vicinity of Boston, and constitute nearly all the
islands in Boston Harbour. On the mainland, Beacon Hill, Bunker Hill, Green Hill,

Powderhorn Hill, Tufts College Hill, Winter Hill, Mount Ida, Corey Hill, Parker Hill,
Wollaston Heights, Prospect Hill, and Telegraph Hill are specimens.
The northeastern corner of Massachusetts and the southeastern corner of New
Hampshire are largely covered with these peculiar-shaped glacial deposits, while they
are numerous as far west as Fitchburg, in Massachusetts, and Ware, N. H., and in the
northeastern part of Connecticut. A little later, also, we shall refer to an interesting
line of them in central New York. Elsewhere in America, except in a portion of
Wisconsin, they rarely occur in such fine development as in New England. In Europe
they are best developed in portions of Ireland.
One’s first impression in examining an exposed section of a drumlin would lead
him to think that the mass was entirely unstratified; but closer examination shows
that there is a coarse stratification, but evidently not produced by water-action. The
accumulation has probably taken place gradually by successive deposits underneath
the glacier itself. Professor William M. Davis has suggested a plausible explanation
which we will briefly state.

Fig. 28.—Drumlins in the vicinity of Boston
(Davis).

The frequency with which drumlins are found to rest upon a mass of projecting
rock, the general co-ordination of the direction of their axes with the direction of the
scratches upon the underlying rock, and the abundance of scratched stones in them,
all support the theory that drumlins are formed underneath the ice-sheet, somewhat in
the way that islands and bars of silt are formed in the delta of a great river. The
movement of ice seems to have been concentrated in pretty definite lines, often
determined by the contour of the bottom, leaving a slacker movement in intervening
areas, which were evidently protected in some cases by projecting masses of rock. In

these areas of slower movement there was naturally an accumulation at the same time
that there was vigorous erosion in the lines of more rapid movement.
There was doubtless a continual transfer of material from the end of the drumlin
which abutted against the moving mass of ice to the lower end, as there is in the
formation of an island in a river. If time enough had elapsed, the whole accumulation
would have been levelled by the glacier and spread over the broader area where the
more rapid lines of movement became confluent, and where the differential motion
was less marked. Drumlins are thus characteristic of areas in the glaciated region
whose floor was originally only moderately irregular, and where there was an
excessive amount of ground-moraine to be transported, and where the movement did
not continue indefinitely. It has been suggested, also, that some of the long belts of
territory in New England and central New York covered by drumlins may represent
old terminal moraines which were subsequently surmounted by a readvance of the
ice, and partially wrought over into their present shape.
It is in New England, also, that kames are to be found in better development than
anywhere else in America. These interesting remnants of the Glacial age are clearly
described by Mr. James Geikie. His account will serve as well for New England as
for Scotland.
The sands and gravels have a tendency to shape themselves into mounds and
winding ridges, which give a hummocky and rapidly undulating outline to the
ground. Indeed, so characteristic is this appearance, that by it alone we are often able
to mark out the boundaries of the deposits with as much precision as we could were
all the vegetation and soil stripped away and the various subsoils laid bare.
Occasionally, ridges may be tracked continuously for several miles, running like
great artificial ramparts across the country. These vary in breadth and height, some of
the more conspicuous ones being upward of four or five hundred feet broad at the
base, and sloping upward at an angle of twenty-five or even thirty-five degrees, to a
height of sixty feet and more above the general surface of the ground. It is most
common, however, to find mounds and ridges confusedly intermingled, crossing and
recrossing each other at all angles, so as to enclose deep hollows and pits between.
Seen from some dominant point, such an assemblage of kames, as they are called,
looks like a tumbled sea—the ground now swelling into long undulations, now rising
suddenly into beautiful peaks and cones, and anon curving up in sharp ridges that
often wheel suddenly round so as to enclose a lakelet of bright clear water.[AZ]
[AZ] The Great Ice Age, pp. 210, 211.

Fig. 29.—Section of kame near Dover, New Hampshire. Length,
three hundred feet; height, forty feet; base, about forty feet above
the Cocheco River, or seventy-five feet above the sea. a, a, gray
clay; b, fine sand; c, c, coarse gravel containing pebbles from six
inches to one foot and a half in diameter; d, d, fine gravel (Upham).

Fig. 30.—Kames in Andover Mass.

In New England attention was first directed to kames in 1842, by President
Edward Hitchcock, in a paper before the American Association of Geologists and
Naturalists, describing the gravel ridges in Andover, Mass. In the accompanying plate
is shown a portion of this kame system, which has a double interest to me from the
fact that it was while living upon the banks of the Shawshin River, near where the
kames and the river intersect, that I began, in 1874, my special study of glacial
deposits. The Andover ridges are composed of imperfectly stratified water-worn
material, and are very sharply defined, from the town of Chelsea, back from the coast
into New Hampshire, for a distance of twenty-five miles. The base of the ridges does
not maintain a uniform level, but the system descends into shallow valleys, and rises
over elevations of one hundred to two hundred feet, without interruption. This
indifference to slight changes of level is specially noticeable where the system

crosses the Merrimac River, just above the city of Lawrence. It is also represented in
the accompanying plate, where the base of the ridges in the immediate valley of the
Shawshin is fifty feet lower than the base of those a short distance to the north, at the
points marked a, b, and c. The ridges here terminate at the surface in a sharp angle,
and are above their base forty-one feet at a, forty-nine feet at b, and ninety-one feet at
c. Between c and b there is an extensive peat-swamp, filling the depression up to the
level of an outlet through which the surplus water has found a passage.

Fig. 31.—Longitudinal kames near Hingham, Massachusetts. The parallel ridges of gravel in the foreground run
nearly east and west, and coalesce at each end, near the edges of the picture, to form an elongated kettle-hole. The
ridges from fifty to sixty feet in height. The kame-stream was here evidently emptying into the ocean a few miles
to the east (Bouvé).

Several systems of kames approximately parallel to this have been traced out in
Massachusetts and New Hampshire, while the remnants of a very extensive system
are found in the Connecticut Valley above the Massachusetts line. But they abound in
greatest profusion in the State of Maine, where Professor George H. Stone has plotted
them with much care. The accompanying map gives only an imperfect representation
of the ramifying systems which he has traced out, and of the extent to which they are
independent of the present river-channels. One of the longest of these extends more
than one hundred miles, crossing the Penobscot River nearly opposite Grand Lake,
and terminating in an extensive delta of gravel and sand in Cherryfield, nearly north
of Mount Desert. This is represented on our map by the shaded portion west of the
Machias River. Locally these ridges are variously designated as “horsebacks,”
“hogbacks,” or “whalebacks,” but that in Andover, Mass., was for some reason called
“Indian Ridge.” Nowhere else in the world are these ridges better developed than in
New England, except it be in southern Sweden, where they have long been known
and carefully mapped.

Fig. 32.—The kames of Maine and southeastern New Hampshire.
(Stone.)

The investigations of Mr. W. 0. Crosby upon the composition of till in eastern
Massachusetts is sufficiently important in its bearings upon the question of glacial
erosion to merit notice at this point.[BA] The object of his investigations was to
determine how much of the so-called ground moraine, or till, consisted of material
disintegrated by mechanical action, and how much by chemical action. The
“residuary clay,” which has arisen from chemical decomposition, would properly be
attributed to the disintegrating agencies of preglacial times, while the clay, which is
strictly mechanical in its origin, remains to represent the true “grist” or “rock flour”
of the Glacial period.
[BA] Proceedings of the Boston Society of Natural History, vol. xxv (1890), pp. 115-
140.

The results of Mr. Crosby’s investigations show that “not more than one-third of
the detritus composing the till of the Boston Basin was in existence before the Ice
age, and that the remaining two-thirds must be attributed to the mechanical action of
the ice-sheet and its accompanying torrents of water. In other words, if we assume the
average thickness of the drift as thirty feet, the amount of glacial erosion can scarcely

fall below twenty feet. After scraping away the residuary clays and half-decomposed
material, the ice-sheet has cut more than an equal depth into the solid rocks.”
Mr. Crosby’s investigations also convinced him that the movement of the till, or
ground moraine, underneath the ice was not en masse, but that “it must have
experienced differential horizontal movements or flowing, in which, normally, every
particle or fragment slipped or was squeezed forward with reference to those
immediately below it, the velocity diminishing downward through the friction of the
underlying ledges.... The glaciation was not limited to masses which were firmly
caught between the ice and the solid ledges, and it was in every case essentially a
slipping and not a rolling movement.... These differential horizontal movements
mean that the till acted as a lubricant for the ice-sheet; and the clayey element,
especially, co-operating in many cases with the pent-up subglacial waters, must have
greatly facilitated the onward progress of the ice.” He concludes, therefore, that the
onward movement of the vast ice-sheet greatly exceeded that of the main part of the
ground moraine, the ice-sheet slipping over the till, the whole being in some degree
analogous to that of a great land-slip. “In both cases the progress of a somewhat
yielding and mobile mass is facilitated by an underlying clayey layer saturated with
water.”

New York, New Jersey, and Pennsylvania.
West of New England the glacial phenomena over the northern part of the United
States are equally marked all the way to the Missouri River, and the boundary-line of
the glaciated region can be traced with little difficulty. It emerges from New York
Bay on Staten Island and enters New Jersey at Perth Amboy. A well-formed moraine
covers the northern part of Staten Island, and upon the mainland marks the boundary
from Perth Amboy, around through Raritan, Plainfield, Chatham, Morris, and
Hanover, to Rockaway, and thence in a southwesterly direction to Belvidere, on the
Delaware River. That portion of New Jersey lying north of this serpentine line of
moraine hills is characterised by the presence of transported boulders, by numerous
lakes of evident glacial origin, and by every other sign of glacial action, while south
of it all these peculiar characteristics are absent. The observant passenger upon the
railroad trains between New York and Philadelphia can easily recognise the moraine
as it is passed through on the Pennsylvania Railroad at Metuchen and on the Bound
Brook Railroad at Plainfield. Near Drakestown, in Morris County, there is a mass of
blue limestone measuring, as exposed, thirty-six by thirty feet, and which was
quarried for years before discovering that it was a boulder brought with other drift
material from many miles to the northwest and lodged here a thousand feet above the
sea.

Across Pennsylvania the glacial boundary passes through Northampton, Monroe,
Luzerne, Columbia, Sullivan, Lycoming, Tioga, and Potter Counties, where it enters
the State of New York, running still in a northwest direction through Allegany and
Cattaraugus Counties to the vicinity of Salamanca. Here it turns to the south nearly at
a right angle, running southwestward to Chautauqua County and re-entering
Pennsylvania in Warren County, and thence passing onward in the same general
direction through Crawford, Venango, Mercer, Butler, and Lawrence Counties to the
Ohio line in Columbiana County, about ten miles north of the Ohio River.
The occurrence of a well-defined terminal moraine to mark the glacial boundary
eastward from Pennsylvania led Professor Lewis and myself, who made the survey of
that State in 1880, to be rather too sanguine in our expectations of finding an equally
well-marked moraine everywhere along the southern margin of the glaciated area;
still, the results are even more interesting than would have been the exact fulfilment
of our expectations, since they more fully revealed to us the great complexity of
effect which is capable of being brought about by ice-action. Before proceeding
farther with the details, therefore, it will be profitable at this point to pause in the
narrative and briefly record a few generalisations that have forced themselves into
prominence during the years in which field-work has been in progress.
Previous to our explorations in Pennsylvania it had been thought that the
indications of ice-action would extend much farther south in the valleys than on the
mountains, and this indeed would have been the case if the glaciers in northern
Pennsylvania had been of local origin; but our experience very soon demonstrated
that the great gathering-place of the snows which produced the glacial movement in
northern Pennsylvania could not have been local, but that over the northern part of
that State there was distinct evidence of a continental movement of ice whose centre
was far beyond the Alleghanies.
For example, we found that the evidences of direct glacial action extended farther
south upon the hills and plateaus than they did in the narrow valleys, while
everywhere on the very southern border of glacial indications we found boulders that
had been brought from the granitic region of northern New York or central Canada. In
eastern Pennsylvania we found indeed a terminal moraine more or less distinctly
marking the southern border over the highlands. This was more specially true in
Northampton and Monroe Counties.
In Northampton County it was very interesting to see long lines of hills, a
hundred or more feet in height and lying several hundred feet above the Delaware
River, composed entirely of glacial débris, much of which had been brought bodily
over the sharp summit of the Blue Ridge, or Kittatinny Mountain, which rises as a
continuous wall to the northwest and is everywhere several hundred feet higher than
the moraine in Northampton County. The summit of Blue Ridge, also, as far south as

the glacial movement extended, shows evident signs of glacial abrasion, some
hundreds of feet evidently having been removed by that means, leaving a well-
defined shoulder, marking the limits of its southwestern border. Resting upon the
summit of the glaciated portion of the Blue Ridge, there are also numerous boulders
of Helderberg limestone, which must have been brought from ledges at least five
hundred feet lower than the places upon which they now lie.
In Monroe County the terminal moraine marking there the extreme limit of the
ice-movement is upon an extensive plateau of Pocono sandstone, about eighteen
hundred feet above sea-level, and five or six hundred feet lower than the crest of the
Alleghany Mountains, a short distance to the north. The moraine hills are here well
marked by the occurrence of circular lakelets and kettle-holes (such as have been
described as characteristic of the shores and islands bordering the south of New
England); by the occurrence of granitic boulders, which must have been brought from
the Adirondacks or Canada; and by the various other indications referred to on a
previous page.
As already intimated, the instructive point in our observations is the fact that,
between Kittatinny Mountain, in Northampton County, and Pocono plateau, in
Monroe County, there is a longitudinal depression, running northeast by southwest,
parallel with the ranges of the mountain system, which is here about a thousand feet
below the respective ridges on either side. This, therefore, is one of the places where
we should have expected a considerable southern extension of the ice, if it had been
largely due to local causes. Now, while there is indeed a gradual southern trend down
the flanks of the mountain, yet, upon reaching the axis of the valley, there appears at
once a very marked change in the character of the deposit, and the influence of
powerful streams of water becomes manifest, and it is evident, upon a slight
inspection, that we have come upon a line of drainage which sustained a peculiar
relation to the continental ice-sheet.
From Stroudsburg, near the Delaware Water-Gap, to Weissport, on the Lehigh
River, a distance of about thirty miles, the valley between the mountains is
continuous, and the elevation at each end very nearly the same. But about half-way
between the two places, near Saylorsburg, there is a river-parting from which the
water now runs on the one hand north to Stroudsburg, and thence to the Delaware
River, and on the other hand south, through Big and Aquonchichola Creeks, to the
Lehigh River. The river-parting is formed by a great accumulation of gravel, whose
summit is about two hundred feet above the level of the valleys into which the creeks
empty at either end; and there are numerous kettle-holes and lakelets in the vicinity,
such as characterize the glacial region in general.
In short, we are, without doubt, here on a well-marked terminal moraine much
modified by strong water-action in a valley of glacial drainage. The gravel and

boulders are all well water-worn, and the material is of various kinds, including
granite boulders from the far north, such as characterise the terminal moraine on the
highlands; but the pebbles are not scratched, and the gravel is more or less stratified.
It is evident that we are here where a violent stream of water poured forth from that
portion of the ice-front which filled this valley, and which found its only outlet in the
direction of the Lehigh River. The gravel can be traced in diminishing quantities to
the southward, in accordance with this theory, while to the northward there extends a
series of gravel ridges, or kames, such as we have shown naturally to owe their origin
to the accumulations taking place in ice-channels formed near the front of a glacier as
it slowly melts away.
From similar occurrences of vast gravel accumulations in other valleys stretching
southward from the glacial margin, we came to expect that, wherever there was an
open, line of drainage from the glaciated region southward, the point of intersection
between the glacial margin and the drainage valley would be marked by an excessive
accumulation of water-worn gravel, diminishing in coarseness and abundance down
the valleys in proportion to the distance from the glacial margin.
For example, the Delaware River emerges from the glaciated region at Belvidere,
and there are there vast accumulations of gravel rising a hundred or more feet above
the present level of the river, while gravel terraces, diminishing in height, mark the
river below to tide-water at Trenton. The Lehigh River leaves the glaciated region at
Hickory Run, a few miles above Mauch Chunk, but the gorge is so steep that there
was little opportunity either for the accumulation of gravel there or for its
preservation. Still, the transported gravel and boulders characteristic of the melting
floods pouring forth from a glacier, are found lining the banks of the Lehigh all along
the lower portion of its course. In the Susquehanna River we have a better example at
Beach Haven, in Luzerne County, where there are very extensive accumulations of
gravel resting on the true glacial deposits of the valley, and extending down the river
in terraces of regularly diminishing height for many miles, and merging into terraces
of moderate elevation which line the Susquehanna Valley throughout the rest of its
course. Above Beach Haven the gravel deposits in the trough of the river valley are
more irregular, and betray the modifying influence of the slowly decaying masses of
ice which belonged to the enveloping continental glacier.
Westward from the north fork of the Susquehanna, similar extensive
accumulations of gravel occur at the intersection of Fishing Creek in Columbia
County, Muncy, Loyalsock, Lycoming, and Pine Creeks in Lycoming County, all
tributary to the Susquehanna River, and all evidently being channels through which
the melting floods of the ice-sheet brought vast quantities of gravel down to the main
stream. Williamsport, on the West Branch of the Susquehanna, is built upon an
extensive terrace containing much granitic material, brought down from the glaciated
region by Lycoming Creek, when it was flooded with the waters melted from the

continental ice-sheet which had here surmounted the Alleghanies and invaded the
valley of the Susquehanna.
Analogous deposits of unusual amounts of gravel, occurring in streams flowing
southward from the glaciated region, occur at Great Valley, Little Valley, and
Steamburg in Cattaraugus County, New York, and at Russelburg and Garland in
Warren County, Pennsylvania, also at Titusville and Franklin in Venango County, and
at Wampum in Lawrence County, of the same State.
As a rule, Professor Lewis and myself found it more difficult to determine with
accuracy the exact point to which the ice extended in the axis of these south-flowing
valleys than we did upon the highlands upon either side; and, in looking for the
positive indications of direct ice-action in these lines of drainage, we were almost
always led up the valley to a considerable distance inside of the line. This arose from
our inexperience in interpreting the phenomena, or rather from our inattention to the
well-known determining facts in the problem. On further reflection it readily
appeared that this was as it should be. The ice-front, instead of extending farther
down in a narrow valley than on the adjoining highlands (where they are of only
moderate elevation) ought not to extend so far, for the subglacial streams would not
only wear away the ice of themselves, but would admit the air into the tunnels formed
by them so as to melt the masses both from below and from above, and thus cause a
recession of the front. If we had understood this principle at the beginning of our
survey, it would have saved us much perplexity and trouble.
A single further illustration of this point will help to an understanding of many
references which will hereafter be made to the water deposits which accumulated in
the lines of drainage running southward from the glaciated area. At Warren, Pa.,
Conewango Creek, which is the outlet from Chautauqua Lake, enters the Alleghany
River after flowing for a number of miles in a deep valley with moderate slopes. In
ascending the creek from Warren, the gravel terraces, which rise twenty-five or thirty
feet above high-water mark, rapidly increase in breadth and height, and the pebbles
become more and more coarse. After a certain distance the regular terraces begin to
give place to irregular accumulations of gravel in ridges and knobs. In the lower
portion of the valley no pebbles could be found which were scratched. Up the valley
a few miles pebbles were occasionally discovered which showed some slight
indications of having been scratched, but which had been subjected to such an
amount of abrasion by water-action as almost to erase the scratches. On reaching
Ackley’s Station, the stream is found to be cutting through a regular terminal
moraine, extending across the valley and full of clearly marked glaciated stones.
Above this terminal moraine the terraces and gravel ridges which had characterised
the valley below disappear, giving place to long stretches of level and swampy land,
which had been subject to overflow.

Something similar to this so often appears, that there can be no question as to its
meaning, which is, that during the farthest extent of the ice the front rested for a
considerable period of time along the line marked by the terminal moraine. During
this period there occurred both the accumulation of the moraine and of the gravel
terraces in the valley below, due to the vast flow of water emerging from the ice-
front, especially during the period when it was most rapidly melting away. Upon the
retreat of the ice, the moraine constituted a dam which has not yet been wholly worn
away. For a while the water was so effectually ponded back by this as to form a lake,
which has since become filled up with sediment and accumulations of peat. From this
it is evident, also, that when the ice began to retreat, the retreat was so continuous and
rapid that no parallel terminal moraines were formed for many miles.
Before leaving this section we will summarise the leading facts concerning the
glacial phenomena north of Pennsylvania and New Jersey. From the observations of
Professor Smock, it appears that, from the southern margin the ascent to the summit
of the ice-sheet was pretty rapid; the depth one mile back from the margin being not
much less than a thousand feet. “Northward the angle of the slope diminished, and
the glacier surface approximated to a great level plain. The distance between the high
southwestern peaks of the Catskills and Pocono Knob in Pennsylvania is sixty miles.
The difference in the elevation of the glacier could not have exceeded a thousand
feet,” [BB] that is, the slope of the surface was about seventeen feet to the mile.
[BB] American Journal of Science, vol. cxxv, 1883, p. 339 et seq.

Professor Dana estimates the thickness of the ice in southern Connecticut to have
been between fifteen hundred and two thousand feet. Attempts to calculate the
thickness of the ice farther north, except from actual discovery of glacial action on
the summits of the mountains, are based upon uncertain data with reference to the
slope necessary to secure glacial movement. In the Alps the lowest mean slopes down
which glaciers move are about two hundred and fifty feet to a mile; but in Greenland,
Jensen found the slope of the Frederickshaab Glacier to be only seventy-five feet to
the mile, while Helland found that of the Jakobshavn Glacier to be only forty-five
feet.
It is doubtful if even that amount is necessary to secure a continental movement
of ice, since, as already remarked, it is unsafe to draw inferences concerning the
movements of large masses of ice from those of smaller masses in more constricted
areas. We have seen, from the glacial deposits on the top of Mount Washington, that
over the northern part of New England the ice was more than a mile in depth. We
have no direct evidence of the depth of the stream which surrounded the Adirondack
Mountains. Nor, on the other hand, are we certain that the Catskills were not
completely enveloped in ice, though most observers, reasoning from negative
evidence, have supposed that to be the case. But from the facts stated concerning the

boulders along the glacial boundary in Pennsylvania, it is certain that the ice was
deep enough to surmount the ridge of the Alleghanies where they are two thousand
and more feet in height. At the least calculation the ice must have been five hundred
feet thick, in order to secure the movement of which there is evidence across the
Appalachian range. Supposing this to be the height of the ice above the sea on the
crest of the Alleghanies, and that the slope of the surface of the ice-sheet was as
moderate as Professor Smock has estimated it (namely seventeen feet to the mile), the
ice would be upwards of six thousand feet in thickness in the latitude of the
Adirondacks, which corresponds closely with the positive evidence Ave have from
the mountains in New England.
A study of the map of New York will make it easy to understand the distribution
of some interesting glacial marks over the State. The distance along the Hudson from
the glacial boundary in the vicinity of New York to the valley of the Mohawk is about
one hundred and sixty miles. Prom the glacial boundary at Salamanca, N. Y., to the
same valley, is not over eighty miles. It is easy to see, therefore, that when, in
advancing, the ice moved southward past the Adirondacks, the east end of the valley
of the Mohawk was reached and closed by the ice, while at the west end of Lake
Ontario the ice-front was still in Canada. Thus the drainage, which naturally followed
the course of the St. Lawrence, would first be turned through the Mohawk.
Afterwards, when the Mohawk had been closed by ice, the vast amount of ponded
water was compelled to seek a temporary outlet over the lower passages leading into
the Susquehanna or into the Alleghany.
A number of such passages exist. One can be traced along the line of the old canal
from Utica to Binghamton, whose highest level is not far from eleven hundred feet.
Another lies in a valley leading south of Cayuga Lake, whose highest point, at
Wilseyville, is nine hundred and forty feet above tide. Another leads south to the
Chemung River from Seneca Lake, whose highest point, at Horseheads, is less than
nine hundred feet above tide. The cols farther west are somewhat more elevated; the
one at Portage, leading from the Genesee River into the Canisteo, being upwards of
thirteen hundred feet, and that of Dayton, leading from Cattaraugus Creek into the
Conewango, being about the same. Of other southern outlets farther west we will
speak later on.
Fixing our minds now upon the region under consideration, in the southern part of
the State of New York, we can readily see that a glacial lake must have existed in
front of the ice while it was advancing, until it had reached the river-partings between
the Mohawk and the St. Lawrence Rivers on the north and the Susquehanna and
Alleghany Rivers on the south. After the ice had attained its maximum extension, and
was in process of retreat, there would be a repetition of the phenomena, only they
would occur in the reverse order. The glacial markings which we see are, of course,
mainly those produced during the general retreat of the ice.

The Susquehanna River stretching out its arms—the Chenango and Chemung
Rivers—to the east and the west, evidently serves as a line of drainage for the vast
glacial floods. These floods have left, along their courses, extensive elevated gravel
terraces, with much material in them which is not local, but which has been washed
out of the direct glacial deposits from the far north. The east-and-west line of the
water-parting throughout the State is characterised by excessive accumulations of
glaciated material, forming something like a terminal moraine, and is designated by
President Chamberlin as “the terminal moraine of the second Glacial epoch,”
corresponding, as he thinks, to the interior line already described as characterising the
south shore of New England.
In the central part of New York the remarkable series of “Finger Lakes,” tributary
to Lake Ontario and emptying into it through the Oswego and Genesee Rivers, all
have a glacial origin. Probably, however, they are not due in any great degree to
glacial erosion, but they seem to occupy north-and-south valleys which had been
largely formed by streams running towards the St. Lawrence when there was, by
some means (probably through the Mohawk River), a much deeper outlet than now
exists, but which has been filled up and obliterated by glacial débris. The ice-
movement naturally centred itself more or less in these north-and-south valleys, and
hence somewhat enlarged them, but probably did not deepen them. The ice, however,
did prevent them from becoming filled with sediment, and on its final retreat gave
place to water.
Between these lakes and Lake Ontario, also, and extending east and west nearly
all the way from Syracuse to Rochester, there is a remarkable series of hills, from one
hundred to two or three hundred feet in height, composed of glacial débris. But while
the range extends east and west, the axis of the individual hills lies nearly north and
south. These are probably remnants of a morainic accumulation which were made
during a pause in the first advance of the ice, and were finally sculptured into their
present shape by the onward movement of the ice. These are really “drumlins,”
similar to those already described in northeastern Massachusetts and southeastern
New Hampshire. In the valley of central New York these have determined the lines of
drainage of the “Finger Lakes,” and formed dams across the natural outlets of nearly
all of them.
North of the State of New York the innumerable lakes in Canada are all of glacial
origin, being mostly due to depressions of the nature of kettle-holes, or to the
damming up of old outlets by glacial deposits. A pretty well-marked line of moraine
hills, formed probably as terminal deposits in the later stages of the Ice age, runs
from near the eastern end of Lake Ontario to the Georgian Bay, passing south of Lake
Simcoe.

The Mississippi Basin.

The physical geography of the glaciated region north of the Ohio River is so
much simpler than that of New England and the Middle States, that its characteristics
can be briefly stated. Ohio, Indiana, and Illinois are covered with nearly parallel
strata of rock mostly of the Carboniferous age. In general, the surface slopes gently to
the west; the average elevation of Ohio being about a thousand feet above tide, while
that of the Great Lakes to the north and of the middle portion of the Mississippi
Valley is less than six hundred feet. The glacial deposits are spread in a pretty even
sheet over the area which was reached by the ice in these States, and the lines of
moraine, of which a dozen or more have been partially traced in receding order, are
much less clearly marked than they are in New England, or in Michigan, and the
States farther to the northwest.
The line marking the southern limit attained by the ice of the Glacial period in
these three States is as follows: Entering Ohio in Columbiana County, about ten miles
north of the Ohio River, the glacial boundary runs westward through New Lisbon to
Canton in Stark County, and thence to Millersburg in Holmes County. A few miles
west of this place it turns abruptly south, passing through Danville in Knox County,
Newark in Licking County, Lancaster in Fairfield County, to Adelphi in Ross County.
Thence bearing more westward it passes through Chillicothe to southeastern
Highland County and northwestern Adams, reaching the Ohio River near Ripley, in
Clermont County. Thence, following the north bank of the Ohio River to Cincinnati,
it crosses the river, and after extending through the northern part of Boone County,
Kentucky, and recrossing the river to Indiana, not far from Rising Sun, it again
follows approximately the north bank of the river to within about ten miles of
Louisville, Ky., where it bends northward running through Clarke, Scott, Jackson,
Bartholomew, and Brown Counties to Martinsville, in Morgan County, where it turns
again west and south and follows approximately the West Branch of the White River
through Owen, Greene, and Knox Counties, where it crosses the main stream of
White River, and, continuing through Gibson and Posey Counties, crosses the
Wabash River near New Harmony.
In Illinois the line still continues southwesterly through White, Gallatin, Saline,
and Williamson Counties, where it reaches its southern limit near Carbondale, in
latitude 37° 40’, and from this point trends northwestward, approximately following
the northeastern bluff of the Mississippi River, to the vicinity of Carondelet, Mo., a
short distance south of St. Louis.
Beyond the Mississippi the line follows approximately the course of the Missouri
River across Missouri, and continues westward to the vicinity of Manhattan, in
Kansas, where it turns northward, keeping about a hundred miles west of the
Missouri River, through eastern Kansas and Nebraska, and striking the river near the
mouth of the Niobrara, in South Dakota. From there the line follows approximately

the course of the Missouri River to the vicinity of Fort Benton, in northwestern
Montana, where the line again bears more northward, running into British America.
It is still in dispute whether the ice extended from the eastern centre far enough
west to join the ice-movement from the Rocky Mountain plateau. Dr. George M.
Dawson[BC] is of the opinion that it did not, but that there was a belt of a hundred
miles or more, east of the Rocky Mountains, which was never covered by true glacial
ice. Mr. Upham[BD] is equally confident that the two ice-movements became
confluent, and united upon the western plateau of Manitoba. The opportunity for such
a difference of opinion arises in the difficulty sometimes encountered of
distinguishing between a direct glacial deposit and a deposit taking place in water
containing boulder-laden icebergs. Where Mr. Upham supposes the ice-fields of the
east and of the west to have been confluent in western Manitoba, Dr. Dawson
supposes there was an extensive subsidence of the land sufficient to admit the waters
of the ocean. Leaving this question for the present undetermined, we will now rapidly
summarise the glacial phenomena west of the third meridian from Washington (which
corresponds nearly with the western boundary of Pennsylvania), and east of the
Rocky Mountains.
[BC] Transactions of the Royal Society of Canada, vol. viii, sec. iv, pp. 54-74.
[BD] American Geologist, vol. vi, September, 1890; Bulletin of the Geological Society
of America, vol. ii, pp. 243-276.

That the glacial movement extended to the southern boundary just delineated is
established by the presence down to that line of all the signs of glacial action, and
their absence beyond. Glacial groovings are found upon the freshly uncovered rock
surfaces at frequent intervals in close proximity to the line all along its course, while
granitic boulders from the far north are scattered, with more or less regularity, over
the whole intervening space between this line and the Canadian highlands. I have
already referred to a boulder of jasper conglomerate found in Boone County,
Kentucky, which must have come from unique outcroppings of this rock north of
Lake Huron. Granitic boulders from the Lake Superior region are also found in great
abundance at the extreme margin mentioned in southern Illinois. West of the Missouri
River it is somewhat more difficult to delineate the boundary with accuracy, on
account of an enveloping deposit of fine loam, technically called “loess.” Loess is
very abundant in the whole valley of the Missouri River below Yankton, South
Dakota, being for a long distance in the vicinity of the river a hundred feet or more in
depth. Over northern Missouri and southern Illinois the deposit is nearly continuous,
but less in depth, and everywhere in that region tends to hide from view the
unstratified glacial deposit continuously underlying it.
A single instance of personal experience will illustrate the condition of things.
While going south from Chicago, in search of the southern limit of glacial action, I

stopped off from the train at Du Quoin, about forty miles north of where I
subsequently found the boundary. Here the whole surface was covered with loess,
two or three feet in depth. Below this was a gravelly soil, three or four feet in
thickness, which contained many scratched pebbles of granite. A well which had
recently been dug, reached the rock at a depth of twenty feet, and revealed a
beautifully polished and scratched surface, betraying, beyond question, the action of
glacial ice. As we shall show a little later, it is probable that, about the time the ice of
the Glacial period had reached its maximum development, this area, which is covered
with loess, was depressed in level, and remained under water during a considerable
portion of the period when the ice-front was retreating.

Fig. 33.—Western face of the kettle-moraine, near Eagle, Waukesha County, Wisconsin. (From a photograph by
President T. C. Chamberlain, United States Geological Survey.)

To such an extent is this portion of the area included in southern Iowa, northern
Missouri, southern Illinois, and the extreme southern portions of Indiana and Ohio
covered with loess, that it has been difficult to determine the relation of its underlying
glacial deposits to the more irregular deposits found farther north. At an early period
of recent investigations, while making a geological survey of the State of Wisconsin,
President T. C. Chamberlin fixed upon the line of moraine hills, which can be seen
upon our map, running southward between Green Bay and Lake Michigan, and
sweeping around in a curve to the right, passing south of Madison and northward
along the line of Wisconsin River, and in another curve to the left, around the
southern end of Lake Michigan, as the “terminal moraine of the second Glacial
epoch.” In Wisconsin the character of this line of moraine hills had been discovered
and described by Colonel Charles Whittlesey, in 1866. It was first named the “kettle-
moraine,” because of the frequent occurrence in it of “kettle-holes.” This line of

moraine hills has been traced with a great degree of confidence across the entire
glaciated area, as shown upon our map, but it is not everywhere equally distinct, and,
as will be observed, follows a very irregular course.
Beginning in Ohio we find it coinciding nearly with the extreme glacial boundary
until it reaches the valley of the Scioto River, on the sixth meridian west from
Washington, where it begins to bear northward and continues in that direction for a
distance of sixty or seventy miles, and then turns southward again in the valley of the
Miami, having formed between these two valleys a sort of medial moraine.[BE] A
similar medial moraine had also been noted by President Chamberlin between the
valleys of the Grand and Cuyahoga Rivers, in the eastern part of Ohio. Indeed, for the
whole distance across Ohio and Indiana, this moraine occurs in a series of loops
pointing to the south, corresponding in general to the five gentle valleys which mark
the territory, namely, those of the Grand and Mahoning Rivers; the Sandusky and
Scioto Rivers; the Great Miami River; the White River; and the Maumee and Wabash
Rivers. Everywhere, however, over this area these morainic accumulations
approximate pretty closely to the extreme boundary of the glaciated region.
[BE] See map at the beginning of the chapter.

In Illinois President Chamberlin’s original determination of the moraine fixed it
near the southern end of Lake Michigan, as shown upon our map, but Mr. Frank
Leverett has subsequently demonstrated that there is a concentric series of moraines
south of this, reaching across the State, (but somewhat obscured by superficial
accumulations of loess referred to) and extending nearly to the latitude of St. Louis.
West of Wisconsin President Chamberlin’s “terminal moraine of the second
Glacial epoch” bends southward through eastern Minnesota, and, sweeping down
through central Iowa, forms, near the middle of the northern part of that State, a loop,
having its southern extremity in the vicinity of Des Moines. The western arm of this
loop runs through Minnesota in a northwesterly direction nearly parallel with the
upper portion of the valley of the Minnesota, until reaching the latitude of the head-
waters of that river, where, in the vicinity of the Sisseton Agency, in Dakota, it turns
to the south by an acute angle, and makes a loop in that State, extending to the
vicinity of Yankton, and with the valley of the James River as its axis. The western
arm of this loop follows pretty closely the line of the eastern edge of the trough of the
Missouri River, constituting what is called the “Missouri Coteau,” which continues
on as a well-marked line of hills running in a northwesterly direction far up into the
Dominion of Canada.
One of the most puzzling glacial phenomena in the Mississippi Valley is the
driftless area which occupies the southeastern portion of Minnesota, the southwestern
part of Wisconsin, and the northwestern corner of Iowa, as delineated upon our map.
This is an area which, while being surrounded on every side by all the characteristic

marks of glaciation, is itself conspicuous for their entire absence. Its rocks preserve
no glacial scratches and are covered by no deposits of till, while northern boulders
avoided it in their journey to more southern latitudes.
The reason for all this is not evident in the topography of the region. The land is
not higher than that to the north of it, nor is there any manifest protection to it by the
highlands south of Lake Superior. Nor yet is there any reason to suppose that any
extensive changes of level in former times seriously affected its relations to the
surrounding country. Professor Dana, however, has called attention to the fact that
even now it is in a region of comparatively light precipitation, suggesting that the
snow-fall over it may always have been insignificant in amount. But this could
scarcely account for the failure of the great ice-wave of the north to overrun it. We
are indebted again to the sagacity of President Chamberlin in suggesting the true
explanation.
By referring to the map it will be noticed that this area sustains a peculiar relation
to the troughs of Lake Michigan and Lake Superior, while from the arrangements of
the moraines in front of these lakes it will be seen that these lake basins were
prominent factors in determining the direction of the movement of the surplus ice
from the north. It is the more natural that they should do so because of their great
depth, their bottoms being in both cases several hundred feet below the present water-
level, reaching even below the level of the sea.
These broad, deep channels seem to have furnished the readiest outlet for the
surplus ice of the North, and so to have carried both currents of ice beyond this
driftless area before they became again confluent. The slight elevation south of Lake
Superior served to protect the area on account of the feebleness of direct movement
made possible by the strength of these diverging lateral ice-currents. The
phenomenon is almost exactly what occurs where a slight obstruction in a river
causes an eddy and preserves a low portion of land below it from submergence. A
glance at the map will make it easily credible that an ice-movement south of
Manitoba, becoming confluent with one from Lake Superior, pushed far down into
the Missouri Valley and spread eastward to the Mississippi River, south of the
unglaciated driftless area, and there became confluent with a similar movement
which had been directed by the valleys of Lake Michigan and Lake Erie. There can
be little doubt that President Chamberlin’s explanation is in the main correct, and we
have in this another illustration of the analogy between the behaviour of moving ice
and that of moving water.

Fig. 34.—Section of the east-and-west glacial furrows, on
Kelly’s Island, preserved by Mr. Younglove. Fine sediment
rests immediately on the rock, with washed pebbles at the
surface.

