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Title: The Andes of Southern Peru

Author: Isaiah Bowman

Release date: June 2, 2013 [eBook #42860]
Most recently updated: October 23, 2024

Language: English

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THE ANDES OF SOUTHERN
PERU
GEOGRAPHICAL RECONNAISSANCE ALONG THE
SEVENTY-THIRD MERIDIAN

BY
ISAIAH BOWMAN
Director of the American Geographical Society

PUBLISHED FOR
THE AMERICAN GEOGRAPHICAL SOCIETY
OF NEW YORK
BY
HENRY HOLT AND COMPANY
1916

Copyright, 1918
BY
HENRY HOLT AND COMPANY

THE QUINN & BODEN CO. PRESS

RAHWAY, N.J.

TO

C. G. B.

PREFACE
THE geographic work of the Yale Peruvian Expedition of 1911 was
essentially a reconnaissance of the Peruvian Andes along the 73rd meridian.
The route led from the tropical plains of the lower Urubamba southward
over lofty snow-covered passes to the desert coast at Camaná. The strong
climatic and topographic contrasts and the varied human life which the
region contains are of geographic interest chiefly because they present so

many and such clear cases of environmental control within short distances.
Though we speak of “isolated” mountain communities in the Andes, it is
only in a relative sense. The extreme isolation felt in some of the world’s
great deserts is here unknown. It is therefore all the more remarkable when
we come upon differences of customs and character in Peru to find them
strongly developed in spite of the small distances that separate unlike
groups of people.
My division of the Expedition undertook to make a contour map of the
two-hundred-mile stretch of mountain country between Abancay and the
Pacific coast, and a great deal of detailed geographic and physiographic
work had to be sacrificed to insure the completion of the survey. Camp
sites, forage, water, and, above all, strong beasts for the topographer’s
difficult and excessively lofty stations brought daily problems that were
always serious and sometimes critical. I was so deeply interested in the
progress of the topographic map that whenever it came to a choice of plans
the map and not the geography was first considered. The effect upon my
work was to distribute it with little regard to the demands of the problems,
but I cannot regret this in view of the great value of the maps. Mr. Kai
Hendriksen did splendid work in putting through two hundred miles of
plane-tabling in two months under conditions of extreme difficulty. Many
of his triangulation stations ranged in elevation from 14,000 to nearly
18,000 feet, and the cold and storms—especially the hailstorms of mid-
afternoon—were at times most severe.
It is also a pleasure to say that Mr. Paul Baxter Lanius, my assistant on
the lower Urubamba journey, rendered an invaluable service in securing
continuous weather records at Yavero and elsewhere, and in getting food
and men to the river party at a critical time. Dr. W. G. Erving, surgeon of
the Expedition, accompanied me on a canoe journey through the lower
gorge of the Urubamba between Rosalina and the mouth of the Timpia, and
again by pack train from Santa Ana to Cotahuasi. For a time he assisted the
topographer. It is due to his prompt surgical assistance to various members
of the party that the field work was uninterrupted. He was especially useful
when two of our river Indians from Pongo de Mainique were accidentally
shot. I have since been informed by their patrón that they were at work
within a few months.
It is difficult to express the gratitude I feel toward Professor Hiram
Bingham, Director of the Expedition, first for the executive care he

displayed in the organization of the expedition’s plans, which left the
various members largely care-free, and second, for generously supplying
the time of various assistants in the preparation of results. I have enjoyed so
many facilities for the completion of the work that at least a year’s time has
been saved thereby. Professor Bingham’s enthusiasm for pioneer field work
was in the highest degree stimulating to every member of the party.
Furthermore, it led to a determination to complete at all hazards the original
plans.
Finally, I wish gratefully to acknowledge the expert assistance of Miss
Gladys M. Wrigley, of the editorial staff of the American Geographical
Society, who prepared the climatic tables, many of the miscellaneous data
related thereto, and all of the curves in Chapter X. Miss Wrigley also
assisted in the revision of Chapters IX and X and in the correction of the
proof. Her eager and in the highest degree faithful assistance in these tasks
bespeaks a true scientific spirit.
Isaiah Bowman.

SPECIAL ACKNOWLEDGMENTS FOR ILLUSTRATIONS
Fig. 28. Photograph by H. L. Tucker, Engineer, Yale Peruvian Expedition
of 1911.
Fig. 43. Photograph by H. L. Tucker.
Fig. 44. Photograph by Professor Hiram Bingham.
Figs. 136, 139, 140. Data for hachured sketch maps, chiefly from
topographic sheets by A. H. Bumstead, Topographer to Professor
Bingham’s Peruvian Expeditions of 1912 and 1914.

CONTENTS
PART I
HUMAN GEOGRAPHY
CHAPTER PAGE
I. The Regions of Peru 1
II. The Rapids and Canyons of the Urubamba 8
III. The Rubber Forests 22
IV. The Forest Indians 36
V. The Country of the Shepherds 46

VI. The Border Valleys of the Eastern Andes 68
VII. The Geographic Basis of Revolutions and of
Human Character in the Peruvian Andes 88
VIII. The Coastal Desert 110
IX. Climatology of the Peruvian Andes 121
X. Meteorological Records From the Peruvian
Andes 157
PART II
PHYSIOGRAPHY OF THE PERUVIAN ANDES
XI. The Peruvian Landscape 183
XII. The Western Andes: the Maritime
Cordillera Or Cordillera Occidental 199
XIII. The Eastern Andes: The Cordillera
Vilcapampa 204
XIV.The Coastal Terraces 225
XV. Physiographic and Geologic Development 233
XVI.Glacial Features 274
Appendix A. Survey Methods Employed in the
Construction of the Seven Accompanying
Topographic Sheets 315
Appendix B. Fossil Determinations 321
Appendix C. Key to Place Names 324
Index 327
TOPOGRAPHIC SHEETS
Camaná Quadrangle 114
Aplao " 120
Coropuna " 188
Cotahuasi " 192
La Cumbre " 202
Antabamba " 282
Lambrama " 304

PART I

HUMAN GEOGRAPHY
CHAPTER I

THE REGIONS OF PERU
LET four Peruvians begin this book by telling what manner of country
they live in. Their ideas are provincial and they have a fondness for
exaggerated description: but, for all that, they will reveal much that is true
because they will at least reveal themselves. Their opinions reflect both the
spirit of the toiler on the land and the outlook of the merchant in the town in
relation to geography and national problems. Their names do not matter; let
them stand for the four human regions of Peru, for they are in many
respects typical men.
The Forest Dweller
One of them I met at a rubber station on the lower Urubamba River.[1]
He helped secure my canoe, escorted me hospitably to his hut, set food and
drink before me, and talked of the tropical forest, the rubber business, the
Indians, the rivers, and the trails. In his opinion Peru was a land of great
forest resources. Moreover, the fertile plains along the river margins might
become the sites of rich plantations. The rivers had many fish and his
garden needed only a little cultivation to produce an abundance of food.
Fruit trees grew on every hand. He had recently married the daughter of an
Indian chief.
Formerly he had been a missionary at a rubber station on the Madre de
Dios, where the life was hard and narrow, and he doubted if there were any
real converts. Himself the son of an Englishman and a Chilean woman, he
found, so he said, that a missionary’s life in the rubber forest was
intolerable for more than a few years. Yet he had no fault to find with the
religious system of which he had once formed a part; in fact he had still a
certain curious mixed loyalty to it. Before I left he gave me a photograph of
himself and said with little pride and more sadness that perhaps I would

remember him as a man that had done some good in the world along with
much that might have been better.
We shall understand our interpreter better if we know who his associates
were. He lived with a Frenchman who had spent several years in Africa as a
soldier in the “Foreign Legion.” If you do not know what that means, you
have yet all the pleasure of an interesting discovery. The Frenchman had
reached the station the year before quite destitute and clad only in a shirt
and a pair of trousers. A day’s journey north lived a young half-breed—son
of a drunken father and a Machiganga woman, who cheated me so badly
when I engaged Indian paddlers that I should almost have preferred that he
had robbed me. Yet in a sense he had my life in his hands and I submitted.
A German and a native Peruvian ran a rubber station on a tributary two
days’ journey from the first. It will be observed that the company was
mixed. They were all Peruvians, but of a sort not found in such relative
abundance elsewhere. The defeated and the outcast, as well as the pioneer,
go down eventually to the hot forested lands where men are forgotten.
While he saw gold in every square mile of his forested region, my
clerical friend saw misery also. The brutal treatment of the Indians by the
whites of the Madre de Dios country he could speak of only as a man
reviving a painful memory. The Indians at the station loved him devotedly.
There was only justice and kindness in all his dealings. Because he had
large interests to look after, he knew all the members of the tribe, and his
word was law in no hackneyed sense. A kindlier man never lived in the
rubber forest. His influence as a high-souled man of business was vastly
greater than as a missionary in this frontier society. He could daily illustrate
by practical example what he had formerly been able only to preach.

Fig. 1—Tropical vegetation, clearing on the river bank and rubber
station at Pongo de Mainique. The pronounced scarp on the
northeastern border of the Andes is seen in the right background.
Fig. 2—Pushing a heavy dugout against the current in the rapids
below Pongo de Mainique. The indian boy and his father in the canoe
had been accidentally shot.

Fig. 3—From the sugar cane, Urubanba Valley, at Colpani. On the
northeastern border of the Cordillera Vilcapampa looking upstream.
In the extreme background and thirteen sixteens of an inch from the
top of the picture is the sharp peak of Salcantay. Only the lower end of
the more open portion of the Canyon of Torontoy is here shown. There
is a field of sugar cane in the foreground and the valley trail is shown
on the opposite side of the river.

He thought the life of the Peruvian cities debasing. The coastal valleys
were small and dry and the men who lived there were crowded and poor
(sic). The plateau was inhabited by Indians little better than brutes. Surely I
could not think that the fine forest Indian was lower than the so-called
civilized Indian of the plateau. There was plenty of room in the forest; and
there was wealth if you knew how to get at it. Above all you were far from
the annoying officials of the government, and therefore could do much as
you pleased so long as you paid your duties on rubber and did not wantonly
kill too many Indians.
For all his kindly tolerance of men and conditions he yet found fault with
the government. “They” neglected to build roads, to encourage
colonization, and to lower taxes on the forest products, which were always
won at great risk. Nature had done her part well—it was only government
that hindered. Moreover, the forested region was the land of the future. If
Peru was to be a great nation her people would have to live largely upon the

eastern plains. Though others spoke of “going in” and “coming out” of the
rubber country as one might speak of entering and leaving a dungeon, he
always spoke of it as home. Though he now lived in the wilderness he
hoped to see the day when plantations covered the plains. A greater Peru
and the forest were inseparable ideas to him.
The Eastern Valley Planter
My second friend lived in one of the beautiful mountain valleys of the
eastern Andes. We walked through his clean cacao orchards and cane fields.
Like the man in the forest, he believed in the thorough inefficiency of the
government; otherwise why were there no railways for the cheaper
transportation of the valley products, no dams for the generation of power
and the storage of irrigation water, not even roads for mule carts? Had the
government been stable and efficient there would now be a dense
population in the eastern valleys. Revolutions were the curse of these
remote sections of the country. The ne’er-do-wells became generals. The
loafer you dismissed today might demand ten thousand dollars tomorrow or
threaten to destroy your plantation. The government troops might come to
help you, but they were always too late.
For this one paid most burdensome taxes. Lima profited thereby, not the
valley planters. The coast people were the favored of Peru anyhow. They
had railroads, good steamer service, public improvements at government
expense, and comparatively light taxes. If the government were impartial
the eastern valleys also would have railways and a dense population. Who
could tell? Perhaps the capital city might be here. Certainly it was better to
have Lima here than on the coast where the Chileans might at any time take
it again. The blessings of the valleys were both rich and manifold. Here was
neither a cold plateau nor the hot plains, but fertile valleys with a vernal
climate.
We talked of much else, but our conversation had always the pioneer
flavor. And though an old man he saw always the future Peru growing
wonderfully rich and powerful as men came to recognize and use the
resources of the eastern valleys. This too was the optimism of the pioneer.
Once started on that subject he grew eloquent. He was provincial but he
was also intensely patriotic. He never missed an opportunity to impress
upon his guests that a great state would arise when people and rulers at last
recognized the wealth of eastern Peru.