The accompanying illustrations will give a better idea than words can do of the
celebrated glacial grooves on the hard limestone islands near Sandusky, in the
western part of Lake Erie. Through the interest aroused in them by an excursion of
the American Association for the Advancement of Science, while meeting in
Cleveland, Ohio, in 1888, the Kelly Island Lime and Transport Company, of which
Mr. M. C. Younglove is the president, has been induced to deed to the Western
Reserve Historical Society for preservation a portion of one of the most remarkable
of the grooves still remaining.
The portion of the groove preserved is thirty-three feet across, and the depth of
the cut in the rock is seventeen feet below the line, extending from rim to rim.
Originally there was probably here a small depression formed by preglacial water
erosion, into which the ice crowded the material, which became its graving-tool, and
so the rasping and polishing went on in increasing degree until this enormous furrow
is the result. The groove, however, is by no means simple, but presents a series of
corrugations merging into each other by beautiful curves. When exposed for a
considerable length it will resemble nothing else so much as a collection of prostrate
Corinthian columns lying side by side on a concave surface.
The direction of these grooves is a little south of west, corresponding to that of
the axis of the lake. This is nearly at right angles to the course of the ice-scratches on
the summit of the water-shed south of this, between the lake and the Ohio River. The

reason for this change of direction can readily be seen by a little attention to the
physical geography. The highlands to the south of the lake rise about seven hundred
feet above it. When the Ice period was at its climax and overran these highlands, the
ice took its natural course at right angles to the terminal moraine and flowed
southeast according to the direction indicated by the scratches on the summit; but
when the supply of ice was not sufficient to overrun the highlands, the obstruction in
front turned the course and the resultant was a motion towards Toledo and the
Maumee Valley, where in the vicinity of Fort Wayne an extensive terminal moraine
was formed.

Fig. 35.—Same as the preceding. (Courtesy of M. C. Younglove.)

The much-mooted question of a succession of glacial epochs finds the most of its
supporting facts in the portion of the glaciated area lying west of Pennsylvania. That
there have been frequent oscillations of the glacial front over this area is certain. But it
is a question whether the glacial deposits south of this distinct line of moraine hills are
so different from those to the north of it as to necessitate the supposition of two
entirely distinct glacial epochs. This can be considered most profitably here.
The following are among the points with reference to which the phenomena south
of the moraine just delineated differ from those north of the line:
1. The glacial deposits to the south appear to be distributed more uniformly than
those to the north. To the north the drift is often accumulated in hills, and is dotted
over with kettle-holes, while to the south these are pretty generally absent. Any one
travelling upon a line of railroad which traverses these two portions of the glaciated
area as indicated upon our map can easily verify these statements.
2. The amount of glacial erosion seems to be much less south of the line of
moraine hills delineated than north of them. Still, glacial striæ are found, almost
everywhere, close down to the extreme margin of the glaciated area.
3. The gravel deposits connected with the drainage of the Glacial period are much
less abundant south of the so-called “terminal moraine of the second Glacial period”
than they are north of it. South of this moraine the water deposits attributed to the
Glacial period are of such fine silt as to indicate slow-moving currents over a gentle
low slope of the surface.

4. The glacial deposits to the south are more deeply coloured than those to the
north, showing that they have been longer exposed to oxidising agencies. Even the
granitic boulders show the marks of greater age south of this line, being disintegrated
to a greater extent than those to the north.
5. And, finally, there occur, over a wide belt bordering the so-called moraine hills
of the second Glacial epoch, extensive intercalated beds of vegetal deposits. Among
the earliest of these to be discovered were those of Montgomery County, Ohio, where,
in 1870, Professor Orton, of the Ohio Survey, found at Germantown a deposit of peat
fourteen feet thick underneath ninety-five feet of till, and there seem also to be glacial
deposits underneath the peat as well as over it. The upper portion of the peat contains
“much undecomposed sphagnous mosses, grasses, and sedges, and both the peat and
the clayey till above it” contain many fragments of coniferous wood which can be
identified as red cedar (Juniperus Virginianus). In numerous other places in that
portion of Ohio fresh-appearing logs, branches, and twigs of wood are found
underneath the till, or mingled with it, much as boulders are. Near Darrtown, in Butler
County, Ohio, red cedar logs were found under a covering of sixty-five feet of till, and
so fresh that the perfume of the wood is apparently as strong as ever. Similar facts
occur in several other counties in the glaciated area of southern Ohio and southern
Indiana. Professor Collett reports that all over southwestern Indiana peat, muck, rotted
stumps, branches, and leaves of trees are found from sixty to one hundred and twenty
feet below the surface, and that these accumulations sometimes occur to a thickness of
from two to twenty feet.

Fig. 36.—Section of till near Germantown, Ohio, overlying
thick bed of peat. The man in the picture stands upon a shelf of
peat from which the till has been eroded by the stream. The dark
spot at the right hand of the picture, just above the water, is an
exposure of the peat. The thickness of the till is ninety-five feet.
The partial stratification spoken of in the text can be seen about
the middle of the picture. The furrows up and down had been
made by recent rains. (United States Geological Survey.)
(Wright.)

Farther to the northwest similar phenomena occur. Professor N. H. Winchell has
described them most particularly in Fillmore and Mower Counties, Minnesota, from
which they extend through a considerable portion of Iowa. In the above counties of
Minnesota a stratum of peat from eighteen inches to six or eight feet in thickness, with
much wood, is pretty uniformly encountered in digging wells, the depth varying from
twenty to fifty feet. This county is near the highest divide in the State of Minnesota,
and from it “flow the sources of the streams to the north, south, and east.” The wood
encountered in this stratum indicates the prevalence f coniferous trees, and the peat
mosses indicate a cool and moist climate.
Nor are intercalated vegetable deposits absent from the vast region farther north
over the area that drains into Hudson Bay. At Barnesville, in Clay County, Minnesota,
which lies in the valley of the Red River of the North, and also in Wilkin County in

the same valley, tamarack wood and sandy black mud containing many snail-shells
have been found from eight to twelve feet below a surface of till; and Dr. Robert Bell
reports the occurrence of limited deposits of lignite between layers of till, far to the
northwest, in Canada, and even upon the southern part of Hudson Bay; while Mr. J. B.
Tyrrell reports[BF] many indications of successive periods of glaciation near the
northern end of the Duck Mountain. The most characteristic indications which he had
witnessed consisted of stratified beds of silt, containing fresh-water shells, with
fragments of plants and fish similar to those living in the lakes of the region at the
present time.
[BF] Bulletin of the Geological Society of America, vol. i, pp. 395-410.

Reviewing these facts with reference to their bearing upon the point under
consideration, we grant, at the outset, that they do indicate a successive retreat and
readvance of the ice over extensive areas. This is specially clear with respect to the
vegetal deposits interstratified with beds of glacial origin. But the question at issue
concerning the interpretation of these phenomena is, Do they necessarily indicate
absolutely distinct glacial epochs separated by a period in which the ice had wholly
disappeared from the glaciated area to the north? That they do, is maintained by
President Chamberlin and many others who have wide acquaintance with the facts.
That they do not certainly indicate a complete disappearance of the ice during an
extensive interglacial epoch, is capable, however, of being maintained, without
forfeiting one’s rights to the respect of his fellow-geologists. The opposite theory is
thus stated by Dr. Robert Bell: “It appears as if all the phenomena might be referred to
one general Glacial period, which was long continued, and consequently accompanied
by varying conditions of temperature, regional oscillations of the surface, and changes
in the distributions of sea and land, and in the currents in the ocean. These changes
would necessarily give rise to local variations in the climate, and might permit of
vegetation for a time in regions which need not have been far removed from extensive
glaciers.”[BG]
[BG] Bulletin of the Geological Society of America, vol. i, pp. 287-310.

At my request, Professor J. E. Todd, of Iowa, whose acquaintance with the region
is extensive, has kindly written out for me his conclusions upon this subject, which I
am permitted to give in his own words:
“I am not prepared to write as I would like concerning the forest-beds and old
soils. I will, however, offer the following as a partial report. I have come to think that
there is considerable confusion on the subject. I believe there are five or six different
things classed under one head.
“1. Recent Much and Soils.—The finest example I have found in the whole
Missouri Valley was twenty feet below silt and clay, in a basin inside the outer

moraine, near Grand View, South Dakota. From my examination of the reported old
soil near Albia, Iowa, I think the most rational way of reconciling the conflicting
statements concerning it is that it also belongs to this class.
“2. Peat or Soil under Loess.—This does not signify much if the loess was formed
in a lake subject to orographic oscillations, or if, as I am coming to believe, it is a
fluviatile deposit of an oscillating river like the Hoang-Ho on the great Chinese plain.
It at least does not mean an interglacial epoch.
“3. Wood and Dirt rearranged, not in situ.—This occurs either in subaqueous or in
subglacial deposits. I have found drift-wood in the lower layers of the loess here, but
not in situ. I have frequently found traces of wood in till in Dakota, but always in an
isolated way. I think, from reading statements about the deposits in eastern Iowa, that
most if not all of the cases are of this sort. Two things have conspired to lead to this
error: one, the influence of Croll’s speculation; and the other, the easy inference of
many well-diggers, and especially well-borers, that what they pass through are always
in layers. In this way a log becomes a forest-bed. Scattered logs and muck fragments
occurring frequently in a region, though at different levels, are readily imagined by an
amateur geologist to be one continuous stratum antedating the glacier or floods (as the
case may be in that particular region), when, in fact, it has been washed down from
the margin of the transporting agent and is contemporaneous with it. I suspect the
prevalence of wood in eastern Iowa may be traced to a depression of the driftless
region during the advance of the glacier, so as to bring the western side of that area
more into the grasp of glacial agencies.
“4. Peat between Subglacial Tills.—If cases of this sort are found, they are in
Illinois, Indiana, and Ohio. Professor Worthen insisted that there were no interglacial
soils or forest-beds in Illinois; and in the cases mentioned in the State reports he
repeatedly explains the sections given by his assistants, so as to harmonize them with
that statement. I think he usually makes his explanations plausible. He was very
confident in referring most of them, to preglacial times. His views, I suppose, will be
published in the long-delayed volume, now about to be issued.
“5. Vegetable Matter between Glacial Till and Underlying Berg Till or other Drift
Deposits.—When one remembers that the front of the great ice-sheet may have been
as long in reaching its southern boundary as in receding from it, and with as many
advance and retrograde movements, we can easily believe that much drift material
would have outrun the ice and have formed deposits so far ahead of it that vegetation
would have grown before the ice arrived to bury it.
“6. Preglacial Soils, etc.—I believe that this will be found to include most in
southern Ohio, if not in Illinois, as Worthen claimed.”

The phenomena of the Glacial period are too vast either to have appeared or to
have disappeared suddenly. By whatever cause the great accumulation of ice was
produced, the advance to the southward must have been slow and its disappearance
must have been gradual, though, as we shall show a little later, the final retreat of the
ice-front occupied but a short time relatively to the whole period which has elapsed
since. As we shall show also, the advent of the Ice period was probably preceded and
accompanied by a considerable elevation of the northern part of the continent Whether
this elevation was contemporaneous upon both sides of the continent is perhaps an
open question; but with reference to the area east of the Rocky Mountains, which is
now under consideration, the centre of elevation was somewhere south of Hudson
Bay. Putting together what we know, from the nature of the case, concerning the
accumulation and movement of glacial ice, and what we know from the relics of the
great glacial invasion, which have enabled us to determine its extent and the vigour of
its action, the course of events seems to have been about as follows:
Throughout the Tertiary period a warm climate had prevailed over British
America, Greenland, and indeed over all the lands in proximity to the north pole, so
far as explorers have been able to penetrate them. The vegetation characterizing these
regions during the Tertiary period indicates a temperature about like that which now
prevails in North Carolina and Virginia. Whatever may be said in support of the theory
that the Glacial period was produced by astronomical causes, in view of present facts
those causes cannot be regarded as predominant; at most they were only co-operative.
The predominant cause of the Glacial period was probably a late Tertiary or post-
Tertiary elevation of the northern part of the continents, accompanied with a
subsidence in the central portion. Of such a subsidence in the Isthmus of Panama
indications are thought to be afforded by the occurrence of late Tertiary or, more
probably, post-Tertiary sea-shells at a considerable elevation on the divide along the
Isthmus of Panama, between the Atlantic and Pacific Oceans. Of this we shall speak
more fully in a later chapter.
Fixing our thoughts upon what is known as the Laurentian plateau, which, though
now in the neighbourhood of but two thousand feet above the sea, was then much
higher, we can easily depict in imagination the beginnings of the great “Laurentide
Glacier,” which eventually extended to the margin already delineated on the south and
southwest in the United States, and spread northward and eastward over an
undetermined area. Year after year and century after century the accumulating snows
over this elevated region consolidated into glacial ice and slowly pushed outward the
surplus reservoirs of cold. For a long time this process of ice-accumulation may have
been accompanied by the continued elevation of the land, which, together with the
natural effect of the enlarging area of ice and snow, would tend to lower the
temperature around the margin and to increase still more the central area of
accumulation.

The vigour of movement in any direction was determined partly by the shape of
the valleys opening southward in which the ice-streams would naturally concentrate,
and partly by those meteorological conditions which determine the extent of snow-fall
over the local centres of glacial dispersion. For example, the general map of North
America in the Ice period indicates that there were two marked subcentres of
dispersion for the great Laurentide Glacier, the eastern one being in Labrador and the
western one north of Lake Superior. In a general way the southern boundary of the
glaciated region in the United States presents the appearance of portions of two
circumferences of circles intersecting each other near the eastern end of Lake Erie.
These circles, I am inclined to believe, represent the areas over which a semi-fluid (or
a substance like ice, which flows like a semi-fluid) would disperse itself from the
subcentres above mentioned.
A study of the contour of the country shows that that also, in a general way,
probably had something to do with the lines of dispersion. The western lobe of this
glaciated area corresponds in its boundary pretty closely with the Mississippi Valley,
having the Ohio River approximately as its eastern arm and the Missouri as its
western, with the Mississippi River nearly in its north and south axis. The eastern lobe
has its farthest extension in the axis of the Champlain and Hudson River Valleys, its
western boundary being thrown more and more northward as the line proceeds to the
west over the Alleghany Mountains until reaching the longitude of the eastern end of
Lake Erie; but this southern boundary is by no means a water-level, nor is the contour
of the country such that it could ever have been a water-level. But it conforms in
nearly every particular to what would be the resultant arising from a pretty general
southward flow of a semi-fluid from the two subcentres mentioned, meeting with the
obstructions of the Adirondacks in northern New York and of the broader Appalachian
uplift in northern Pennsylvania.
How far south the area of glacial accumulation may have extended cannot be
definitely ascertained, but doubtless at an early period of the great Ice age the northern
portions of the Appalachian range in New York, New England, New Brunswick, and
Nova Scotia became themselves centres of dispersion, while only at the height of the
period did all their glaciers become confluent, so that there was one continuous ice-
sheet.
In the western portion of the area covered by the Laurentide Glacier, the
depression occupied by the Great Lakes, especially Lakes Michigan and Superior,
evidently had a marked influence in directing the flow of ice during the stages which
were midway between the culmination of the Ice period and both its beginning and its
end. This would follow from the great depth of these lakes, the bottom of Lake
Michigan being 286 feet below sea-level, and that of Lake Superior 375 feet, making
a total depth of water of about 900 and 1,000 feet respectively. Into these oblong
depressions the ice would naturally gravitate until they were filled, and they would

become the natural channels of subsequent movement in the direction of their longest
diameters, while the great thickness of ice in them would make them the conservative
centres of glacial accumulation and action after the ice had begun to retreat.
These deductions from the known nature of ice and the known topography of the
region are amply sustained by a study of the detailed map showing the glacial geology
in the United States. But on this we can represent indeed only the marks left by the ice
at various stages of its retreat, since, as already remarked, the marks of each stage of
earlier advance would be obliterated by later forward movements. We may presume,
however, that in general the marks left by the retreating ice correspond closely with
those actually made and obliterated by the advancing movement.
From observations upon the glaciers of Switzerland and of Alaska, it is found that
neither the advance nor the retreat of these glaciers is constant, but that, in obedience
to meteorologic agencies not fully understood, they advance and retreat in alternate
periods, at one time receding for a considerable distance, and at other times regaining
the lost ground and advancing over the area which has been uncovered by their retreat.
“M. Forel reports, from the data which he has collected with much care, that there
have been in this century five periods in the Alpine glaciers: of enlargement, from
1800 (?) to 1815; of diminution, from 1815 to 1830; of enlargement, from 1830 to
1845; of diminution, from 1845 to 1875; and of enlargement again, from 1875
onward. He remarks further that these periods correspond with those deduced by Mr.
C. Lang for the variations for the precipitations and temperature of the air; and,
consequently, that the enlargement of the glaciers has gone forward in the cold and
rainy period, and the diminution in the warm and the dry.”[BH]
[BH] American Journal of Science, vol. cxxxii, 1886, p. 77.

When, now, we attentively consider the combination of causes necessary to
produce the climatic conditions of the great Ice age of North America, we shall be
prepared to find far more extensive variations in the progress of the continental
glacier, both during its advance and during its retreat, than are to be observed in any
existing local glaciers.
With respect to the arguments adduced in favor of a succession of glacial epochs
in America the following criticisms are pertinent:
1. So far as we can estimate, a temporary retreat of the front, lasting a few
centuries, would be sufficient to account for the vegetable accumulations that are
found buried beneath the glacial deposits in southern Ohio, Indiana, central Illinois,
and Iowa, while a temporary readvance of the ice would be sufficient to bury the
vegetable remains beneath a freshly accumulated mass of till. Thus, as Dr. Bell
suggested, the interglacial vegetal deposits do not necessarily indicate anything more
than a temporary oscillation of the ice-front, and do not carry with them the necessity

of supposing a disappearance of the ice from the whole glaciated area. Thus the
introduction of a whole Glacial period to account for such limited phenomena is a
violation of the well-known law of parsimony, which requires us in our explanations
of phenomena to be content with the least cause which is sufficient to produce them.
In the present instance a series of comparatively slight oscillations of the ice-front
during a single glacial period would seem to be sufficient to account for all the buried
forests and masses of vegetal débris that occur either in the United States or in the
Dominion of Canada.
2. Another argument for the existence of two absolutely distinct glacial periods in
North America has been drawn from the greater oxidation of the clays and the more
extensive disintegration of certain classes of the boulders found over the southern part
of the glaciated area of the Mississippi Valley, than has taken place in the more
northerly regions. Without questioning this statement of fact (which, however, I
believe to be somewhat exaggerated), it is not difficult to see that the effects probably
are just what would result from a single long glacial period brought about by such
causes as we have seen to be probably in operation in America. For if one reflects
upon the conditions existing when the Glacial period began, he will see that, during
the long ages of warm climate which characterised the preceding period, the rocks
must have been extensively disintegrated through the action of subaërial agencies. The
extent to which this disintegration takes place can be appreciated now only by those
who reside outside of the glaciated area, where these agencies have been in
uninterrupted action. In the Appalachian range south of the glaciated region the
granitic masses and strata of gneiss are sometimes found to be completely
disintegrated to a depth of fifty or sixty feet; and what seem to be beds of gravel often
prove in fact to be horizontal strata of gneiss from which the cementing material has
been removed by the slow action of acids brought down by the percolating water.
Now, there can be no question that this process of disintegration had proceeded to
a vast extent before the Glacial period, so that, when the ice began to advance, there
was an enormous amount of partially oxidised and disintegrated material ready to be
scraped off with the first advance of ice, and this is the material which would naturally
be transported farthest to the south; and thus, on the theory of a single glacial period,
we can readily account for the greater apparent age of the glacial débris near the
margin. This débris was old when the Glacial period began.
3. With reference to the argument for two distinct glacial periods drawn from the
smaller apparent amount of glacial erosion over the southern part of the glaciated area,
we have to remark that that would occur in case of a single ice-invasion as well as in
case of two distinct ice-invasions, in which the later did not extend so far as the
former.

From the very necessity of the case, glacial erosion diminishes as the limit of the
extent of the glaciation is approached. At the very margin of the glacier, motion has
ceased altogether. Back one mile from the margin only one mile of ice-motion has
been active in erosion, while ten miles back from its front there has been ten times as
much moving ice actually engaged in erosion, and in the extreme north several
hundred times as much ice, Thus it is evident that we do not need to resort to two
glacial periods to account for the relatively small amount of erosion exhibited over the
southern portion of our glaciated area.
At the same time, it should be said that the indications of active glacial erosion
near the margin are by no means few or small. In Lawrence County, Pennsylvania, on
the very margin of the glaciated area, Mr. Max Foshay[BI] has discovered very
extensive glacial grooves, indicating much vigour of ice-action even beyond the more
extensive glacial deposits which Professor Lewis and myself had fixed upon as the
terminal moraine. In Highland and Butler Counties, Ohio, and in southwestern Indiana
and southern Illinois, near the glacial margin, glacial grooves and striæ are as clear
and distinct in many cases as can anywhere be found; while upon the surface of the
limestone rocks within the limits of the city of St. Louis, where the glacial covering is
thin, and where disintegrating agencies had had special opportunities to work, I found
very clear evidences of a powerful ice-movement, which had planed and scratched the
rock surface; and at Du Quoin, Illinois, as already related, the fragments thrown up
from the surface of the rock, fifty or sixty feet below the top of the soil, were most
beautifully planed and striated. It should be observed, also, that this whole area is so
deeply covered with débris that the extent of glacial erosion underneath is pretty
generally hid from view.
[BI] Bulletin of the Geological Society, vol. ii, pp. 457-464.

4. The uniformity of the distribution of the glacial deposits over the southern
portion of the glaciated area in the Mississippi Valley is partly an illusion, due to the
fact that there was a vast amount of deposition by water over that area during the
earlier stages of the ice-retreat. This has been due partly to the gentler slope which
would naturally characterise the borders of an area of elevation, and partly to an
extensive subsidence which seems to have begun soon after the ice had reached its
farthest extent of motion.
It should be borne in mind that at all times a glacier is accompanied by the issue of
vast streams of water from its front, and that these of course increase in volume when
the climax has been reached and the ameliorating influences begin to melt away the
accumulated mass of ice and to add the volume of its water to that produced by
ordinary agencies. As these subglacial streams of water poured out upon the more
gentle slopes of the area in front of the ice, they would distribute a vast amount of fine
material, which would settle into the hollow places and tend to obscure the
irregularities of the previous direct glacial deposit.

Such an instance came clearly under my own observation in the vicinity of
Yankton, in South Dakota, where, upon visiting a locality some miles from any river,
and to which workmen were resorting for sand, I found that the deposit occupied a
kettle-hole, filling it to its brim, and had evidently been superimposed by a temporary
stream of water flowing over the region while the ice was still in partial occupation of
it. Thus, no doubt, in many cases, the original irregularities of the direct glacial
deposits have been obliterated, even where there has been no general subsidence.
But, in the area under consideration, the loess, or loam, is so extensive that it is
perhaps necessary to suppose that the central portions of the Mississippi Valley were
subjected to a subsidence amounting to about five hundred feet; so that the glacial
streams from the retreating ice-front met the waters of the ocean in southern Illinois
and Indiana; thus accounting for the extensive fine silt which has done so much over
that region to obscure the glacial phenomena.

West of the Rocky Mountains.
The glacial phenomena in the United States west of the Rocky Mountains must be
treated separately, since American geologists have ceased to speak of an all-pervading
ice-cap extending from the north pole. But, as already said, the glaciation of North
America has proceeded from two definite centres of ice-accumulation, one of which
we have been considering in the pages immediately preceding. The great centre of
glacial dispersion east of the Rocky Mountains is the region south of Hudson Bay, and
the vast ice-field spreading out from that centre is appropriately named the Laurentide
Glacier. The movement of ice in this glacial system was outward in all directions from
the Laurentian hills, and extended west several hundred miles, well on towards the
eastern foot of the Rocky Mountains.
The second great centre of glacial dispersion occupies the vast Cordilleran region
of British Columbia, reaching from the Rocky Mountains on the northeast to the Coast
Range of the Pacific on the southwest, a width of four hundred miles. The length is
estimated by Dr. Dawson to be twelve hundred miles. The principal centre of ice-
accumulation lies between the fifty-fifth and the fifty-ninth parallel. From this centre
the movement was in all directions, but chiefly to the northwest and to the south. The
movement of the Cordilleran glaciers extended northwest to a distance of three
hundred and fifty miles, leaving their moraines far down in the Yukon Valley on the
Lewes and Pelly Rivers.[BJ] Southward the Cordilleran Glacier moved to a distance of
six hundred miles, extending to the Columbia River, in the eastern part of the State of
Washington.
[BJ] See George M. Dawson, in Science, vol. xi, 1888, p. 186, and American Geologist,
September, 1890, pp. 153-162.

From this centre, also, the ice descended to the sea-level upon the west, and filled
all the channels between Vancouver’s Island and the mainland, as well as those in the
Alexander Archipelago of Alaska. South of Vancouver’s Island a glacier pushed out
through the straits of Juan de Fuca to an unknown distance. All the islands in Puget
Sound are composed of glacial débris, resembling in every respect the terminal
moraines which have been described as constituting many of the islands south of the
New England coast. The ice-movement in Puget Sound, however, was probably
northward, resulting from glaciers which are now represented by their diminutive
descendants on the flanks of Mount Rainier.
South of the Columbia River the country was never completely enveloped by the
ice, but glaciers extended far down in the valleys from all the lofty mountain-peaks. In
Idaho there are glacial signs from the summit of the Rocky Mountains down to the
westward of Lake Pend d’Oreille. In the Yellowstone Park there are clear indications
that the whole area was enveloped in glacial ice. An immense boulder of granite,
resting upon volcanic deposits, may be found a little west of Inspiration Point, on the
Yellowstone Cañon. Abundant evidences of glacial action are also visible down the
Yellowstone River to the vicinity of Livingston, showing that that valley must have
been filled with glacial ice to a depth of sixteen hundred feet. To the west the glaciers
from the Yellowstone Park extended to the border of Idaho, where a clearly marked
terminal moraine is to be found in the Tyghee Pass, leading over from the western fork
of the Madison River into Lewis Fork of the Snake River. South of Yellowstone Park
the Teton Mountains were an important centre for the dispersion of local glaciers, but
they did not descend upon the western side much below the 6,000-foot level, and only
barely came to the edge of the great Snake River lava plains. To the east the
movement from the Teton Mountains joined that from various other lofty mountains,
where altogether they have left a most intricate system of glacial deposits, in whose
reticulations Jackson’s Lake is held in place.

Fig. 37.—Moraines of Grape Creek, Sangre del Cristo
Mountains, Colorado (after Stevenson).

In Utah extensive glaciers filled all the northern valleys of the Uintah Mountains,
and extended westward in the Wahsatch range to the vicinity of Salt Lake City. The
mountain region of Colorado, also, had its glaciers, occupying the head-waters of the
Arkansas, the Platte, the Gunnison, and the Grand Rivers. The most southern point in
the Rocky Mountains at which signs of local glaciers have been noted is near the
summits of the San Juan range, in southwestern Colorado. Here a surface of about
twenty-five square miles, extending from an elevation of 12,000 feet down to 8,000
feet, shows every sign of the former presence of moving ice. The greater part of the
glaciation in Colorado is confined to elevations above 10,000 feet.
The whole range of the Sierra Nevada through Oregon, and as far south as the
Yosemite Valley in California, formerly sustained glaciers of far greater size than any
which are now found in those mountains. In general these glaciers were much longer
on the western side of the Sierra Nevada than on the eastern. On the eastern side
glaciers barely came down to Lake Tahoe and Lake Mono in California. The State of
Nevada seems to have been entirely free from glaciers, although it contains numerous
mountain-peaks more than ten thousand feet high. In the Yosemite Cañon glaciers
extended down the Merced River to the mouth of the cañon; while in the Tuolumne
River, a few miles to the north, the glaciers which still linger about the peaks of
Mount Dana filled the valley for a distance of forty miles.
It is a question among geologists whether or not the glaciation west of the Rocky
Mountains was contemporaneous with that of the eastern part of the continent. The
more prevalent opinion among those who have made special study of the phenomena
is that the development of the Cordilleran glaciers was independent of that of the
Laurentide system. At any rate, the intense glaciation of the Pacific coast seems to

have been considerably later than that of the Atlantic region. Of this we will speak
more particularly in discussing the questions of the date and the cause of the Glacial
period. It is sufficient for us here simply to say that, from his extensive field
observations throughout the Cordilleran region, Dr. George M. Dawson infers that
there have been several successive alternations of level on the Pacific coast
corresponding to successive glacial and interglacial epochs, and that when there was a
period of elevation west of the Rocky Mountains there was a period of subsidence to
the east, and vice versa. In short, he supposes that the east and west for a long time
played a game of seesaw, with the Rocky Mountains as the fulcrum. We give his
scheme in tabulated form.

Scheme of Correlation of the Phenomena of the Glacial Period in the Cordilleran
Region and in the Region of the Great Plains.

CORDILLERAN REGION. REGION OF THE GREAT PLAINS.
Cordilleran zone at a high elevation. Correlative subsidence and
Period of most severe glaciation and submergence of the great plains, with
maximum development of the great possible contemporaneous increased
Cordilleran Glacier. elevation of the Laurentian axis and
maximum development of ice upon it.
Deposition of the lower boulder-clay of
the plains.

Gradual subsidence of the Correlative elevation of the western
Cordilleran region and decay of the part, at least, of the great plains, which
great glacier, with deposition of the was probably more or less irregular and
boulder-clay of the interior plateau and led to the production of extensive lakes
the Yukon basin, of the lower boulder- in which interglacial deposits, including
clay of the littoral and probably also, at peat, were formed.
a later stage (and with greater
submergence), of the interglacial silts of
the same region.

Re-elevation of the Cordilleran Correlative subsidence of the plains,
region to a level probably as high as or which (at least in the western part of the
somewhat higher than the present. region) exceeded the first subsidence
Maximum of second period of and extended submergence to the base
glaciation. of the Rocky Mountains near the forty-
ninth parallel. Formation of second

boulder-clay, and (at a later stage)
dispersion of large erratics.

Partial subsidence of the Cordilleran Correlative elevation of the plains,
region, to a level about 2,500 feet lower or at least of their western portion,
than the present. Long stage of stability. resulting in a condition of equilibrium as
Glaciers of the second period between the plains and the Cordillera,
considerably reduced. Upper boulder- their relative levels becoming nearly as
clay of the coast probably formed at this at present. Probable formation of the
time, though perhaps in part during the Missouri coteau along a shore-line
second maximum of glaciation. during this period of rest.

Renewed elevation of the Simultaneous elevation of the great
Cordilleran region, with one well- plains to about their present level, with
marked pause, during which the littoral final exclusion of waters in connection
stood about 200 feet lower than at with the sea. Lake Agassiz formed and
present. Glaciers much reduced, and eventually drained towards the close of
diminishing in consequence of general this period. This simultaneous
amelioration of climate towards the movement in elevation of both great
close of the Glacial period. areas may probably have been
connected with a more general northern
elevation of land at the close of the
Glacial period.

In New Zealand the marks of the Glacial period are unequivocal The glaciers
which now come down from the lofty mountains upon the South Island of New
Zealand to within a few hundred feet of the sea then descended to the sea-level. The
longest existing glacier in New Zealand is sixteen miles, but formerly one of them had
a length of seventy-eight miles. One of the ancient moraines contains a boulder from
thirty to forty feet in diameter, and the amount of glacial débris covering the
mountain-sides is said to be enormous. Reports have also been recently brought of
signs of ancient glaciers in Australia.

Fig. 38.—Generalised view of the whole glaciated region of North
America. The area of motionless ground-ice is shown by the white
lines in northern part of Alaska.

According to Darwin, there are distinct signs of glaciation upon the plains of
Patagonia sixty or seventy miles east of the foot of the mountains, and in the Straits of
Magellan he found great masses of unstratified glacial material containing boulders
which were at least one hundred and thirty miles away from their parent rock; while
upon the island of Chiloe he found embedded in “hardened mud” boulders which
must have come from the mountain-chains of the continent. Agassiz also observed
unquestionable glacial phenomena on various parts of the Fuegian coast, and indeed
everywhere on the continent south of latitude 37°. Between Concepcion and Arauco,
in latitude 37°, Agassiz observed, near the sea-level, a glacial surface well marked
with furrows and scratches, and as well preserved, he says, “as any he had seen under
the glaciers of the present day.”

Fig. 39.—Quartzite boulder of 45 cubic metres, on Mont
Lachat, 800 metres above the valley of the Belley, in Ain,
France (Falsan).

CHAPTER VI.

ANCIENT GLACIERS IN THE EASTERN
HEMISPHERE.
About two million square miles of northern Europe were covered with perennial
ice during the Glacial period. From the scratches upon the rocks, and from the
direction in which material has been transported, it is evident that the main centre of
radiation is to be found in the mountains of Scandinavia, and that the glaciers still
existing in Norway are the lineal descendants of those of the great Ice age.
So shallow are the Baltic Sea and the German Ocean, that their basins were easily
filled with ice, upon which Scandinavian boulders could be transported westward to
the east shore of England, southward into the plains of Germany, and eastward far out
upon the steppes of Russia. The islands north of Scotland bear marks also of an ice-
movement from the direction of Norway. If Scotland itself was not overrun with
Scandinavian glaciers, the reason was that it had ice enough of its own, and from its
highlands set up a counter-movement, which successfully resisted the invasion from
the Scandinavian Peninsula. But, elsewhere in Europe, Scandinavian ice moved freely
outward to the extent of its capacity. Then, as now also, the Alps furnished centres for
ice-movement, but the glaciers were limited to the upper portions of the valleys of the
Rhône, the Rhine, and the Danube upon the west and north, and to a still smaller area
upon the southern side.

Fig. 40.

Central and Southern Europe.
The main centres of ice-movement in the Alps during the Glacial period are the
same as those which furnish the lingering glaciers of the present time. From the water-
shed between the Rhine, the Rhône, and the Aar, glaciers of immense size descended
all the valleys now occupied by those streams. The valley of the Rhône between the
Bernese and the Pennine Alps was filled with a glacier of immense depth, which was
maintained by fresh supplies from tributaries upon either side as far down as
Martigny. Glacial markings at the head of the Rhône Valley are found upon the
Schneestock,[BK] at an elevation above the sea of about 11,500 feet (3,550 metres), or
about 1,500 feet above the present surface of the Rhône Glacier. At Fiesch, about
twenty miles below, where tributaries from the Bernese Oberland snow-fields were
received, the thickness of the glacier was upwards of 5,000 feet (1,680 metres). Near
Martigny, about fifty miles farther down the valley, where the glacier was abruptly
deflected to the north, the depth of the ice was still upwards of 1,600 metres. From
Martigny northward the thickness of the ice decreased rapidly for a few miles, where,
at the enlargement of the valley above the head of Lake Geneva, it was less than 1,200
metres in thickness, and spread out over the intervening plain as far as Chasseron,
with a nearly level surface, transporting, as we have before said, Alpine boulders to
the flanks of the Juras, and landing them about 3,000 feet (1,275 metres) above the
level of Lake Geneva. The width of the main valley is here about fifty miles, making
the slope of the surface of the ice about twenty feet to the mile.

[BK] A. Falsan’s La Période Grlaciaire étudiée principalement en France et en Suisse,
chapitre xv.

From its “vomitory,” at the head of Lake Geneva, the ice of the ancient Rhône
Glacier spread to the right and to the left, while its northern boundary was abruptly
terminated by the line of the Jura Mountains. The law of glacial motion was, however,
admirably illustrated in the height to which the ice rose upon the flanks of the Jura. At
Chasseron, in the direct line of its onward motion, it rose to its highest point, while
both to the southwest and to the northeast, along the line of the Juras, the ice-action
was limited to constantly decreasing levels.
Down the valley of the Rhône the direction of motion was determined by the
depression of Lake Geneva, at the lower end of which it received its main tributary
from Mont Blanc, which had come down from Chamouni through the valley of the
river Arve. From this point it was deflected by a spur of the Jura Mountains more and
more southward to the vicinity of Culoz, near the mouth of Lake Bourget. Here the
glacier coming down from the western flanks of the Alps, through the upper valley of
the Isère, past Chambéry, became predominant, and deflected the motion to the west
and north, whither the ice extended to a line passing through Bourg, Lyons, and
Vienne, leaving upon one of the eminences on which Lyons is built a boulder several
feet in diameter, which is duly preserved and labelled in the public park in that portion
of the city. Farther south, glaciers of less extent marked the Alps most of the way to
the Mediterranean, but they were not at all comparable in size to those from the
central region.
To the right of Lake Geneva the movement started by the Rhône Glacier spread
eastward, being joined in the vicinity of Berne by the confluent ice-stream which
descended from the north flank of the Bernese Oberland, through the valley of the
Aar. These united streams filled the whole valley with ice as far down as Soleure.[BL]
[BL] See map of Rhône Glacier, on p. 58.

Click on map to view larger sized.

Farther eastward, other ice-streams from the Alps became predominant, one of
which, moving down the Reuss, deployed out upon the country lying north of Lucerne
and Zug. Still farther down, the ancient glacier which descended the Limmatt spread
itself out over the hills and lowlands about Zürich, one of its moraines of retrocession
nearly dividing the lake into two portions.
Guyot and others have shown that the superficial deposits of this portion of
Switzerland are just such as would be distributed by glaciers coming down from the
above-mentioned Alpine valleys. Uniting together north of Zürich, these glaciers
pushed onward as far as the Rhine below Schaffhausen. In Frickthal the glacial ice
was still 1,200 feet thick, and at Kaisterberg between 400 and 500 feet.
At Lucerne there is a remarkable exposure of pot-holes, and a glaciated surface
such as could be produced only by the combined action of moving ice and running
water; thus furnishing to tourists an instructive object-lesson. Among the remarkable
instances of boulders transported a long distance in Switzerland, is that of a block of
granite carried from the Valais to the vicinity of Soleure, a distance of one hundred

and fifteen miles, which weighs about 4,100 tons. “The celebrated Pierre-à-Bot, above
Neufchâtel, measures 50’ × 20’ × 40’, and contains about 40,000 cubic feet of stone;
while the Pierre-des-Marmettes, near Monthey, contains no less than 60,840 cubic
feet.”
The ancient glacier of the Rhine, receiving its initial impulse in the same centre as
that of the Rhône, fully equalled it in all its dimensions. Descending eastward from its
source near the Schneestock to Chur, a distance of fifty miles, it turned northward and
continued forty-five miles farther to the head of Lake Constance, where it spread out
in fan-shape, extending northwest to Thiengen, below Schaffhausen, and covering a
considerable area north and northeastward of the lake, reaching in the latter direction
Ulm, upon the Danube—the whole distance of the movement being more than one
hundred and fifty miles. Through other valleys tributary to the Danube, glaciers
descended upon the upper plains of Bavaria, from the Tyrolese Alps to the vicinity of
Munich. From Gross Glockner as a centre in the Noric Alps, vast rivers of ice, of
which the Pasterzen Glacier is the remnant, poured far down into the valleys of the
Inn and the Enns on the north and into that of the Drave on the southeast. Farther
eastward in this part of Europe the mountains seem to have been too low to have
furnished centres for any general dispersion of glacial ice.
Upon the south side of the Alps the ancient glaciers
spread far out upon the plains of Lombardy, where
moraines of vast extent and of every description
enable the student to determine the exact limits of the
ancient ice-action. From the southern flanks of Mont
Blanc and Monte Rosa, and from the snow-fields of
the western Alps, glaciers of great volume descended
into the valley of Dora Baltea (vale of Aosta), and on
emerging from the mountain valley Spread Out over
the plains around Ivrea, leaving moraine hills in some
instances 1,500 feet in height. The total length of this
glacier was as much as one hundred and twenty miles.
From the snow-fields in the vicinity of Mont Cenis, Fig. 41.—Map showing the Lines of
also, glaciers extended down the Dora Ripera to the Débris extending from the Alps into
vicinity of Turin, and down other valleys to a less the Plains of the Po (after Lyell). A.
Crest of the Alpine water-shed; B.
extent. The lateral moraines of the Diore, on the south Névé-fields of the ancient glaciers; C.
side of Mont Blanc, at the head of the Dora Baltea, are Moraines of ancient glaciers.
2,000 feet above the present river, and extend upon the Click on image to view larger sized.
left bank for a distance of twenty miles.
From the eastern Alps, glaciers descended through all the valleys of the Italian
lakes and deposited vast terminal moraines, which still obstruct the drainage, and
produce the charming lakes of that region. A special historic interest pertains to the

series of concentric moraines south of Lake Garda, since it was in the reticulations of
this glacial deposit that the last great battle for Italian liberty was fought on June 24,
1859. Defeated in the engagements farther up the valley of the Po, the Austrian
general Benedek took his final stand to resist the united forces of France and Italy
behind an outer semicircle of the moraine hills south of this lake (some of which are
500 or 600 feet above the surrounding country), with his centre at Solferino, about ten
miles from Peschera. Here, behind this natural fortification, he awaited the enemy,
who was compelled to perform his manœuvres on the open plain which spread out on
every side. But the natural fortifications furnished by the moraine hills were too
extensive to be defended by an army of moderate size. The troops of Napoleon and
Victor Immanuel concentrated at Solferino and broke through the line. Thus the day
was lost to the Austrians, and they retired from Lombardy, leaving to Italy both the
artificial and the natural fortifications that guard the southern end of this important
entrance to the Tyrolese Alps. When once his attention is called to the subject, the
traveller upon the railroad cannot fail to notice this series of moraines, as he enters it
through a tunnel at Lonato on the west, and emerges from it at Soma Campagna,
eighteen or twenty miles distant to the east. A monument celebrating the victory
stands upon a moraine hill about half-way between, at Martino della Battaglie.
In other portions of central and southern Europe the mountains were too low to
furnish important centres for glacial movements. Still, to a limited extent, the signs of
ancient glaciers are seen in the mountains of the Black Forest, in the Harz and
Erzgebirge, and in the Carpathians on the east and among the Apennines on the south.
In Spain, also, there were limited ice-fields on the higher portions of the Sierra
Nevada and in the mountains of Estremadura, and perhaps in some other places. In
France, small glaciers were to be found in the higher portions of the Auvergne, of the
Morvan, of the Vosges, and of the Cevennes; while, from the Pyrenees, glaciers
extended northward throughout nearly their whole extent. The ice-stream descending
from the central mass of Maladetta through the upper valley of the Garonne, was
joined by several tributaries, and attained a length of about forty-five miles.

The British Isles.
During the climax of the Glacial period the Hebrides to the north of Scotland were
covered with ice to a depth of 1,600 feet. How far westward of this it moved out to the
sea, it is of course impossible to tell. But in the channels between the Hebrides and
Scotland it is evident that the water was completely expelled by the ice, and that, from
a height of 1,600 feet above the Hebrides to the northern shores of Scotland, there was
a continuous ice-field sloping southward at the rate of about twenty-five feet a mile.
Scotland itself was completely enveloped in glacial ice. Prevented by the
Scandinavian Glacier from moving eastward, the Scotch movement was compelled to
be westward and southward. On the southwest the ice-stream reached the shores of

Ireland, and became confluent with the glaciers that enveloped that island, completely
filling the Irish Sea.
There are so many controverted points respecting the glacial geology of England,
and they have such an important bearing upon the main question of this volume, that a
pretty full discussion of them will be necessary. I have recently been over enough of
the ground myself to become satisfied of the general correctness of the views
entertained by my late colleague, the lamented Professor Henry Carvill Lewis, whose
death in 1888 took place before the publication of his most mature conclusions. But
the lines of investigation to which he gave so powerful an impulse have since been
followed out by an active body of scientific observers. To give the statement of facts
greater precision and authority, I have committed the preparation of it to the Secretary
of the Northwest of England Boulder Committee, Percy F. Kendall, F. G. S., Lecturer
on Geology at the Yorkshire College, Leeds, and at the Stockport Technical School,
England.[BM]
[BM] Mr. Kendall’s contribution extends to page 181.

“All the characteristic evidences of the action of land-ice can be found in the
greatest perfection in many parts of England and Wales. Drumlins, kames, roches
moutonnées, far-travelled erratics, terminal moraines, and perched blocks, all occur.
There are, besides, in the wide-spread deposits of boulder-clay which cover so many
thousands of square miles on the low grounds lying on either side of the Pennine
chain, evidences of the operation of ice-masses of a size far exceeding that of the
grandest of existing European glaciers. But, while the proofs of protracted and severe
glaciation are thus patent, there are, nevertheless, many apparently anomalous
circumstances which arrest the attention when the whole country is surveyed. The
glacial phenomena appear to be strictly limited to the country lying to the northward
of a line extending from the Bristol Channel to the mouth of the Thames; and within
the glaciated area there are many extensive tracts of land devoid of ‘drift’ or other
indications of ice-action.
“By comparison with the phenomena displayed in the North American continent,
English glacial geology must seem puny and insignificant; but, just as with the
features of the ‘Solid Geology,’ we have compressed within the narrow limits of our
isles an epitome of the features which across the Atlantic require a continent for their
exposition. It has resulted from this concentration that English geology requires a
much closer and more minute investigation. And the difficulty which has been
experienced by glacial geologists of dealing with an involved series of facts has, in the
absence of any clue leading to the co-ordination of a vast series of more or less
disconnected observations, resulted in the adoption, to meet certain local anomalies,
of explanations which were very difficult if not impossible of reconciliation with facts
observed in adjacent areas. Thus, to account for shell-bearing drift extending up to the
water-shed on one side of a lofty range of hills, a submergence of the land to a depth

of 1,400 feet has been postulated; leaving for independent explanation the fact, that
the opposite slopes of the hills and the low ground beyond were absolutely destitute of
drift or of any evidence of marine action.
“In the following pages I must adopt a somewhat dogmatic tone, in order to
confine myself within the limits of space which are imposed; and trust rather to the
cohesion and consistency of the explanations offered and to a few pregnant facts than
to the weighing and contrasting of rival theories.
“The facts point conclusively to the action in the British Isles of a series of
glaciers radiating outward from the great hill chains or clusters, and, as the
refrigeration progressed, becoming confluent and moving though in the same general
direction, yet with less regard to the minor inequalities of the ground. During these
two stages many glaciers must have debouched upon the sea-coast, with the
consequent production of icebergs, which floated off with loads of boulders and
dispersed them in the random fashion which is a necessary characteristic of transport
by floating ice.
“With a further accentuation of the cold conditions the discharge of bergs from
terminal fronts which advanced into the extremely shallow seas surrounding the
British shores would be quite inadequate to relieve the great press of ice, and a further
coalescence of separate elements must have resulted. In the case of enclosed seas—as,
for example, the Irish Sea—the continued inthrust of glacier-ice would expel the water
completely; and the conjoined ice-masses would take a direction of flow the resultant
of the momentum and direction of the constituent elements. In other cases—as, for
example, in the North Sea—extraneous ice approaching the shores might cause a
deflection of the flow of the native glaciers, even though the foreign ice might never
actually reach the shore.
“To such a system of confluent glaciers, and to the separate elements out of which
they grew, and into which, after the culmination, they were resolved, I attribute the
whole of the phenomena of the English and Welsh drift. And only at one or two points
upon the coast, and raised but little above the sea-level, can I recognise any signs of
marine action.
“The Preglacial Level of the Land.—There is very little direct evidence bearing
upon this point. In Norfolk the famous forest bed, with its associated deposits, stands
at almost precisely the level which it occupied in preglacial times. At Sewerby, near
Flamborough Head, there is an ancient beach and ‘buried cliff’ which the sea is now
denuding of its swathing of drift-deposits, and its level can be seen to be almost
absolutely coincident with the present beach. Mr. Lamplugh, whose description of the
‘Drifts of Flamborough Head,’[BN] constitutes one of the gems of glacial literature,
considers that there is clear evidence that the land stood at this level for a long period.
The beach is covered by a rain-wash of small extent, and that in turn by an ancient

deposit of blown sand, while the lowest member of the drift series of Yorkshire covers
the whole. Mr. Lamplugh thinks that the blown sand may indicate a slight elevation of
the land; but the beach appears to me to be the storm beach, and the reduction in the
force of the waves such as would result from the approach of an ice-front a few miles
to the seaward would probably produce the necessary conditions.
[BN] Quarterly Journal of the Geological Society, vol. xlvii.

“Six miles to the northward of Flamborough, at Speeton, a bed of estuarine silt
containing the remains of mollusca in the position of life occurs at an altitude of
ninety feet above high-water mark. Mr. Lamplugh inclines to the opinion that this bed
is of earlier date than the ‘buried cliff’; he also admits the possibility that its superior
altitude may be due to a purely local upward bulging of the soft Lower Cretaceous
clays upon which the estuarine bed rests by the weight of the adjacent lofty chalk
escarpment.
“The evidence obtained from inland sections and borings in different parts of
England has been taken to indicate a greater altitude in preglacial times. Thus, in
Essex, deep-borings have revealed the existence of deep drift-filled valleys, having
their floors below sea-level. The valley of the Mersey is a still better example.
Numerous borings have been made in the neighbourhood of Widnes and at other
places in the lower reaches of the river, making it clear that there is a channel filled
with drift and extending to 146 feet below mean sea-level. This, with several other
instances, has been taken to indicate a greater altitude for the land in preglacial times,
since a river could not erode its channel to such a depth below sea-level. The
argument appears inconclusive for one principal reason: no mention is made of any
river gravels or other alluvium in the borings. Indeed, there is an explicit statement
that the deposits are all glacial, showing that the channel must have been cleared out
by ice. This, therefore, leaves open the vital question, whether the deposits removed
were marine or fluviatile. It may be remarked that the great estuary of the Mersey has
undoubtedly been produced by a post-glacial (and probably post-Roman) movement
of depression.
“The Preglacial Climate.—In all speculations regarding the cause of the Glacial
epoch, due account must be taken of the undoubted fact that it came on with extreme
slowness and departed with comparative suddenness. In the east of England an almost
perfect and uninterrupted sequence of deposits is preserved, extending from the early
part of the Pliocene period down to the present day.
“These in descending order are:
“1. Post-glacial sands, gravels, etc.
“2. Glacial series.

“3. The ‘Forest Bed’ and associated marine deposits.
“4. Chillesford clay and sand.
“5. The many successive stages of the Red Crag. (The Norwich Crag is a local
variation of the upper part of the Red Crag.)
“6. The Coralline Crag.
“The fossils preserved in these deposits, apart from the physical indications,
exhibit the climatal changes which accompanied their deposition. The Coralline Crag
contains a fauna consisting mainly of species which now range to the Mediterranean,
many of them being restricted to the warm southern waters. Associated with these are
a few boreal forms, but they are represented in general by few individuals. Here and
there in the deposits of this age far-travelled stones are to be found, but they are
always accounted great rarities.
“The Red Crag consists of an irregular assemblage of beaches and sand-banks of
widely different ages, but their sequence can be made out with ease by a study of the
fauna. In the oldest deposits, Mediterranean species are very numerous, while the
boreal forms are comparatively rare; but in successive later deposits the proportions
are very gradually reversed, and from the overlying Chillesford series the
Mediterranean species are practically absent. The physical indications run pari passu
with the paleontological, and in the newer beds of the Red Crag far-travelled stones
are common.
“In the Forest Bed series there is a marine band—the Leda myalis bed—which
contains an almost arctic assemblage of shells; while at about the same horizon plant
remains have been found, including such high northern species as Salix polaris and
Betula nana.
“The glacial deposits do not, in my opinion, contain anywhere in England or
Wales a genuine intrinsic fauna, such shells as occur in the East Anglian glacial
deposits having been derived in part from a contemporary sea-bed, and, for the rest,
from the older formations, down perhaps to the Coralline Crag. In the post-glacial
deposits we have hardly any trace of a survival of the boreal forms, and I consider that
the whole marine fauna of the North Sea was entirely obliterated at the culmination of
the Glacial epoch, and that the repeopling in post-glacial times proceeded mainly from
the English Channel, into which the northern forms never penetrated.

"The Great Glacial Centres.
“Where such complex interactions have to be described as were produced by the
conflicting glaciers of the British Isles it is difficult to deal consecutively with the

phenomena of any one area, but with short digressions in explanation of special points
it may be possible to accomplish a clear presentation of the facts.
“Wales.—The phenomena of South Wales are comparatively simple. Great
glaciers travelled due southward from the lofty Brecknock Beacons, and left the
characteristic moutonnée appearance upon the rocky bed over which they moved. The
boulder-transport is in entire agreement with the other indications, and there are no
shells in the drift. The facts awaiting explanation are the occurrence in the boulder-
clays of Glamorganshire, at altitudes up to four hundred feet, of flints, and of igneous
rocks somewhat resembling those of the Archæan series of the Wrekin. At Clun, in
Shropshire, a train of erratics (see map) has been traced back to its source to the
westward. On the west coast, in Cardigan Bay, the boulders are all such as might have
been derived from the interior of Wales. At St. David’s Peninsula, Pembrokeshire,
striæ occur coming in from the northwest, and, taken with the discovery of boulders of
northern rocks, may point to a southward extension of a great glacier produced by
confluent sheets that choked the Irish Sea. Information is very scanty regarding large
areas in mid-Wales, but such as can be gathered seems to point to ice-shedding having
taken place from a north and south parting line. In North Wales, much admirable work
has been done which clearly indicates the neighbourhood of Great Arenig (Arenig
Mawr) as the radiant point for a great dispersal of blocks of volcanic rock of a
characteristic Welsh type.
“Ireland.—A brief reference must be made to Ireland, as the ice which took origin
there played an important part in bringing about some strange effects in English
glaciation, which would be inexplicable without a recognition of the causes in
operation across the Irish Sea. Ireland is a great basin, surrounded by an almost
continuous girdle of hills. The rainfall is excessive, and the snow-fall was probably
more than proportionately great; therefore we might expect that an ice-sheet of very
large dimensions would result from this combination of favouring conditions. The
Irish ice-sheet appears to have moved outward from about the centre of the island, but
the main flow was probably concentrated through the gaps in the encircling
mountains.
“Galloway.—The great range of granite mountains in the southwestern corner of
Scotland seems to have given origin to an immense mass of ice which moved in the
main to the southward, and there are good grounds for the belief that the whole ice-
drainage of the area, even that which gathered on the northern side of the water-shed,
ultimately found its way into the Irish Sea basin and came down coastwise and across
the low grounds of the Rinns of Galloway, being pushed down by the press of
Highland ice which entered the Firth of Clyde. It is a noteworthy fact that marine
shells occur in the drift in the course taken by the ice coming on to the extremity of
Galloway from the Clyde.

“The Lake District.—A radial flow of ice took place down the valleys from about
the centre of the Cumbrian hill-plexus, but movement to the eastward was at first
forbidden by the great rampart of the Cross Fell escarpment, which stretches like a
wall along the eastern side of the Vale of Eden.
“During the time when the Cumbrian glaciers had unobstructed access to the
Solway Frith, to the Irish Sea, and to Morecambe Bay, the dispersal of boulders of
characteristic local rocks would follow the ordinary drainage-lines; but, as will be
shown later, a state of affairs supervened in the Irish Sea which resulted, in many
cases, in a complete reversal of the ice-flow.
“The Pennine Chain was the source of glaciers of majestic dimensions upon both
its flanks in the region north of Skipton, but to the southward of that breach in the
chain (see map) no evidence is obtainable of any local glaciers.
"The Confluent Glaciers.
“With the growth of ice-caps upon the great centres a condition of affairs was
brought about in the Irish Sea productive of results which will readily be foreseen.
The enormous volumes of ice poured into the shallow sea from north, south, east, and
west, resulted in such a congestion as to necessitate the initiation of some new
systems of drainage.
“The Irish Sea Glacier.—The ice from Galloway, Cumbria, and Ireland became
confluent, forming what the late Professor Carvill Lewis termed ‘the Irish Sea
Glacier,’ and took a direction to the southward. Here it came in diametrical conflict
with the northward-flowing element of the Welsh sheet, which it arrested and
mastered; and the Irish Sea Glacier bifurcated, probably close upon the precipitous
Welsh coast to the eastward of the Little Orme’s Head, and the two branches flowed
coastwise to eastward and westward, keeping near the shore-line.
“The westerly branch swept round close to the coast in a southwesterly direction,
and completely overrode Anglesea; striating the rock-surfaces from northeast to
southwest (see map), and strewing the country with its bottom-moraine, containing
characteristic northern rocks, such as the Galloway granites, the lavas and granites of
the central and western portions of the Lake District, and fragments of shells derived
from shell-banks in the Irish Sea. One episode of this phase of the ice-movement was
the invasion of the first line of hills between the Menai Straits and Snowdon. The
gravels and sands of Fridd-bryn-mawr, Moel Tryfaen, and Moel-y-Cilgwyn, are the
coarser washings of the bottom-moraine, and consequently contain such rock-
fragments and shells as characterise it. From Moel-y-Cilgwyn southward, evidence is
lacking regarding the course taken by the glacier, but it probably passed over or
between the Rivals Mountains (Yr Eifl), and down Cardigan Bay at some distance

from the coast in confluence with the ice from mid-Wales; and, as I have suggested,
may have passed over St. David’s Head.
“Returning now towards the head of the glacier we may follow with advantage its
left bank downward. The ice-flow on the Cumberland coast appears to have resembled
very much that in North Wales. A great press of ice from the northward (Galloway)
seems to have had a powerful ‘easting’ imparted to it by the conjoint influences of the
thrust of the Irish ice and the inflow of ice from the Clyde. Whatever may have been
the cause, the effect is clear: about Ravenglass cleavage took place, and a flow to
northward and to southward, each bending easterly. By far the larger mass took a
southerly course and bent round Black Combe, over Walney, and a strip of the
mainland about Barrow in Furness, and out into and across Morecambe Bay. Its limits
are marked in the field by the occurrence of the same rocks which characterise it in
Anglesea, viz., the granites of Galloway and of west and central Cumbria.
“The continued thrust shouldered in the glacier upon the mainland of Lancashire,
but the precise point of emergence has not yet been traced, though it cannot be more
than a few miles from the position indicated on the map. I should here remark, that all
along the boundaries the Irish Sea Glacier was confluent with local ice, except,
probably, in that part of the Pennine chain to the southward of Skipton. Down to
Skipton there was a great mass of Pennine ice which was compelled to take an almost
due southerly course, and thus to run directly athwart the direction of the main hills
and valleys. A sharp easterly inflection of the Irish Sea Glacier carried it up the valley
of the Ribble, and thence, under the shoulder of Pendle, to Burnley, where Scottish
granites are found in the boulder-clay.
“On the summit of the Pennine water-shed, at Heald Moor, near Todmorden
(1,419 feet), boulder-clay has been found containing erratics belonging to this
dispersion; while in the gorge of the Yorkshire Calder, which flows along the eastern
side of the same hill, not a vestige of such a deposit is to be found, saving a few erratic
pebbles at a distance of eight or ten miles, which were probably carried down by
flood-wash from the edge of the ice.
“From this point the limits of the ice may be traced along the flanks of the Pennine
chain at an average altitude of about 1,100 feet.
“At one place the erratics can be traced to a position which would indicate the
formation of an extra-morainic lake having its head at a col about 1,000 feet above
sea-level, separating it from the valley of an eastward-flowing stream, the Wye, about
twelve miles down which a few granite blocks have been found. Other extra-morainic
lakes must have been formed, but very little information has been collected regarding
them. The Irish Sea Glacier can be shown to have spread across the whole country to
the westward of the line I have traced, and beyond the estuary of the Dee.

“I may now follow its boundaries on the Welsh coast, and pursue the line to the
final melting-place of the glacier. From the Little Orme’s Head the line of confluence
with the native ice is pretty clearly defined. It runs in, perhaps, half a mile from the
shore, until the broad low tract of the Vale of Clwyd is reached. Here the northern ice
obtained a more complete mastery, and pushed in even as far as Denbigh. This
extreme limit was probably attained as a mere temporary episode. Horizontal striæ on
a vertical face of limestone on the crags dominating the mouth of the vale on the
eastern side attest beyond dispute the action of a mass of land-ice moving in from the
north.
“I may here remark, that in this district the deposits furnish a very complete record
of the events of the Glacial period. In the cliffs on the eastern side of the Little Orme’s
Head, and at several other points along the coast towards the east, a sequence may be
observed as follows:
“4. Boulder-clay with northern erratics and shells.
“3. Sands and gravels with northern erratics and shells.
“2. Boulder-clay with northern erratics and shells.
“1. Boulder-clay with Welsh erratics and no shells.
“A similar succession is to be seen in the Vale of Clwyd. The interpretation is
clear: In the early stages of glaciation the Welsh ice spread without hindrance to, and
laid down, bed No. 1; then the northern ice came down, bringing its typical erratics
and the scourings of the sea-bottom, and laid down the variable series of clays, sands,
and gravels which constitute Nos. 2, 3, and 4 of the section.
“In the Vale of Clwyd an
additional interest is imparted to the
study of the drift from the
circumstance that the remains of man
have been found in deposits in caves
sealed with drift-beds. The best
example is the Cae Gwyn caves, in
which flint implements and the
bones and teeth of various extinct
Fig. 42.—The Cefn Cave, in Vale of Clwyd. (Trimmer.) a, animals were found embedded in
Entrance; b, mud with pebbles and wood covered with ‘cave-earth’ which was overlaid by
stalagmite; c, mud, bones, and angular fragments of bedded deposits of shell-bearing
limestone; d, sand and silt, with fragments of marine shells; e,
fissure; f, northern drift; g, cave cleared of mud; h, river Elwy, drift, with erratics of the northern
100 feet below; i, limestone rock. type.

“It has been supposed that the drift-deposits were marine accumulations; but it is
inconceivable that the cave could ever have been subjected to wave-action without the
complete scouring out of its contents.
“To resume the delineation of the limits of the great Irish Sea Glacier: From the
Vale of Clwyd the boundary runs along the range of hills parallel to the estuary of the
Dee at an altitude of about nine hundred feet. As it is traced to the southeast it
gradually rises, until at Frondeg, a few miles to the northward of the embouchure of
the Yale of Llangollen, it is at a height of 1,450 feet above sea-level. Thence it falls to
1,150 feet at Gloppa, three miles to the westward of Oswestry, and this is the most
southerly point to which it has been definitely traced on the Welsh border, though
scattered boulders of northern rocks are known to occur at Church Stretton.
“Along the line from the Vale of Clwyd to Oswestry the boundary is marked by a
very striking series of moraine-mounds. They occur on the extreme summits of lofty
hills in a country generally almost driftless, and their appearance is so unusual that
one—Moel-y-crio—at least has been mistaken for an artificial tumulus. The limitation
of the dispersal of northern erratics by these mounds is very clear and sharp; and
Mackintosh, in describing those at Frondeg, remarked that, while no northern rocks
extended to the westward of them, so no Welsh erratics could be found to cross the
line to the eastward. There are Welsh erratics in the low grounds of Cheshire and
Shropshire, but their distribution is sporadic, and will be explained in a subsequent
section.
“Having thus followed around the edges of this glacier, it remains to describe its
termination. It is clear that the ice must have forced its way over the low water-shed
between the respective basins of the Dee and the Severn. So soon as this ridge (less
than 500 feet above the sea) is crossed, we find the deposits laid down by the glacier
change their character, and sands and gravels attain a great predominance.[BO] Near
Bridgenorth, and, at other places, hills composed of such materials attain an altitude of
200 feet. From Shrewsbury via Burton, and thence, in a semicircular sweep, through
Bridgenorth and Enville, there is an immense concentration of boulders and pebbles,
such as to justify the designation of a terminal moraine. To the southward, down the
valley of the Severn, existing information points to the occurrence merely of such
scattered pebbles as might have been carried down by floods. In the district lying
outside this moraine there is a most interesting series of glacial deposits and of
boulders of an entirely different character. (See map.)
[BO] Mackintosh, Q. J. G. S.

“From the neighbourhood of Lichfield, through some of the suburbs of
Birmingham, and over Frankley Hill and the Lickey Hills to Bromsgrove, there is a
great accumulation of Welsh erratics, from the neighbourhood, probably, of Arenig
Mawr.

“The late Professor Carvill Lewis suggested that these Arenig rocks might have
been derived from some adjacent outcrop of Palæozoic rocks—a suggestion having its
justification in the discoveries that had been made of Cumbrian rocks in the Midlands.
To test the matter, an excavation was made at a point selected on Frankley Hill, and a
genuine boulder-clay was found, containing erratics of the same type as those found
upon the surface.
“The explanation has since been offered that this boulder-clay was a marine
deposit laid down during a period of submerge nee.[BP] Apart from the difficulty that
the boulder-clay displays none of the ordinary characteristics of a marine deposition,
but possesses a structure, or rather absence of structure, in many respects quite
inconsistent with such an origin, and contains no shells or other remains of marine
creatures, it must be pointed out that no theory of marine notation will explain the
distribution of the erratics, and especially their concentration in such numbers at a
station sixty or seventy miles from their source.
[BP] Proceedings of the Birmingham Philosophical Society, vol. vi, Part I, p. 181.

“Upon the land-ice hypothesis this difficulty disappears. During the early stages of
the Glacial period the Welsh ice had the whole of the Severn Valley at its mercy, and a
great glacier was thrust down from Arenig, or some other point in central Wales,
having an initial direction, broadly speaking, from west to east. This glacier extended
across the valley of the Severn, sweeping past the Wrekin, whence it carried blocks of
the very characteristic rocks to be lodged as boulders near Lichfield; and it probably
formed its terminal moraine along the line indicated. (See lozenge-shaped marks on
the map.) As the ice in the north gathered volume it produced the great Irish Sea
Glacier, which pressed inland and down the Vale of Severn in the manner I have
described, and brushed the relatively small Welsh stream out of its path, and laid down
its own terminal moraine in the space between the Welsh border and the Lickey Hills.
It seems probable that the Welsh stream came mainly down the Vale of Llangollen,
and thence to the Lickey Hills. Boulders of Welsh rocks occur in the intervening tract
by ones and twos, with occasional large clusters, the preservation of any more
connected trail being rendered impossible by the great discharge of water from the
front of the Irish Sea Glacier, and the distributing action of the glacier itself.
“Within the area in England and Wales covered by the Irish Sea Glacier all the
phenomena point to the action of land-ice, with the inevitable concomitants of
subglacial streams, extra-morainic lakes, etc. There is nothing to suggest marine
conditions in any form except the occurrence of shells or shell fragments; and these
present so many features of association, condition, and position inconsistent with,
what we should be led to expect from a study of recent marine life, that conchologists
are unanimous in declaring that not one single group of them is on the site whereon
the shells lived. It is a most significant fact—one out of a hundred which could be
cited did space permit—that in the ten thousand square miles of, as it is supposed,

recently elevated sea-bottom, not a single example of a bivalve shell with its valves in
apposition has ever been found! Nor has a boulder or other stone been found
encrusted with those ubiquitous marine parasites, the barnacles.
“The evidences of the action of land-ice within the area are everywhere apparent
in the constancy of direction of— (1.) Striæ upon rock surfaces. (2.) The terminal
curvature of rocks. (3.) The ‘pull-over’ of soft rocks. (4.) The transportal of local
boulders. (5.) The orientation of the long axes of large boulders. (6.) The false bedding
of sands and gravels. (7.) The elongation of drift-hills. (8.) The relations of ‘crag and
tail.’ There is a similar general constancy, too, in the directions of the striæ upon large
boulders. Upon the under side they run longitudinally from southeast (or thereabouts)
to northwest, while upon the upper surface they originate at the opposite end, showing
that the scratches on the under side were produced by the stone being dragged from
northwest to southeast, while those on the top were the product of the passage of
stone-laden ice over it in the same direction.
“Such an agreement cannot be fortuitous, but must be attributed to the operation of
some agent acting in close parallelism over the whole area. To attribute such regularity
to the action of marine currents is to ignore the most elementary principles of marine
hydrology. Icebergs must, in the nature of things, be the most erratic of all agents, for
the direction of drift is determined—among other varying factors—by the draught of
the berg. A mass of small draught will be carried by surface currents, while one of
greater depth will be brought within the influence of under-currents; and hence it not
infrequently happens that while floe-ice is drifting, say, to the southeast, giant bergs
will go crashing through it to the northwest. There are tidal influences also to be
reckoned with, and it is matter of common knowledge that flotsam and jetsam travel
back and forth, as they are alternately affected by ebb and flood tide.
“Bearing these facts in mind, it is surely too much to expect that marine ice should
transport boulders (how it picked up many of them also requires explanation) with
such unfailing regularity that it can be said without challenge,[BQ] ‘boulders in this
district [South Lancashire and Cheshire] never occur to the north or west of the parent
rock.’ The same rule applies without a single authentic exception to the whole area
covered by the eastern branch of the Irish Sea Glacier; and hence it comes about that
not a single boulder of Welsh rock has ever been recorded from Lancashire.
[BQ] Brit. Assoc. Report, 1890, p. 343.

“The Solway Glacier.—The pressure which forced much of the Irish Sea ice
against the Cumbrian coast-line caused, as has been described, a cleavage of the flow
near Ravenglass, and, having followed the southerly branch to its termination in the
midlands, the remaining moiety demands attention.

“The ‘easting’ motion carried it up the Solway Frith, its right flank spreading over
the low plain of northern Cumberland, which it strewed with boulders of the well-
known ‘syenite’ (granophyre) of Buttermere. When this ice reached the foot of the
Cross Fell escarpment, it suffered a second bifurcation, one branch pushing to the
eastward up the valley of the Irthing and over into Tyneside, and the other turning
nearly due southward and forcing its way up the broad Vale of Eden.
“Under the pressure of an enormous head of ice, this stream rose from sea-level,
turned back or incorporated the native Cumbrian Glacier which stood in its path, and,
having arrived almost at the water-shed between the northern and the southern
drainage, it swept round to the eastward and crossed over the Pennine water-shed; not,
however, by the lowest pass, which is only some 1,400 feet above sea-level, but by the
higher pass of Stainmoor, at altitudes ranging from 1,800 to 2,000 feet. The lower part
of the course of this ice-flow is sufficiently well characterised by boulders of the
granite of the neighbourhood of Dalbeattie in Galloway; but on its way up the Vale of
Eden it gathered several very remarkable rocks and posted them as way-stones to
mark its course. One of these rocks, the Permian Brockram, occurs nowhere in situ at
altitudes exceeding 700 feet, yet in the course of its short transit it was lifted about a
thousand feet above its source. The Shap granite (see radiant point on map) is on the
northern side of the east and west water-sheds of the Lake District, and reaches its
extreme elevation, (1,656 feet) on Wasdale Pike; yet boulders of it were carried over
Stainmoor, at an altitude of 1,800 feet literally by tens of thousands.
“This Stainmoor Glacier passed directly over the Pennine chain, past the mouths
of several valleys, and into Teesdale, which it descended and spread out in the low
grounds beyond. Pursuing its easterly course, it abutted upon the lofty Cleveland Hills
and separated into two streams, one of which went straight out to sea at Hartlepool,
while the other turned to the southward and flowed down the Vale of York, being
augmented on its way by tributary glaciers coming down Wensleydale. The final
melting seems to have taken place somewhere a little to the southward of York; but
boulders of Shap granite by which its extension is characterised have been found as
far to the southward as Royston, near Barnsley.
“The other branch of the Solway Glacier—that which travelled due eastward—
passed up the valley of the Irthing, and over into that of the Tyne, and out to sea at
Tynemouth. It carried the Scottish granites with it, and tributary masses joined on
either hand, bringing characteristic boulders with them.
“The fate of those elements of the Solway Frith Glacier which reached the sea is
not left entirely to conjecture. The striated surfaces near the coast of Northumberland
indicate a coastwise flow of ice from the northward—probably from the Frith of Forth
—and the glaciers coming out from the Tyne and Tees were deflected to the
southward.

“There is conclusive evidence that this ice rasped the cliffs of the Yorkshire coast
and pressed up into some of the valleys. Where it passed the mouth of the Tees near
Whitby it must have had a height of at least 800 feet, but farther down the coast it
diminished in thickness. It nowhere extended inland more than a mile or two, and for
the most part kept strictly to the coast-line. Along the whole coast are scattered
erratics derived from Galloway and the places lying in the paths of the glaciers. In
many places the cliffs exhibit signs of rough usage, the rocks being crumpled and
distorted by the violent impact of the ice. At Filey Brigg a well-scratched surface has
been discovered, the striation being from a few degrees east of north.
“At Speeton the evidence of ice-sheet or glacier-work is of the most striking
character. On the top of the cliffs of Cretaceous strata a line of moraine-hills has been
laid down, extending in wonderful perfection for a distance of six miles. They consist
of a mixture of sand, gravel, and a species of clay-rubble, with occasional masses of
true boulder-clay, the whole showing the arched bedding so characteristic of such
accumulations. At the northerly end the moraine keeps close to the edge of the chalk
cliffs, which are there 400 feet high, and the hills are frequently displayed in section;
but as the elevation of the cliffs declines they fall back from the edge of the cliffs and
run quite across the headland of Flamborough, and are again exposed in section in
Bridlington Bay. One remarkable and significant fact is pointed out, namely, that
behind this moraine, within half a mile and at a lower level, the country is almost
absolutely devoid of any drift whatever.
“The interpretation of
these phenomena is as
follows: When the valley-
glaciers reached the sea
they suffered the
deflection which has been
mentioned, partly as the
result of the interference
of ice from the east of
Scotland, but also
influenced directly by the
cause which operated
upon the Scottish ice and
gave direction to it—that
is, the impact of a great
glacier from Scandinavia,
which almost filled the
North Sea, and turned in
the eastward-flowing ice
upon the British coast.

Fig. 43.—Moraine between Speeton and Flamborough (Lamplugh). “It is easy to see how
this pressure must have
forced the glacier-ice
against the Yorkshire coast, but vertical chalk cliffs 400 feet in height are not readily
surmounted by ice of any thickness, however great, and so it coasted along and
discharged its lateral moraine upon the cliff-tops. As the cliffs diminished in height we
find the moraine farther inland, and, as I have pointed out, the ice completely overrode
Flamborough Head. Amongst the boulders at Flamborough are many of Shap granite,
a few Galloway granites, a profusion of Carboniferous rocks, brought by the Tyne
branch of the Sol way Glacier as well as by that of Stainmoor, and, besides many torn
from the cliffs of Yorkshire, a few examples of unquestionable Scandinavian rocks,
such as the well-known Rhomben-porphyr. It is important to note that about ten to
twenty miles from the Yorkshire coast there is a tract of sea-bottom called by trawlers
‘the rough ground,’ in allusion to the fact that it is strewn with large boulders, amongst
which are many of Shap granite. This probably represents a moraine of the Teesdale
Glacier, laid down at a time when the Scandinavian Glacier was not at its greatest
development.
“On the south side of Flamborough Head the ‘buried cliff’ previously alluded to
occurs. The configuration of the country shows—and the conclusion is established by
numerous deep-borings—that the preglacial coast-line takes a great sweep inland from
here, and that the plain of Holderness is the result of the banking-up of an immense
thickness of glacial débris. In the whole country reviewed, from Tynemouth to
Bridlington, wherever the ice came on to the land from the seaward, it brought in
shells and fragmentary patches of the sea-bottom involved in its ground moraine.
Space does not permit of a detailed description of the several members of the
Yorkshire Drift, and I pass on to deal in a general way with the glacial phenomena of
the eastern side of England.
“The East Anglian Glacier.—The influence of the Scandinavian ice is clearly seen
in the fact that the entire ice-movement down the east coast south of Bridlington was
all from the seaward. Clays, sands, and gravels, the products of a continuous mass of
land-ice coming from the northeast are spread over the whole country, from the Trent
to the high grounds on the north of London overlooking the Thames.
“The line of extreme extension of these drift-deposits runs from Finchley (near
London), in the south across Hertfordshire, through Cambridgeshire, with outlying
patches at Gogmagog and near Buckingham, and northwestward over a large portion
of Leicestershire into the upper waters of the Trent, embracing the elevated region of
Palæozoic rocks at Charnwood Forest, near Leicester.
“Reserving the consideration of the very involved questions connected with the
drifts of the upper part of the Trent Valley, I may pass on to join the phenomena of the

southeastern counties with those at Flamborough Head. From Nottinghamshire the
limits of the drift of the East Anglian Glacier seem to run in a direction nearly due
west to east, for the great oolitic escarpment upon which Lincoln Cathedral is built is
absolutely driftless to the northward of the breach about Sleaford. However, along the
western flank of the oolitic range true boulder-clay occurs, bordering and doubtless
underlying the great fen-tract of mid-Lincolnshire; and the great Lincolnshire Wolds
appear to have been completely whelmed beneath the ice.
“The most remarkable of the deposits in this area is the Great Chalky Boulder-
Clay, which consists of clay containing much ground-up chalk, and literally packed
with well-striated boulders of chalk of all sizes, from minute pebbles up to blocks a
foot or more in diameter. Associated with them are boulders of various foreign rocks,
and many flints in a remarkably fresh condition, and still retaining the characteristic
white coat, except where partially removed by glacial attrition.
“One of the perplexing features of the glacial phenomena in the eastern counties of
England is the extension of true chalky boulder-clay to the north London heights at
Finchley and elsewhere; for only the faintest traces are to be found in the gravel
deposits of the Thames Valley of any wash from such a deposit, or from a glacier
carrying such materials.
“It has been suggested that the deposit may have been laid down in an extra-
morainic lake, or in an extension of the North. Sea, but these suggestions leave the
difficulty just where it was. If a lake or sea could exist without shores, a glacier-
stream might equally dispense with banks. Within the area of glaciation, defined
above, abundant evidence of the action of land-ice is obtainable, though striated
surfaces are extremely rare—a fact attributable to the softness of the chalk and clays
which occupy almost the whole area. Well-striated surfaces are found on the harder
rocks, as, for example, on the oolitic limestone at Dunston, near Lincoln.
“Mr. Skertchly has remarked that the proofs of the action of land-ice are
irrefragable. The Great Chalky Boulder-Clay covers an area of 3,000 square miles,
and attains an altitude of 500 feet above the sea-level, thus bespeaking, if the product
of icebergs, ‘an extensive gathering-ground of chalk, having an elevation of more than
500 feet. But where is it? Certainly not in Western Europe, for the chalk does not
attain so great an elevation except in a few isolated spots.’[BR]
[BR] Geikie’s Great Ice Age, p. 360.