The Highland Shepherd
The people who live in the lofty highlands and mountains of Peru have
several months of real winter weather despite their tropical latitude. In the
midst of a snowstorm in the Maritime Cordillera I met a solitary traveler
bound for Cotahuasi on the floor of a deep canyon a day’s journey toward
the east. It was noon and we halted our pack trains in the lee of a huge rock
shelter to escape the bitter wind that blew down from the snow-clad peaks
of Solimana. Men who follow the same trails are fraternal. In a moment we
had food from our saddle-bags spread on the snow under the corner of a
poncho and had exchanged the best in each other’s collection as naturally as
friends exchange greetings. By the time I had told him whence and why in
response to his inevitable questions we had finished the food and had
gathered a heap of tola bushes for a fire. The arriero (muleteer) brought
water from a spring in the hollow below us. Though the snow thickened, the
wind fell. We were comfortable, even at 16,000 feet, and called the place
“The Salamanca Club.” Then I questioned him, and this is what he said:
“I live in the deep valley of Cotahuasi, but my lands lie chiefly up here
on the plateau. My family has held title to this puna ever since the Wars of
Liberation, except for a few years after one of our early revolutions. I travel
about a great deal looking after my flocks. Only Indians live up here. Away
off yonder beyond that dark gorge is a group of their huts, and on the bright
days of summer you may see their sheep, llamas, and alpacas up here, for
on the floors of the watered valleys that girdle these volcanoes there are
more tender grasses than grow on this despoblado. I give them corn and
barley from my irrigated fields in the valley; they give me wool and meat.
The alpaca wool is most valuable. It is hard to get, for the alpaca requires
short grasses and plenty of water, and you see there is only coarse tufted
ichu grass about us, and there are no streams. It is all right for llamas, but
alpacas require better forage.
“No one can imagine the poverty and ignorance of these mountain
shepherds. They are filthier than beasts. I have to watch them constantly or
they would sell parts of the flocks, which do not belong to them, or try to
exchange the valuable alpaca wool for coca leaves in distant towns. They
are frequently drunk.”
“But where do they get the drink?” I asked. “And what do you pay
them?”

“Oh, the drink is chiefly imported alcohol, and also chicha made from
corn. They insist on having it, and do better when I bring them a little now
and then. They get much more from the dealers in the towns. As for pay, I
do not pay them anything in money except when they bring meat to the
valley. Then I give them a few reales apiece for the sheep and a little more
for the llamas. The flocks all belong to me really, but of course the poor
Indian must have a little money. Besides, I let him have a part of the yearly
increase. It is not much, but he has always lived this way and I suppose that
he is contented after a fashion.”
Then he became eager to tell what wealth the mountains contained in
soil and climate if only the right grasses were introduced by the
government.
“Here, before us, are vast punas almost without habitations. If the
officials would bring in hardy Siberian grasses these lava-covered plateaus
might be carpeted with pasture. There would be villages here and there. The
native Indians easily stand the altitude. This whole Cordillera might have
ten times as many people. Why does the government bother about
concessions in the rubber forests and roads to the eastern valleys when there
are these vast tracts only requiring new seeds to develop into rich pastures?
The government could thus greatly increase its revenues because there is a
heavy tax on exported wool.”
Thus he talked about the bleak Cordillera until we forgot the pounding of
our hearts and our frequent gasps for breath on account of the altitude. His
rosy picture of a well-populated highland seemed to bring us down nearer
sea level where normal folks lived. To the Indians the altitude is nothing. It
has an effect, but it is slight; at any rate they manage to reproduce their kind
at elevations that would kill a white mother. If alcohol were abolished and
better grasses introduced, these lofty pastures might indeed support a much
larger population. The sheep pastures of the world are rapidly disappearing
before the march of the farmer. Here, well above the limit of cultivation, is
a permanent range, one of the great as well as permanent assets of Peru.
The Coastal Planter
The man from the deep Majes Valley in the coastal desert rode out with
me through cotton fields as rich and clean as those of a Texas plantation. He
was tall, straight-limbed, and clear-eyed—one of the energetic younger

generation, yet with the blood of a proud old family. We forded the river
and rode on through vineyards and fig orchards loaded with fruit. His
manner became deeply earnest as he pictured the future of Peru, when her
people would take advantage of scientific methods and use labor-saving
machinery. He said that the methods now in use were medieval, and he
pointed to a score of concrete illustrations. Also, here was water running to
waste, yet the desert was on either hand. There should be dams and canals.
Every drop of water was needed. The population of the valley could be
easily doubled.

Fig. 4—Large ground moss--so-called yareta--used for fuel. It occurs
in the zone of Alpine vegetation and is best developed in regions where
the snowline is highest. The photograph represents a typical occurrence
between Cotahuasi and Salamanca, elevation 16,000 feet (4,880 m.).
The snowline is here at 17,500 feet (5,333 m.). In the foreground is the
most widely distributed tola bush, also used for fuel.
Fig. 5.—Expedition’s camp near Lamgrama, 15,500 feet (4,720 m.),
after a snowstorm The location is midway in the pasture zone.

Fig. 6—Irrigated Chili Valley on the outskirts of Arequipa. The
lower slopes of El Misti are in the left background. The Alto de los
Huesos or Plateau of Bones lies on the farther side of the valley.
Fig. 7—Crossing the highest pass (Chuquito) in the Cordillera
Vilcapampa, 14,500 feet (4,420 m.). Grazing is here carried on up to the
snowline.

Capital was lacking but there was also lacking energy among the people.
Slipshod methods brought them a bare living and they were too easily
contented. Their standards of life should be elevated. Education was still for
the few, and it should be universal. A new spirit of progress was slowly
developing—a more general interest in public affairs, a desire to advance
with the more progressive nations of South America,—and when it had
reached its culmination there would be no happier land than coastal Peru,
already the seat of the densest populations and the most highly cultivated
fields.

These four men have portrayed the four great regions of Peru—the
lowland plains, the eastern mountain valleys, the lofty plateaus, and the
valley oases of the coast. This is not all of Peru. The mountain basins have
their own peculiar qualities and the valley heads of the coastal zone are
unlike the lower valleys and the plateau on either hand. Yet the chief
characteristics of the country are set forth with reasonable fidelity in these

individual accounts. Moreover the spirit of the Peruvians is better shown
thereby than their material resources. If this is not Peru, it is what the
Peruvians think is Peru, and to a high degree a man’s country is what he
thinks it is—at least it is little more to him.
CHAPTER II

THE RAPIDS AND CANYONS OF THE URUBAMBA
AMONG the scientifically unexplored regions of Peru there is no other so
alluring to the geographer as the vast forested realm on the eastern border of
the Andes. Thus it happened that within two weeks of our arrival at Cuzco
we followed the northern trail to the great canyon of the Urubamba (Fig. 8),
the gateway to the eastern valleys and the lowland plains of the Amazon. It
is here that the adventurous river, reënforced by hundreds of mountain-born
tributaries, finally cuts its defiant way through the last of its great
topographic barriers. More than seventy rapids interrupt its course; one of
them, at the mouth of the Sirialo, is at least a half-mile in length, and long
before one reaches its head he hears its roaring from beyond the forest-clad
mountain spurs.
The great bend of the Urubamba in which the line of rapids occurs is one
of the most curious hydrographic features in Peru. The river suddenly
changes its general northward course and striking south of west flows
nearly fifty miles toward the axis of the mountains, where, turning almost in
a complete circle, it makes a final assault upon the eastern mountain ranges.
Fifty miles farther on it breaks through the long sharp-crested chain of the
Front Range of the Andes in a splendid gorge more than a half-mile deep,
the famous Pongo de Mainique (Fig. 9).
Our chief object in descending the line of rapids was to study the canyon
of the Urubamba below Rosalina and to make a topographic sketch map of
it. We also wished to know what secrets might be gathered in this hitherto
unexplored stretch of country, what people dwelt along its banks, and if the
vague tales of deserted towns and fugitive tribes had any basis in fact.