“It has been further pointed out by Mr. Skertchly, that the condition of the flints in
this deposit furnishes strong evidence that they could not have been carried by floating
ice nor upon a glacier, for, in either of the latter events, there must have been some
exposure to the weather, which, as he remarks, would have rendered them worthless to
the makers of gun-flints, whereas they are now regularly collected for their use.

Fig. 44.—Diagram-section near Cromer (Woodward). 6. Gravel and sand (Middle Glacial) resting on contorted
drift (loam, sand, and marl, with large included boulders of chalk); 5. Cromer till: 4. Laminated clay and sands
(Leda myalis bed); 3. Fresh-water loams and sands: 3a. Black fresh-water bed of Runton (upper fresh-water
bed); 2. Forest bed—laminated clays and sands, with roots and débris of wood, bones of mammalia, estuarine
mollusca, etc., the upper part in places penetrated by rootlets (rootlet bed); 2a. Weybourn crag; 1. Chalk with
flints; * Large included boulder of chalk.

“The way in which the boulder-clay is related to the rocks upon which it rests is a
conclusive condemnation of any theory of floating ice; for example, where it rests
upon Oxford Clay, it contains the fossils characteristic of that formation, as it is
largely made up of the clay itself. The exceptions to this rule are as suggestive as
those cases which conform to it. Each outcrop yields material to the boulder-clay to
the south westward, showing a pull-over from the northeast.
“One of the most remarkable features of the drift of this part of England is the
inclusion of gigantic masses of rock transported for a short distance from their native
outcrop, very often with so small a disturbance that they have been mapped as in situ.
Examples of chalk-masses 800 feet in length, and of considerable breadth and
thickness, have been observed in the cliffs near Cromer, in Norfolk, but they are by no
means restricted to situations near the coast. One example is mentioned in which
quarrying operations had been carried on for some years before any suspicion was
aroused that it was merely an erratic. The huge boulders were probably dislodged
from the parent rock by the thrust of a great glacier, which first crumbled the beds,
then sheared off a prominent fold and carried it along. This explanation we owe to Mr.
Clement Reid.[BS] The drift-deposits of this region frequently contain shells, but they
rarely constitute what may be termed a consistent fauna, usually showing such an
association as could only be found where some agent had been at work gathering
together shells of different habitats and geological age.
[BS] See Geology of the Country around Cromer, and Geology of Holderness, Memoirs
of Geological Survey of England and Wales.

Fig. 45.—Section at right angles to the cliff through the westerly chalk bluff at Trimingham, Norfolk,
showing the manner in which chalk masses are incorporated into the till (Clement Reid). Scale, 250 fret to an
inch. A. Level of low-water spring-tides; B. Chalk, with sandy bed at *; C. Forest-bed series, etc., seen in the
cliffs a few yards north and south of this point; D. Cromer till, stiff lead-colored boulder-clay; E. Fine, chalky
sands, much false-bedded; F. Contorted drift, brown bouldery-clay with marked bedding- or fluxion-structure;
G. The bed, above the white line were seen and measured by more snow and measured by Mr. Reid; * Chalk
seen in situ on beach.
“If the ice-sheet, instead of flowing over the beds, happens to plough into them or abut against them, it
would bend up a boss of chalk, as at Beeston. A more extensive disturbance, like that at Trimingham drives
before it a long ridge of the bads, and nips up the chalk, till, like a cloth creased by the sliding of a heavy
book, it is folded into an inverted anticlinal. A slight increase of pressure, and the third stage is reached—the
top of the anticlinal being entirely sheared off, the chalk boulder driven up an incline, and forced into the
overlying boulder-clays.” (Clement Reid.)

“Attempts have been made to correlate the deposits over the whole area, but with
very indifferent success. A consideration of the consequences of the invasion of the
country by an ice-stream from the northeast will prepare us for any conceivable
complication of the deposits.
“The main movement was against the drainage of the country, so that the ice-front
must have been frequently in water. There would be aqueous deposition and erosion;
the kneading up of morainic matter into ground-moraine; irregularities of distribution
and deposition due to ice floating in an extra-morainic lake; flood-washes at different
points of overflow; and other confusing causes, which make it rather matter for
surprise that any order whatever is traceable.
“I now turn to the valley of the Trent. We find that it occupies such a position that
it would be exposed, successively or simultaneously, to the action of ice-streams of
most diverse origin. I have shown that the area to the westward of Lichfield was
invaded at one period by a Welsh glacier, and at a subsequent one by the Irish Sea
Glacier, and both of these streams entered the valley of the Trent or some of its
affluents. From the eastward, again, the great North Sea Glacier encroached in like
manner, carrying the Great Chalky Boulder-Clay even into the drainage area of the
westward-flowing rivers near Coventry.
“The glacial geology of the Trent Valley from Burton to Nottingham has been ably
dealt with by Mr. R. M. Deeley,[BT] who recognises a succession which may be

generalised as follows: (1.) A lower series containing rocks derived from the Pennine
chain; (2.) A middle series containing rocks from the eastward (chalky boulder-clay,
etc.); and (3.) An upper series with Pennine rocks. Mr. Deeley thinks the Pennine
débris may have been brought by glaciers flowing down the valleys of the Dove, the
Wye, and the Derwent; but, while recognising the importance of the testimony
adduced, especially that of the boulders, I am compelled to reserve judgment upon this
point until something like moraines or other evidences of local glaciers can be shown
in those valleys. In their upper parts there is not a sign of glaciation. Some of the
deposits described must have been laid down by land-ice; while the conformation of
the country shows that during some stages of glaciation a lake must have existed into
which the different elements of the converging glaciers must have projected. This
condition will account for the remarkable commingling of boulders observed in some
of the deposits. Welsh, Cumbrian, and Scottish rocks occur in the western portion of
the Trent Valley. The overflow of the extra-morainic lake would find its way into the
valleys of the Avon and Severn, and may be taken to account for the abundance of
flints in some of the gravels.
[BT] Quarterly Journal Geological Society, vol. xlii, p. 437.

“The Isle of Man.—This little island in mid-seas constituted in the early stages of
the Glacial epoch an independent centre of glaciation, and from some of its valleys
ice-streams undoubtedly descended to the sea; but with the growth of the great Irish
Sea Glacier the native ice was merged in the invading mass, and at the climax of the
period the whole island was completely buried, even to its highest peak (Snae Fell,
2,054 feet), beneath the ice. The effects of this general glaciation are clearly seen in
the mantle of unstratified drift material which overspread the hills; in the moutonnée
appearance of the entire island; and in the transport of boulders of local rocks. The
striations upon rock surfaces show a constancy of direction in agreement with the
boulder-transport which can be ascribed to no other agency than a great continuous
sheet of such dimensions as to ignore minor hills and valleys.
“The disposition of the striæ is equally conclusive, for we find that on a stepped
escarpment of limestone both the horizontal and the vertical faces are striated
continuously and obliquely from the one on to the other, showing that the ice had a
power of accommodating itself to the surface over which it passed that could not be
displayed by floating ice. There is a remarkable fact concerning the distribution of
boulders on this island which would strike the most superficial observers, namely, that
foreign rocks are confined to the low grounds. It might be argued that the local ice
always retained its individuality, and so kept the foreign ice with its characteristic
boulders at bay. But, apart from the a priori improbability of so small a hill-cluster
achieving what the Lake District could not accomplish, the fact that Snae Fell, an
isolated conical hill, is swathed in drift from top to bottom, is quite conclusive that the
foreign ice must have got in. Why, then, did it carry no stones with it? The following

suggestion I make not without misgivings, though there are many facts to which I
might appeal that seem strongly corroborative:
“The hilly axis of the island runs in a general northeast and southwest direction,
and it rises from a great expanse of drift in the north with singular abruptness, some of
the hills being almost inaccessible to a direct approach without actual climbing. I
imagine that the ice which bore down upon the northern end of the island was, so far
as its lower strata were concerned, unable to ascend so steep an acclivity, and was
cleft, and flowed to right and left. The upper ice, being of ice-sheet origin, would be
relatively clean, and this flowing straight over the top of the obstruction would
glaciate the country with such material as was lying loose upon the ground or could be
dislodged by mere pressure. It would appear from published descriptions that the Isle
of Arran offers the same problem, and I would suggest the application of the same
solution to it.
“Marine shells occur in the Manx drift, but only in such situations as were reached
by the ice-laden with foreign stones. They present similar features of association of
shells of different habitat, and perhaps of geological age, to those already referred to
as being common characteristics of the shell-faunas of the drift of the mainland. Four
extinct species of mollusca have been recognised by me in the Manx drift.
“The Manx drift is of great interest as showing, perhaps better than any locality
yet studied, those features of the distribution of boulders of native rocks which attest
so clearly the exclusive action of land-ice. There are in the island many highly
characteristic igneous rocks, and I have found that boulders of these rocks never occur
to the northward of the parent mass, and very rarely in any direction except to the
southwest.
“Cumming observed in regard to one rock, the Foxdale granite, that whereas the
highest point at which it occurs in situ was 657 feet above sea-level, boulders of it
occurred in profusion within 200 feet of the summit of South Barrule (1,585 feet), a
hill two miles only, in a southwesterly direction, from the granite outcrop.
“They also occur on the summit of Cronk-na-Irrey-Lhaa, 1,449 feet above sea-
level. The vertical uplift has been 728 and 792 feet respectively.
“In the low grounds of the north of the island a finely developed terminal moraine
extends in a great sweep so as to obstruct the drainage and convert thousands of acres
of land into lake and morass, which is only now yielding to artificial drainage. Many
fine examples of drumlin and esker mounds occur at low levels in different parts of
the island; and it was remarked nearly fifty years ago by Cumming, that their long
axes were parallel to the direction of ice-movement indicated by the striated surfaces
and the transport of boulders.

“The foreign boulders are mainly from the granite mountains of Galloway, but
there are many flints, presumably from Antrim, a very small number of Lake District
rocks, and a remarkable rock containing the excessively rare variety of hornblende,
Riebeckite. This has now been identified with a rock on Ailsa Crag, a tiny islet in the
Frith of Clyde; and a Manx geologist, the Rev. S. N. Harrison, has discovered a single
boulder of the highly characteristic pitchstone of Corriegills, in the Isle of Arran.
“The So-called Great Submergence.
“It may be convenient to adduce some additional facts which render the theory of
a great submergence of the country south of the Cheviots untenable.
“The sole evidence upon which it rests is the occurrence of shells, mostly in an
extremely fragmentary condition, in deposits occurring at various levels up to about
1,400 feet above sea-level: A little space may profitably be devoted to a criticism of
this evidence.
“Moel Tryfaen (‘The Hill of the Three Rocks’).—This celebrated locality is on the
first rise of the ground between the Menai Straits and the congeries of hills
constituting ‘Snowdonia’; and when we look to the northward from the top of the hill
(1,350 feet) we see the ground rising from the straits in a series of gentle undulations
whose smooth contours would be found from a walk across the country to be due to
the thick mask of glacial deposits which obliterates the harsher features of the solid
rocks.
“The deposits on Moel Tryfaen are exposed in a slate-quarry on the northern
aspect of the hill near the summit, and consist of two wedges of structureless boulder-
clay, each thinning towards the top of the hill. The lower mass of clay, wherever it
rests upon the rock, contains streaks and irregular patches of eccentric form, of sharp,
perfectly angular fragments of slate; and the underlying rock may be seen to be
crushed and broken, its cleavage-laminæ being thrust over from northwest to
southeast—that is, up-hill. The famous ‘shell-bed’ is a thick series of sands and
gravels interosculated with the clays on the slope of the hill, but occupying the entire
section above the slate towards the top. The bedding shows unmistakable signs of the
action of water, both regular stratification and false bedding being well displayed. The
stones occurring in the clays are mainly if not entirely Welsh, including some from the
interior of the country, and they are not infrequently of large size—two or three tons’
weight—and well scratched.
“The stones found in the sands and gravels include a great majority of local rocks,
but besides these there have been recorded the following:
Rock. Source. Highest Minimum
point uplift

in situ. in feet.
Granite Eskdale, Cumberland 1,286 64
Granite Criffel, Galloway ..... ...
Flint Antrim (?) 1,000 350
To these I can add:
Granophyre Buttermere, Cumberland ..... ...
Eurite [BU] Ailsa Craig, Frith of Clyde 1,097 253
[BU] The altitude at which this rock occurs on Ailsa Craig has not been announced, so 1
have put it as the extreme height of the island.

“The shells in the Moel Tryfaen deposit have been fully described, so far as the
enumeration of species and relative frequency are concerned, but little has been said
as to their absolute abundance and their condition. The shells are extremely rare, and
daring a recent visit a party of five persons, in an assiduous search of about two hours,
succeeded in finding five whole shells and about two ounces of fragments. The
opportunities for collecting are as good as could be desired. The sections exposed
have an aggregate length of about a quarter of a mile, with a height varying from ten
to twenty feet of the shelly portion; and besides this there are immense spoil-banks,
upon whose rain-washed slopes fossil-collecting can be carried on under the most
favorable conditions.
“I would here remark, that the occurrence of small seams of shelly material of
exceptional richness has impressed collectors with the idea that they were dealing
with a veritable shell-bed, when the facts would bear a very different interpretation. A
fictitious abundance is brought about by a process of what may be termed
‘concentration,’ by the action of a gently flowing current of water upon materials of
different sizes and different specific gravities. Shells when but recently vacated
consist of materials of rather high specific gravity, penetrated by pores containing
animal matter, so that the density of the whole mass is far below that of rocks in
general, and hence a current too feeble to move pebbles would yet carry shells.
Illustrations of this process may be observed upon any shore in the concentration of
fragments of coal, corks, or other light material.
“Regarding the interpretation of these facts: The commonly received idea is, that
the beds were laid down in the sea during a period of submergence, and that the shells
lived, not perhaps on the spot, but somewhere near, and that the terminal curvature of
the slate was produced by the grounding of icebergs which also brought the boulders.
But if this hypothesis were accepted, it would be necessary to invest the flotation of
ice with a constancy of direction entirely at variance with observed facts, for the
phenomena of terminal curvature is shown" with perfect persistence of direction
wherever the boulder-clay rests upon the rock; and, further, there is the highly
significant fact, that neither the sands and gravels nor the rock upon which they rest

show any signs of disturbance or contortion, such as must have been produced if
floating ice had been an operative agent.
“The uplift of foreign rocks is equally significant; and when we take into account
the great distances from which they have been borne and the frequency with which
such an operation must have been repeated, the inadequacy becomes apparent of
Darwin’s ingenious suggestion, that it might have been effected by a succession of
uplifts by shore-ice during a period of slow subsidence; while the character and
abundance of the molluscan remains invest with a species of irony the application of
the term ‘shell-bed’ to the deposit.
“I now turn to the alternative explanation (see ante, p. 145), viz., that the whole of
the phenomena were produced by a mass of land-ice which was forced in upon Moel
Tryfaen from the north or northwest, overpowering any Welsh ice which obstructed its
course. This view is in harmony with the observations regarding the ‘terminal
curvature’ of the slates, the occurrence of sharp angular chips of slate in the boulder-
clay, and the coincidence of direction of these indications of movement with the carry
of foreign stones. The few shells and shell-crumbs in the sands and gravels would,
upon this hypothesis, be the infinitesimal relics of huge shell-banks in the Irish Sea
which were destroyed by the glacier and in part incorporated in its ground-moraine or
involved in the ice itself. The sands and gravels would represent the wash which
would take place wherever, by the occurrence of a ‘nunatak’ or by approach to the
edge of the ice, water could have a free escape.
“Two principal objections have been urged to the land-ice explanation of the Moel
Tryfaen deposits. An able critic asks, ‘Can, then, ice walk up-hill?’ To this we answer,
Given a sufficient ‘head’ behind it, and ice can certainly achieve that feat, as every
roche moutonnée proves. If it be granted that ice on the small scale can move up-hill,
there is no logical halting-place between the uplift of ten or twenty feet to surmount a
roche moutonnée, and an equally gradual elevation to the height of Moel Tryfaen.
Furthermore, the inland ice of Greenland is known to extrude its ground-moraine on
the ‘weather-side’ of the nunataks, and the same action would account for the material
uplifted on Moel Tryfaen.
“The second objection brought forward was couched in somewhat these terms: ‘If
the Lake District had its ice-sheet, surely Wales had one also. Could not Snowdonia
protect the heart of its own domain?’ Of course, Wales had its ice-sheet, and the
question so pointedly raised by the objector needs an answer; and though it is merely
a question of how much force is requisite to overcome a certain resistance (both
factors being unknown), still there are features in the case which render it specially
interesting and at the same time comparatively easy of explanation. It seems rather
like stating a paradox, yet the fact is, that it was the proximity of Snowdon which, in
my opinion, enabled the foreign ice to invade Wales at that point.

“A glance at the map will show that the ‘radiant point’ of the Welsh ice was
situated on or near Arenig Mawr, and that the great mass of Snowdon stands quite on
the periphery of the mountainous regions of North Wales, so that it would oppose its
bulk to fend off the native ice-sheet and prevent it from extending seaward in that
direction.

Fig. 46.—Section across Wales to show the relationship of native to foreign ice.

“As a consequence, the only Welsh ice in position to obstruct the onward march of
the invader would be such trifling valley-glaciers as could form on the western slopes
of Snowdon itself.
“The peak of Snowdon is 3,570 feet above sea-level, and Arenig Mawr, 2,817 feet
high, is eighteen miles to the eastward, and a broad, deep valley with unobstructed
access to Cardigan Bay intervenes; so, if any ice from the central mass made its way
over the Snowdonian range, it performed a much more surprising feat than that
involved in the ascent of Moel Tryfaen from the westward.
“The profile shows in diagrammatic form the probable relations of the foreign to
the native ice at the time when the Moel Tryfaen deposits were laid down.
“From what has been said regarding the great glaciers, it would seem that ice
advanced upon the land from the seaward in several parts of the coast of England,
Wales, and the Isle of Man. Now, it is in precisely those parts of the country, and those
alone, that the remains of marine animals occur in the glacial deposits. If the dispersal
of the shells found in the drift had been effected by the means I have suggested, it
would follow, as an inevitable consequence, that wherever shells occur there should
also be boulders which have been brought from beyond the sea. This I find to be the
case, and in two instances the discovery of shells was preliminary to the extension of
the boundaries of the known distribution of boulders of trans-marine origin.
“The officers of the Geological Survey some years ago observed the occurrence of
‘obscure fragments of marine shells’ in a deposit at Whalley, Lancashire, in which
they could find only local rocks. One case such as this would be fatal to the theory of
the remanié origin of the shells, but on visiting the section with Mr. W. A. Downham,
I found, amongst the very few stones which occurred in the shell-bearing sand at the
spot indicated, two well-marked examples of Cumbrian volcanic rocks, and, at a little
distance, large boulders of Scottish granites.

“The second case is more striking. The announcement was made that shells had
been found on a hill called Gloppa near Oswestry, in Shropshire, and, as it lay about
five miles to the westward of Mackintosh’s boundary of the Irish Sea Glacier, and
therefore well within the area of exclusively Welsh boulders, it furnished an excellent
opportunity of putting the theory to the test. An examination of the boulders
associated with the shells showed that the whole suite of Galloway and Cumbrian
erratics such as belong to the Irish Sea Glacier were present in great abundance. Not
only this, but in the midst of the series of shell-bearing gravels I observed a thin
lenticular bed of greenish clay, which upon examination was found to be crowded
with well-scratched specimens of Welsh rocks; but neither a morsel of shell nor a
single pebble of a foreign rock could be found, either by a careful examination in the
field or by washing the clay at home, and examining with a lens the sand and stones
separated out.
“The fact that predictions such as these have been verified affords a very striking
corroboration of the theory put forward; and, though shells cannot be found in every
deposit in which they might, ex hypothesi, be found, yet the strict limitation of them to
situations which conform to those assigned upon theoretical grounds cannot be
ascribed to mere coincidence. If the land had ever been submerged during any part of
the Glacial epoch to a depth of 1,400 feet, it is inconceivable that clear and
indisputable evidence should not be found in abundance in the sheltered valleys of the
Lake District and Wales, which would have been deep, quiet fiords, in which vast
colonies of marine creatures would have found harbour, as they do in the deep lochs
of Scotland to-day.
“It has been urged, in explanation of this absence of marine remains in the great
hill-centres, that the ‘second glaciation’ might have destroyed them; but to do this
would require that the ice should make a clean and complete sweep of all the loose
deposits both in the hollows of the valleys and on the hill-sides, and further that it
should destroy all the shells and all the foreign stones which floated in during the
submergence. At the same time we should have to suppose that the drift which lay in
the paths of the great glaciers was not subjected to any interference whatever. But,
assuming that these difficulties were explained, there would still remain the fact that
the valleys which have never been glaciated—as, for example, those of Derbyshire—
show no signs whatever of any marine deposits, nor of marine action in any form
whatever.
“The sea leaves other traces also, besides shells, of its presence in districts that
have really been submerged, yet there are no signs whatever to be found of them in all
England, except the post-glacial raised beaches. Furthermore, in all the area occupied
by glacial deposits there are no true sea-beaches, no cliffs nor sea-worn caves, no
barnacle-encrusted rocks, nor rocks bored by Pholas or Saxicava. Are we to believe
that these never existed; or that, having existed, they have been obliterated by

subsequent denudations? To make good the former proposition, it would be necessary
as a preliminary to show that the movement of subsidence and re-elevation was so
rapid, and the interval between so brief, that no time was allowed for any marine
erosion to take place. If this were so, it would be the most stupendous catastrophe of
which we have any geological record; but we are not left in doubt regarding the
duration of the submerged condition, for the occurrence of forty feet of gravel upon
the summits of the hills indicates plainly that, if they were accumulated by the sea, the
land must have stood at that level for a very long period, amply sufficient for the
formation of a well-marked coast-line.
“The alternative proposition, that post-glacial denudation had removed the traces
of subsidence, is equally at variance with the evidence. Post-glacial denudation has
left kames and drumlins, and all the other forms of glacial deposits, in almost perfect
integrity; the small kettle-holes are not yet filled up; and it is therefore quite out of the
question that the far more enduring features, such as sea-cliffs, shore platforms, and
beaches, should have been destroyed.
“The only reasonable conclusion is, that these evidences of marine action never
existed, because the land in glacial times was never depressed below its present level.
If the level were different at all (as I think may have been the case on the western side
of England), it was higher, and not lower.
“The details of the submergence hypothesis have, so far as I am aware, never been
dealt with by its advocates, otherwise I cannot but think that it would have been
abandoned long since. It has been stated in general terms that the subsidence was
greatest in the north and diminished to zero in the south, but no attempt was made to
trace the evidence of extreme subsidence across country and along the principal hill-
ranges—in fact, to see how it varied in every direction.
“If we take a traverse of England, say from Flamborough Head upon the east to
Moel Tryfaen on the west, and accept as evidence of submergence any true glacial
deposits (except, as in the case of the interior of Wales, the deposits are obviously the
effects of purely local glaciers and contain, therefore, no shells), we shall find that the
subsidence, if any, must have been not simply differential but sporadic.

Fig. 47.—Section of the cliff on the east side of South Sea Landing, Flamborough Head. Scale, 120 feet to 1
inch; length of section 290 yards; average height, 125 feet. (See above map of moraine between Speeton and
Flamborough.)

Explanation.—4. Brownish boulder-clay, a band of pebbles; 4a, in places about seven feet from top. 3.
Washed gravel, with thin sand-seams, well-bedded, pebbles chiefly erratics. 2. “Basement” boulder-clay,
with many included patches of sand, gravel, and silt; 2a, at B, one of these 2b contain shells. 1b. Sand and
silt, overlying and in places interbedded with 1. 1. Rubble of angular and subangular chalk-blocks and
gravel, with occasional erratic, passes partly into chalky boulder-clay, 1a. x. White chalk, without flints,
surface much shaken.

“At Flamborough Head shelly drift attains an altitude of 400 feet, but half a mile
from the coast the country is practically driftless even at lower levels. The Yorkshire
Wolds were not submerged. On the western flanks of the wolds drift comes in at about
100 to 150 feet, and persists, probably, under the post-glacial warp, from which it again
protrudes on the western side of the valley of the Ouse, and however the drift between
there and the Pennine water-shed may be interpreted, it shows not a sign of marine
origin; but, even granting that it did, we find that it does not reach within a thousand
feet of the water-shed. When the water-shed is crossed, however, abundant glacial
deposits are met with which are not to be differentiated from others at slightly lower
levels which contain shells.

Fig. 48.—Enlarged section of the shelly sand and surrounding clay at B in preceding figure. Scale, 4 feet to 1
inch.

Explanation.—2. “Basement” boulder-clay. 2a. Pure compact blue and brown clay of aqueous origin, bedding
contorted and nearly obliterated, but the mass is cut up by shearing planes. 2b. Irregular seam, and scattered
streaks, of greenish-yellow sand with many marine shells. 2c. Patch of pale-yellow sand, different from 2b,
without trace of fossils.

“If we suppose that the line of our traverse crosses the Pennine Chain at Heald
Moor, we shall find that on the eastern side no traces of drift occur above about 300
feet; while the very summit of the water-shed is occupied by boulder-clay, and thence

downward the trace is practically continuous, and at about 1,000 feet and downward the
drift contains marine shells. Across the great plain of Lancashire and Cheshire the
‘marine’ drift is fully developed—though it may be remarked in parentheses that it
contains a shallow-water fauna, albeit ex hypothesi deposited, in part at least, in a depth
of 200 fathoms of water—and to the Welsh border at Frondeg, where it again reaches a
water-shed at an altitude of 1,450 feet; but at 100 yards to the westward of the summit
all traces of subsidence disappear, and through the centre of Wales no sign is visible;
then we emerge on the western slopes at Moel Tryfaen, and they assume their fullest
dimensions, though only to finish abruptly on the hill-top, and put in no appearance in
the lower grounds which extend from there to the sea.
“The conclusions pointed to by the evidence (and, as I have endeavoured to show,
all the evidence which existed at the close of the Glacial period is there still) are, that a
subsidence of the Yorkshire Wolds took place on the east, but not in the centre or west;
that the Pennine Chain was submerged on the western side to a depth of 1,400 feet, and
on the east to not more than 300 feet, even on opposite sides of the same individual hill;
that all the lowlands between, say, Bacup and the Welsh border, were submerged, and
that the hills near Frondeg partook of this movement, but only on their eastern sides;
that the centre of Wales was exempt, but that the summit of Moel Tryfaen forms an
isolated spot submerged, while the surrounding country escaped. These absurdities
might be indefinitely multiplied, and they must follow unless it be admitted that the
phenomena are the results of glacial ice, and that ice can move ‘up-hill.’
“The south of England certainly has partaken of no movement of subsidence. A line
drawn from Bristol to London will leave all the true glacial deposits to the northward,
except a bed of very questionable boulder-clay at Watchet, and a peculiar deposit of
clayey rubble which has been produced on the flanks of the Cornish hills probably, as
the late S. V. Wood, Jr, suggested, by the slipping of material over a permanently frozen
subsoil.
“For the remainder of the southern area the evidence is plain that there has been no
considerable subsidence during glacial times. The presence over large areas of chalk
country of the ‘clay with flints’—a deposit produced by the gradual solution of the
chalk and the accumulation in situ of its insoluble residue—is absolute demonstration
that for immense periods of time the country has been exempt from any considerable
aqueous action. The enormous accumulations of china clay upon the granite bosses of
Cornwall and Devon tell the same tale. A few erratics have been found at low levels at
various points on the southern coasts, usually not above the reach of the waves. These
consist of rocks which may have been floated by shore-ice from the Channel Islands or
the French coast.
“This imperfect survey of the evidence against the supposed submergence has been
rendered the more difficult by the fact that it is not considered necessary to produce the
evidence of marine shells in all cases. Indeed, it has been argued that post-Tertiary beds

covering thousands of square miles might be absolutely destitute of shells without
prejudice to the theory of their formation in the sea.
“But such a suggestion, one would think, could hardly come from anyone familiar
with marine Tertiary deposits, or even with the appearance of modern sea-beaches.
Admitting, however, for the purposes of argument, that the beaches along a great extent
of coast might be devoid of shells, it cannot be argued that the deep waters were
destitute of life; and hence the boulder-clays, if of marine origin, should contain a great
abundance of shells and other remains, and, once entombed, it is beyond belief that they
could all be removed from such a deposit in the short lapse of post-glacial time.
“Now, some of the boulder-clays—as, for example, those of Lancashire and
Cheshire—are held to be of marine origin, and this is indeed a vital necessity to the
submergence theory; for, if these are not marine deposits, neither are the other shelly
deposits; but these boulder-clays are absolutely indistinguishable from those lying
within the hill-centres, and, as it passes belief that such deposits could be of diverse
origin and yet possess an identical structure and arrangement, then we should have a
right to demand that these clays should have enclosed shells and should still contain
them, but they do not.
“I may here mention that I am informed by Mr. W. Shone, F. G. S.—and he was
good enough to permit me to quote the statement—that the boulder-clay of Cheshire
and the shelly boulder-clay of Caithness are ‘as like as two peas.’ The importance of this
comparison lies in the fact that, since Croll’s classical description, all observers have
agreed that it was the product of land-ice which moved in upon the land out of the
Dornoch Firth. It was pointed out then, as since has been done for England, that it was
only where the direction of ice-movement was from the seaward that any shells occur in
the boulder-clay.
“The Dispersion of Erratics of Shap Granite.—So great a significance attaches to
the peculiar distribution of this remarkable rock, that I may add a few details here which
could not be conveniently introduced elsewhere.
“This granite occupies an area which lies just to the northward of the water-shed
between the basins of the Lime and the Eden, and its extreme elevation is 1,656 feet.
Boulders occur in large numbers as far to the northward as Cross Fells, while, as already
described, they pass over Stainmoor and are dispersed in great numbers along the route
taken by the great Stainmoor branch of the Solway Glacier. But a considerable number
of the boulders also found their way to the southward, and a well-marked trail can be
followed down into Morecambe Bay; and at Hest Bank, to the north of Lancaster, the
boulder-clay contains many examples, together with the ‘mica-trap’ of the Kendal and
Sedbergh dykes and other local rocks, but no shells or erratics from other sources than
the country draining into Morecambe Bay. To the southward the ice which bore these
rocks was deflected by the great Irish Sea Glacier, and, so far as present information
enables me to state, the Shap granite blocks mark the course of the medial moraine

between these two ice-streams. It has been found near Garstang, at Longridge, and at
Whalley, this being the exact line of junction of the Irish Sea Glacier with the ice from
Morecambe Bay and the Pennine Chain.
“It is a very remarkable and significant fact, that not a single authentic occurrence of
the rock across the boundary indicated has yet been recorded.”

Northern Europe.
On passing over the shallow German Sea from England to the Continent, the
southern border of the Scandinavian ice-field is found south of the Zuyder Zee, between
Utrecht and Arnhem—the moraine hills in the vicinity of Arnhem being quite marked,
and a barren, sandy plain dotted with boulders and irregular moraine hills extending
most of the way to the Zuyder Zee. From Arnhem the southern boundary of the great
ice-field runs “eastward across the Rhine Valley, along the base of the Westphalian
Hills, around the projecting promontory of the Hartz, and then southward through
Saxony to the roots of the Erzgebirge. Passing next southeastward along the flanks of
the Riesen and Sudeten chain, it sweeps across Poland into Russia, circling round by
Kiev, and northward by Nijni-Novgorod towards the Urals.”[BV] Thence the boundary
passes northward to the Arctic Ocean, a little east of the White Sea.
[BV] A. Geikie’s Text-Book of Geology, p. 885.

The depth of this northern ice-sheet is proved to have been upwards of 1,400 feet
where it met the Hartz Mountains, for it has deposited northern débris upon them to that
height; while, as already shown, it must have been over 2,000 feet in the main valley of
Switzerland. In Norway it is estimated that the ice was between 6,000 and 7,000 feet
thick.
The amount of work done by the continental glaciers of Europe in the erosion,
transportation, and deposition of rock and earthy material is immense. According to
Helland, the average depth of the glacial deposits over North Germany and
northwestern Russia is 150 German feet, i. e., about 135 English feet. As the deposition
towards the margin of a glacier must be commensurate with its erosion near the centre
of movement, this vast amount implies a still greater proportionate waste in the
mountains of Scandinavia, where the area diminishes with every contraction of the
circle. Two hundred and fifty feet is therefore not an extravagant calculation for the
amount of glacial erosion in the Scandinavian Peninsula.
It is not difficult to see how the Scandinavian mountains were able to contribute so
much soil to the plains of northern Germany and northwestern Russia. Previous to the
Glacial period, a warm climate extended so far north as to permit the growth of semi-
tropical vegetation in Spitsbergen, Greenland, and the northern shores of British
America. Such a climate, with its abundant moisture and vegetation, afforded most
favourable conditions for the superficial disintegration of the rocks. When, therefore,

the cold of the Glacial period came on, the moving currents of ice would have a
comparatively easy task in stripping the mantle of soil from the hills of Norway and
Sweden, and transporting it towards the periphery of its movement. Of course, erosion
in Scandinavia meant subglacial deposition beyond the Baltic. Doubtless, therefore, the
plains of northern Germany, with their great depth of soil, are true glacial deposits,
whose inequalities of surface have since been much obliterated, through the general
influences of the lapse of time, and by the ceaseless activity of man.
An interesting series of moraines in the north of Germany, bordering the Baltic Sea,
was discovered in 1888 by Professor Salisbury, of the United States Geological Survey.
Its course lies through Schleswig-Holstein, Mecklenburg, Potsdam (about forty miles
north of Berlin), thence swinging more to the north, and following nearly the line
between Pomerania and West Prussia, crossing the Vistula about twenty miles south of
Dantzic, thence easterly to the Spirding See, near the boundary of Poland.
Among the places where this moraine can be best seen are—“1. In Province
Holstein, the region about (especially north of) Eutin; 2. Province Mecklenburg, north
of Crivitz, and between Bütow and Kröpelin; 3. Province Brandenburg, south of
Reckatel, between Strassen and Bärenbusch, south of Fürstenberg and north of
Everswalde, and between Pyritz and Solden; 4. Province Posen, east of Locknitz, and at
numerous points to the south, and especially about Falkenburg, and between
Lompelburg and Bärwalde. This is one of the best localities. 5. Province West Preussen,
east of Bütow; 6. Province Ost Preussen, between Horn and Widikin.”
Comparing these with the moraines of America, Professor Salisbury remarks:
“In its composition from several members, in its variety of development, in its
topographic relations, in its topography, in its constitution, in its associated deposits, and
in its wide separation from the outermost drift limit, this morainic belt corresponds to
the extensive morainic belt of America, which extends from Dakota to the Atlantic
Ocean. That the one formation corresponds to the other does not admit of doubt. In all
essential characteristics they are identical in character. What may be their relations in
time remains to be determined.”

Fig. 49.—Map showing the glaciated area of Europe according to J. Geikie, and the moraines in Britain and Germany
according to Lewis and Salisbury.

The physical geography of Europe is so different from that of America, that there
was a marked difference in the secondary or incidental effects of the Glacial period
upon the two regions. In America the continental area over which the glaciers spread is
comparatively simple in its outlines. East of the Rocky Mountains, as we have seen, the
drainage of the Glacial period was, for a time, nearly all concentrated in the Mississippi
basin, and the streams had a free course southward.
But in Europe there was no free drainage to the south, except over a small portion of
the glaciated area in central Russia, about the head-waters of the Dnieper, the Don, and
the Volga; though the Danube and the Rhône afforded free course for the waters of a
portion of the great Alpine glaciers. But all the great rivers of northern Europe flow to
the northward, and, with the exception of the Seine, they all for a time encountered the
front of the continental ice-sheet. This circumstance makes it difficult to distinguish
closely between the direct glacial deposits in Europe and those which are more or less
modified by water-action. At first sight it would seem also somewhat hazardous to
attempt to correlate with any portion of the Glacial period the deposition of the gravelly
and loamy deposits in valleys, which, like those of the Seine and Somme, lie entirely
outside of the glaciated area.
Upon close examination, however, the elements of doubt more and more disappear.
The Glacial period was one of great precipitation, and it is natural to suppose that the
area of excessive snow-fall extended considerably beyond the limit of the ice-front.

During that period therefore, the rivers of central France must have been annually
flooded to an extent far beyond anything which is known at the present time. Since
these rivers flowed to the northward, at a period when, during the long and severe
winters, the annual accumulation of ice near their mouths was excessive, ice-gorges of
immense extent, such as now form about the mouths of the Siberian rivers, would
regularly occur. We are not surprised, therefore, to find, even in these streams, abundant
indications of the indirect influence of the great northern ice-sheet.
The indications referred to consist of high-level gravel terraces occasionally
containing boulders, of from four to five tons weight, which have been transported for a
considerable distance. The elevation of the terraces above the present flood-plains of the
Seine and Somme reaches from 100 to 150 feet. We are not to suppose, however, that
even in glacial times the floods of the river Seine could have filled its present valley to
that height. The highest flood in this river known in historic times rose only to a height
of twenty-nine feet. Mr. Prestwich estimates that, without taking into consideration the
more rapid discharge, a flood of sixty times this magnitude would be required to fill the
present valley to the level of the ancient gravels, while at Amiens the shape of the valley
of the Somme is such that five hundred times the mean average of the stream would be
required to reach the high-level gravels. The conclusion, therefore, is that the troughs of
these streams have been largely formed by erosion since the deposition of the high-level
gravels.
Connected with these terrace gravels in northern France is a loamy deposit,
corresponding to the loess in other parts of Europe, and to a similar deposit to which we
have referred in describing the southwestern part of the glaciated area in North America.
In northern France this fine silt overlies the high-level gravel deposits, and, as Mr.
Prestwich has pretty clearly shown, was deposited contemporaneously with them during
the early inundations and before the stream had eroded its channel to its present level.
The distribution of loess in Europe was doubtless connected with the peculiar
glacial conditions of the continent. Its typical development is in the valley of the Rhine,
where it is described by Professor James Geikie “as a yellow or pale greyish-brown,
fine-grained, and more or less homogeneous, consistent, non-plastic loam, consisting of
an intimate admixture of clay and carbonate of lime. It is frequently minutely perforated
by long, vertical, root-like tubes which are lined with carbonate of lime—a structure
which imparts to the loess a strong tendency to cleave or divide in vertical planes. Thus
it usually presents upright bluffs or cliffs upon the margins of streams and rivers which
intersect it. Very often it contains concretions or nodules of irregular form.... Land-
shells and the remains of land animals are the most common fossils of the loess, but
occasionally fresh-water shells and the bones of fresh-water fish occur.”
“From the margins of the modern alluvial flats which form the bottoms of the
valleys it rises to a height of 200 or 300 feet above the streams—sweeping up the slopes
of the valleys, and imparting a rich productiveness to many districts which would

otherwise be comparatively unfruitful. From the Rhienthal itself it extends into all the
tributary valleys—those of the Neckar, the Main, the Lahn, the Moselle, and the Meuse,
being more or less abundantly charged with it. It spreads, in short, like a great winding-
sheet over the country—lying thickly in the valleys and dying off upon the higher slopes
and plateaux. Wide and deep accumulations appear likewise in the Rhône Valley, as also
in several other river-valleys of France, as in those of the Seine, the Saône, and the
Garonne, and the same is the case with many of the valleys of middle Germany, such as
those of the Fulda, the Werra, the Weser, and the upper reaches of the great basin of the
Elbe. It must not be supposed that the loess is restricted to valleys and depressions in the
surface of the ground.
“It is true that it attains in these its greatest thickness, but extensive accumulations
may often be followed far into the intermediate hilly districts and over the neighbouring
plateaux. Thus the Odenwald, the Taunus, the Vogelgebirge, and other upland tracts, are
cloaked with loess up to a considerable height. Crossing into the drainage system of the
Danube, we find that this large river and many of its tributaries flow through vast tracts
of loess. Lower Bavaria is thickly coated with it, and it attains a great development in
Bohemia, Upper and Lower Austria, and Moravia—in the latter country rising to an
elevation of 1,300 feet. It is equally abundant in Hungary, Galicia, Bukowina, and
Transylvania. From the Danubian flat lands and the low grounds of Galicia it stretches
into the valleys of the Carpathians, up to heights of 800 and 2,000 feet. In some cases it
goes even higher—namely, to 3,000 feet, according to Zeuschner, and to 4,000 or 5,000
feet, according to Korzistka. These last great elevations, it will be understood, are in the
upper valleys of the northern Carpathians. In Roumania loess is likewise plentiful, but it
has not been observed south of the Balkans. East of the Carpathians—that is to say, in
the regions watered by the Dniester, the Dnieper, and the Don—loess appears also to be
wanting, and to be represented by those great steppe-deposits which are known as
Tchernozen, or black earth.”[BW]
[BW] Prehistoric Europe, pp. 144-146.

The shells found in the loess indicate both a colder and a wetter climate during its
deposition than that which now exists. The relics of land animals are infrequently found
in the deposit, yet they do occur, but mostly in fragmentary condition—the principal
animals represented being the mammoth, the rhinoceros, the reindeer, and the horse;
which is about the same variety as is found in the gravel deposits of the Glacial period,
both in western Europe and in America.
A species of loess—differing, however, somewhat in color from that on the Rhine—
covers the plains of northeastern France up to an elevation of 700 feet above the the sea,
where, as we have already said, it overlies the high-level gravels of the Seine and the
Somme. Above this height the superficial soil in France is evidently merely the
decomposed upper surface of the native rock.

The probable explanation of all these deposits, included under the term “loess,” is
the same as that already given by Prestwich of the loamy deposits of northern France.
But in case of rivers, which, like the Rhine, encountered the ice-front in their northward
flow, a flooded condition favouring the accumulation of loess was doubtless promoted
by the continental ice-barrier. In the case of the Danube and the Rhône, however, where
there was a free outlet away from the glaciated region, the loess in the upper part of the
valleys must have accumulated in connection with glacial floods quite similar to those
which we have described as spreading over the imperfectly formed water-courses of the
Mississippi basin during the close of the Ice age. That the typical loess is of glacial
origin is pretty certainly shown, both by its distribution in front of glaciers and by its
evident mechanical origin when studied under the microscope. It is, in short, the fine
sediment which gives the milky whiteness to glacial rivers.
In central Russia there is a considerable area in which the glacial conditions were, in
one respect, similar to those in the northern part of the Mississippi Valley in the United
States. In both regions the continental ice-sheet surmounted the river partings, and
spread over the upper portion of an extensive plain whose drainage was to the south.
The Dnieper, the Don, and the western branch of the Volga, like the Ohio and the
Mississippi, have their head-waters in the glaciated region. In some other respects, also,
there is a resemblance between the plains bordering the glaciated region in central
Russia and those which in America border it in the Mississippi Valley. Mr. James Geikie
is of the opinion that the extensive belt of black earth adjoining the glaciated area in
Russia, and constituting the most productive agricultural portion of the country, derives
its fertility, as does much of the Mississippi Valley, from the blanket of glacial silt
spread pretty evenly over it. Thus it would appear that in Europe, as in America, the ice
of the Glacial period was a most beneficent agent, preparing the face of the earth for the
permanent occupation of man. On both continents the seat of empire is in the area once
occupied by the advance of the great ice-movements of that desolate epoch.

Asia.
East of the Urals, in northern Asia, there is no evidence of moving ice upon the land
during the Glacial period; but at Yakutsk, in latitude 62° north, the soil is frozen at the
present time to an unknown depth, and many of the Siberian rivers, as they approach
and empty into the Arctic Sea, flow between cliffs of perpetual ice or frozen ground.
The changes that came over this region during the Glacial period are impressively
indicated by the animal remains which have been preserved in these motionless icy
cliffs. In the early part of the period herds of mammoth and woolly rhinoceros roamed
over the plains of Siberia, and waged an unequal warfare with the slowly converging
and destructive forces. The heads and tusks of these animals were so abundant in
Siberia that they long supplied all Russia with ivory, besides contributing no small
amount for export to other countries. “In 1872 and 1873 as many as 2,770 mammoth-
tusks, weighing from 140 to 160 pounds each, were entered at the London clocks.”[BX]

So perfectly have the carcasses of these extinct animals been preserved in the frozen soil
of northern Siberia that when, after the lapse of thousands of years, floods have washed
them out from the frozen cliffs, dogs and wolves and bears have fed upon their flesh
with avidity. In some instances even “portions of the food of these animals were found
in the cavities of the teeth. Microscopic examination showed that they fed upon the
leaves and shoots of the coniferous trees which then clothed the plains of Siberia.” A
skeleton and parts of the skin, and some of the softer portions of the body of a
mammoth, discovered in 1799 in the frozen cliff near the mouth of the Lena, was
carried to St. Petersburg in 1806, from which it was ascertained that this huge animal
was “covered with alight-coloured, curly, very thick-set hair one to two inches in length,
interspersed with darker-colored hair and bristles from four to eighteen inches
long.”[BY]
[BX] Prestwich’s Geology, vol. ii, p. 460.
[BY] Prestwich’s Geology, vol. ii, p. 460.

In the valleys of Sikkim and eastern Nepaul, in northern India, glaciers formerly
extended 6,000 feet lower than now, or to about the 5,000-foot level, and in the western
Himalayas to a still lower level. The higher ranges of mountains in other portions of
Asia also show many signs of former glaciation. This is specially true of the Caucasus,
where the ancient glaciers were of vast extent. According, also, to Sir Joseph Hooker,
the cedars of Lebanon flourish upon an ancient moraine. Of the glacial phenomena in
other portions of Asia little is known.

Africa.
Northern and even central Africa must likewise come in for their share of attention.
The Atlas Mountains, rising to a height of 13,000 feet, though supporting none at the
present time, formerly sustained glaciers of considerable size. Moraines are found in
several places as low as the 4,000-foot level, and one at an altitude of 4,000 feet is from
800 to 900 feet high, and completely crosses and dams up the ravine down which the
glacier formerly came.
Some have supposed that there are indubitable evidences of former glaciation in the
mountain-ranges of southwestern Africa between latitude 30° and 33°, but the evidence
is not as unequivocal as we could wish, and we will not pause upon it.
The mountains of Australia, also, some of which rise to a height of more than 7,000
feet, are supposed to have been once covered with glacial ice down to the level of 5,800
feet, but the evidence is at present too scanty to build upon. But in New Zealand the
glaciers now clustering about the peaks in the middle of the South Island, culminating in
Mount Cook, are but diminutive representatives of their predecessors. This is indicated
by extensive moraines in the lower part of the valleys and by the existence of numerous

lakes, attributable, like so many in Europe and North America, to the irregular
deposition of morainic material by the ancient ice-sheet.[BZ]
[BZ] See With Axe and Rope in the New Zealand Alps, by G. E. Mannering, 1891.

CHAPTER VII.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD.
We will begin the consideration of this part of our subject, also, with the
presentation of the salient facts in North America, since that field is simpler than any
field in the Old World.
The natural drainage basins of North America east of the Rocky Mountains are
readily described. The Mississippi River and its branches drain nearly all the region
lying between the Appalachian chain and the Rocky Mountains and south of the
Dominion of Canada and of the Great Lakes. All the southern tributaries to the Great
Lakes are insignificant, the river partings on the south being reached in a very short
distance. The drainage of the rather limited basin of the Great Lakes is northeastward
through the St. Lawrence River, leaving nearly all of the Dominion of Canada east of
the Rocky Mountains to pour its surplus waters northward into Hudson Bay and the
Arctic Ocean. With the exception of the St. Lawrence River, these are essentially
permanent systems of drainage. To understand the extent to which the ice of the Glacial
period modified these systems, we must first get before our minds a picture of the
country before the accumulation of ice began.

Preglacial Erosion.
Reference has already been made to the elevated condition of the northern and
central parts of North America at the beginning of the Glacial period. The direct proof
of this preglacial elevation is largely derived from the fiords and great lake basins of the
continent. The word “fiord” is descriptive of the deep and narrow inlets of the sea
specially characteristic of the coasts of Norway, Denmark. Iceland, and British
Columbia. Usually also fiords are connected with valleys extending still farther inland,
and occupied by streams.
Fiords are probably due in great part to river erosion when the shores stood at
considerably higher level than now. Slowly, during the course of ages, the streams wore
out for themselves immense gorges, and were assisted, perhaps, to some extent by the
glaciers which naturally came into existence during the higher continental elevation.
The present condition of fiords, occupied as they usually are by great depths of sea-

water, would be accounted for by recent subsidence of the land. In short, fiords seem
essentially to be submerged river gorges, partially silted up near their mouths, or
perhaps partially closed by terminal moraines.
It is not alone in northwestern Europe and British Columbia that fiords are found,
but they characterize as well the eastern coast of America north of Maine, while even
farther south, both on the Atlantic and on the Pacific coast, some extensive examples
exist, whose course has been revealed only to the sounding-line of the Government
survey.
The most remarkable of the submerged fiords in the middle Atlantic region of the
United States is the continuation of the trough of Hudson River beyond New York Bay.
As long ago as 1844 the work of the United States Coast Survey showed that there was
a submarine continuation of this valley, extending through the comparatively shallow
waters eighty miles or more seaward from Sandy Hook.

Fig. 50.—Map showing old channel and mouth of the Hudson (dewberry).

The more accurate surveys conducted from 1880 to 1884 have brought to our
knowledge the facts about this submarine valley almost as clearly as those relating to
the inland portion of it above New York city. According to Mr. A. Lindenkohl,[CA] this
submarine valley began to be noticeable in the soundings ten miles southeast of Sandy
Hook. The depth of the water where the channel begins is nineteen fathoms (114 feet).
Ten miles out the channel has sunk ninety feet below the general depth of the water on
the bank, and continues at this depth for twenty miles farther. This narrow channel
continues with more or less variation for a distance of seventy-five miles, where it
suddenly enlarges to a width of three miles and to a depth of 200 fathoms, or 1,200 feet,
and extends for a distance of twenty-five miles, reaching near that point a depth of 474
fathoms, or 2,844 feet. According to Mr. Lindenkohl, this ravine maintains for half its
length "a vertical depth of more than 2,000 feet, measuring from the top of its banks,
and the banks have a nearly uniform slope of about 14°.” The mouth of the ravine opens
out into the deep basin of the central Atlantic.

[CA] Bulletin of the Geological Society of America, vol. i, p. 564; American Journal of
Science, June, 1891.

With little question there is brought to light in these remarkable investigations a
channel eroded by the extension of the Hudson River, into the bordering shelf of the
Atlantic basin at a time when the elevation of the continent was much greater than now.
This is shown to have occurred in late Tertiary or post-Tertiary times by the fact that the
strata through which it is worn are the continuation of the Tertiary deposits of New
Jersey. The subsidence to its present level has probably been gradual, and, according to
Professor Cook, is still continuing at the rate of two feet a century.
Similar submarine channels are found extending out from the present shore-line to
the margin of the narrow shelf bordering the deep water of the central Atlantic running
from the mouth of the St. Lawrence River, through St. Lawrence Bay, and through
Delaware and Chesapeake Bays.[CB] All these submerged fiords on the Atlantic coast
were probably formed during a continental elevation which commenced late in the
Tertiary period, and reached the amount of from 2,000 to 3,000 feet in the northern part
of the continent.
[CB] See Lindenkohl in American Journal of Science, for June, 1891.

Fig. 51.—New York harbor in preglacial times looking south, from south end
of New York Island (Newberry).

To this period must probably be referred also the formation of the gorge, or more
properly fiord, of the Saguenay, which joins the St. Lawrence below Quebec. The great
depth of this fiord is certainly surprising, since, according to Sir William Dawson, its
bottom, for fifty miles above the St. Lawrence, is 840 feet below the sea-level, while the
bordering cliffs are in some places 1,500 feet above the water. The average width is
something over a mile.

It seems impossible to account for such a deep gorge extending so far below the sea-
level, except upon the supposition of a long-continued continental elevation, which
should allow the stream to form a cañon to an extent somewhat comparable with that of
the cañons of the Colorado and other rivers in the far West. Then, upon the subsidence
of the continent to the present level, it would remain partially or wholly submerged, as
we find it at the present time. During the Glacial period it was so filled with ice as to
prevent silting up. The rivers entering the Pacific Ocean, both in the United States and
in British Columbia, are also lost in submerged channels extending out to the deeper
waters of the Pacific basin in a manner closely similar to the Atlantic streams which
have been mentioned.
During this continental elevation which preceded, accompanied, and perhaps
brought on the Glacial period, erosion must have proceeded with great intensity along
all the lines of drainage, and throughout the whole region which is now covered, and to
a considerable extent smoothed over, by glacial deposits, and the whole country must
have presented a very different appearance from what it does now.
A pretty definite idea of its preglacial condition can probably be formed by studying
the appearance of the regions outside of and adjoining that which was covered by the
continental glacier. The contrast between the glaciated and the unglaciated region is
striking in several respects aside from the presence and absence of transported rocks and
other débris, but in nothing is it greater than in the extent of river erosion which is
apparent upon the surface. For example, upon the western flanks of the Alleghanies the
regions south of the glacial limit is everywhere deeply channeled by streams. Indeed, so
long have they evidently been permitted to work in their present channels that, wherever
there have been waterfalls, they have receded to the very head-waters, and no cataracts
exist in them at the present time. Nor are there in the unglaciated region any lakes of
importance, such as characterize the glaciated region. If there have been lakes, the lapse
of time has been sufficient for their outlets to lower their beds sufficiently to drain the
basins dry.
On entering the glaciated area all this is changed. The ice-movement has
everywhere done much to wear down the hills and fill the valleys, and, where there was
débris enough at command, it has obliterated the narrow gorges originally occupied by
the preglacial streams. Thus it has completely changed the minor lines of superficial
drainage, and in many instances has produced most extensive and radical changes in the
whole drainage system of the region. In the glaciated area, channels buried beneath
glaciated débris are of frequent occurrence, while many of the streams which occupy
their preglacial channels are flowing at a very much higher level than formerly, the
lower part of the channel having been silted up by the superabundant débris accessible
since the glacial movement began.

Buried Outlets and Channels.

It is easy to see how the great number of shallow lakes which frequent the glaciated
region were formed by the irregular deposition of glacial débris, but it is somewhat
more difficult to trace out the connection between the Glacial period and the Great
Lakes of North America, several of which are of such depth that their bottoms are some
hundreds of feet below the sea-level, Lake Erie furnishing the only exception. This lake
is so shallow that it is easy to see how its basin may have been principally formed by
river erosion, while it is evident that such must have been the mode of its formation,
since it is surrounded by sedimentary strata lying nearly in a horizontal position.

Fig. 52.—Section across the valley of the Cuyahoga River, twenty
miles above its mouth (Claypole).

That Lake Erie is really nothing but a “glacial mill-pond” is proved also by much
direct evidence, especially that derived from the depth of the buried channels of the
streams flowing into it from the south. Of these, the Cuyahoga River, which enters the
lake at Cleveland, has been most fully investigated. In searching for oil, some years ago,
borings were made at many places for twenty-five miles above the mouth of the river.
As a result, it appeared that for the whole distance the rocky bottom of the gorge was
about two hundred feet below the present bottom of the river, while the river itself is
two or three hundred feet below the general level of the country, occupying a trough
about half a mile in width, with steep, rocky sides. These facts indicate that at one time
the river must have found opportunity to discharge its contents at a level two hundred
feet below that of the present lake, while an examination of the material filling up the
bottom of the gorge to its present level shows it to be glacial débris, thus proving that
the silting up was accomplished during the Glacial period.
As the water of Lake Erie is for the most part less than one hundred feet in depth,
and is nowhere much more than two hundred feet deep, it is clear that the preglacial
outlet which drained it down to the level of the rocky bottom of the Cuyahoga River
must have destroyed the lake altogether. Hence Ave may be certain that, before the
Glacial period, the area now covered by the lake was simply a broad, shallow valley
through which there coursed a single river of great magnitude, with tributary branches
occupying deep gorges. Professor J. W. Spencer has shown with great probability that
the old line of drainage from Lake Erie passed through the lower part of the valley of
Grand River, in Canada, and entered Lake Ontario at its western extremity, and that
during the great Ice age this became so completely obstructed with glacial débris as to
form an impenetrable dam, and to cause the pent-up water to flow through the Niagara
Valley, which chanced to furnish the lowest opening.

In speaking of the present area of Lake Erie, however, as being then occupied by a
river valley, we do not mean to imply that it was not afterwards greatly modified by
glacial erosion; for undoubtedly this was the case, whatever views we may have as to
the relative efficiency of ice and water in scooping out lake basins.
In the case of Lake Erie, we need suppose no change of level to account for the
erosion of its basin, but only that, since the strata in which it is situated were deposited,
time enough had elapsed for a great river to cut a gorge extending from the western end
of Lake Ontario through to the present bed of Lake Erie, and that here a great
enlargement of the valley was occasioned by the existence of deep beds of soft shale
which could easily be worn away by a ramifying system of tributary streams. Rivers
acting at present relative levels would be amply sufficient to produce the results which
are here manifest.
But in the case of Lakes Ontario, Huron, Michigan, and Superior, whose depths
descend considerably below the sea-level, we must suppose that they were, in the main,
eroded when the continent was so much elevated that their bottoms were brought above
tide-level. The depth of Lake Ontario implies the existence of an outlet more than four
hundred feet lower than at present, which, of course, could exist only when the general
elevation was more than four hundred feet greater than now.
The existence of an outlet at that depth seems to be proved also by the fact that at
Syracuse, where numerous wells have been sunk to obtain brine for the manufacture of
salt, deposits of sand, gravel, and rolled stones, four hundred and fifty feet thick, are
penetrated without reaching rock. Since this lies in the basin of Lake Ontario, it follows
that if the basin itself has been produced by river erosion, the land must have been of
sufficient height to permit an outlet through a valley, or cañon, of the required depth,
and this outlet must now be buried beneath the abundant glacial débris that covers the
region.
Professor Newberry, who has studied the vicinity carefully, is of the opinion that
there is ample opportunity for such a line of drainage to have extended through the
Mohawk Valley to the Hudson River. But, at Little Falls, a spur of the Adirondack
Mountains projects into the valley, and the Archæan rocks over which the river runs are
so prominent and continuous that some have thought it impossible for the requisite
channel to have ever existed there. Extensive deposits of glacial débris, however, are
found in the vicinity, especially in places some distance to the north, and in Professor
Newberry’s opinion the existence of a buried channel around the obstruction upon the
north side is by no means improbable.
The preglacial drainage of Lake Huron has not been determined with any great
degree of probability. Professor Spencer formerly supposed that it passed from the
southern end of the lake through London, in the western part of Ontario, and reached the
Erie basin near Port Stanley, and so augmented the volume of the ancient river which
eroded the buried cañon from Lake Erie to Lake Ontario. But he now supposes, though

the evidence is by no means demonstrative, that the waters of Lake Huron passed into
Lake Ontario by means of a channel extending from Georgian Bay to the vicinity of
Toronto.
With a fair degree of probability, the basin of Lake Superior is supposed by
Professor Newberry to have been joined to that of Lake Michigan by some passage,
now buried, considerably to the west of the Strait of Mackinac, and thence to have had
an outlet southward from the vicinity of Chicago directly into the Mississippi River. Of
this there is considerable evidence furnished by deeply buried channels which have been
penetrated by borings in various places in Kankakee, Livingston, and McLean Counties,
Illinois; but the whole area extending from Lake Michigan to the Mississippi is so
deeply covered with glacial débris that the surface of the country gives no satisfactory
indication of the exact lines of preglacial drainage.
Some of the most remarkable instances of ancient river channels buried by the
glacial deposits have been brought to light in southwestern Ohio, where there has been
great activity in boring for gas and oil. At St. Paris, Champaign County, for example, in
a locality where the surface of the rock near by was known to be not far below the
general level, a boring was begun and continued to a depth of more than five hundred
feet without reaching rock, or passing out of glacial débris.
Many years ago Professor Newberry collected sufficient facts to show that pretty
generally the ancient bed of the Ohio River was as much as 150 feet below that over
which it now flows. During a continental elevation the erosion had proceeded to that
extent, and then the channel had been silted up during the Glacial period with the
abundant material carried down by the streams from the glaciated area. One of the
evidences of the preglacial depth of the channel of the Ohio was brought to light at
Cincinnati, where “gravel and sand have been found to extend to a depth of over one
hundred feet below low-water mark, and the bottom of the trough has not been
reached.” In the valley of Mill Creek, also, “in the suburbs of Cincinnati, gravel and
sand were penetrated to the depth of 120 feet below the stream before reaching rock.”
But from the general appearance of the channel, Professor J. F. James was led to
surmise that a rock bottom extended all the way across the present channel of the Ohio,
between Price Hill and Ludlow, Ky., a short distance below Cincinnati, which would
preclude the possibility of a preglacial outlet at the depth disclosed in that direction. Mr.
Charles J. Bates (who was inspector of the masonry for the Cincinnati Southern
Railroad while building the bridge across the Ohio at this point) informs me that Mr.
James’s surmise is certainly correct, and that his “in all probability” may be displaced
by “certainly,” since the bedded rocks supposed by Professor James to extend across the
river a few feet below its present bottom were found by the engineers to be in actual
existence.
In looking for an outlet for the waters of the upper Ohio which should permit them
to flow off at the low level reached in the channel at Cincinnati, Professor James was

led to inspect the valley extending up Mill Creek to the north towards Hamilton, where
it joins the Great Miami. The importance of Mill Creek Valley is readily seen in the fact
that the canal and the railroads have been able to avoid heavy grades by following it
from Cincinnati to Hamilton. As a glance at a map will show, it is also practically but a
continuation of the northerly course pursued by the Ohio for twenty miles before
reaching Cincinnati. This, therefore, was a natural place in which to look beneath the
extensive glacial débris for the buried channel of the ancient Ohio, and here in all
probability it has been found. The borings which have been made in Milk Creek Valley
north of Cincinnati, show that the bedded rock lies certainly thirty-four feet below the
low-water mark of the Ohio just below Cincinnati, while at Hamilton, twenty-five miles
north of Cincinnati, where the valley of the Great Miami is reached, the bedded rock of
the valley lies as much as ninety feet below present low-water mark in the Ohio.
Other indications of the greater depth of the preglacial gorge of the Ohio are
abundant. “At the junction of the Anderson with the Ohio, in Indiana, a well was sunk
ninety-four feet below the level of the Ohio before rock was found.” At Louisville, Ky.,
the occurrence of falls in the Ohio seemed at first to discredit the theory in question, but
Professor Newberry was able to show that the falls at Louisville are produced by the
water’s being now compelled to flow over a rocky point projecting from the north side
into the old valley, while to the south there is ample opportunity for an old channel to
have passed around this point underneath the city on the south side. The lowlands upon
which the city stands are made lands, where glacial débris has filled up the old channel
of the Ohio.
Above Cincinnati the tributaries of the Ohio exhibit the same phenomena. At New
Philadelphia, Tuscarawas County, the borings for salt-wells show that the Tuscarawas is
running 175 feet above its ancient bed. The Beaver, at the junction of the Mahoning and
Shenango, is flowing 150 feet above the bottom of its old trough, as is demonstrated by
a large number of oil-wells bored in the vicinity. Oil Creek is shown by the same proofs
to run from 75 to 100 feet above its old channel, and that channel had sometimes
vertical and even overhanging walls.[CC]
[CC] Geological Survey of Ohio, vol. ii, pp. 13, 14.

The course of preglacial drainage in the upper basin of the Alleghany River is
worthy of more particular mention. Mr. Carll, of the Pennsylvania Geological Survey,
has adduced plausible reasons for believing that previous to the Glacial period the
drainage of the valley of the upper Alleghany north of the neighbourhood of Tidioute, in
Warren County, instead of passing southward as now, was collected into one great
stream flowing northward through the region of Cassadaga Lake to enter the Lake Erie
basin at Dunkirk, N. Y. The evidence is that between Tidioute and Warren the present
Alleghany is shallow, and flows over a rocky basin; but from Warren northward along
the valley of the Conewango, the bottom of the old trough lies at a considerably lower
level, and slopes to the north. Borings show that in thirteen miles the slope of the
preglacial floor of Conewango Creek to the north is 136 feet. The actual height above

tide of the old valley floor at Fentonville, where the Conewango crosses the New York
line, is only 964 feet; while that of the ancient rocky floor of the Alleghany at Great
Bend, a few miles south of Warren, was 1,170 feet. Again, going nearer the head-waters
of the Alleghany, in the neighbourhood of Salamanca, it is found that the ancient floor
of the Alleghany is, at Carrollton, 70 feet lower than the ancient bed of the present
stream at Great Bend, about sixty miles to the south; while at Cole’s Spring, in the
neighbourhood of Steamburg, Cattaraugus County, N. Y., there has been an
accumulation of 315 feet of drift in a preglacial valley whose rocky floor is 155 feet
below the ancient rocky floor at Great Bend. Unless there has been a great change in
levels, there must, therefore, have been some other outlet than the present for the waters
collecting in the drainage basin to the north of Great Bend.[CD]
[CD] For a criticism of Mr. Carll’s views, see an article on Pleistocene Fluvial Planes of
Western Pennsylvania, by Mr. Frank Leverett, in American Journal of Science, vol. xlii, pp.
200-212.

While there are numerous superficial indications of buried channels running towards
Lake Erie in this region, direct exploration has not been made to confirm these
theoretical conclusions. In the opinion of Mr. Carll, Chautauqua Lake did not flow
directly to the north, but, passing through a channel nearly coincident with that now
occupied by it, joined the northerly flowing stream a few miles northeast from
Jamestown.[CE] It is probable, however, that Chautauqua did not then exist as a lake,
since the length of preglacial time would have permitted its outlet to wear a continuous
channel of great depth corresponding to that known to have existed in the Conewango
and upper Alleghany.
[CE] Second Geological Survey of Pennsylvania, vol. iii.

The foregoing are but a few of the innumerable instances where the local lines of
drainage have been disturbed, and even permanently changed, by the glacial deposits.
Almost every lake in the glaciated region is a witness to this disturbance of the
established lines of drainage by glacial action, while in numerous places where lakes do
not now exist they have been so recently drained that their shore-lines are readily
discernible.
An interesting instance of the recent disappearance of one of these glacial lakes is
that of Runaway Pond, in northern Vermont. In the early part of the century the
Lamoille River had its source in a small lake in Craftsbury, Orleans County. The sources
of the Missisquoi River were upon the same level just to the north, and the owner of a
mill privilege upon this latter stream, desiring to increase his power by obtaining access
to the water of the lake, began digging a ditch to turn it into the Missisquoi, but no
sooner had he loosened the thin rim of compact material which formed the bottom and
the sides of the inclosure, than the water began to rush out through the underlying and
adjacent quicksands. This almost instantly enlarged the channel, and drained the whole
body of water oft 3 in an incredibly short time. As a consequence, the torrent went
rushing down through the narrow valley, sweeping everything before it; and nothing but

the unsettled condition of the country prevented a disaster like that which occurred in
1889 at Johnstown, Pa. Doubtless there are many other lakes held in position by equally
slender natural embankments. Artificial reservoirs are by no means the only sources of
such danger.
The buried channel of the old Mississippi River in the vicinity of Minneapolis is
another instructive example of the instability of many of the present lines of drainage.
The gorge of the Mississippi River extending from Fort Snelling to the Falls of St.
Anthony at Minneapolis is of post-glacial origin. One evidence of this is its narrowness
when contrasted with the breadth of the valley below Fort Snelling. Below this point the
main trough of the Mississippi has a width of from two to eight miles, and the faces of
the bluffs on either side show the marks of extreme age. The tributary streams also have
had time to wear gorges proportionate to that of the main stream, and the agencies
which oxidise and discolor the rocks have had time to produce their full effects. But
from Fort Snelling up to Minneapolis, a distance of about seven miles, the gorge is
scarcely a quarter of a mile in width, and the faces of the high, steep bluffs on either
side are remarkably fresh looking by comparison with those below; while the tributary
gorges, of which that of the Minnehaha River is a fair specimen, are very limited in their
extent.
Upon looking for the cause of this condition of things we observe that the broad
trough of the Mississippi River, which had characterised it all the way below Fort
Snelling, continues westward, without interruption, up the valley of the present
Minnesota River, and, what seems at first most singular, it does not cease at the sources
of the Minnesota, but, through Lake Traverse and Big Stone Lake, is continuous with
the trough of the Red River of the North.

Fig. 53.—Map of Mississippi River from Fort Snelling to
Minneapolis and the vicinity, showing the extent of the
recession of the Falls of St. Anthony since the great Ice
age. Notice the greater breadth of the valley of the
Minnesota River as described in the text (Winchell).

Deferring, however, for a little the explanation of this, we will go back to finish the
history of the preglacial channel around the Falls of St. Anthony. As early as the year
1876 Professor N. H. Winchell had collected sufficient evidence from wells, one of
which had been sunk to a depth of one hundred and seventy-five feet, to show that the
preglacial course of the stream corresponding to the present Mississippi River ran to the
west of Minneapolis and of the Falls of Minnehaha, and joined the main valley some
distance above Fort Snelling, as shown in the accompanying map.
This condition of things was at one time very painfully brought to the notice of the
citizens of Minneapolis. A large part of the wealth of the city at that time consisted of
the commercial value of the water-power furnished by the Falls of St. Anthony. To
facilitate the discharge of the waste water from their wheels, some mill-owners dug a
tunnel through the soft sandstone underlying the limestone strata over which the river
falls; but it very soon became apparent that the erosion was proceeding with such
rapidity that in a few years the recession of the falls would be carried back to the

preglacial channel, when the river would soon scour out the channel and destroy their
present source of wealth. The citizens rallied to protect their property, and spent
altogether as much as half a million dollars in filling up the holes that had been
thoughtlessly made; but so serious was the task that they were finally compelled to
appeal for aid to the United States Government. Permanent protection was provided by
running a tunnel, some ways back from the falls, completely across the channel, through
the soft sandstone underlying the limestone, and filling this up with cement hard enough
and compact enough to prevent the further percolation of the water from above.

Ice-Dams.
The foregoing changes in lines of drainage due to the Glacial period were produced
by deposits of earthy material in preglacial channels. Another class of temporary but
equally interesting changes were produced by the ice itself acting directly as a barrier.
Many such lakes on a small scale are still in existence in various parts of the world.
The Merjelen See in Switzerland is a well-known instance. This is a small body of water
held back by the great Aletsch Glacier, in a little valley leading to that of the Fiesch
Glacier, behind the Eggischorn. At irregular intervals the ice-barrier gives way, and
allows the water to rush out in a torrent and flood the valley below. Afterwards the ice
closes up again, and the water reaccumulates in preparation for another flood.
Other instances in the Alps are found in the Mattmark See, which fills the portion of
the Saas Valley between Monte Rosa and the Rhône. This body of water is held in place
by the Allalin Glacier, which here crosses the main valley. The Lac du Combal is held
back by the Glacier de Miage at the southern base of Mont Blanc. “A more famous case
is that of the Gietroz Glacier in the valley of Bagnes, south of Martigny. In 1818 this
lake had grown to be a mile long, and was 700 feet wide and 200 feet deep. An attempt
was made to drain it by cutting through the ice, and about half the water was slowly
drawn off in this way; but then the barrier broke, and the rest of the lake was emptied in
half an hour, causing a dreadful flood in the valley below. In the Tyrol, the Vernagt
Glacier has many times caused disastrous floods by its inability to hold up the lake
formed behind it. In the northwestern Himalaya, the upper branches of the Indus are
sometimes held back in this way. A noted flood occurred in 1835; it advanced twenty-
five miles in an hour, and was felt three hundred miles down-stream, destroying all the
villages on the lower plain, and strewing the fields with stones, sand, and mud.”[CF]
[CF] Professor William M. Davis in. Proceedings of the Boston Society of Natural
History, vol. xxi, pp. 350, 351.

In Greenland such temporary obstructions are frequent, forming lakes of
considerable size. Instances occur, in connection with the Jakobshavn and the
Frederickshaab Glaciers, and in the North Isortok and Alangordlia Fiords.

Frequently, also, bodies of water of considerable size are found in depressions of the
ice itself, even at high levels. I have myself seen them covering more than an acre, and
as much as a thousand feet above the sea-level, upon the surface of the Muir Glacier,
Alaska. They are reported by Mr. I. C. Russell[CG] of larger size and at still higher
elevations upon the glaciers radiating from Mount St. Elias; while the explorers of
Greenland mention them of impressive size upon the surface of its continental ice-sheet.
[CG] See National Geographic Magazine, vol. iii, pp. 116-120.

With these facts in mind we can the more readily enter into the description which
will now be given of some temporary lakes of vast size which were formed by direct
ice-obstructions during portions of the period.
One of the most interesting of these is illustrated upon the accompanying map,
which will need little description.

Fig. 54.—Map showing the effect of the glacial dam at Cincinnati (Claypole). (From Transactions of the Edinburgh
Geological Society.)

While tracing the boundary-line of the glaciated area in the Mississippi Valley
during the summer of 1882, I discovered the existence of unmistakable glacial deposits
in Boone County, Kentucky, across the Ohio River, from Cincinnati.[CH]; These deposits
were upon the height of land 550 feet above the Ohio River, or nearly 1,000 feet above
the sea, which is about the height of the water-shed between the Licking and Kentucky
Rivers. As the Ohio River occupies a trough of erosion some hundreds of feet in depth,
and extending all the way from this point to the mountains of western Pennsylvania, it

would follow that the ice which conveyed boulders across the Ohio River at Cincinnati,
and deposited them upon the highlands between the Licking and Kentucky Rivers,
would so obstruct the channel of the Ohio as to pond the water back, and hold it up to
the level of the lowest pass into the Ohio River farther down. Direct evidences of
obstruction by glacial ice appear also for a distance of fifty or sixty miles, extending
both ways, from Cincinnati.
[CH] The existence of portions of this evidence had previously been pointed out by Mr.
Robert B. Warder and Dr. George Sutton (see Geological Reports of Indiana, 1872 and 1878).