Fig. 8—Sketch map showing the route of the Yale-Peruvian
Expedition of 1911 down the Urubamba Valley, together with the area
of the main map and the changes in the delineation of the bend of the
Urubamba resulting from the surveys of the Expedition. Based on the
“Mapa que comprende las ultimas exploraciones y estudios verificados
desde 1900 hasta 1906,” 1:1,000,000, Bol. Soc. Geogr. Lima, Vol. 25, No.
3, 1909. For details of the trail from Rosalina to Pongo de Mainique see
“Plano de las Secciones y Afluentes del Rio Urubamba: 1902-1904,”
scale 1:150,000 by Luis M. Robledo in Bol. Soc. Geogr. Lima, Vol. 25,
No. 4, 1909. Only the lower slopes of the long mountain spurs can be
seen from the river; hence only in a few places could observations be
made on the topography of distant ranges. Paced distances of a half
mile at irregular intervals were used for the estimation of longer
distances. Directions were taken by compass corrected for magnetic
deviation as determined on the seventy-third meridian (See Appendix
A). The position of Rosalina on Robledo’s map was taken as a base.

We could gather almost no information as to the nature of the river
except from the report of Major Kerbey, an American, who, in 1897,
descended the last twenty miles of the one hundred we proposed to
navigate. He pronounced the journey more hazardous than Major Powell’s
famous descent of the Grand Canyon in 1867—an obvious exaggeration.
He lost his canoe in a treacherous rapid, was deserted by his Indian guides,
and only after a painful march through an all but impassable jungle was he
finally able to escape on an abandoned raft. Less than a dozen have
ventured down since Major Kerbey’s day. A Peruvian mining engineer
descended the river a few years ago, and four Italian traders a year later
floated down in rafts and canoes, losing almost all of their cargo. For nearly
two months they were marooned upon a sand-bar waiting for the river to
subside. At last they succeeded in reaching Mulanquiato, an Indian

settlement and plantation owned by Pereira, near the entrance to the last
canyon. Their attempted passage of the worst stretch of rapids resulted in
the loss of all their rubber cargo, the work of a year. Among the half dozen
others who have made the journey—Indians and slave traders from down-
river rubber posts—there is no record of a single descent without the loss of
at least one canoe.
To reach the head of canoe navigation we made a two weeks’ muleback
journey north of Cuzco through the steep-walled granite Canyon of
Torontoy, and to the sugar and cacao plantations of the middle Urubamba,
or Santa Ana Valley, where we outfitted. At Echarati, thirty miles farther on,
where the heat becomes more intense and the first patches of real tropical
forest begin, we were obliged to exchange our beasts for ten fresh animals
accustomed to forest work and its privations. Three days later we pitched
our tent on the river bank at Rosalina, the last outpost of the valley
settlements. As we dropped down the steep mountain slope before striking
the river flood plain, we passed two half-naked Machiganga Indians
perched on the limbs of a tree beside the trail, our first sight of members of
a tribe whose territory we had now entered. Later in the day they crossed
the river in a dugout, landed on the sand-bar above us, and gathered brush
for the nightly fire, around which they lie wrapped in a single shirt woven
from the fiber of the wild cotton.

Fig. 9—The upper Fig. 10—The lower
entrance to the Pongo half of a two-
de Mainique, where thousand-foot cliff,
the Urubamba crosses granite Canyon of

the Front Range of the Torontoy, Urubamba
Andes in a splendid Valley. The wall is
gateway 4,000 feet developed almost
deep. The river is entirely along joint
broken by an almost planes. It is here that
continuous line of the Urubamba River
rapids. crosses the granite
axis of the Cordillera
Vilcapampa, the
easternmost system of
the Andes of southern
Peru. Compare also
Figs. 144 and 145.

Fig. 11—A temporary shelter-hut on a sand-bar near the great bend
of the Urubamba (see map, Fig. 8). The Machiganga Indians use these
cane shelters during the fishing season, when the river is low.
Fig. 12—Thirty-foot canoe in a rapid above Pongo de Mainique.

Rosalina is hardly more than a name on the map and a camp site on the
river bank. Some distance back from the left bank of the river is a sugar
plantation, whose owner lives in the cooler mountains, a day’s journey
away; on the right bank is a small clearing planted to sugar cane and yuca,

and on the edge of it is a reed hut sheltering three inhabitants, the total
population of Rosalina. The owner asked our destination, and to our reply
that we should start in a few days for Pongo de Mainique he offered two
serious objections. No one thought of arranging so difficult a journey in less
than a month, for canoe and Indians were difficult to find, and the river trip
was dangerous. Clearly, to start without the loss of precious time would
require unusual exertion. We immediately despatched an Indian messenger
to the owner of the small hacienda across the river while one of our peons
carried a second note to a priest of great influence among the forest Indians,
Padre Mendoza, then at his other home in the distant mountains.
The answer of Señor Morales was his appearance in person to offer the
hospitality of his home and to assist us in securing canoe and oarsmen. To
our note the Padre, from his hill-top, sent a polite answer and the offer of
his large canoe if we would but guarantee its return. His temporary illness
prevented a visit to which we had looked forward with great interest.
The morning after our arrival I started out on foot in company with our
arriero in search of the Machigangas, who fish and hunt along the river
bank during the dry season and retire to their hill camps when the heavy
rains begin. We soon left the well-beaten trail and, following a faint
woodland path, came to the river bank about a half day’s journey below
Rosalina. There we found a canoe hidden in an overhanging arch of vines,
and crossing the river met an Indian family who gave us further directions.
Their vague signs were but dimly understood and we soon found ourselves
in the midst of a carrizo (reed) swamp filled with tall bamboo and cane and
crossed by a network of interlacing streams. We followed a faint path only
to find ourselves climbing the adjacent mountain slopes away from our
destination. Once again in the swamp we had literally to cut our way
through the thick cane, wade the numberless brooks, and follow wild
animal trails until, late in the day, famished and thirsty, we came upon a
little clearing on a sand-bar, the hut of La Sama, who knew the
Machigangas and their villages.
After our long day’s work we had fish and yuca, and water to which had
been added a little raw cane sugar. Late at night La Sama returned from a
trip to the Indian villages down river. He brought with him a half-dozen
Machiganga Indians, boys and men, and around the camp fire that night
gave us a dramatic account of his former trip down river. At one point he
leaped to his feet, and with an imaginary pole shifted the canoe in a swift