The consequences connected with this state of things are of the most interesting
character.
The bottom of the Ohio River at Cincinnati is 432 feet above the sea-level. A dam of
550 feet would raise the water in its rear to a height of 982 feet above tide. This would
produce a long, narrow lake, of the width of the eroded trough of the Ohio, submerging
the site of Pittsburg to a depth of 281 feet, and creating slack water up the Monongahela
nearly to Grafton, West Virginia, and up the Alleghany as far as Oil City. All the
tributaries of the Ohio would likewise be filled to this level. The length of this slack-
water lake in the main valley, to its termination up either the Alleghany or the
Monongahela, was not far from one thousand miles. The conditions were also peculiar
in this, that all the northern tributaries rose within the southern margin of the ice-front,
which lay at varying distances to the north. Down these there must have poured during
the summer months immense torrents of water to strand boulder-laden icebergs on the
summits of such high hills as were lower than the level of the dam.
Naturally enough, this hypothesis of a glacial dam at Cincinnati aroused
considerable discussion, and led to some differences of opinion. Professors I. C. White
and J. P. Lesley, whose field work has made them perfectly familiar with the upper Ohio
and its tributaries, at once supported the theory, with a great number of facts concerning
certain high-level terraces along the Alleghany and Monongahela Rivers; while
additional facts of the same character have been brought to light by myself and others.
In general, it may be said that in numerous places terraces occur at a height so closely
corresponding to that of the supposed dam at Cincinnati, that they certainly strongly
suggest direct dependence upon it. The upward limit of these terraces in the
Monongahela River is 1,065 feet, and they are found in various places in situations
which indicate that they were formed in still water of such long standing as would
require an obstruction below of considerable permanence.
One of the most decisive cases adduced by Professor White occurs near
Morgantown, in West Virginia, of which he gives the following description:
“Owing to the considerable elevation—275 feet—of the fifth terrace above the
present river-bed in the vicinity of Morgantown, its deposits are frequently found far
inland from the Monongahela, on tributary streams. A very extensive deposit of this
kind occurs on a tributary one mile and a half northeast of Morgantown; and the region,

which includes three or four square miles, is significantly known as the ‘Flats.’ The
elevation of the ‘Flats’ is 275 feet above the river, or 1,065 feet above tide. The deposits
on this area consist almost entirely of clays and fine, sandy material, there being very
few boulders intermingled. The depth of the deposit is unknown, since a well sunk on
the land of Mr. Baker passed through alternate beds of clay, fine sand, and muddy trash,
to a depth of sixty-five feet without reaching bed-rock. In some portions of the clays
which make up this deposit, the leaves of our common forest-trees are found most
beautifully preserved.
“At Clarksburg, where the river unites with Elk Creek, there is a wide stretch of
terrace deposits, and the upper limit is there about 1,050 feet above tide, or only 130
feet above low-water (920 feet); while at Weston, forty miles above (by the river), these
deposits cease at seventy feet above low water, which is there 985 feet above tide. It
will thus be observed that the upper limit of the deposits retains a practical horizontality
from Morgantown to Weston, a distance of one hundred miles, since the upper limit has
the same elevation above tide (1,045 to 1,065 feet) at every locality.
“These deposits consist of rounded boulders of sandstone, with a large amount of
clay, quicksand, and other detrital matter. The country rock in this region consists of the
soft shales and limestones of the upper coal-measures, and hence there are many ‘low
gaps’ from the head of one little stream to that of another, especially along the
immediate region of the river; and in every case the summits of these divides, where
they do not exceed an elevation of 1,050 feet above tide, are covered with transported or
terrace material; but where the summits go more than a few feet above that level we find
no transported material upon them, but simply the decomposed country rock.”
Other noteworthy terraces naturally attributable to the Cincinnati ice-dam are to be
found in the valley of the Kanawha, in West Virginia, and one of special significance on
the pass between the valleys of the Ohio and Monongahela, west of Clarksburg, West
Virginia. According to Professor White, there is at this latter place “a broad, level
summit, having an elevation of 1,100 feet, in a gap about 300 feet below the enclosing
hills. This gap, or valley, is covered by a deposit of fine clay. The cut through it is about
thirty feet, and one can observe the succession of clays of all kinds and of different
colours, from yellow on the surface down to the finest white potter’s clay at the level of
the railway, where the cut reaches bed-rock, thus proving that the region has been
submerged.”[CI]
[CI] Bulletin of the Geological Society of America, vol. i, p. 478.

Another crucial case I have myself described at Bellevue, in the angle of the Ohio
and Alleghany Rivers, about five miles below Pittsburg, where the gravel terrace is
nearly 300 feet above the river, making it about 1,000 feet above the sea. A significant
circumstance connected with this terrace is that not only does its height correspond with
that of the supposed obstruction at Cincinnati, but it contains many pebbles of Canadian
origin, which could not have got into the valley of the Alleghany before the Glacial

period, and could only have reached their present position by being brought down the
Alleghany River upon floating ice, or by the ordinary movement of gravel along the
margin of a river. Thus this terrace, while corresponding closely with the elevation of
those on the Monongahela River, is directly connected with the Glacial period, and
furnishes a twofold argument for our theory.
A still stronger case occurs at Beech Flats, at the head of Ohio Brush Creek, in the
northwest corner of Pike County, Ohio, where, at an elevation of about 950 feet above
the sea, there is an extensive flat-topped terrace just in front of the terminal moraine.
This terrace consists of fine loam, such as is derived from the glacial streams, but which
must have been deposited in still water. The occurrence of still water at that elevation
just in front of the continental ice-sheet is best accounted for by the supposed dam at
Cincinnati. Indeed, it is extremely difficult to account for it in any other way.
There are, however, two other methods of attempting to account for the class of
facts above cited in support of the ice-dam theory, of which the most plausible is, that in
connection with the Glacial period there was a subsidence of the whole region to an
extent of 1,100 feet.
The principal objection heretofore alleged against this supposition is that there are
not corresponding signs of still-water action at the same level on the other side of the
Alleghany Mountains. This will certainly be fatal to the subsidence theory, if it proves
true. But it is possible that sufficient search for such marks has not yet been made on the
eastern side of the mountains.
The other theory to account for the facts is, that the terraces adduced in proof of the
Cincinnati ice-dam were left by the streams in the slow process of lowering their beds
from their former high levels. This is the view advocated by President T. C. Chamberlin.
But the freshness of the leaves and fragments of wood, such as were noted by Professor
White at Morgantown, and the great extent of fine silt occasionally resting upon the
summits of the water-sheds, as described above, near Clarksburg, bear strongly against
it. Furthermore, to account for the terrace described at Bellevue, which contains
Canadian pebbles, President Chamberlin is compelled to connect the deposit with his
hypothetical first Glacial epoch, and to assume that all the erosion of the Alleghany and
Monongahela Rivers, and indeed of the whole trough of the Ohio River, took place in
the interval between the “first” and the “second” Glacial periods (for he would connect
the glacial deposits upon the south side of the river at Cincinnati with the first Glacial
epoch)—all of which, it would seem, is an unnecessary demand upon the forces of
Nature, when the facts are so easily accounted for by the simple supposition of the dam
at Cincinnati.[CJ]
[CJ] See matter discussed more at length in the lee Age, pp. 326-350, 480-500; Bulletin of
the United States Geological Survey, No. 58, pp. 76-100; Popular Science Monthly, vol. xlv,
pp. 184-199. Per contra, Mr. Frank Leverett, in American Geologist, vol. x, pp. 18-24.

Fig. 55.—Map showing the condition of things when the ice-front had withdrawn about on hundred and
twenty miles, and while it still filled the valley of the Mohawk. The outlet was then through the Wabash.
Niagara was not yet born (Claypole). (Transactions of the Edinburgh Geological Society.)

We have already described[CK] the various temporary lakes and lines of drainage
caused by the direct obstruction of the northward outlets to the basin of the Great Lakes.
In connection with the map, it will be unnecessary to do anything more here than add a
list of such temporary southern outlets from the Erie-Ontario basin.[CL] The first is at
Fort Wayne, Indiana, through a valley connecting the Maumee River basin with that of
the Wabash. The channel here is well defined, and the high-level gravel terraces down
the Wabash River are a marked characteristic of the valley. The elevation of this col
above the sea is 740 feet. Similar temporary lines of drainage existed from the St.
Mary’s River to the Great Miami, at an elevation of 942 feet; from the Sandusky River
to the Scioto, through the Tymochtee Gap, at an elevation of 912 feet; from Black River
to the Killbuck (a tributary of the Muskingum) through the Harrisville Gap, at 911 feet;
from the Cuyahoga into the Tuscarawas Valley, through the Akron Gap, at 971 feet;
from Grand River into the Mahoning, through the Orwell Gap, 938 feet; from
Cattaraugus Creek, N. Y., into the Alleghany Valley through the Dayton Gap, about
1,300 feet; between Conneaut Creek and Shenango River, at Summit Station, 1,141 feet;
from the Genesee River, N. Y., into the head-waters of the Canisteo, a branch of the
Susquehanna, at Portageville, 1,314 feet; from Seneca Lake to Chemung River, at
Horseheads, 879 feet; from Cayuga Lake to the valley of Cayuga Creek, at Spencer, N.
Y., 1,000 feet; from Utica, N. Y., into the Chenango Valley at Hamilton, about 900 feet.
[CK] See pp. 92 seq., 199 seq.
[CL] See also accompanying map.

Fig. 56.—Map illustrating a stage in the recession of the ice in Ohio.
For a section of the deposit in the bed of this lakelet, see page 200. The
gravel deposits formed at this stage along the outlet into the Tuscarawas
River are very clearly marked (Claypole). (Transactions of the
Edinburgh Geological Society.)

Perhaps it would have been best to give this list in the reverse order, which would be
more nearly chronological, since it is clear that the highest outlets are the oldest. We
should then have to mention, after the Fort Wayne outlet, two others at lower levels
which are pretty certainly marked by distinct beach ridges upon the south side of Lake
Erie. The first was opened when the ice had melted back from the south peninsula of
Michigan to the water-shed across from the Shiawassee and Grand Rivers, uncovering a
pass which is now 729 feet above the sea. This continued to be the outlet of Lake Erie-
Ontario until the ice had further retreated beyond the Strait of Mackinac, when the water
would fall to the level of the old outlet from Lake Michigan into the Illinois River,
which is a little less than 600 feet, where it would remain until the final opening of the

Mohawk River in New York attracted the water in that direction, and lowered the level
to that of the pass from Lake Ontario to the Mohawk at Rome.[CM]
[CM] Mr. Warren Upham, in the Bulletin of the Geological Society of America, vol. ii, p.
259.

A study of these lines of temporary drainage during the Glacial period sheds much
light upon the long lines of gravel ridges running parallel with the shores of Lake Erie
and Lake Ontario. South of Lake Erie a series of four ridges of different elevations can
be traced. In Lorain County, Ohio, the highest of these is 220 feet above the lake; the
next 160 feet; the next 118 feet; and the lower one 100 feet, which would make them
respectively 795, 755, 715, and 700 feet above tide.
These gravel ridges are evidently old beach lines, and indicate the different levels up
to which the water was held by ice-obstructions across the various outlets of the
drainage valley. The material in the ridges is water-worn and well assorted, and in
coarseness ranges from fine sand up to pebbles several inches in diameter. The
predominant material in them is of local origin. Where the rocks over which they run
are sandstone, the material is chiefly sand, and where the outcropping rock is shale, the
ridges consist chiefly of the harder nodules of that formation which have successfully
resisted the attrition of the waves. Ordinarily these ridges are steepest upon the side
facing the lake. According to Mr. Upham, who has driven over them with me, the Lake
Erie ridges correspond, both in general appearance and in all other important respects,
to those which he has so carefully surveyed around the shores of the ancient Lake
Agassiz in Minnesota and Manitoba, an account of which will be given a little farther on
in this chapter.

Fig. 57.—Section of the lake ridges near Sandusky, Ohio.

We are not permitted, however, to assume that there have been no changes of level
since the deposition of these beaches surrounding the ancient glacial Lake Erie-Ontario.
On the contrary, there appears to have been a considerable elevation towards the east
and northeast in post-glacial times. The highest ridge south of Lake Erie, which at Fort
Wayne is about 780 feet high, is now about 795 feet in Lorain County. The second of
the ridges above-mentioned, which is about 740 feet above tide at Cleveland, Ohio, rises
to 870 feet where the last traces of it have been discovered at Hamburg, N. Y. The third
ridge, which is 673 feet at Cleveland, has risen to the height of 860 feet at Crittenden,
about one hundred miles to the east of Buffalo, N. Y.
A similar eastern increase of elevation is discoverable in the main ridge surrounding
Lake Ontario. What Professor Spencer calls the Iroquois beach, which is 363 feet above
tide at Hamilton, Ontario, has risen to a height of 484 feet near Syracuse, N. Y.; while
farther to the northeast, in the vicinity of Watertown, it is upwards of 800 feet above
tide.
There is also a similar northward increase of elevation in the beaches surrounding
the higher lands of Ontario eastward of Lake Huron and Georgian Bay.
All this indicates that at the close of the Glacial period there was a subsidence of
several hundred feet in the area of greatest ice-accumulation lying to the east and north
of the Great Lake region. The formation of these ridges occurred during that period of

subsidence. The re-elevation which followed the disappearance of the ice of course
carried with it these ridges, and brought them to their present position.[CN]
[CN] See Spencer, in Bulletin of the Geological Society of America, vol. ii, pp. 465-476.

In returning to consider more particularly the remarkable gorge joining the
Minnesota with the Red River of the North, we are brought to the largest of the glacial
lakes of this class, and to the typical place in America in which to study the temporary
changes of drainage produced by the ice itself daring the periods both of its advance and
of its retreat.

Fig. 58.—Map showing the stages of recession of the ice in
Minnesota as
described in the text (Upham).
Click on image to view larger sized.

By turning to our general map of the glaciated region of the United States,[CO] one
can readily see the relation of the valley between Lake Traverse and Big Stone Lake to
an area marked as the bed of what is called Lake Agassiz. During the Glacial period
Brown’s Valley, the depression joining these two lakes, was the outlet of an immense
body of water to the north, whose natural drainage was towards Hudson Bay or the
Arctic Ocean, but which was cut off, by the advancing ice, from access to the ocean-
level in that direction, and was compelled to seek an exit to the south.
[CO] See page 66.

Thus for a long period the present Minnesota River Valley was occupied by a stream
of enormous dimensions, and this accounts for the great size of the trough—the present
Minnesota being but an insignificant stream winding about in this deserted channel of
the old “Father of Waters,” and having as much room as a child of tender age would
have in his parent’s cast-off garments. This glacial stream has been fittingly named
River Warren, after General Warren, who first suggested and proved its existence, and
so we have designated it on the accompanying map of Minnesota.
Lake Traverse is fifteen miles long, and the water is nowhere more than twenty feet
deep. Big Stone Lake is twenty-six miles long, and of about the same depth. Brown’s
Valley, which connects the two, is five miles long, and the lakes are so nearly on a level
that during floods the water from Lake Traverse sometimes overflows and runs to the
south as well as to the north.

Fig. 59.—Glacial terrace near the boundary of the glaciated area, on Raccoon Creek, a tributary of the Licking River,
in Granville, Licking County, Ohio. Height about fifty feet.

The trough occupied by these lakes and valley is from one mile to one mile and a
half in width and about 120 feet in depth. If we had been permitted to stand upon the
bluffs overlooking it during the latter part of the Glacial period, we should have seen the
whole drainage of the north passing by our feet on its way to the Gulf of Mexico. As lie
follows down the valley of the Minnesota River, the observant traveller, even now,
cannot fail to see in the numerous well-preserved gravel terraces the high-water marks
of that stream when flooded with the joint product of the annual precipitation over the
vast area to the north, and of the still more enormous quantities set free by the melting
of the western part of the great Laurentide Glacier.

Numerous other deserted water-ways in the northwestern part of the valley of the
Mississippi have been brought to light in the more recent geological surveys, both in the
United States and in Canada. During a considerable portion of the Glacial period the
Saskatchewan, the Assiniboine, the Pembina, and the Cheyenne Rivers, whose present
drainage is into the Red River of the North, were all turned to the south, and their
temporary channels can be distinctly traced by deserted water-courses marked by lines
of gravel deposits.[CP]
[CP] For further particulars, see Ice Age, pp. 293 et seq.

In Dakota, Professor J. E. Todd has discovered large deserted channels on the
southwestern border of the glaciated region near the Missouri River, where evidently
streams must have flowed for a long distance in ice-channels when the ice still
continued to occupy the valley of the James River. From these channels of ice in which
the water was held up to the level of the Missouri Coteau the water debouched directly
into channels with sides and bottom of earthy material, which still show every mark of
their former occupation by great streams.[CQ]
[CQ] For particulars, see Ice Age, p. 292.

In Minnesota, also, there is abundant evidence that while the northeastern part of the
valley from Mankato to St. Paul was occupied by ice, the drainage was temporarily
turned directly southward across the country through Union Slough and Blue Earth
River into the head-waters of the Des Moines River in Iowa.

Ancient River Terraces.
The interest of the whole inquiry respecting the relation of man to the Glacial period
in America concentrates upon these temporary lines of southern drainage. Wherever
they existed, the swollen floods of the Glacial period have left their permanent marks in
the deposition of extensive gravel terraces. The material thus distributed is derived
largely from the glacial deposits through which they run and out of which they emerge.
While the height of the terraces depended upon various conditions which must be
studied in detail, in general it may be said that it corresponds pretty closely with the
extent of the area whose drainage was turned through the channel during the prevalence
of the ice. The height of the terraces and the coarseness of the material seem also to
have been somewhat dependent upon the proximity of their valleys to the areas of most
vigorous ice-action, and this, in turn, seems to lie in the rear of the moraines which
President Chamberlin has attributed to the second Glacial epoch. Southward from this
belt of moraines the terraces uniformly and gradually diminish both in height and in the
coarseness of their gravel, until they finally disappear in the present flood-plain of the
Mississippi River.

Fig. 60.—Ideal section across a river-bed in drift region: b b b, old river-
bed; R, the present river; t t, upper or older terraces; t′ t′, lower terraces.

An interesting illustration of this principle is to be observed in the continuous valley
of the Alleghany and Ohio Rivers. The trough of this valley was reached by the
continental glacier at only a few points, the ice barely touching it at Salamanca, N. Y.,
Franklin, Pa., and Cincinnati, Ohio. But throughout its whole length the ice-front was
approximately parallel to the valley, and occupied the head-waters of nearly all its
tributaries. Now, wherever tributaries which could be fed by glacial floods, enter the
trough of the main stream, they brought down an excessive amount of gravel, and
greatly increased the size of the terrace in the trough itself, and from the mouth of each
such tributary to that of the next one below there is a gradual decrease in the height of
the terrace and in the coarseness of the material.
This law is illustrated with special clearness in Pennsylvania between Franklin and
Beaver. Franklin is upon the Alleghany River, at the last point where it was reached
directly by the ice. Below this point no tributary reaches it from the glaciated region,
and none such reaches the Ohio after its junction with the Alleghany until we come to
the mouth of Beaver Creek, about twenty-five miles below Pittsburg.
But at this point the Ohio is joined by a line of drainage which emerges from the
glaciated area only ten or twelve miles to the north, and whose branches occupy an
exceptionally large glaciated area. Accordingly, there is at Beaver a remarkable increase
in the size of the glacial terrace on the Ohio. In the angle down-stream between the
Beaver and the Ohio there is an enormous accumulation of granitic pebbles, many of
them almost large enough to be called boulders, forming the delta terrace, upon which
the city is built and rising to a height of 135 feet above the low-water mark in the Ohio.
In striking confirmation of our theory, also, the terrace in the Ohio Valley upon the
upper side of Beaver Creek is composed of fine material, largely derived from local
rocks and containing but few granitic pebbles.
From the mouth of Beaver Creek, down the Ohio, the terrace is constant (sometimes
upon one side of the river and sometimes upon the other), but, according to rule, the
material of which it is composed gradually grows finer, and the elevation of the terrace
decreases. According to rule, also, there is a notable increase in the height of the terrace
below each affluent which enters the river from the glaciated region. This is specially
noticeable below Marietta, at the mouth of the Muskingum, whose head-waters drain an
extensive portion of the glaciated area. From the mouth of the Little Beaver to this point
the tributaries of the Ohio are all small, and none of them rise within the glacial limit.
Hence they could contribute nothing of the granitic material which enters so largely into

the formation of the river terrace; but below the mouth of the Muskingum the terrace
suddenly ascends to a height of nearly one hundred feet above low-water mark.
Again, at the mouth of the Scioto at Portsmouth, there is a marked increase in the
size of the terrace, which is readily accounted for by the floods which came down the
Scioto Valley from the glaciated region. The next marked increase is at Cincinnati, just
below the mouth of the Little Miami, whose whole course lay in the glaciated region,
and whose margin is lined by very pronounced terraces. At Cincinnati the upper terrace
upon which the city is built is 120 feet above the flood-plain.
Twenty-five miles farther down the river, near Lawrenceburg, these glacial terraces
are even more extensive, the valley being there between three and four miles wide, and
being nearly filled with gravel deposits to a height of 112 feet above the flood-plain.
Below this point the terraces gradually diminish in height, and the material becomes
finer and more water-worn, until it merges at last in the flood-plain of the Mississippi.
The course of the Wabash River is too long to permit it to add materially to the size of
the terraces which characterise the broader valley of the Ohio below the Illinois line.
It is in terraces such as these just described that we find the imbedded relics of man
which definitely connect him with the great Ice age. These have now been found in the
glacial terraces of the Delaware River at Trenton, N. J.; in similar terraces in the valley
of the Tuscarawas River at New Comerstown, and in the valley of the Little Miami at
Loveland and Madisonville, in Ohio; on the East Fork of White River, at Medora, Ind.;
and still, again, at Little Falls, in the trough of the Mississippi, some distance above
Minneapolis, Minn.
I append a list of the points at which various streams from the Atlantic Ocean to the
Mississippi River emerge from the glacial boundary, and below which the terraces are
specially prominent. Of course, with the retreat of the ice, the formation of the terraces
continued northward in the glaciated area to a greater or less distance, according to the
extent of the valley or to the length of time during which the drainage was temporarily
turned into it. These points of emergence are: In the Delaware Valley, at Belvidere, N.
J.; in the Susquehanna, at Beach Haven, Pa.; in the Conewango, at Ackley, Warren
County; in Oil Creek, above Titusville: in French Creek, a little above Franklin; in
Beaver Creek, at Chewtown, Lawrence County; on the Middle Fork of Little Beaver,
near New Lisbon, Ohio; on the east branch of Sandy Creek, at East Rochester,
Columbiana County; on the Nimishillin, at Canton, Stark County; on the Tuscarawas, at
Bolivar; on Sugar Creek, at Beech City; on the Killbuck, at Millersburg, Holmes
County; on the Mohican, near the northeast corner of Knox County; on the Licking
River, at Newark; on Jonathan Creek, Perry County; on the Hocking, at Lancaster; on
the Scioto, at Hopetown, just above Chillicothe; on Paint Creek, and its various
tributaries, between Chillicothe and Bainbridge; and on the Wabash, above New
Harmony, Ind.; to which may be added the Ohio River itself, at its junction with the
Miami, near Lawrenceburg.

Another class of terraces having most interesting connection with the Glacial period
is found in the arid basins west of the Rocky Mountains. Over wide areas in Utah and
Nevada the evaporation now just balances the precipitation, and all the streams
disappear in shallow bodies of salt water of moderate dimensions, of which Great Salt
Lake in Utah, and Mono, Pyramid, and North Carson Lakes in Nevada, are the most
familiar examples. These occupy the lowest sinks of enclosed basins of great depth.
But there is abundant evidence that in consequence of the increased precipitation
and diminished evaporation of the Glacial period one of these basins was filled to the
brim and the other to a depth of several hundred feet. These former enlargements have
been named after the first explorers of the region, Captains Lahontan and Bonneville,
and are shown on the accompanying sketch map by the shading surrounding the existing
lakes.
Lake Lahontan has been carefully studied by Mr. I. C. Russell, and has been found
to extend from the boundary of Oregon to latitude 38° 30’ south, a distance of two
hundred and sixty miles. The Central Pacific Railroad runs through its dried-up bed
from Golconda to Wadsworth, a distance of one hundred and sixty-five miles. The
terraces of the former lake are distinctly traceable at a height of 700 feet above the
present level of Lake Mono.
Lake Bonneville, whose present representative is Great Salt Lake, is the subject of a
recent monograph by Mr. G. K. Gilbert, from which it appears that this ancient body of
water occupied 19,750 square miles—an area about ten times that of the present lake. At
the time of its maximum extension its depth was 1,000 feet, while Great Salt Lake
ranges only from fifteen to fifty feet in depth.
The pass through which the discharge finally took place is at Red Rock, on the Utah
and Northern Railroad, at the head of Cache Valley on the south and the lower part of
Marsh Creek Valley on the north. During the long period preceding and accompanying
the gradual rise of water in the Utah basin to the level of the highest terrace, Marsh
Creek (the upper portion of which comes from the mountains on the east and turns at
right angles) had been at work depositing a delta of loose material in the col which
separates the two valleys. This deposit rested upon a stratum of limestone at the bottom
of the pass, and covered it with sand, clay, and gravel to a depth of 375 feet. Thus, when
the water was approaching its upper level, the only barrier to prevent its escape was this
unstable accumulation of loose material upon top of the rock. It would have required,
therefore, no prophet’s eye to predict that the way was preparing for a tremendous
débâcle.

Fig. 61.—Map of the Quaternary Lakes. Bonneville and Lahontan
(after Gilbert and Russell).

The critical point at length was reached. After remaining nearly at the elevation of
the pass for a considerable period, during which the 1,000-foot shore-line was formed,
the crisis came when the water began to flow northward towards Snake River. Once
begun in such loose material, the channel rapidly enlarged until soon a stream equal to
Niagara, and at times probably much larger, was pouring northward through the valley
heretofore occupied by the insignificant rivulets of Marsh Creek and the Port Neuf. It is
impossible to tell how rapidly the loose barrier wore away, but there is abundant
evidence in the valley below that not only the present channel of the lower part of
Marsh Creek, but the whole bottom of the valley for a mile or more in width, was for a
considerable time covered by a rapid stream from ten to twenty feet in depth, and
descending at the rate of thirteen feet to the mile.
The continuance of this flood was dependent upon the amount of water to be
discharged, which, as we have seen, was that contained in an area of 20,000 square
miles, with a depth of 375 feet. A stream of the size of Niagara would occupy about
twenty-five years in the discharge of such a mass, and this may fairly be taken as a
measure of the time through which it lasted. When the loose material lying above the
strata of limestone in Red Rock Pass had been washed away, the lake then continued at
that level for an indefinite period, with an overflow regulated by the annual precipitation
of the drainage basin. This stage of the lake, during which it occupied 13,000 square
miles and was 625 feet above its present level, is also marked by an extensive and
persistent shore-line all around the basin. But, finally, the balance again turned when the
evaporation exceeded the precipitation, and the vast body of water has since dwindled to
its present insignificant dimensions.
My own interest in this discovery of Mr. Gilbert is enhanced by the explanation it
gives of a phenomenon in the Snake River Valley which I was unable to solve when on
the ground in 1890. The present railroad town of Pocatello is situated just where this
flood emerged from the narrower valley of Marsh Creek and the Port Neuf, and spread

itself out upon the broad plain of the Snake River basin. The southern edge of the plain
upon which the city is built is a vast boulder-bed covered with a thin stratum of sand
and gravel. Everywhere, in sinking wells and digging ditches on the vacant lots and in
the streets of the city, water-worn boulders of a great variety of material and sometimes
three or four feet in diameter are encountered. I was debarred from regarding this as a
terminal moraine, both by the water-worn character of the boulders and by the absence
of any sign of ice-action in the surrounding mountains, and I was equally debarred from
attributing it to any ordinary stream of water, both by the size of the boulders and the
fact that for a mile or more up the Port Neuf Valley there is an intervale, forty or fifty
feet below the surface at Pocatello, and occupying the whole width of the valley, in
which there is only gravel and fine sand, through which the present Port Neuf pursues a
meandering course. The upper end of this short intervale is bounded by the terminus of
a basaltic stream which had flowed down the valley and filled it to a considerable depth,
but had subsequently been much eroded by violent water-action.
In the light of Mr. Gilbert’s discoveries, however, everything is clear. The
tremendous débâcle which he has brought within the range of scientific vision would
naturally produce just the condition of things which is so puzzling at Pocatello. Coming
down through the restricted channel with sufficient force to roll along boulders of great
size and to clear them all out from the upper portion of the valley, the torrent would
naturally deposit them where the current was first checked, a mile below the lava cliffs.
The plunge of the water over these cliffs would keep a short space below clear from
boulders, and the more moderate stream of subsequent times would fill in the
depression with the sand and gravel now occupying it.
What other effects of this remarkable outburst may be traced farther down in the
Snake River Valley I cannot say, but it will be surprising if they do not come to light and
help to solve some of the many geological problems yet awaiting us in this interesting
region.
It should have been said that during the formation of the 625-foot, or so-called
Provo shore-line, glaciers descended from the cañons on the west flank of the Wahsatch
Mountains, and left terminal moraines to mark the coincidence of the Glacial period
with that stage of the enlargement of the lake. Evidences of a similar coincidence are to
be found on the high-level terraces surrounding Lake Mono, to which glaciers formerly
descended from the western flanks of the Sierra Nevada.
The ancient shore-lines surrounding Lakes Bonneville and Lahontan bear evidence
also of various other episodes in the Glacial period. Evidently there were two periods of
marked increase in the size of the lakes, with an arid period intervening. During the first
rise the level of Bonneville attained to within ninety feet of the second, and numerous
beaches were formed, and a large amount of yellow clay deposited. Then it seems to
have been wholly evaporated, while its soluble mineral matter was precipitated, and so
mingled with silt that it did not readily redissolve during the second great rise of water.

Partly on this account, and partly through the influence of the outlet into the Snake
River, the lake was nearly fresh during its second enlargement.

European Facts.
In Chapter VI it came in place to mention many of the facts connected with the
influence of the Glacial period upon the drainage systems of Europe. We there discussed
briefly the probable influence of the ice-obstructions that extended across the mouths of
the Dwina, the Vistula, the Oder, the Elbe, the Weser, and the Rhine. The drainage of the
obstructed rivers in Russia was perhaps turned southward into the Caspian and Black
Seas, and then assisted in forming the fertile soil of the plains in the southern part of
that empire.
The obstructed drainage of the German rivers was probably turned westward in front
of the ice through the Straits of Dover or across the southern part of England. This was
during the climax of the Glacial period; but later, according to Dawkins, during a period
in which the land of the British Isles stood about 600 feet above its present level, the
streams of the eastern coast—namely, "the Thames, Medway, Humber, Tyne, and others,
joined the Rhine, the Weser, and the Elbe, to form a river flowing through the valley of
the ocean. In like manner, the rivers of the south of England and of the north of France
formed a great river flowing past the Channel Islands due west into the Atlantic, and the
Severn united with the rivers of the south of Ireland; while those to the east of Ireland
joined the Dee, Mersey Ribble, and Lune, as well as those of western Scotland,
ultimately reaching the Atlantic to the west of the Hebrides. The water-shed between the
valleys of the British Channel and the North Sea is represented by a ridge passing due
south from Folkestone to Dieppe, and that between the drainage area and the Severn and
its tributaries on the one hand, and of the Irish Channel on the other, by a ridge from
Holyhead westward to Dublin.
“This tract of low, undulating land which surrounded Britain and Ireland on every
side consisted not merely of rich hill, valley, and plain, but also of marsh-land studded
with lakes, like the meres of Norfolk, now indicated by the deeper soundings. These
lakes were very numerous to the south of the Isle of Wight and off the coast of Norfolk
and Suffolk.”[CR]
[CR] Early Man in Britain, p. 151.

The evidence first regarded by scientific men to be demonstrative of the formation
of extensive lakes during the Glacial period by the direct influence of ice-dams exists in
the Parallel Roads of Glen Roy in Scotland.

Fig. 62.—Parallel roads of Glen Roy.

According to the description of Sir Charles Lyell, "Glen Roy is situated in the
western Highlands, about ten miles north of Fort William, near the western end of the
great glen of Scotland, or Caledonian Canal, and near the foot of the highest of the
Grampians, Ben Nevis. Throughout nearly its whole length, a distance of more than ten
miles, three parallel roads or shelves are traced along the steep sides of the mountains,
each maintaining a perfect horizontality, and continuing at exactly the same level on the
opposite sides of the glen. Seen at a distance they appear like ledges, or roads, cut
artificially out of the sides of the hills; but when we are upon them, we can scarcely
recognize their existence, so uneven is their surface and so covered with boulders. They
are from ten to sixty feet broad, and merely differ from the side of the mountain by
being somewhat less steep.
“On closer inspection, we find that these terraces are stratified in the ordinary
manner of alluvial or littoral deposits, as may be seen at those points where ravines have
been excavated by torrents. The parallel shelves, therefore, have not been caused by
denudation, but by the deposition of detritus, precisely similar to that which is dispersed
in smaller quantities over the declivities of the hills above. These hills consist of clay-
slate, mica-schist, and granite, which rocks have been worn away and laid bare at a few
points immediately above the parallel roads. The lowest of these roads is about 850 feet
above the level of the sea, and the next about 212 feet higher, and the third 82 feet
above the second. There is a fourth shelf, which occurs only in a contiguous valley
called Glen Gluoy, which is twelve feet above the highest of all the Glen Roy roads, and
consequently about 1,156 feet above the level of the sea. One only, the lowest of the
three roads of Glen Roy, is continued through Glen Spean, a large valley with which
Glen Roy unites. As the shelves, having no slope towards the sea like ordinary river
terraces, are always at the same absolute height, they become continually more elevated
above the river in proportion as we descend each valley; and they at length terminate

very abruptly, without any obvious cause, or any change either in the shape of the
ground or in the composition or hardness of the rocks.” [CS]
[CS] Antiquity of Man, pp. 252, 253.

Early in his career Charles Darwin studied these ancient beaches, and ascribed them
to the action of the sea during a period of continental subsidence. In this view he was
supported by the majority of geologists until the region was visited by Agassiz, who saw
at once the true explanation. If these were really sea-beaches, similar deposits should be
found at the same elevation on other mountains than those surrounding Glen Roy. Their
absence elsewhere points, therefore, to some local cause, which was readily suggested
to the trained eye of one like Agassiz, then fresh from the study of Alpine glaciers, who
saw that these beaches were formed upon the margin of temporary lakes, held back
during the Glacial period (as the Merjelen See now is) by a glacier which came out of
one glen and projected itself directly across the course of another, and thus obstructed
its drainage. The glacier of Glen Spean had pushed itself across Glen Roy, as the great
Aletsch Glacier in Switzerland now pushes itself across the little valley behind the
Eggishorn.

CHAPTER VIII.

RELICS OF MAN IN THE GLACIAL PERIOD.
In Glacial Terraces of the United States.
Although the first clear evidence of glacial man was discovered in Europe, the
problem is so much simpler on the Western Continent that we shall find it profitable to
study the American facts first. We will therefore present a summary of them at once, and
then proceed to the more obscure problems of European archæology.
The first definite discovery of human relics clearly connected with, glacial deposits
in America, and of the same age with them, was made by Dr. C. C. Abbott, at Trenton,
N. J., in the year 1875. The city of Trenton is built upon a delta terrace about three miles
wide which occurs at the head of tide-water on the Delaware River. This terrace bears
every mark of having been deposited by a torrential stream which came down the valley
during the closing period of the great Ice age. The material of which the terrace consists
is all water-worn. According to the description of Professor N. S. Shaler:

Fig. 63.—The glaciated portion is shaded. The shading on the Lehigh
and Delaware Rivers indicates glacial terraces, which are absent from
the Schuylkill.

“The general structure of the mass is neither that of ordinary boulder-clay nor of
stratified gravels, such as are formed by the complete rearrangement by water of the
elements of simple drift-deposits. It is made up of boulders, pebbles, and sand, varying
in size from masses containing one hundred cubic feet or more to the finest sand of the
ordinary sea-beaches. There is little trace of true clay in the deposit; there is rarely
enough to give the least trace of cementation to the masses. The various elements are
rather confusedly arranged; the large boulders not being grouped on any particular level,
and their major axes not always distinctly coinciding with the horizon. All the pebbles
and boulders, so far as observed, are smooth and water-worn, a careful search having
failed to show evidence of distinct glacial scratching or polishing on their surfaces. The
type of pebble is the subovate or discoidal, and though many depart from this form, yet

nearly all observed by me had been worn so as to show that their shape had been
determined by running water. The materials comprising the deposit are very varied, but
all I observed could apparently with reason be supposed to have come from the
extensive valley of the river near which they lie, except perhaps the fragments of some
rather rare hypogene rocks.”
A conclusive proof of the relation of
this Trenton delta terrace to the Glacial
period is found in the fact that the gravel
deposit is continuous with terraces
extending up the trough of the valley of
the Delaware to the glaciated area and
beyond. As, however, the descent of the
river-bed is rapid (about four feet to the
mile) from the glacial border down to
tide-water, the terrace is not remarkably
high, being only about fifteen or twenty Fig. 64.—Palæolith found by Abbott in New Jersey,
feet above the present flood-plain. But it slightly reduced.
is continuous, and similar in
composition with the great enlargement
in the delta at Trenton. Without doubt, therefore, the deposit represents the overwash
gravel of the Glacial period.
Fortunately for science, Dr. C. C. Abbott, whose tastes for archæological
investigations were early developed, had his residence upon the border of this glacial
delta terrace at Trenton, and as early as 1875 began to find rough-stone implements of a
peculiar type in the talus of the bank where the river was undermining the terrace. In
turning his attention to the numerous fresh exposures of gravel made by railroad and
other excavations during the following year, he found several of the implements in
undisturbed strata, some of which were sixteen feet below the surface. Since that time
he has continued to make discoveries at various intervals. In 1888 he had found four
hundred implements of the palæolithic type at Trenton, sixty of which had been taken
from recorded depths in the gravel, two hundred and fifty from the talus at the bluff
facing the river, and the remainder from the surface, or derived from collectors who did
not record the positions or circumstances under which they were found.

Fig. 65.—Section across the Delaware River at Trenton. New Jersey: a,
a, Philadelphia red gravel and brick-clay (McGee’s Columbia deposit);
b. b, Trenton gravel, in which the implements are found: c, present
flood-plain of the Delaware River (after Lewis). (From Abbott’s
Primitive Industry.)

The material from which the implements at Trenton are made is argillite—that is, a
clay slate which has been so metamorphosed as to be susceptible of fracture, almost like
flint. It is, however, by no means capable of being worked into such delicate forms as
flint is. But as it is the only material in the vicinity capable of being chipped, prehistoric
men of that vicinity were compelled to make a virtue of necessity and use the inferior
material. Of all the implements found by Dr. Abbott in the gravel, only one was flint;
while upon the surface innumerable arrow-heads of flint have been found. The
transition, also, in the type of implements is as sudden as that in the kind of material of
which they are made. Below the superficial deposit of black soil, extending down to the
depth of about one foot, the modern Indian flint implements entirely disappear, and
implements of palæolithic type only are found.

Fig. 66.—Section of the Trenton gravel in which the implements
described in the text are found. The shelf on which the man
stands is made in process of excavation. The gravel is the same
above and below (photograph by Abbott).

Fig. 67.—Face view of argillite implement, found
by Dr. C. C. Abbott, in 1876, at Trenton, New
Jersey, in gravel, three feet from face of bluff, and
twenty-two feet from the surface (No. 10,985)
(Putnam).

In the year 1882, after I had traced the glacial boundary westward from the
Delaware River, across the States of Pennsylvania, Ohio, and Indiana, I was struck with
the similarity between the terrace at Trenton and numerous terraces which I had
attributed to the Glacial age in Ohio and the other States. It adds much to the interest of
subsequent discoveries to note that in 1884, in my report to the Western Reserve
Historical Society upon the glacial boundary of Ohio, I wrote as follows:
“The gravel in which they [Dr. Abbott’s implements] are found is glacial gravel
deposited upon the banks of the Delaware when, during the last stages of the Glacial
period, the river was swollen with vast floods of water from the melting ice. Man was
on this continent at that period when the climate and ice of Greenland extended to the
mouth of New York Harbor. The probability is, that if he was in New Jersey at that time,
he was also upon the banks of the Ohio, and the extensive terrace and gravel deposits in
the southern part of our State should be closely scanned by archæologists. When
observers become familiar with the rude form of these palæolithic implements, they will

doubtless find them in abundance. But whether we find them or not in this State [Ohio],
if you admit, as I am compelled to do, the genuineness of those found by Dr. Abbott, our
investigation into the glacial phenomena of Ohio must have an important archæological
significance, for they bear upon the question of the chronology of the Glacial period,
and so upon that of man’s appearance in New Jersey.”