rapid, turned it aside from imminent wreck, and shouting at the top of his
voice over the roar of the water finally succeeded in evading what he had
made seem certain death in a whirlpool. We kept a fire going all night long
for we slept upon the ground without a covering, and, strange as it may
appear, the cold seemed intense, though the minimum thermometer
registered 59° F. The next morning the whole party of ten sunned
themselves for nearly an hour until the flies and heat once more drove them
to shelter.
Returning to camp next day by a different route was an experience of
great interest, because of the light it threw on hidden trails known only to
the Indian and his friends. Slave raiders in former years devastated the
native villages and forced the Indian to conceal his special trails of refuge.
At one point we traversed a cliff seventy-five feet above the river, walking
on a narrow ledge no wider than a man’s foot. At another point the dim trail
apparently disappeared, but when we had climbed hand over hand up the
face of the cliff, by hanging vines and tree roots, we came upon it again.
Crossing the river in the canoe we had used the day before, we shortened
the return by wading the swift Chirumbia waist-deep, and by crawling
along a cliff face for nearly an eighth of a mile. At the steepest point the
river had so under-cut the face that there was no trail at all, and we swung
fully fifteen feet from one ledge to another, on a hanging vine high above
the river.
After two days’ delay we left Rosalina late in the afternoon of August 7.
My party included several Machiganga Indians, La Sama, and Dr. W. G.
Erving, surgeon of the expedition. Mr. P. B. Lanius, Moscoso (the arriero),
and two peons were to take the pack train as far as possible toward the
rubber station at Pongo de Mainique where preparations were to be made
for our arrival. At the first rapid we learned the method of our Indian
boatmen. It was to run the heavy boat head on into shallow water at one
side of a rapid and in this way “brake” it down stream. Heavily loaded with
six men, 200 pounds of baggage, a dog, and supplies of yuca and sugar cane
our twenty-five foot dugout canoe was as rigid as a steamer, and we
dropped safely down rapid after rapid until long after dark, and by the light
of a glorious tropical moon we beached our craft in front of La Sama’s hut
at the edge of the cane swamp.
Here for five days we endured a most exasperating delay. La Sama had
promised Indian boatmen and now said none had yet been secured. Each

day Indians were about to arrive, but by nightfall the promise was broken
only to be repeated the following morning. To save our food supply—we
had taken but six days’ provisions—we ate yuca soup and fish and some
parched corn, adding to this only a little from our limited stores. At last we
could wait no longer, even if the map had to be sacrificed to the work of
navigating the canoe. Our determination to leave stirred La Sama to final
action. He secured an assistant named Wilson and embarked with us,
planning to get Indians farther down river or make the journey himself.
On August 12, at 4.30 P.M., we entered upon the second stage of the
journey. As we shot down the first long rapid and rounded a wooded bend
the view down river opened up and gave us our first clear notion of the
region we had set out to explore. From mountain summits in the clouds
long trailing spurs descend to the river bank. In general the slopes are
smooth-contoured and forest-clad from summit to base; only in a few places
do high cliffs diversify the scenery. The river vista everywhere includes a
rapid and small patches of playa or flood plain on the inside of the river
curves. Although a true canyon hems in the river at two celebrated passes
farther down, the upper part of the river flows in a somewhat open valley of
moderate relief, with here and there a sentinel-like peak next the river.
A light shower fell at sunset, a typical late-afternoon downpour so
characteristic of the tropics. We landed at a small encampment of
Machigangas, built a fire against the scarred trunk of a big palm, and made
up our beds in the open, covering them with our rubber ponchos. Our Indian
neighbors gave us yuca and corn, but their neighborliness went no further,
for when our boatmen attempted to sleep under their roofs they drove them
out and fastened as securely as possible the shaky door of their hut.
All our efforts to obtain Indians, both here and elsewhere, proved
fruitless. One excuse after another was overcome; they plainly coveted the
trinkets, knives, machetes, muskets, and ammunition that we offered them;
and they appeared to be friendly enough. Only after repeated assurances of
our friendship could we learn the real reason for their refusal. Some of them
were escaped rubber pickers that had been captured by white raiders several
years before, and for them a return to the rubber country meant
enslavement, heavy floggings, and separation from their numerous wives.
The hardships they had endured, their final escape, the cruelty of the rubber
men, and the difficult passage of the rapids below were a set of
circumstances that nothing in our list of gifts could overcome. My first

request a week before had so sharpened their memory that one of them
related the story of his wrongs, a recital intensely dramatic to the whole
circle of his listeners, including myself. Though I did not understand the
details of his story, his tones and gesticulations were so effective that they
held me as well as his kinsmen of the woods spellbound for over an hour.
It is appalling to what extent this great region has been depopulated by
the slave raiders and those arch enemies of the savage, smallpox and
malaria. At Rosalina, over sixty Indians died of malaria in one year; and
only twenty years ago seventy of them, the entire population of the Pongo,
were swept away by smallpox. For a week we passed former camps near
small abandoned clearings, once the home of little groups of Machigangas.
Even the summer shelter huts on the sand-bars, where the Indians formerly
gathered from their hill homes to fish, are now almost entirely abandoned.
Though our men carefully reconnoitered each one for fear of ambush, the
precaution was needless. Below the Coribeni the Urubamba is a great silent
valley. It is fitted by Nature to support numerous villages, but its vast
solitudes are unbroken except at night, when a few families that live in the
hills slip down to the river to gather yuca and cane.
By noon of the second day’s journey we reached the head of the great
rapid at the mouth of the Sirialo. We had already run the long Coribeni
rapid, visited the Indian huts at the junction of the big Coribeni tributary,
exchanged our canoe for a larger and steadier one, and were now to run one
of the ugliest rapids of the upper river. The rapid is formed by the gravel
masses that the Sirialo brings down from the distant Cordillera Vilcapampa.
They trail along for at least a half-mile, split the river into two main
currents and nearly choke the mouth of the tributary. For almost a mile
above this great barrier the main river is ponded and almost as quiet as a
lake.
We let our craft down this rapid by ropes, and in the last difficult passage
were so roughly handled by our almost unmanageable canoe as to suffer
from several bad accidents. All of the party were injured in one way or
another, while I suffered a fracture sprain of the left foot that made painful
work of the rest of the river trip.
At two points below Rosalina the Urubamba is shut in by steep mountain
slopes and vertical cliffs. Canoe navigation below the Sirialo and Coribeni
rapids is no more hazardous than on the rapids of our northern rivers,