Fig. 68.—Argillite implement found by Dr. C. C Fig. 69.—Chipped pebble of black chert, found
Abbott, March, 1879, at A. K. Rowan’s farm, by Dr. C. L. Metz. October, 1885, at
Trenton, New Jersey, in gravel sixteen feet from Madisonville, Ohio, in gravel eight feet from
surface: a, face view; b, side view (No. 11,286) surface under clay: a, face view; b, side view.
(Putnam).

The expectation of finding evidence of preglacial man in Ohio was justified soon
after this (in 1885), when Dr. C L. Metz, while co-co-operating with Professor F. W.
Putnam, of the Peabody Museum, Cambridge, Mass., in field work, discovered a flint
implement of palæolithic type in undisturbed strata of the glacial terrace of the Little
Miami River, near his residence at Madisonville, Ohio. In 1887 Dr. Metz found another
implement in the terrace of the same river, at Loveland, about twenty-five miles farther
up the stream. The implement at Madisonville occurred eight feet below the surface,
and about a mile back from the edge of the terrace; while that at Loveland was found in
a coarser deposit, about a quarter of a mile back from the present stream, and thirty feet
below the surface. Mastodon-bones also were discovered in close proximity to the
implement at Loveland.

Fig. 70.

Interest in these investigations was still further increased by the report of Mr.
Hilborne T. Cresson, of Philadelphia, that in 1886, with my map of the glaciated region
in hand, he had found an implement of palæolithic type in undisturbed strata of the
glacial terrace bordering the East Branch of White River, near the glacial boundary at
Medora, Jackson County, Ind. The terrace was about fifty feet above the flood-plain of
the river.
Later still, in October, 1889, Mr. W. C. Mills, of Newcomerstown, Tuscarawas
County, Ohio, found in that town a finely shaped flint implement sixteen feet below the
surface of the terrace of glacial gravel which lines the margin of the Tuscarawas Valley.
[CT]
Mr. Mills was not aware of the importance of this discovery until meeting with me
some months later, when he described the situation to me, and soon after sent the
implement for examination. In company with Judge C. C. Baldwin, President of the
Western Reserve Historical Society, and several others, a visit was made to Mr. Mills,
and we carefully examined the gravel-pit in which the implement occurred, and
collected evidence which was abundant to corroborate all his statements. The implement
in question is made from a peculiar flint which is found in the Lower Mercer limestone,
of which there are outcrops a few miles distant, and it resembles in so many ways the
typical implements found by Boucher de Perthes, at Abbeville, that, except for the
difference in the material from which it is made, it would be impossible to distinguish it

from them. The similarity of pattern is too minute to have originated except from
imitation.
[CT] For typical section of a glacial terrace in Ohio, see p. 227.

Fig. 71.—The smaller is the palæolith from Newcomerstown,
the larger from Amiens (face view), reduced one half in
diameter.

In 1877, a year after the discoveries by Dr. Abbott in New Jersey, some rude quartz
implements were discovered by Professor N. H. Winchell in the glacial terraces of the
upper Mississippi, in the vicinity of Little Falls, Morrison County, Minn. This locality
was afterwards more fully explored by Miss Franc E. Babbitt, who succeeded in finding
so large a number of the implements as to set at rest all question concerning their human
origin. According to Mr. Warren Upham, the glacial flood-plain of the Mississippi is
here about three miles wide, with an elevation of from twenty-five to thirty feet above
the river. It is in a stream near the bottom of this glacial terrace that the most of Miss
Babbitt’s discoveries were made, and Mr. Upham has pretty clearly shown that the
gravel of the terrace overlying them was mostly deposited while the ice-front was still
lingering about sixty miles farther north, in the vicinity of Itasca Lake.[CU]

[CU] For a general map, see p. 66; also p. 225.

Fig. 72.—Edge view of the preceding.

Fig. 73.—Section across the Mississippi Valley at Little Falls,
Minnesota, showing the stratum in which chipped quartz fragments
were found by Miss F. E. Babbitt, as described in the text (Upham).

Up to this time the above are all the instances in which the relics of man are
directly and indubitably connected with deposits of this particular period east of the
Rocky Mountains. Probably it is incorrect to speak of these as preglacial, for the
portion of the period at which the deposits incorporating human relics were made is
well on towards the close of the great Ice age, since these terraces were, in some cases,
and may have been in all cases, deposited after the ice-front had withdrawn nearly, if
not quite, to the water-shed of the St Lawrence basin. It may be difficult to demonstrate
this with reference to the gravel deposits at Trenton, Madisonville, and Medora, but it
is evident at a glance in the case of Newcomerstown and Little Falls.
That the implement-bearing gravel of Trenton, N. J., belongs to the later stages of
the Glacial period is evident from its relation to what Professor H. Carvill Lewis called
“the Philadelphia red gravel and brick-clay,” but which, from its large development in

the District of Columbia at Washington, is called by Mr. McGee the “Columbia
deposit.” The city of Philadelphia is built upon this formation in the Delaware Valley,
and the brick for its houses is obtained from it; the cellar of each house ordinarily
furnishing clay enough for its brick walls. This clay is of course a deposit in
comparatively still water, which would imply deposition during a period of land
subsidence. But that it was ice-laden water which flooded the banks is shown by the
frequent occurrence of large blocks of stone in the deposits, such as could have been
transported only in connection with floating ice. The boulders in the Columbia
formation clearly belong to the individual river valleys in which they are found, and
doubtless are to be connected with the flooded condition of those valleys when, by
means of a northerly subsidence, the gradient of the streams was considerably less than
now.

Fig. 74.—Quartz implement, found by Miss F. E. Babbitt,
1878, at Little Falls, Minnesota, in modified drift, fifteen feet
below surface: a, face view; b, profile view. The black
represented on the cut is the matrix of the quartz vein (No.
31,323) (Putnam).

There is some difference of opinion in respect to the extent of this subsidence, and,
indeed, respecting the height attained by the Philadelphia brick-clay, or McGee’s
Columbia deposit. Professor Lewis (whose residence was at Philadelphia, and who had

devoted much time to field observations) insisted that the deposit could not be found
higher than from 180 to 200 feet above the immediate flood-plain of the river valleys
where they occur. But, without entering upon this disputed question, it is sufficient to
consider the bearing of the facts that are accepted by all—namely, that towards the
close of the Glacial period there was a marked subsidence of the land on the eastern
coast of North America, increasing towards the north.
Fully to comprehend the situation, we need to bring before the mind some of the
indirect effects of the Glacial period in this region. The most important of these was the
necessary projection of subglacial conditions over a considerable belt of territory to the
south of that actually reached by glacial ice; so that, while there are no clear
indications of the existence of local glaciers in the Appalachian Mountains south of the
central part of Pennsylvania, there are many indications of increased snow-fall upon
the mountains, connected with prolonged winters and with a great increase of spring
floods and ice-gorges upon the annual breaking up of winter.

These facts have been stated in detail by Mr. McGee,[CV] from whose report it
appears that, on the Potomac at Washington, the surface of the Columbia deposit is 150
feet above tide, and that the deposit itself contains many boulders, some of which are
as much as two or three feet in diameter. These are mingled with the gravel in such a
way as to show that they must have been brought down by floating ice from the head-
waters of the Potomac when the winters were much more severe than now. That this
deposit is properly the work of the river is shown by the entire absence of marine
shells.
[CV] Seventh Annual Report of the United States Geological Survey for 1885 and 1886,
pp. 537-646.

According to Mr. McGee, also, there is a gradual decrease in the height of these
delta terraces of the Columbia period as they recede from the glacial boundary—that at
the mouth of the Susquehanna being 245 feet, that of the Potomac 140 feet, that on the
Rappahannock 125, that on the James 100, and that on the Roanoke 75; while the size
of the transported boulders along the streams also gradually diminishes in the same
order. During the Columbia period the Susquehanna River transported boulders fifty
times the size now transported, while the Potomac transported them only up to twenty
times, the Rappahannock only ten times, the James only five, and the Roanoke only
two or three times the size of those now transported. This progressive diminution, both
in the extent of the deposit and in the coarseness of the material deposited by these
rivers at about the time of the maximum portion of the Glacial period, is what would
naturally be expected under the conditions supposed to exist in connection with the
great Ice age, and is an important confirmation of the glacial theory.
That the period of subsidence and more intense glacial conditions during which the
Columbia deposits took place, preceded, by a long interval, the deposition of the gravel
terraces at Trenton, N. J., and the analogous deposits in the Mississippi Valley where

palæolithic implements have been found, is evident enough. The Trenton gravel was
deposited in a recess in the Columbia deposit which had been previously worn out by
the stream. Indeed, in every place where opportunity offers for direct observation the
Trenton gravel is seen to be distinctly subsequent to the other. It was not buried by the
Philadelphia red gravel and brick-clay, but to a limited degree overlies and buries it.
The data for measuring the absolute length of time between these two stages of the
Glacial period are very indefinite. Mr. McGee, however, supposes that since the
Columbia period a sufficient time has elapsed for the falls of the Susquehanna to
recede more than twenty miles and for those of the Potomac eighteen miles, and this
through a rock which is exceedingly obdurate. But, in channels opening, as these do,
freely outward, it is difficult to tell in what epochs the erosion has been principally
performed, since there are no buried channels, as in the glaciated area, enabling us to
determine whether or not much of the eroding work of the river may have been
accomplished in preglacial times.
The lapse of time which, upon the least calculation, separates the Columbia epoch
from the Trenton, gives unusual importance to any discovery of palæolithic
implements which may be made in the earlier deposits. We are bound, therefore, to
consider with special caution the reported discovery of an implement in these deposits
at Claymont, Delaware. The discovery was made by Dr. Hilborne T. Cresson, on July
13, 1887, during the progress of an extensive excavation in constructing the Baltimore
and Ohio Railroad, nineteen miles south of Philadelphia. The implement was from
eight to nine feet below the surface. As there is so much chance for error of judgment
respecting the undisturbed condition of the strata, and as there was so little opportunity
for Dr. Cresson to verify his conclusion, we may well wait for the cumulative support
of other discoveries before building a theory upon it; still, it will be profitable to
consider the situation.

Fig. 75.—Argillite implement, found by H. T. Cresson, 1887, in
Baltimore and Ohio Railroad cut, one mile from Claymont,
Delaware, in Columbia gravel, eight to nine feet below the
overlying clay bed: a, face view; b, side view (No. 45,726)
(Putnam).

Both Mr. McGee and myself have visited the locality with Dr. Cresson, and there
can be no doubt that the implement occurred underneath the Columbia gravel. The line
of demarcation is here very sharp between that gravel and the decomposed strata of
underlying gneiss rock, which appears in our illustration as a light band in the middle
of the section exposed. Some large boulders which could have been moved only in
connection with floating ice are found in the overlying deposit near by. This excavation
is about one mile and a half west of the Delaware River, and about 150 feet above it,
being nearly at the uppermost limit of the Columbia deposit in that vicinity.

Fig. 76.—General section of Baltimore and Ohio cut, near Claymont, Delaware, where Mr. Cresson found
palæolithic implements figured in the text (from photograph by Cresson).

The age of these deposits in which implements have been found at Claymont and at
Trenton will be referred to again when we come to the specific discussion of the date
of the Glacial period. It is sufficient here to bring before our minds clearly, first, the
fact that this at Claymont is connected with the river floods accompanying the ice at its
time of maximum extension, and when there was a gradually increasing or differential
depression of the country to an unknown extent to the northward.
Two radically different theories are presented to account for the deposits variously
known as the Columbia gravel and the Philadelphia brick-clay. Mr. McGee, in the
monograph above referred to, supposes them to have been deposited during a period of
a general subsidence of the coast-line; so that they took place at about tide-level. Mr.
Upham, on the other hand, supposes them to have been deposited during the period of
general elevation to whose influence he mainly attributes the Glacial period itself. In
his view much of the shallow sea-bottom adjoining the present shore off from
Delaware and Chesapeake Bays was then a land-surface, and the Hudson, the
Delaware, and the Susquehanna Rivers, coming down from the still higher elevations
of the north, flowed through extensive plains so related to the northern areas of
elevation that deposition was occurring in their valleys, owing in part to the flooded
condition of the streams, in part to the differential elevation, and in part to the
superabundance of silt and other débris furnished by the melting ice-sheet in the head-
waters of these streams.

The deposits of Trenton gravel occurred much later, at a time when the ice had
melted far back towards the head-waters of the Delaware, and after the land had nearly
resumed its present relations of level, if indeed it had not risen northward to a still
greater relative height.
As would be expected from the climatic conditions accompanying the Glacial
epoch, man’s companions in the animal world were very different during the period
when the high-level river gravels of America were forming from those with which he is
now associated. From the remains actually discovered, either in these gravels or in
close proximity to them, we infer that, while the mastodon was the most frequent of the
extinct quadrupeds with which man then had to contend in that region, he must have
been familiar also with the walrus, the Greenland reindeer, the caribou, the bison, the
moose, and the musk ox.

In the Glacial Terraces of Europe.
The existence of glacial man in Europe was first determined in connection with the
high-level river gravels already described in the valley of the Somme, situated in
Picardy in the northern part of France. Here in 1841 Boucher de Perthes began to
discover rudely fashioned stone implements in undisturbed strata of the gravel terraces,
whose connection with the Glacial period we have already made clear. But for nearly
twenty years his discoveries were ignored by scientific men, although he made
persistent efforts to get the facts before them, and published a full account of them with
illustrations as early as 1847. Some suggested fraud on the part of the workmen; others
without examination declared that the gravel must have been disturbed; while others,
still, denied altogether the artificial character of the implements.

Fig. 77.—Section across valley of the Somme: 1, peat, twenty to
thirty feet thick, resting on gravel, a; 2, lower-level gravels, with
elephant-bones and flint implements, covered with river-loam
twenty to forty feet thick; 3, upper-level gravels, with similar
fossils covered with loam, in all, thirty feet thick; 4, upland-loam,
five to six feet thick; 5, Eocene-Tertiary.

At length, Dr. Regillout, an eminent physician residing at Amiens, about forty
miles higher up the Somme than Abbeville, visited Boucher de Perthes, and, upon
seeing the similarity between the gravel terraces at Abbeville and Amiens, returned
home to look for similar implements in the high-level gravel-pits at St. Acheul, a
suburb of Amiens. Almost immediately he discovered flint implements there of the
same pattern with those at Abbeville, and in undisturbed strata of the gravel terrace,
where it rested on the original chalk formation, at a height of 90 feet above the river. In

the course of four years, Dr. Regillout found several hundred of these implements, and
in 1854 published an illustrated report upon the discoveries.
Still the scientific world remained incredulous until the years 1858 and 1859, when
Dr. Falconer, Mr. Prestwich, Mr. John Evans, Mr. Flower, Sir Charles Lyell, of
England, and MM. Pouchet and Gaudry, of France, visited Abbeville and Amiens, and
succeeded in making similar discoveries for themselves. Additional discoveries at St.
Acheul have continued up to the present time whenever excavations have gone on at
the gravel-pits. Mr. Prestwich estimates that there is an implement to every cubic metre
of gravel, and says that he himself has brought away at different times more than two
hundred specimens, and that the total number found in this one locality can hardly be
under four thousand. “The gravel-beds are on the brow of a hill 97 feet above the river
Somme,” and besides the relics of man contain numerous fluviatile and land shells
together with “teeth and bones of the mammoth, rhinoceros, horse, reindeer, and red
deer, but not of the hippopotamus,”[CW] bones of the latter animal being found here
only in the gravels of the lower terraces, where they are less than thirty feet above the
river, and mark a considerably later stage in the erosion of the valley. While many of
the implements found at Amiens seem to have been somewhat worn and rolled, “others
are as sharp and fresh as when first made.... The bedding of the gravel is extremely
irregular and contorted, as though it had been pushed about by a force acting from
above; and this, together with the occurrence of blocks of Tertiary sandstone of
considerable size, leads to the inference that both are due to the action of river-ice. In
the Seine Valley blocks of still larger size, and transported from greater distances, are
found in gravels of the same age.”
[CW] Prestwich’s Geology, vol. ii, p. 481.

“Flint implements are found under similar conditions in many of the river-valleys
of other parts of France, especially in the neighbourhood of Paris; of Mons in Belgium;
in Spain, in the neighbourhood of Madrid, in Portugal, in Italy, and in Greece; but they
have not been discovered in the drift-beds of Denmark, Sweden, or Russia, nor is there
any well-authenticated instance of the occurrence of palæoliths in Germany.”[CX]
[CX] Prestwich’s Geology, vol. ii, pp. 481, 482.

When once the fact had been established that man was in northern France at the
time of the deposition of the high-level gravels of the Somme and the Seine, renewed
attention was directed to terraces of similar age in southern England. One of these is
that upon which the city of London is built, and which, according to Lyell’s
description, “extends from above Maidenhead through the metropolis to the sea, a
distance from west to east of fifty miles, having a width varying from two to nine
miles. Its thickness ranges commonly from five to fifteen feet.”[CY]
[CY] Antiquity of Man, pp. 154, 155.

For a long time geologists had been familiar with the fact that these terraces of the
Thames contain the remains of numerous extinct animals, among which are included
the mammoth and a species of rhinoceros. Upon directing special attention to the
subject, it was found that, at various intervals, the remains of man, also, had been
reported from the same deposits. As long ago as 1715 Mr. Conyers discovered a
palæolithic implement, in connection with the skeleton of an elephant, at Black Mary’s,
near Gray’s Inn Lane, London. This implement is preserved in the British Museum,
and closely resembles typical specimens from the gravel at Amiens. Other implements
of similar character have been found in the valley of the Wey near Guilford, also in the
valley of the Darent, near Whitstable in Kent, and between Heme Bay and the
Reculvers. While the exact position of these implements in the gravel had not been so
positively noted as in the case of those found at Amiens and Abbeville, there can be
little doubt that man, in company with the extinct animals mentioned, inhabited the
valley of the Thames at a period when its annual floods spread over the whole terrace-
plain upon which the main part of London is built.
In the valley of the Ouse, however, near Bedford, the discovery of palæolithic
implements in the gravel terraces connected with the Glacial period and in intimate
association with bones of the elephant, rhinoceros, hippopotamus, and other extinct
animals, has been as fully established as in the valley of the Somme. The discoveries
here were first made in the year 1860, by Mr. James Wyatt, in a gravel-pit at
Biddenham, two miles northwest of Bedford. Two flint implements were thrown out by
workmen in one day from undisturbed strata thirteen feet below the surface, and
numerous other specimens have since been found in a similar situation.
The valley of the Ouse is bordered on either side by sections of a superficial
blanket of glacial drift containing many transported boulders of considerable size. The
valley is here about two miles wide, and ninety feet deep. The gravel deposit, however,
in which the implements were found, is only about thirty feet above the present level of
the river, and hence represents the middle period of the work of the river in erosion.
Another locality in England in which similar discoveries have been made, is at
Hoxne, about five miles from Diss, in Suffolk County. Like that in the valley of the
Thames, however, the implements were found a long time before the significance of
the discovery was recognized. Mr. John Frere reported the discovery to the Society of
Antiquaries in 1801, and gave some of the implements both to the society and to the
British Museum, in whose collections they are still preserved. The implements are of
the true palæolithic type, and existed in such abundance, and were so free from signs of
wear, that the conclusion seemed probable that a manufactory of them had been
uncovered. As many as five or six to the square yard are said to have been found.
Indeed, their numbers were so great that the workmen “had emptied baskets of them
into the ruts of the adjoining road before becoming aware of their value.”

The deposit in which they are found is situated in the valley of Gold Brook, a
tributary of the Waveney. The implements occurred about twelve feet below the
surface, in fresh-water deposits, filling a hollow eroded in the glacial deposit covering
that part of England. This, therefore, is clearly either of post-glacial or of late glacial
age.
Still another locality in which similar palæolithic implements were found in
undisturbed gravel of this same age in eastern England is Icklingham, in the valley of
the Lark, where the situation is quite similar to that already described at Bedford, on
the Ouse.
The last place we will stop to mention in England which was visited by palæolithic
man, during or soon after the Glacial epoch, is to be found in the vicinity of
Southampton. At this time the Isle of Wight was joined to the mainland, and not
improbably England itself to the Continent. The river, then flowing through the
depression of the Solent and the Southampton Water, occupied a much higher level
than now, leaving terraces along the shore at various places, in which the tools of
palæolithic man have been discovered.
Though these are the best authenticated discoveries connecting man with the
Glacial period in England, they are by no means the only probable cases. Almost every
valley of southern England furnishes evidence of a similar but less demonstrative
character.

In Cave Deposits.
The discovery of the remains of man in the high-level river-gravels deposited near
the close of the Glacial period led to a revision of the evidence which had from time to
time been reported connecting the remains of man with those of various extinct
animals in cave deposits both in England and upon the Continent.

The British Isles.
As early as 1826, Rev. J. MacEnery, a Roman Catholic priest residing near
Torquay, in Devonshire, England, had made some most remarkable discoveries in a
cavern at Kent’s Hole, near his home; but, owing to his early death, and to the
incredulity of that generation of scientific men, his story was neither credited nor
published till 1859. About this time, a new cave having been discovered not far away,
at Brixham, the best qualified members of the Royal Society (Lyell, Phillips, Lubbock,
Evans, Vivian, Pengelly, Busk, Dawkins, and Sanford) were deputed to see that it was
carefully explored. Mr. Pengelly, who had had twenty years’ experience in similar
explorations, directed and superintended the work. Every portion of the contents was
examined with minutest care. Kent’s Hole is “180 to 190 feet above the level of mean

tide, and about 70 feet above the bottom of the valley immediately adjacent.”[CZ] In
one chamber the excavation was about sixty feet square. The contents were arranged in
the following order:
[CZ] Dawkins’s Cave-Hunting, p. 325.

Fig. 78.—Mouth of Kent’s Hole.

1. A surface of dark earth a few inches thick, containing Roman pottery, iron and
bronze spear-heads, together with polished stone weapons. There were, too, in this
stratum bones of cows, goats, and horses, mingled with large quantities of charcoal.
2. Below this was a stalagmite floor from one to three feet thick, formed by the
dripping of lime-water from the roof.
3. Under this crust of stalagmite was a compact deposit of red earth, from two to
thirteen feet thick.[DA] Flint implements of various kinds and charcoal were also found
at different depths; also an awl, or piercer; a needle with the eye large enough to admit
small pack-thread; and three harpoon-heads made out of bone and deer’s horn.
[DA] Dawkins’s Cave-Hunting, p. 326; Lyell’s Antiquity of Man, p. 101.

4. Flint implements were also obtained in a conglomerate (breccia) still below this.
The fossil bones in this cave belonged to the same species of animals as those
discovered in a cave near Wells.
The Brixham cave occurs near the small village of that name, not far from Torquay.
The entrance to it is about ninety-five feet above high water. Its deposits, in descending

order, are: 1. Stalagmitic floor from six to twelve or fifteen inches in thickness. 2. A
thin breccia of limestone fragments cemented together by carbonate of lime. This had
accumulated about the mouth, so as to fill up the entrance. 3. A layer of blackish earth
about one foot in thickness 4. A deposit of from two to four feet thick, consisting of
clayey loam, mingled with fragments of limestone, from small bits up to rocks
weighing a ton. Bounded pebbles of other material were also occasionally met with. 5.
Shingle consisting of rounded pebbles largely of foreign material.
All these strata, except the third, contained fossils of some kind, but the fourth was
by far the richest repository. Among the bones found are those of the mammoth, the
woolly rhinoceros, the horse, the ox, the reindeer, the cave-lion, the cave-hyena, and
the cave-bear. Associated with these remains a number of worked flints was found. In
one place the bones of an entire leg of a cave-bear occurred in such a position as to
show that they must have been bound together by the ligaments when they were
buried. Immediately below these bones a flint implement was found.[DB]
[DB] See Pengelly’s Reports to the Devonshire Association, 1867.

The hyena’s den, at Wookey Hole, near Wells, in Somerset, was carefully explored
by Professor Boyd Dawkins, who stood by and examined every shovelful of material
as it was thrown out.
This cave alone yielded 35 specimens of palæolithic art, 467 jaws and teeth of the
cave-hyena, 15 of the cave lion, 27 of the cave-bear, 11 of the grizzly bear, 11 of the
brown bear, 7 of the wolf, 8 of the fox, 30 of the mammoth, 233 of the woolly
rhinoceros, 401 of the horse, 16 of the wild ox, 30 of the bison, 35 of the Irish elk, and
30 of the reindeer (jaws and teeth only).
In Derbyshire numerous caves were explored by Professor Dawkins at Cress well
Crags, which, in addition to flint implements and the remains of the animals occurring
in the Brixham cave, yielded the bones of the machairodus, an extinct species of tiger
or lion which lived during the Tertiary period.
The Victoria cave, near Settle, in west Yorkshire, is the only other one in England
which we need to mention. In this there were no remains found which could be
positively identified as human, but the animal remains in the lower strata of the cave
deposit were so different from those in the upper bed as to indicate the great lapse of
time which separated the two. This cave is 1,450 feet above the sea-level, and there
were found in the upper strata of the floor, down to a depth of from two to ten feet,
many remains of existing animals. Then, for a distance of twelve feet, there occurred a
clay deposit, containing no organic remains whatever, but some well-scratched
boulders. Below this was a third stratum of earth mingled with limestone fragments, at
the base of which were numerous remains of the mammoth, rhinoceros, hippopotamus,
bison, hyena, etc. One bone occurred which was by some supposed to be human, but
by others to have belonged to a bear. This lower stratum is, without much doubt,

preglacial, and the thickness of the deposit intervening between it and the upper
fossiliferous bed is taken by some to indicate the great lapse of time separating the
period of the mammoth and rhinoceros in England from the modern age. The scratched
boulders in the middle stratum of laminated clay, would indicate certainly that the
material found its way into the cave during the Glacial epoch, when ice filled the
whole valley of the Ribble, which flows past the foot of the hill, and whose bed is 900
feet below the mouth of the cave.
In North Wales the Vale of Clwyd contains numerous caves which were occupied
by hyenas in preglacial times and with their bones are associated those of the
mammoth, the rhinoceros, the hippopotamus, the cave-lion, the cave-bear, and various
other animals. Flint implements also were found in the cave at Cae Gwyn, near the
village of Tremeirchon, on the eastern side of the valley, opposite Cefn, and about four
miles distant. We have already given an illustration of the Cefn cave (see page 148). It
will be observed that this valley of the Clwyd opens to the north, and has a pretty rapid
descent to the sea from the Welsh mountains, and was in position to be obstructed by
the Irish Sea glacier, so as to have been occupied at times by one of the characteristic
marginal lakes of the Glacial period. It is evident also that the northern ice prevailed
over the Welsh ice for a considerable portion of the lower part of the valley; for
northern drift is the superficial deposit upon the hills on the sides of the valley up to a
height of over 500 feet. From the investigations of Mr. C. E. De Rance, F. G. S.,[DC] it
is equally clear also that the northern drift, which until lately sealed up the entrance of
the cave, was subsequent to its occupation by man, and this was the opinion formed by
Sir Archibald Geikie, Director General of the Geological Survey of the United
Kingdom, as the result of special investigations which he made of the matter.[DD]
[DC] Proceedings of the Yorkshire Geological Society for 1888, pp. 1-20.
[DD] See De Ranee, as above, p. 17; and article by H. Hicks, in Quarterly Journal of
Geological Society, vol. xlii, p. 3; Geological Magazine, May, 1885, p. 510.

From the caves in the Vale of Clwyd as many as 400 teeth of rhinoceros, 500 of
horse, 180 of hyena, and 15 of mammoth have been taken. A section of the cave
deposits in the cave at Cae Gwyn is as follows:
“Below the soil for about eight feet a tolerably stiff boulder-clay, containing many
ice-scratched boulders and narrow bands and pockets of sand. Below this about seven
feet of gravel and sand, with here and there bands of red clay, having also many ice-
scratched boulders. The next deposit was a laminated brown clay, and under this was
found the bone-earth, a brown, sandy clay with small pebbles and with angular
fragments of limestone, stalagmites, and stalactites. During the excavations it became
clear that the bones had been greatly disturbed by water action; that the stalagmite
floor, in parts more than a foot in thickness, and massive stalactites, had also been
broken and thrown about in all positions; and that these had been covered afterwards
by clays and sand containing foreign pebbles. This seemed to prove that the caverns,

now 400 feet above ordnance datum, must have been submerged subsequently to their
occupation by the animals and by man. In Dr. Hicks’s opinion, the contents of the
cavern must have been disturbed by marine action during the great submergence in
mid-glacial times, and afterwards covered by marine sands and by an upper boulder-
clay, identical in character with that found at many points in the Vale of Clwyd. The
paleontological evidence suggests that the deposits in question are not preglacial, but
may be equivalent to the Pleistocene deposits of our river-valleys.”[DE]
[DE] H. B. Woodward’s Geology of England and Wales, pp. 543, 544

If the views of Professor Lewis and Mr. Kendall are correct concerning the unity of
the Glacial period in England, the shelly and sandy deposits connected with these
Clwydian caves at an elevation of 400 feet or more would be explained in connection
with the marginal lakes which must have occupied the valley during both the advance
and the retreat of the ice-front; the shells having been carried up from the sea-bottom
by the ice-movement, after the manner supposed in the case of those at Macclesfield
and Moel Tryfaen. If, therefore, the statements concerning the discovery of flint
implements in this Cae Gwyn cave can be relied upon, this is the most direct evidence
yet obtained in Europe of man’s occupation of the island during the continuance of the
Glacial period.
In all these caves it is to be noted that there is a sharp line of demarcation between
the strata containing palæolithic implements and those containing only the remains of
modern animals. Palæolithic implements are confined to the lower strata, which in
some of the caves are separated from the upper by a continuous bed of stalagmite, to
which reference will be made when discussing the chronology of the Glacial period.
The remains of extinct animals also are confined to the lower beds.
The caves which we have been considering in England are all in limestone strata,
and have been formed by streams of water which have enlarged some natural fissures
both by mechanical action in wearing away the rocks, and by chemical action in
dissolving them. Through the lowering of the main line of drainage, caverns with a dry
floor are at length left, offering shelter and protection both to man and beast.
Oftentimes, but not always, some idea of the age of these caverns may be obtained by
observing the depth to which the main channel of drainage to which they were
tributary has been lowered since their formation. But to this subject also we will return
when we come specifically to discuss the chronological question.

The Continent.
Systematic explorations in the caves of Belgium were begun in 1833 by Dr.
Schmerling, in the valley of the Meuse, near his residence in Liége. The Meuse is here
bordered by limestone precipices 200 or more feet in height. Opening out from these
rocky walls are the entrances to the numerous caverns which have rendered the region

so famous. To get access to the most important of these, Dr. Schmerling had to let
himself down over a precipice by a rope tied to a tree, and then to creep along on all-
fours through intricate channels to reach the larger chambers which it was his object to
explore. In the cave at Engis, on the left bank of the Meuse, about eight miles above
Liége, he found a human skull deeply buried in breccia in company with many bones
of the extinct animals previously stated to have been associated with man during the
Glacial period. This so-called “Engis skull” was by no means apelike in its character,
but closely resembled that of the average Caucasian man. But this established the
association upon the Continent of man with some of the extinct animals of the Glacial
period.
The vicinity of Liége has also furnished us another
cavern whose contents are of the highest importance,
ranking indeed as perhaps the most significant single
discovery yet made. The cave referred to is on the
property of the Count of Beauffort, in the commune of
Spy, in the province of Namur in Belgium. For the
facts relating to it we are indebted to Messrs: Lohest
and Fraipont, the former Professor of Geology and the
latter of Anatomy in the University of Liége. The
exploration of the cave was made in 1886, and the full
report with illustrations published in the following year Fig. 79.—Engis skull, reduced (after
Lyell.)
in Archives de Biologie.[DF] The significance of this
discovery is enhanced by the light it sheds upon and
the confirmation it brings to the famous Neanderthal
skull and others of similar character, which for a long
time had been subjects of vigorous discussion.
Before describing it, therefore, we will give a brief
account of the previous discoveries.
[DF] See pp. 587, 757.

The famous Neanderthal skull was brought to Fig. 80.—Comparison of forms of skulls:
light in 1857 by workmen in a limestone-quarry, near a, European; b, the Neanderthal man; c, a
chimpanzee (after Lyell).
Düsseldorf, in the valley of the Neander, a small
tributary to the Rhine. By these workmen a cavern
was opened upon the southern side of the winding
ravine, about sixty feet above the stream and one hundred feet below the top of the
cliff. The skull attracted much attention from its supposed possession of many apelike
characteristics; indeed, it was represented by some to be a real intermediate link
between man and the anthropoid apes. The accompanying cut enables one to compare
the outline of the Neanderthal skull with that of a chimpanzee on the one hand and of
the highly developed European on the other. The apelike peculiarities of this skull
appear in its vertical depression, in the enormous thickness of the bony ridges just

above the eyes, and in the gradual slope of the back part of the head, together with
some other characteristics which can only be described in technical language; so that it
was pronounced by the highest authorities the most apelike of human crania which had
yet been discovered. Unfortunately, the jaw was not found. The capacity of the skull,
however, was seventy-five cubic inches, which is far above that of the highest of the
apes, being indeed equal to the average capacity of Polynesian and Hottentot skulls.
[DG]
Huxley well remarks that “so large a mass of brain as this would alone suggest
that the pithecoid tendencies indicated by this skull did not extend deep into the
organization.”
[DG] Huxley’s Man’s Place in Nature, p. 181.

Upon extending inquiries, it was found
that the Neanderthal type of skull is one which
still has representatives in all nations; so that
it is unsafe to infer that the individual was a
representative of all the individuals living in
his time. The skull of Bruce, the celebrated
Scotch hero, was a close reproduction of the
Neanderthal type; while, according to
Quatrefages,[DH] the skull of the Bishop of
Toul in the fourth century “even exaggerates
some of the most striking features of the
Neanderthal cranium. The forehead is still
more receding, the vault more depressed, and
the head so long that the cephalic index is 69-
41.” The discovery of Messrs. Fraipont and
Lohest adds much to our definite knowledge Fig. 81.—Skull of the Man of Spy. (From
of the Neanderthal type of man, since the photograph.)
Belgic specimens are far more complete than
any others heretofore found, there being in
their collection two skulls, together with the jawbones and most of the other parts of
the frame. In this case also there is no suspicion that the deposits had been disturbed,
so as to admit any intrusion of human relics into the company of relics of an earlier
age. According to M, Lohest, there were three distinct ossiferous beds, separated by
layers of stalagmite. All the ossiferous beds contained the remains of the mammoth,
but in the upper stratum they were few, and probably intrusive. The implements found
in this were also of a more modern type. In the second stratum from the top numerous
hearths were found with burnt wood and ashes, together with the bones of the
rhinoceros, the horse, the mammoth, the cave-bear, and the cave-hyena, all of which
were abundant, while there were also specimens of the Irish elk, the reindeer, the bison,
the cave-lion, and several other species. In this layer also there were numerous

implements of ivory, together with ornaments and some faint indications of carving
upon the rib of a mammoth, besides a few fragments of pottery.
[DH] Human Species, p. 310,

It was in the third, or lowest, of these beds that the skeletons were found. Here they
were associated with abundant remains of the rhinoceros, the horse, the bison, the
mastodon, the cave-hyena, and a few other extinct species. Flint implements also, of
the “Mousterien” pattern (which, according to the opinion of the French archæologists,
is characteristic of middle palæolithic times), were abundant Neither of the skeletons
was complete, but they were sufficiently so to give an adequate idea of the type to
which they belong, and one of the skulls is nearly perfect. According to M. Fraipont,
“one of these skulls is apparently that of an old woman, the other that of a middle-aged
man. They are both very thick; the former is clearly dolichocephalic (long-headed,
index 70), the other less so. Both have very prominent eyebrows and large orbits, with
low, retreating foreheads, excessively so in the woman. The lower jaws are heavy. The
older has almost no projecting chin. The teeth are large, and the last molar is as large as
the others. These points are characteristic of an inferior and the oldest-known race. The
bones indicate, like those of the Neanderthal and Naulette specimens, small, square-
shouldered individuals.” They were “powerfully built, with strong, curiously curved
thigh-bones, the lower ends of which are so fashioned that they must have walked with
a bend at the knees.” [DI]
[DI] Huxley, Nineteenth Century, vol. xxviii (November, 1890), p. 774.

Other crania from various Quaternary deposits in Europe seem to warrant the
inference that this type of man was the prevalent one during the early part of the
Palæolithic age. As long ago as 1700 a skull of this type was exhumed in Canstadt, a
village in the neighbourhood of Stuttgart, in Würtemberg. This was found in
coexistence with the extinct animals whose bones we have described as so often
appearing in the high-level river-gravel of the Glacial age. But the importance of the
discovery at Canstadt was not appreciated until about the middle of the present century.
From the priority of the discovery, and of the discussion among German
anthropologists concerning it, it has been thought proper, however, by some to give the
name of this village to the race and call it the “Canstadt race.” But, whatever name
prevails, it is important in our reading to keep in mind that the man of Canstadt, the
man of Neanderthal, and the man of Spy are identical in type, and probably in age.
Similar discoveries have been made in various other places. Among these are a lower
jaw of the same type discovered in 1865 by M. Dupont, at Naulette, in the valley of the
Lesse, in Belgium, and associated with the remains of extinct animals; a jawbone
found in a grotto at Arcy; a fragment of a skull found in 1865 by Faudel, in the loess of
Eguisheim, near Colmar; a skull at Olmo, discovered in 1863, in a compact clayey
deposit forty-five feet below the surface; and a skull discovered in 1884 at Marcilly.