except at the two “pongos” or narrow passages. The first occurs at the
sharpest point of the abrupt curve shown on the map; the second is the
celebrated Pongo de Mainique. In these narrow passages in time of high
water there is no landing for long stretches. The bow paddler stands well
forward and tries for depth and current; the stern paddler keeps the canoe
steady in its course. When paddlers are in agreement even a heavy canoe
can be directed into the most favorable channels. Our canoemen were
always in disagreement, however, and as often as not we shot down rapids
at a speed of twenty miles an hour, broadside on, with an occasional bump
on projecting rocks or boulders whose warning ordinary boatmen would not
let go unheeded.
The scenery at the great bend is unusually beautiful. The tropical forest
crowds the river bank, great cliffs rise sheer from the water’s edge, their
faces overhung with a trailing drapery of vines, and in the longer river
vistas one may sometimes see the distant heights of the Cordillera
Vilcapampa. We shot the long succession of rapids in the first canyon
without mishap, and at night pitched our tent on the edge of the river near
the mouth of the Manugali.
From the sharp peak opposite our camp we saw for the first time the
phenomenon of cloud-banners. A light breeze was blowing from the
western mountains and its vapor was condensed into clouds that floated
down the wind and dissolved, while they were constantly forming afresh at
the summit. In the night a thunderstorm arose and swept with a roar through
the vast forest above us. The solid canopy of the tropical forest fairly
resounded with the impact of the heavy raindrops. The next morning all the
brooks from the farther side of the river were in flood and the river
discolored. When we broke camp the last mist wraiths of the storm were
still trailing through the tree-tops and wrapped about the peak opposite our
camp, only parting now and then to give us delightful glimpses of a forest-
clad summit riding high above the clouds.
The alternation of deeps and shallows at this point in the river and the
well-developed canyon meanders are among the most celebrated of their
kind in the world. Though shut in by high cliffs and bordered by mountains
the river exhibits a succession of curves so regular that one might almost
imagine the country a plain from the pattern of the meanders. The
succession of smooth curves for a long distance across existing mountains
points to a time when a lowland plain with moderate slopes drained by

strongly meandering rivers was developed here. Uplift afforded a chance
for renewed down-cutting on the part of all the streams, and the incision of
the meanders. The present meanders are, of course, not the identical ones
that were formed on the lowland plain; they are rather their descendants.
Though they still retain their strongly curved quality, and in places have
almost cut through the narrow spurs between meander loops, they are not
smooth like the meanders of the Mississippi. Here and there are sharp
irregular turns that mar the symmetry of the larger curves. The alternating
bands of hard and soft rock have had a large part in making the course more
irregular. The meanders have responded to the rock structure. Though
regular in their broader features they are irregular and deformed in detail.
Deeps and shallows are known in every vigorous river, but it is seldom
that they are so prominently developed as in these great canyons. At one
point in the upper canyon the river has been broadened into a lake two or
three times the average width of the channel and with a scarcely perceptible
current; above and below the “laguna,” as the boatmen call it, are big rapids
with beds so shallow that rocks project in many places. In the Pongo de
Mainique the river is at one place only fifty feet wide, yet so deep that there
is little current. It is on the banks of the quiet stretches that the red forest
deer grazes under leafy arcades. Here, too, are the boa-constrictor trails
several feet wide and bare like a roadway. At night the great serpents come
trailing down to the river’s edge, where the red deer and the wildcat, or so-
called “tiger,” are their easy prey.
It is in such quiet stretches that one also finds the vast colonies of water
skippers. They dance continuously in the sun with an incessant motion from
right to left and back again. Occasionally one dances about in circles, then
suddenly darts through the entire mass, though without striking his equally
erratic neighbors. An up-and-down motion still further complicates the
effect. It is positively bewildering to look intently at the whirling multitude
and try to follow their complicated motions. Every slight breath of wind
brings a shock to the organization of the dance. For though they dance only
in the sun, their favorite places are the sunny spots in the shade near the
bank, as beneath an overhanging tree. When the wind shakes the foliage the
mottled pattern of shade and sunlight is confused, the dance slows down,
and the dancers become bewildered. In a storm they seek shelter in the
jungle. The hot, quiet, sunlit days bring out literally millions of these tiny
creatures.

One of the longest deeps in the whole Urubamba lies just above the
Pongo at Mulanquiato. We drifted down with a gentle current just after
sunset. Shrill whistles, like those of a steam launch, sounded from either
bank, the strange piercing notes of the lowland cicada, cicada tibicen. Long
decorated canoes, better than any we had yet seen, were drawn up in the
quiet coves. Soon we came upon the first settlement. The owner, Señor
Pereira, has gathered about him a group of Machigangas, and by marrying
into the tribe has attained a position of great influence among the Indians.
Upon our arrival a gun was fired to announce to his people that strangers
had come, upon which the Machigangas strolled along in twos and threes
from their huts, helped us ashore with the baggage, and prepared the
evening meal. Here we sat down with five Italians, who had ventured into
the rubber fields with golden ideas as to profits. After having lost the larger
part of their merchandise, chiefly cinchona, in the rapids the year before,
they had established themselves here with the idea of picking rubber.
Without capital, they followed the ways of the itinerant rubber picker and
had gathered “caucho,” the poorer of the two kinds of rubber. No capital is
required; the picker simply cuts down the likeliest trees, gathers the
coagulated sap, and floats it down-stream to market. After a year of this life
they had grown restless and were venturing on other schemes for the great
down-river rubber country.

Fig. 13—Composition Fig. 14—The mule
of tropical vegetation trail in the rain forest
in the rain forest between Rosalina and
above Pongo de Pongo de Mainique.
Mainique, elevation Each pool is from one

2,500 feet (760 m.). and a half to two feet
Scores of species occur deep. Even in the dry
within the limits of a season these holes are
single photograph. full of water, for the
sunlight penetrates the
foliage at a few places
only.

Fig. 15—Topography and vegetation from the Tocate pass, 7,100 feet
(2,164 m.), between Rosalina and Pongo de Mainique. See Fig. 53a.
This is in the zone of maximum rainfall. The cumulo-nimbus clouds are
typical and change to nimbus in the early afternoon.
Fig. 16—The Expedition’s thirty-foot canoe at the mouth of the
Timpia below Pongo de Mainique.

A few weeks later, on returning through the forest, we met their carriers
with a few small bundles, the only part of their cargo they had saved from
the river. Without a canoe or the means to buy one they had built rafts,
which were quickly torn to pieces in the rapids. We, too, should have said
“pobres Italianos” if their venture had not been plainly foolish. The rubber
territory is difficult enough for men with capital; for men without capital it
is impossible. Such men either become affiliated with organized companies
or get out of the region when they can. A few, made desperate by risks and
losses, cheat and steal their way to rubber. Two years before our trip an
Italian had murdered two Frenchmen just below the Pongo and stolen their

rubber cargo, whereupon he was shot by Machigangas under the leadership
of Domingo, the chief who was with us on a journey from Pongo de
Mainique to the mouth of the Timpia. Afterward they brought his skull to
the top of a pass along the forest trail and set it up on a cliff at the very edge
of Machiganga-land as a warning to others of his kind.
At Mulanquiato we secured five Machigangas and a boy interpreter, and
on August 17 made the last and most difficult portion of our journey. We
found these Indians much more skilful than our earlier boatmen. Well-
trained, alert, powerful, and with excellent team-play, they swept the canoe
into this or that thread of the current, and took one after another of the
rapids with the greatest confidence. No sooner had we passed the Sintulini
rapids, fully a mile long, than we reached the mouth of the Pomareni. This
swift tributary comes in almost at right angles to the main river and gives
rise to a confusing mass of standing waves and conflicting currents
rendered still more difficult by the whirlpool just below the junction. So
swift is the circling current of the maëlstrom that the water is hollowed out
like a great bowl, a really formidable point and one of our most dangerous
passages; a little too far to the right and we should be thrown over against
the cliff-face; a little too far to the left and we should be caught in the
whirlpool. Once in the swift current the canoe became as helpless as a chip.
It was turned this way and that, each turn heading it apparently straight for
destruction. But the Indians had judged their position well, and though we
seemed each moment in a worse predicament, we at last skimmed the edge
of the whirlpool and brought our canoe to shore just beyond its rim.
A little farther on we came to the narrow gateway of the Pongo, where
the entire volume of the river flows between cliffs at one point no more than
fifty feet apart. Here are concentrated the worst rapids of the lower
Urubamba. For nearly fifteen miles the river is an unbroken succession of
rapids, and once within its walls the Pongo offers small chance of escape.
At some points we were fortunate enough to secure a foothold along the
edge of the river and to let our canoe down by ropes. At others we were
obliged to take chances with the current, though the great depth of water in
most of the Pongo rapids makes them really less formidable in some
respects than the shallow rapids up stream. The chief danger here lies in the
rotary motion of the water at the sharpest bends. The effect at some places
is extraordinary. A floating object is carried across stream like a feather and
driven at express-train speed against a solid cliff. In trying to avoid one of

these cross-currents our canoe became turned midstream, we were thrown
this way and that, and at last shot through three standing waves that half
filled the canoe.
Below the worst rapids the Pongo exhibits a swift succession of natural
wonders. Fern-clad cliffs border it, a bush resembling the juniper reaches its
dainty finger-like stems far out over the river, and the banks are heavily
clad with mosses. The great woods, silent, impenetrable, mantle the high
slopes and stretch up to the limits of vision. Cascades tumble from the cliff
summits or go rippling down the long inclines of the slate beds set almost
on edge. Finally appear the white pinnacles of limestone that hem in the
narrow lower entrance or outlet of the Pongo. Beyond this passage one
suddenly comes out upon the edge of a rolling forest-clad region, the rubber
territory, the country of the great woods. Here the Andean realm ends and
Amazonia begins.
From the summits of the white cliffs 4,000 feet above the river we were
in a few days to have one of the most extensive views in South America.
The break between the Andean Cordillera and the hill-dotted plains of the
lower Urubamba valley is almost as sharp as a shoreline. The rolling plains
are covered with leagues upon leagues of dense, shadowy, fever-haunted
jungle. The great river winds through in a series of splendid meanders, and
with so broad a channel as to make it visible almost to the horizon. Down
river from our lookout one can reach ocean steamers at Iquitos with less
than two weeks of travel. It is three weeks to the Pacific via Cuzco and
more than a month if one takes the route across the high bleak lava-covered
country which we were soon to cross on our way to the coast at Camaná.

CHAPTER III

THE RUBBER FORESTS
THE white limestone cliffs at Pongo de Mainique are a boundary
between two great geographic provinces (Fig. 17). Down valley are the vast
river plains, drained by broad meandering rivers; up valley are the rugged
spurs of the eastern Andes and their encanyoned streams (Fig. 18). There
are outliers of the Andes still farther toward the northeast where hangs the
inevitable haze of the tropical horizon, but the country beyond them differs
in no important respect from that immediately below the Pongo.

Fig. 17—Regional diagram of the Eastern Andes (here the
Cordillera Vilcapampa) and the adjacent tropical plains. For an
explanation of the method of construction and the symbolism of the
diagram see p. 51.

The foot-path to the summit of the cliffs is too narrow and steep for even
the most agile mules. It is simply impassable for animals without hands. In
places the packs are lowered by ropes over steep ledges and men must
scramble down from one projecting root or swinging vine to another. In the
breathless jungle it is a wearing task to pack in all supplies for the station
below the Pongo and to carry out the season’s rubber. Recently however the
ancient track has been replaced by a road that was cut with great labor, and
by much blasting, across the mountain barrier, and at last mule transport has
taken the place of the Indian.
In the dry season it is a fair and delightful country—that on the border of
the mountains. In the wet season the traveler is either actually marooned or
he must slosh through rivers of mud and water that deluge the trails and
break the hearts of his beasts (Fig. 14). Here and there a large shallow-
rooted tree has come crashing down across the trail and with its four feet of
circumference and ten feet of plank buttress it is as difficult to move as a
house. A new trail must be cut around it. A little farther on, where the valley
wall steepens and one may look down a thousand feet of slope to the bed of
a mountain torrent, a patch of trail has become soaked with water and the

mules pick their way, trembling, across it. Two days from
Yavero one of our mules went over the trail, and though
she was finally recovered she died of her injuries the
following night. After a month’s work in the forest a mule
must run free for two months to recover. The packers
count on losing one beast out of five for every journey
into the forest. It is not solely a matter of work, though
this is terrific; it is quite largely a matter of forage. In spite
of its profusion of life (Fig. 13) and its really vast wealth
of species, the tropical forest is all but barren of grass.
Sugar cane is a fair substitute, but there are only a few
cultivated spots. The more tender leaves of the trees, the
young shoots of cane in the carrizo swamps, and the
grass-like foliage of the low bamboo are the chief
substitutes for pasture. But they lead to various disorders,
besides requiring considerable labor on the part of the
dejected peons who must gather them after a day’s heavy Fig. 18—Index
work with the packs. map for the nine

Overcoming these enormous difficulties is expensive regional diagrams
in the pages
and some one must pay the bill. As is usual in a pioneer
following. A
region, the native laborer pays a large part of it in
unrequited toil; the rest is paid by the rubber consumer. represents 17 ; B,
For this is one of the cases where a direct road connects 42; C, 36; D, 32;
the civilized consumer and the barbarous producer. What a E, 34; F, 25; G, 26;
and H, 65.
story it could tell if a ball of smoke-cured rubber on a
New York dock were endowed with speech—of the wet
jungle path, of enslaved peons, of vile abuses by immoral agents, of all the
toil and sickness that make the tropical lowland a reproach!