M. Dupont has brought to light much additional testimony to glacial man from
other caves in different parts of Belgium. In all he has explored as many as sixty. Three
of these, in the valley of the Montaigle, situated about one hundred feet above the river,
contained both remains of man and many bones of the mammoth and other associated
animals, which had evidently been brought in for food.
In the hilly parts of Germany, also, and in Hungary, and even in the Ural Mountains
in Russia, and in one of the provinces of Siberia, the remains of the rhinoceros, and
most of the other animals associated with man in glacial times, have been found in the
cave deposits which have been examined. Though it can not be directly proved that
these animals were associated with man in any of these places, still it is interesting to
see how wide-spread the animals were in northern Europe and Asia during the Glacial
period.
Some northern animals, also, spread at this time into southern Europe—remains of
the reindeer having been discovered on the south slope of the Pyrenees, but the remains
of the mammoth, the woolly rhinoceros, and the musk ox, have not been found so far
south.
African species of the elephant, however, seem at one time to have had free range
throughout Spain, and the hippopotamus roamed in vast herds over the valleys of
Sicily, while several species of pygmy elephants seem to be peculiar to the island of
Malta.
In the case of all the cave deposits referred to (with possibly the exception of those
of Victoria, England, and Cae Gwyn, Wales), the evidence of man’s existence during
the Glacial period is inferential, and consists largely in the fact that he was associated
with various extinct animals which did not long survive that period, or with animals
that have since retired from Europe to their natural habitat in mountain-heights or high
latitudes. The men whose remains are found in the high-level river-drift, and in the
caverns described, were evidently not in possession of domestic animals, as their bones
are conspicuous for their absence in all these places. The horse, which would seem to
be an exception, was doubtless used for food, and not for service.
If we were writing upon the general subject of the antiquity and development of the
human race, we should speak here in detail of several other caves and rock shelters in
France and southern Europe, where remains of man belonging to an earlier period have
been found. We should mention the rock shelter of Cro-Magnon in the valley of
Vezère, as well as that of Mentone, where entire human skeletons were found. But it is
doubtful if these and other remains from caves which might be mentioned belong in
any proper sense to the Glacial period. The same remarks should be made also with
reference to the lake-dwellings in Switzerland, of which so much has been written in
late years. All these belong to a much later age than the river-drift man of whom we are

speaking, and of whom we have such abundant evidence both in Europe and in
America.

1
Fig. 82.—Tooth of Machairodus neogæus, × 6 (drawn from a cast).
Fig. 83.—Perfect tooth of an Elephas, found in Stanislaus County,
1
California, 8 natural size.

Extinct Animals associated with Man during the Glacial
Period.
This is the proper place in which to speak more fully of the extinct animals which
accompanied man in his earliest occupation of Europe and America, and whose
remains are so abundant in the river-drift gravel and in the caves of England, in
connection with the relics of man. Among these animals are
The Lion, which is now confined, to Africa and the warmer portions of Asia. But in
glacial times a large species of this genus ranged over Europe from Sicily to central
England.
The saber-toothed Tiger, with tusks ten inches long: (Machairodus latidens), is now
extinct. This species was in existence during the latter part of the Tertiary period, but
continued on until after man’s appearance in the Glacial period. The presence of this
animal would seem to indicate a warm climate.
The Leopard (Felis pardus) is now confined to Africa and southern Asia, and the
larger islands adjoining; but during man’s occupation of Europe in the Glacial epoch he
was evidently haunted at every step by this animal; for his bones are found as far north
in England as palæolithic man is known to have ranged.
The Hyena. Two species of this animal are found in the bone-caves of Europe.
During the Glacial epoch they ranged as far up as northern England, but they are now
limited to Africa and southwestern Asia.

1
Fig. 84.—Skull of Hyena spelæa, × 4.

The Elephant is represented in the Preglacial and Glacial epochs by several species,
some of which ranged as far north as Siberia. The African elephant is not now found
north of the Pyrenees and the Alps. But a species of dwarf elephant, but four or five
feet in height, has already been referred to as having occupied Malta and Sicily; and
still another species has been found in Malta, whose average height was less than three
feet. An extinct species (Elephas antiquus), whose remains are found in the river-drift
and in the lower strata of sediment in many caverns as far north as Yorkshire, England,
was of unusual size, and during the Glacial period was found on both sides of the
Mediterranean. But the species most frequently met with in palæolithic times was the
mammoth (Elephas primigenius). This animal, now extinct, accompanied man in
nearly every portion both of Europe and North America, and lingered far down into
post-glacial times before becoming extinct. This animal was nearly twice the weight of
the modern elephant, and one third taller. Occasionally his tusks were more than twelve
feet long, and curved upward in a circle. It is the carcasses of this animal which have
been found in the frozen soil of Siberia and Alaska. It had a thick covering of long,
black hair, with a dense matting of reddish wool at the roots. During the Glacial period
these animals must have roamed in vast herds over the plains of northern France and
southern England, and the northern half of North America.

Fig. 85.—Celebrated skeleton of mammoth, in St.
Petersburg museum.

Fig. 86.—Molar tooth of mammoth (Elephas
primigenius): a, grinding surface; b, side view.

The Hippopotamus is at present a familiar animal in the larger rivers of Africa, but
is not now found in Europe. During the Glacial period, however, he ranged as far north
as Yorkshire, England, and his remains were found in close association with those of
man, both in Europe and on the Pacific coast in America. Twenty tons of their bones
have been taken from a single cave in Sicily.[DJ]
[DJ] Prestwich’s Geology, vol. ii, p. 508.

The mammoth and the rhinoceros we know to have been
adapted to cold climates by the possession of long hair and
thick fur, but the hippopotamus by its love for water would
seem to be precluded from the possession of this protective
covering. It is suggested, however, by Sir William Dawson,
that he may have been adapted to arctic climates by a fatty
covering, as the walrus is at the present time. A difficulty in
Fig. 87.—Tooth of Mastodon
Americanus.
accounting for many of the remains of the hippopotamus in
some of the English caverns is that they are so far away
from present or possible water-courses. But it would seem
that due credit has not been ordinarily given to the migratory instincts of the animal. In
southern Africa they are known to “travel speedily for miles over land from one pool of
a dried-up river to another; but it is by water that their powers of locomotion are
surpassingly great, not only in rivers, but in the sea.... The geologist, therefore, may
freely speculate on the time when herds of hippopotami issued from North African
rivers, such as the Nile, and swam northward in summer along the coasts of the
Mediterranean, or even occasionally visited islands near the shore. Here and there they
may have landed to graze or browse, tarrying awhile, and afterwards continuing their
course northward. Others may have swum in a few summer days from rivers in the
south of Spain or France to the Somme, Thames, or Severn, making timely retreat to
the south before the snow and ice set in.” [DK]

[DK] Lyell, Antiquity of Man, p. 180,

The Mastodon (Mastodon Americanus), (Fig. 88), “is probably the largest land
mammal known, unless we except the Dinotherium. It was twelve to thirteen feet high,
and, including the tusks, twenty-four to twenty-five feet long. It differed from the
elephant chiefly in the character of its teeth. The difference is seen in Figs. 86 and 87.
The elephant’s tooth given above (Fig. 86) is sixteen inches long, and the grinding
surface eight inches by four.”

Fig. 88.—Mastodon Americanus (after Owen).

The mastodon, together with the mammoth, made their appearance about the
middle of the Miocene epoch. At the close of the Tertiary period the mastodon became
extinct on the Eastern Continent, but continued in North America to be a companion of
man well on toward the close of the Glacial period. Many perfect skeletons have been
found in the deposits of this period in North America. “One magnificent specimen was
found in a marsh near Newburg, New York, with its legs bent under the body, and the
head thrown up, evidently in the very position in which it mired. The teeth were still
filled with the half-chewed remnants of its food, which consisted of twigs of spruce,
fir, and other trees; and within the ribs, in the place where the stomach had been, a
large quantity of similar material was found.”[DL]
[DL] Le Conte’s Geology (edition of 1891), p. 582.

The Rhinoceros is now confined to Africa and southern
Asia; but the remains of four species have been found in
America, Europe, and northern Asia, in deposits of the Glacial
period. In company with that of the mammoth, already spoken
of, a carcass of the woolly rhinoceros was found in 1771 in
the frozen soil of northern Siberia. The bones of other species

have been found as far north as Yorkshire, England. In the Fig. 89.—Skeleton of
Rhinoceros tichorhinus.
valley of the Somme there was found “the whole hind limb of
a rhinoceros, the bones of which were still in their true
relative position. They must have been joined together by ligaments and even
surrounded by muscles at the time of their interment.” An entire skeleton was found
near by. The gravel terrace in which these occurred is about forty feet above the floor
of the valley, and must have been formed subsequent to some of the strata which
contained the remains of human art. In America the bones are found in the gold-
bearing gravels of California, in connection with human remains.
The Bear was represented in
Europe in palæolithic times by three
species, of which only one exists there
at the present time. But during the
Glacial period the grizzly bear, now
confined to the western part of
America, and the extinct cave-bear
were companions, or enemies as the
case may be, of man throughout
Europe. The cave-bear was of large
Fig. 90.—Skull of cave-bear (Ursus spelæus),
size, and his bones occur almost
everywhere in the lower strata of
sediment in the caves of England.
The Great Irish Elk, or deer, is now extinct, though it is supposed by some to have
lingered until historic times. Its remains are found widely distributed over middle
Europe in deposits of palæolithic age.
The Horse was also, as we have seen, a very constant
associate of man in middle Europe during the Palæolithic
age, but probably not as a domesticated animal. The
evidence is pretty conclusive that he was prized chiefly for
food. About some of the caves in France such immense
quantities of their bones are found that they can be
accounted for best as refuse-heaps into which the useless
bones had been thrown after their feasts, after the manner
of the disposal of shells of shell-fish. In America the horses
associated with man were probably of a species now
Fig. 91.—Skeleton of the Irish
extinct. The skull of one (Equus excelsus) recently found
elk (Cervus megaceros). in Texas, in Pleistocene deposits, associated with human
implements, is, according to Cope, intermediate in
character between the horse and quagga.[DM] The frontal
bone was crushed in in a manner to suggest that it had been knocked in the head with a

stone hammer, such as was found in the same bed. Possibly, therefore, man’s love of
horse-flesh may have been an important element in securing the extinction of the
species in America.
[DM] American Naturalist, vol. xxv (October, 1891), p. 912.

Besides these animals there were associated with man at this time the Musk Sheep
and the Reindeer, both now confined to the regions of the far north, but during the
Glacial period ranging into southern France, and mingling their bones with those both
of man and of the southern species already enumerated.

Fig. 92.—Musk-sheep (Ovibos moschatius).

The Wolverine, the Arctic Fox, the Marmot, the Lemming—all now confined to
colder regions—at that time mingled on the plains of central Europe with the species
mentioned as belonging now to Africa and southern Asia. The Ibex, also, and the
Snowy Vole and Chamois descended to the plains from their mountain-heights, and
joined in the strange companionship of animals from the north and from the south.
Besides these extremes there were associated with man during the Glacial period
numerous representatives of the temperate group of existing animals, such as the bison,
the horse, the stag, the beaver, the hare, the rabbit, the otter, the weasel, the wild-cat,
the fox, the wolf, the wild boar, and the brown bear.
To account for this strange intermingling of arctic and
torrid species of animals, especially in Europe, during man’s
occupancy of the region in glacial times, various theories
have been resorted to, but none of them can be said to be
altogether satisfactory. One hypothesis is that the bones of
these diverse animals became mingled by reason of the great
range of the annual migration of the species. The reindeer,
Fig. 93.—Reindeer.
for example, still performs extensive annual migrations. In
summer it ventures far out upon the tundras of North
America and Siberia to feed upon the abundant vegetation
that springs up like magic under the influence of the long days of sunshine; while, as

winter approaches, it returns to the forests of the interior. Or in other places this animal
and his associates, like birds of passage, move northward in summer to escape the heat,
and southward in the winter to escape the extreme cold. Many of the other animals also
are more or less migratory in their habits.
Thus it is thought that during the Glacial period, when man occupied northern
France and southern England, the reindeer, the musk sheep, the arctic fox, and perhaps
the hippopotamus and some other animals, annually vibrated between northern
England and southern France, a slight elevation of the region furnishing a land passage
from England to the continent; while the chamois and other Alpine species vibrated as
regularly between the valleys in winter and the mountain-heights in summer. The
habits of these species are such that it is not difficult to see how in their case this
migration could have taken place.
Professor Boyd Dawkins attempts to reduce the difficulty by supposing that the
Glacial epoch was marked by the occurrence of minor periods of climatic variation,
during which, in comparatively short periods, the isothermal lines vibrated from north
to south, and vice versa. In this view the southern species gradually crowded upon the
northern during the periods of climatic amelioration, until they reached their limit in
central England, and then in turn, as the climate became more rigorous, slowly
retreated before the pressure of their northern competitors. Meanwhile the hyena
sallied forth from his various caves, over this region, at one time of the year to feed
upon the reindeer, and at another time of the year upon the flesh of the hippopotamus,
in both cases dragging their bones with him to his sheltered retreat in the limestone
caverns[DN] which he shared at intervals with palæolithic man.
[DN] Early Man in Britain, p. 114.

The theory of Mr. James Geikie is that the period, while one of great precipitation,
was characterised by a climate of comparatively even temperature, in which there was
not so great a difference as now between the winters and the summers, the winters not
being so cold and the summers not so hot as at present. This is substantially the
condition of things in southern Alaska at the present time, where extensive glaciers
come down to the sea-level, even though the thermometer at Sitka rarely goes below
zero (Fahrenheit). It is, therefore, easy to conceive that if there were extensive plains
bordering the Alaskan archipelago, so as to furnish ranging grounds for more southern
species, the animals of the north and the animals of the south might partially occupy
the same belt of territory, and their bones become mingled in the same river deposits.
In order to clear the way for either of these hypotheses to account for the mingling
of arctic and torrid species characteristic of the period under consideration in Europe,
we must probably suppose such an elevation of the region to the south as to afford land
connection between Europe and Africa. This would be furnished by only a moderate
amount of elevation across the Strait of Gibraltar and from the south of Italy to the

opposite shore in Africa; and there are many indications, in the distribution of species,
of the existence in late geological times of such connection.
It should also be observed that the present capacities and habits of species are not a
certain criterion of their past habits and capacities. As already remarked, both the
rhinoceros and the mammoth of glacial times were probably furnished with a woolly
protection, which enabled them to endure more cold than their present descendants
could do, while the elephant is even now known to be able to endure the rigors of the
climate at great elevations upon the Himalaya Mountains. We can easily imagine these
species to have been adjusted to quite different climatic conditions from those which
now seem necessary to their existence. In the case of the hippopotamus, also, it is quite
possible, as already suggested, that it is more inclined to migration than is generally
supposed.
Geikie’s theory of the prevalence of an equable climate during a portion of the
Glacial period in Europe is thought to be further sustained by the character of the
vegetation which then covered the region, as well as by the remains of the mollusks
which occupied the waters. Then “temperate and southern species like the ash, the
poplar, the sycamore, the fig-tree, the Judas-tree, the laurel, etc., overspread all the low
ground of France, as far north at least as Paris.... It was under such conditions,”
continues Geikie, "that the elephants, rhinoceroses, and hippopotamuses, and the vast
herds of temperate cervine and bovine species ranged over Europe, from the shores of
the Mediterranean up to the latitude of Yorkshire, and probably even farther north still;
and from the borders of Asia to the Western Ocean. Despite the presence of numerous
fierce carnivora—lions, hyenas, tigers, and others—Europe at that time, with its shady
forests, its laurel-margined streams, its broad and deep-flowing rivers, a country in
every way suited to the needs of a race of hunters and fishers—must have been no
unpleasant habitation for palæolithic man.
“This, however, is only one side of the picture. There was a time when the climate
of Pleistocene Europe presented the strongest contrast to those genial conditions—a
time when the dwarf birch of the Scottish Highlands, and the arctic willow, with their
northern congeners, grew upon the low grounds of middle Europe. Arctic animals, such
as the musk sheep and the reindeer, lived then, all the year round, in the south of
France; the mammoth ranged into Spain and Italy; the glutton descended to the shores
of the Mediterranean; the marmot came down to the low grounds at the foot of the
Apennines; and the lagomys inhabited the low-lying maritime districts of Corsica and
Sardinia. The land and fresh-water shells of many Pleistocene deposits tell a similar
tale; boreal, high alpine, and hyperborean forms are characteristic of these
accumulations in central Europe; even in the southern regions of our continent the
shells testify to a former colder and wetter climate.”[DO]
[DO] Prehistoric Europe, p. 67.

In Mr. Geikie’s view these facts indicate two Glacial periods, with an intervening
epoch of mild climate. In the opinion of others they are readily explainable by the
coming on and departure of a single Ice age, with its various minor episodes.

Earliest Remains of Man on the Pacific Coast of North
America.
Most interesting evidence concerning the antiquity of man in America, and his
relation to the Glacial period, has come from the Pacific coast. During the height of the
mining activity in California, from 1850 to 1860, numerous reports were rife that
human remains had been discovered in the gold-bearing gravel upon the flanks of the
Sierra Nevada Mountains. These reports did not attract much scientific attention until
they came to relate to the gravel deposits found deeply buried beneath a flow of lava
locally known as the Sonora or Tuolumne Table Mountain. This lava issued from a
vent near the summit of the mountain-range, and flowed down the valley of the
Stanislaus River for a distance of fifty or sixty miles, burying everything in the valley
beneath it, and compelling the river to seek another channel. The thickness of the lava
averages about one hundred feet, and so long a time has elapsed since the eruption that
the softer strata on either side of the valley down which it flowed have been worn away
to such an extent that the lava now rises nearly everywhere above the general level,
and has become a striking feature in the landscape, stretching for many miles as a flat-
topped ridge about half a mile in width, and presenting upon the sides a perpendicular
face of solid basalt for a considerable distance near the lower end of the flow.

Fig. 94.—Section across Table Mountain, Tuolumne County, California:
L, lava; G, gravel; S, slate; R, old river-bed; R′, present river-bed.

Fig. 95.—Calaveras Skull. (From Whitney.)

It was under this mountain of lava that the numerous implements and remains of
man occurred which were reported to Professor J. D. Whitney when he was conducting
the geological survey of California between 1860 and 1870. The implements consisted
of stone mortars and pestles, suitable for use in grinding acorns and other coarse
articles of food. There were, however, some rude articles of ornament. In one of the
mining shafts penetrating the gravel underneath Table Mountain, near Sonora, there
was reported to have been discovered, in 1857, a human jawbone, one portion of which
was sent by responsible parties to the Boston Society of Natural History, and another
part to the Philadelphia Academy of Sciences, in whose collections the fragments can
now be seen.
Interest reached a still higher pitch when, in 1860, an entire human skull with some
other human bones was reported to have been discovered under this same lava deposit,
a few miles from Sonora, at Altaville, in Calaveras County, and hence known as the
“Calaveras skull.” Persistent efforts were made soon after to discredit the genuineness
of this discovery. Bret Harte showered upon it the shafts of his ridicule, and various
other persons gave currency to the story that the whole report originated in a joke
played by the miners upon unsuspecting geologists. These attacks were so successful
that many conservative archæologists and men of science have refused to accept the
skull as genuine.

Recent events, however, have brought such additional evidence[DP] to the support
of this discovery that it would seem unreasonable any longer to refuse to credit the
testimony. At the meeting of the Geological Society of America, at Washington, in
January, 1891, Mr. George P. Becker, of the United States Geological Survey, who for
some years has had charge of investigations relating to the gold-bearing gravels of the
Pacific coast, presented the affidavit of Mr. J. H. Neale, a well-known mining engineer
of unquestionable character, stating that he had taken a stone mortar and pestle,
together with some spear-heads (which through Mr. Becker he presented to the
Society), from undisturbed strata of gravel underneath the lava of Table Mountain, near

Rawhide Gulch, a few miles from Sonora. At the same meeting Mr. Becker presented a
pestle which Mr. Clarence King, the first director of the United States Geological
Survey, took with his own hands out of undisturbed gravel under this same lava
deposit, near Tuttletown, a mile or two from the preceding locality mentioned.
[DP] See Bulletin Geological Society of America, 1891, pp. 189-200.

I was so fortunate, also, as to be able to report to the Society at the same meeting
the discovery, in 1887, of a small stone mortar by Mr. C. McTarnahan, the assistant
surveyor of Tuolumne County. This mortar was found by Mr. McTarnahan in the
Empire mine, which penetrates the gravel underneath Table Mountain, about three
miles from Sonora, and not far from the other localities above mentioned. The place
where the mortar was found is about one hundred and seventy-five feet in from the
edge of the superincumbent lava, which is here about one hundred feet in thickness. At
my request, this mortar was presented by its owner, Mrs. M. J. Darwin, to the Western
Reserve Historical Society of Cleveland, Ohio, in whose collection it can now be seen.
These three independent instances, each of them authenticated by the best of
evidence, have such cumulative force that probably few men of science will longer
stand out against it.
Associated with these discoveries, there is to be mentioned another, which was
brought to my notice by Mr. Charles Francis Adams in October, 1889.[DQ] This was a
miniature clay image of a female form, about one inch and a half in length, and
beautifully formed, which was found, in August, 1889, by Mr. M. A. Kurtz, while
boring an artesian well at Nampa, Ada County, Idaho. The strata passed through
included, near the surface, fifteen feet of lava. Underneath this, alternating beds of clay
and quicksand occurred to a depth of three hundred and twenty feet, where there
appeared indications of a former surface soil lying just above the bed-rock, from which
the clay image was brought up in the sand-pump.
[DQ] See Proceedings Boston Society Natural History, January, 1890, and February,
1891.

Fig. 96.—Three views of Nampa image drawn to scale.
The middle one is from a photograph.

I devoted the summer of 1890 to a careful study of the lava deposits both in Idaho
and in California, with a view to learning their significance with reference to these
discoveries. The main facts brought to light by this investigation are that in the Snake
River Valley, Idaho, there are not far from twelve thousand square miles of territory
covered with a continuous stratum of basaltic lava, extending nearly across the entire
diameter of the State from east to west. Nampa, where the miniature image was
discovered, is within five miles of the western limit of this lava-flow, and where it had
greatly thinned out. The relative age of the lava is shown by its relation to Tertiary beds
of shale and sandstone, containing numerous fossils of late Pliocene species. These are
overlaid in this vicinity by the lava, thus determining its post-Tertiary character.
Examination with reference to the more precise determination of age reveals channels
of erosion formed since the lava-flow took place, which, when studied sufficiently, will
probably lead to valuable approximate results. At present I can only say that the
amount of erosion since the lava eruptions of western Idaho is not excessive, and very
likely may be brought within a period of from ten thousand to twenty thousand years.
The enormous erosion in the cañon of the Snake River, near Shoshone Falls, in central
Idaho, is doubtless of a much earlier date than that in the Boise River, near Nampa.

Fig. 97.—Map showing Pocatello, Nampa,
and the valley of Snake River.

The disturbances created in this part of the valley by the bursting of the barriers
between the glacial Lake Bonneville and the Snake River, already described (see
above, page 233), have not been worked out. There can be no doubt, however, that
interesting results will come to light in connection with the problem; for Pocatello, the
point at which the débâcle reached the Snake River plain, is about 2,000 feet higher
than Nampa, and 350 miles distant, and the water must have poured into the valley
faster than the river in its upper portion could have discharged it. By just what channels
the mighty current worked down to the lower levels on the western borders of the State
it would be most interesting as well as instructive to know.
A study of the situation in Tuolumne and Calaveras Counties, California, reveals a
state of things closely resembling, in important respects, that in western Idaho. At first
sight the impression is made that an immense lapse of time must have occurred since
the volcanic eruption which furnished the lava of Table Mountain. The Stanislaus River

flows in a channel of erosion a thousand feet or more lower than the ancient channel
filled by lava, and in two or three places cuts directly across it. An immense amount of
time, also, would seem to be required to permit the smaller local streams to have worn
away so much of the sides of the ancient valley as to allow the lava deposit now so
continuously to rise above the general surface. Still, the question of absolute time
cannot be considered separately without much further study. It is by no means certain
that, when the lava-stream poured down the mountain, it always followed the lowest
depressions; but at certain points it may have been dammed up in its course by its own
accumulations so as to be turned off into what was then an ancient abandoned channel.

Fig. 98.—Section along the line, north and south: r′ r′, old
river-beds; r r, present river-beds; L, lava; sl, slate.

The forms of animal and vegetable life with which the remains of man under Table
Mountain are associated, are, indeed, to a considerable extent, species now extinct in
California, and some of them no longer exist anywhere in the world. But a suggestion
of Professor Prestwich, in England, made with reference to the extinct forms of life
associated with human remains in the glacial deposits in Europe, is revived by Mr.
Becker, of the Geological Survey, with reference to the California discoveries; his
inference being, not that man is so extremely ancient in California, but that many of
these plants and animals have continued to a more recent date than has ordinarily been
supposed.
The connection of these lava-flows on the Pacific coast with the Glacial period is
unquestionably close. For some reason which we do not fully understand, the vast
accumulation of ice in North America during the Glacial period is correlated with
enormous eruptions of lava west of the Rocky Mountains, and, in connection with
these events, there took place on the Pacific coast an almost entire change in the plants
and animals occupying the region. Mr. Warren Upham is of the opinion that on the
Pacific coast they lingered much later than in the region east of the Rocky Mountains.
Indeed, it is pretty certain that not many centuries have elapsed since the glacial
phenomena of the Sierra Nevada Mountains were much more pronounced than they are
at the present time, and it is equally certain that there have been vast eruptions of lava
in California within three hundred years.
From these data, therefore, Mr. Becker has real foundation for his suggestion that
perhaps in the Glacial period California was a kind of health resort for Pliocene
animals, as it is at the present time for man; or, at any rate, that the later date of the
accumulations permitted the animals to survive there much longer than in the region
east of the Rocky Mountains.

Further discussion of the preceding facts will profitably be deferred until, in the
next two chapters, the questions of the cause and date of the Glacial period have been
considered.

CHAPTER IX.

THE CAUSE OF THE GLACIAL PERIOD.
In searching for the cause of the Glacial period, it is evident that we must endeavor
to find conditions which will secure over the centre of the glaciated area either a great
increase of snow-fall or a great decrease in the mean annual temperature, or both of
these conditions combined in greater or less degree. As can be seen, both from the
nature of the case and from the unglaciated condition of Siberia and northern Alaska, a
low degree of temperature is not sufficient to produce permanent ice-fields. If the
snow-fall is excessively meagre, even the small amount of heat in an arctic summer
will be sufficient to melt it all away.
From the condition of Greenland, however, it appears that a moderate amount of
precipitation where it is chiefly in the form of snow may produce enormous glaciers if
at the same time the average temperature is low. In southeastern Alaska, on the other
hand, the glaciers are of enormous size, though the mean annual temperature is by no
means low, for there the great amount of snow-fall amply compensates for the higher
temperature.
Snow stores the cold and keeps it in a definite place. If the air becomes chilled,
circulation at once sets in, and the cold air is transferred to warmer regions; but if there
is moisture in the air, so that snow forms, the cold becomes locked up, as it were, and
falls to the earth.
The amount of cold thus locked up in snow is enormous. To melt one cubic foot of
ice requires as much heat as would raise the temperature of a cubic foot of water 176°
Fahrenheit. To melt a “layer of ice only one inch and a half thick would require as
much heat as would raise a stratum of air eight hundred feet thick from the freezing-
point to the tropical heat of 88° Fahrenheit.” It is the slowness with which ice melts
which enables it to accumulate as it does, both in winter and upon high mountains and
in arctic regions. Captain Scoresby relates that when near the north pole the sun would
sometimes be so hot as to melt the pitch on the south side of his vessel, while water
was freezing on the north side, in the shade, owing to the cooling effect of the masses
of ice with which he was surrounded.

Thus it will appear that a change in the direction of the moist winds blowing from
the equator towards the poles might produce a Glacial epoch. If snow falls upon the
ocean it cools the water, but through the currents, everywhere visible in the sea, the
temperature in the water in the different parts soon becomes equalized. If, however, the
snow falls upon the land, it must be melted by the direct action of the sun and wind
upon the spot where it is. If the heat furnished by these agencies is not sufficient to do
it year by year, there will soon be such an accumulation that glaciers will begin to
form. It is clear, therefore, that the conditions producing a Glacial period are likely to
prove very complicated, and we need not be surprised if the conclusions to which we
come are incapable of demonstration.
Theories respecting the cause of the Glacial period may be roughly classified as
astronomical and geological. Among the astronomical theories, one which has
sometimes been adduced is that the solar system in its movement through space is
subjected to different degrees of heat at different times. According to this theory, the
temperate climate which characterised the polar regions during the Tertiary period, and
continued up to the beginning of the Glacial epoch, was produced by the influence of
the warmer stretches of space through which the whole solar system was moving at
that time; while the Glacial period resulted from the influence upon the earth of the
colder spaces through which the system subsequently moved.
While it is impossible absolutely to disprove this hypothesis, it labors under the
difficulty of having little positive evidence in its favor, and thus contravenes a
fundamental law of scientific reasoning, that we must have a real cause upon which to
rest our theories. In endeavouring to explain the unknown, we should have something
known to start with. But in this case we are not sure that there are any such variations
in the temperature of the space through which the solar system moves. This theory,
therefore, cannot come in for serious consideration until all others have been absolutely
disproved. As we shall also more fully see, in the subsequent discussion, the
distribution of the ice during the Glacial period was not such as to indicate a gradual
extension of it from the north pole, but rather the accumulation upon centres many
degrees to the south.
Closely allied with the preceding theory is the supposition broached by some
astronomers that the sun is a variable star, dependent to some extent for its heat upon
the impact of meteorites, or to the varying rapidity with which the contraction of its
volume is proceeding.
It is well known that when two solid bodies clash together, heat is produced
proportionate to the momentum of the two bodies. In other words, the motion which is
arrested is transformed into heat. Mr. Croll, in his last publication[DR] upon the subject,
ingeniously attempted to account for the gaseous condition of the nebulæ and the heat
of the sun and other fixed stars by supposing it to be simply transformed motion.
According to this theory, the original form of force imparted to the universe was that

exerted in setting in motion innumerable dark bodies, which from time to time have
collided with each other. The effects of such collisions would be to transform a large
amount of motion into heat and its accompanying forms of molecular force. The
violence of the compact of two worlds would be so great as to break them up into the
original atoms of which they are composed, and the heat set free would be sufficient to
keep the masses in a gaseous condition and cause them to swell out into enormous
proportions. From that time on, as the heat radiated into space, there would be the
gradual contraction which we suppose is going on in all the central suns, accompanied,
of course, with a gradual decline of the heat-energy in the system.
[DR] Stellar Evolution and its Relation to Geological Time.

Now, it is well known that the earth and the solar system in their onward progress
pass through trains of meteorites. The tails of some of the comets are indeed pretty
clearly proved to be streams of ponderable matter, through which, from time to time,
the minor members of the solar system plunge, and receive some accession to their
bulk and weight. The shooting-stars, which occasionally attract our attention in the sky,
mark the course of such meteorites as they pass through the earth’s atmosphere, and are
heated to a glow by the friction with it. It has been suggested, therefore, that the sun
itself may at times have its amount of heat sensibly affected by such showers of
meteorites or asteroids. Upon this theory the warm period of the Tertiary epoch, for
instance, may have been due to the heat temporarily added to the sun by impact with
minor astronomical bodies. When, afterwards, it gradually cooled down, receiving
through a long period no more accessions of heat from that source, the way was
prepared for the colder epoch of the Glacial period, which, in turn, was dispelled by
fresh showers of meteorites upon the sun, sufficient to produce the amelioration of
climate which we experience at the present time.
As intimated, this theory is closely allied to the preceding, the principal difference
being that it limits the effects of the supposed cause to the solar system, and looks to
our sun as the varying source of heat-supply. It has the advantage over that, however,
of possessing a more tangible vera causa. Meteorites, asteroids, and comets are known
to be within this system, and have occasional collisions with other members of it. But
the principal objection urged against the preceding theory applies here, also, with equal
force. The accumulations of ice during the Glacial period were not determined by
latitude. In North America the centre of accumulation was south of the Arctic Circle—
a fact which points clearly enough to some other cause than that of a general lowering
of the temperature exterior to the earth.
The same objections would bear against the theory ably set forth by Mr. Sereno E.
Bishop, of Honolulu, which, in substance, is that there may be considerable variability
in the sun’s emission of heat, owing to fluctuations in the rate of the shrinkage of its
diameter, brought about by the unequal struggle between the diminishing amount of
heat in the interior and the increasing force of the gravitation of its particles, and by the

changes in the enveloping atmosphere of the sun, which, like an enswathing blanket,
arrests a large portion of the radiant heat from the nucleus, and is itself evidently
subject to violent movements, some of which seem to carry it down to the sun’s
interior. Unknown electrical forces, he thinks, may also combine to add an element of
variability. These supposed changes may be compared to those which take place upon
the surface of the earth when, at irregular intervals, immense sheets of lava, like those
upon the Pacific coast of North America, are exuded in a comparatively brief time, to
be succeeded by a long period of rest. The heat thus brought to the surface of the earth
would add perceptibly to that radiated from it into space in ordinary times. Something
similar to this upon the sun, it is thought, might produce effects perceptible upon the
earth, and account for alternate periods of heat and cold.
A fourth astronomical theory is that there has been a shifting of the earth’s axis;
that at the time of the Glacial period the north pole, instead of being where it now is,
was somewhere in the region of central Greenland. This attractive theory has been
thought worthy of attention by President T. C. Chamberlin and by Professor G. C.
Comstock,[DS] but it likewise labours under a twofold difficulty: First, the shifting of
the poles observed (450 feet per year) is too slight to have produced the changes within
any reasonable time, and it is not likely to have been continuous for a long period. But
still more fatal to the theory is the fact that the warm climate preceding the Glacial
period seems to have extended towards the present north pole upon every side; a
temperate flora having been found in the fossil plants of the Tertiary beds in Greenland
and northern British America, as well as upon Nova Zembla and Spitzbergen.
[DS] See papers by these gentlemen read at the meeting of the American Association for
the Advancement of Science, in Washington, in August, 1891. Professor Comstock’s paper
appeared in the American Journal of Science for January, 1893.

A fifth astronomical theory, and one which has of late years been received with
great favour, is that so ably advocated by the late Dr. James Croll and by Professor
James Geikie. Following the suggestions of the astronomer Adhémar, these writers
have attempted to show that not only one Glacial epoch, but a succession of such
epochs, has been produced in the world by the effect of the changes which are known
to have taken place in the eccentricity of the earth’s orbit when combined with the
precession of the equinoxes—another calculable astronomical cause.

Fig. 99.—Diagram showing effect of precession: A. condition of things now;
B. as it will be 10,500 years hence. The eccentricity is of course greatly
exaggerated.

It is well known that the earth’s orbit is elliptical; that is, it is longer in one
direction than in the other, so that the sun is one side of the centre. During the winter of
the northern hemisphere the earth is now about three million miles nearer the sun than
in the summer; but the summer makes up for this distance by being about seven days
longer than the winter. Through the precession of the equinoxes this state of things will
be reversed in ten thousand five hundred years; at which time we shall be nearer the
sun during our northern summer, and farther away in winter, our winter then being also
longer than our summer. Besides, through the unequal attraction of the planets the
eccentricity of the earth’s orbit periodically increases and diminishes, so that there have
been periods when the earth was ten million five hundred thousand miles farther from
the sun in winter than in summer; at which times, also, the winter was nearly twenty-
eight days longer than the summer. Such an extreme elongation of the earth’s orbit
occurred about two hundred and fifty thousand years ago.
It is easy to assume that such a change in astronomical conditions would produce
great effects upon the earth’s climate; and equally easy to connect with those effects
the vast extension of ice during the Glacial period. Since, also, this period of extreme
eccentricity terminated only eighty thousand years ago, the close of the Glacial period
would, perhaps, upon Mr. Croll’s theory, be comparatively a recent event; for if the
secular summer of the earth’s eccentricity lags relatively as far behind the secular
movements as the annual summer does behind the vernal equinox, we should, as
Professor Charles H. Hitchcock suggests, have to place the complete breaking up of the
Ice period as late as forty thousand years ago.[DT]
[DT] Geology of New Hampshire, vol. iii, p.327.

We have no space to indicate, as it deserves, the comparative merits and demerits
of this ingenious theory. It would, however, be a great calamity to have geologists
accept it without scrutiny. It is, indeed, a part of the business of geologists to doubt

such theories until they are verified by a thorough examination of all accessible
terrestrial evidence bearing upon the subject. There is no reason to question the reality
of the variations in the relative positions of the earth and the sun assumed by Mr. Croll;
though there may be serious doubt whether the effects of those changes upon climate
would be all that is surmised, since equal amounts of heat would fall upon the earth
during summer, whether made longer or shorter by the cause referred to. During the
short summers the earth is so much nearer the sun that it receives each season
absolutely as much heat as it does during the longer summers, when it is so much
farther away from the sun. Thus the theory rests at last upon the question what would
become of the heat reaching the earth in these differing conditions. It is plausibly urged
by Mr. Croll that when a hemisphere of the earth is passing through a period of long
winters the radiation of heat will be so excessive that the temperature would fall much
below what it would during the shorter winters; and so ice and snow would accumulate
far beyond the usual amount. It is also supposed that the effect of the summer’s sun in
melting the ice during the short summer would be diminished through natural increase
of the amount of foggy and cloudy weather.
Adhémar’s theory is supposed by Sir Robert Ball, Royal Astronomer of Ireland, to
be considerably re-enforced by a discovery which he has made concerning the
distribution of heat upon the earth during the seasons culminating in the summer and
winter solstices. Croll had assumed, on the authority of Herschel, that a hemisphere of
the earth during the longer winter in aphelion would receive the same actual amount of
heat which would fall upon it during the shorter summer in perihelion; whereas,
according to Dr. Ball’s discovery, “of the total amount of heat received from the sun on
a hemisphere of the earth in the course of a year, sixty-three per cent is received during
the summer and thirty-seven per cent during the winter.”[DU] When, therefore, the
summers occur in perihelion the heat is more intense than Croll had supposed, and, at
the same time, the winters occurring in aphelion are more deficient in heat than he had
assumed. This discovery of Dr. Ball will not, however, materially affect the discussion
of Croll’s theory upon its inherent merits, since it is simply an intensification of the
causes invoked by him. We will therefore let it stand or fall in the light of the general
considerations hereafter to be adduced.
[DU] Cause of an Ice Age, p. 90.

The aid of theoretical consequent changes in the volume of the Gulf Stream, and in
the area of the trade-winds, has also to be invoked by Mr. Croll. The theory likewise
receives supposed confirmation from facts alleged concerning the present climate of
the southern hemisphere which is passing through the astronomical conditions thought
to be favourable to its glaciation. The antarctic continent is completely enveloped in
ice, even down to the sixty-seventh degree of latitude. A few degrees nearer the pole
Sir J. C. Boss describes the ice as rising from the water in a precipitous wall one
hundred and eighty feet high. In front of such a wall, and nearly twenty degrees from
the south pole, this navigator sailed four hundred and fifty miles! Voyagers, in general,