Fig. 19—Moss-draped trees in the rain forest near Abra Tocate
between Rosalina and Pongo de Mainique.
Fig. 20—Yavero, a rubber station on the Yavero (Paucartambo)
River, a tributary of the Urubamba. Elevation 1,600 feet (490 m.).

In the United States the specter of slavery haunted the national
conscience almost from the beginning of national life, and the ghost was
laid only at the cost of one of the bloodiest wars in history. In other
countries, as in sugar-producing Brazil, the freeing of the slaves meant not a
war but the verge of financial ruin besides a fundamental change in the
social order and problems as complex and wearisome as any that war can
bring. Everywhere abolition was secured at frightful cost.

Fig. 21—Clearing in the tropical forest between Rosalina and
Pabellon. This represents the border region where the forest-dwelling
Machiganga Indians and the mountain Indians meet. The clearings are
occupied by Machigangas whose chief crops are yuca and corn; in the
extreme upper left-hand corner are grassy slopes occupied by Quechua
herdsmen and farmers who grow potatoes and corn.

The spirit that upheld the new founders of the western republics in
driving out slavery was admirable, but as much cannot be said of their work
of reconstruction. We like to pass over those dark days in our own history.
In South America there has lingered from the old slave-holding days down
to the present, a labor system more insidious than slavery, yet no less
revolting in its details, and infinitely more difficult to stamp out. It is called
peonage; it should be called slavery. In Bolivia, Peru, and Brazil it
flourishes now as it ever did in the fruitful soil of the interior provinces
where law and order are bywords and where the scarcity of workmen will
long impel men to enslave labor when they cannot employ it. Peonage is
slavery, though as in all slave systems there are many forms under which
the system is worked out. We commonly think that the typical slave is one
who is made to work hard, given but little food, and at the slightest
provocation is tied to a post and brutally whipped. This is indeed the fate of
many slaves or “peons” so-called, in the Amazon forests; but it is no more
the rule than it was in the South before the war, for a peon is a valuable

piece of property and if a slave raider travel five hundred miles through
forest and jungle-swamp to capture an Indian you may depend upon it that
he will not beat him to death merely for the fun of it.
That unjust and frightfully cruel floggings are inflicted at times and in
some places is of course a result of the lack of official restraint that drunken
owners far from the arm of the law sometimes enjoy. When a man obtains a
rubber concession from the government he buys a kingdom. Many of the
rubber territories are so remote from the cities that officials can with great
difficulty be secured to stay at the customs ports. High salaries must be
paid, heavy taxes collected, and grafting of the most flagrant kind winked
at. Often the concessionaire himself is chief magistrate of his kingdom by
law. Under such a system, remote from all civilizing influences, the rubber
producer himself oftentimes a lawless border character or a downright
criminal, no system of government would be adequate, least of all one like
peonage that permits or ignores flagrant wrongs because it is so expensive
to enforce justice.
The peonage system continues by reason of that extraordinary difficulty
in the development of the tropical lowland of South America—the lack of a
labor supply. The population of Amazonia now numbers less than one
person to the square mile. The people are distributed in small groups of a
dozen to twenty each in scattered villages along the river banks or in
concealed clearings reached by trails known only to the Indians. Nearly all
of them still live in the same primitive state in which they lived at the time
of the Discovery. In the Urubamba region a single cotton shirt is worn by
the married men and women, while the girls and boys in many cases go
entirely naked except for a loincloth or a necklace of nuts or monkeys’ teeth
(Fig. 23). A cane hut with a thatch to keep out the heavy rains is their
shelter and their food is the yuca, sugar cane, Indian corn, bananas of many
kinds, and fish. A patch of yuca once planted will need but the most trifling
attention for years. The small spider monkey is their greatest delicacy and
to procure it they will often abandon every other project and return at their
own sweet and belated will.

Fig. 22—Trading with Machiganga Indians in a reed swamp at
Santao Anato, Urubamba Valley, before Rosalina. Just outside the
picture on the right is a platform on which corn is stored for protection
against rodents and mildew. On the left is the corner of a grass-
thatched cane hut.

In the midst of this natural life of the forest-dwelling Indian appears the
rubber man, who, to gather rubber, must have rubber “pickers.” If he lives
on the edge of the great Andean Cordillera, laborers may be secured from
some of the lower valleys, but they must be paid well for even a temporary
stay in the hot and unhealthful lowlands. Farther out in the great forest
country the plateau Indians will not go and only the scattered tribes remain
from which to recruit laborers. For the nature-life of the Indian what has the
rubber gatherer to offer? Money? The Indian uses it for ornament only.
When I once tried with money to pay an Indian for a week’s services he
refused it. In exchange for his severe labor he wanted nothing more than a
fish-hook and a ring, the two costing not more than a penny apiece! When
his love for ornament has once been gratified the Indian ceases to work. His
food and shelter and clothing are of the most primitive kind, but they are the
best in the world for him because they are the only kind he has known. So
where money and finery fail the lash comes in. The rubber man says that
the Indian is lazy and must be made to work; that there is a great deal of
work to be done and the Indian is the only laborer who can be found; that if
rubber and chocolate are produced the Indian must be made to produce
them; and that if he will not produce them for pay he must be enslaved.

Fig. 23—Ornaments and fabrics of the Machiganga Indians at
Yavero. The nuts are made up into strings, pendants, and heavy
necklaces. To the left of the center is one that contains feathers and four
drumsticks of a bird about the size of a small wild turkey—probably
the so-called turkey inhabiting the eastern mountain valleys and the
adjacent border of the plains, and hunted as an important source of
food. The cord in the upper right-hand corner is used most commonly
for heel supports in climbing trees. The openwork sack is convenient
for carrying game, fish, and fruit; the finely woven sacks are used for
carrying red ochre for ornamenting or daubing faces and arms. They
are also used for carrying corn, trinkets, and game.

It is a law of the rubber country that when an Indian falls into debt to a
white man he must work for the latter until the debt is discharged. If he runs
away before the debt is canceled or if he refuses to work or does too little
work he may be flogged. Under special conditions such laws are wise. In
the hands of the rubber men they are the basis of slavery. For, once the
rubber interests begin to suffer, the promoters look around for a chance to
capture free Indians. An expedition is fitted out that spends weeks exploring
this river or that in getting on the track of unattached Indians. When a
settlement is found the men are enslaved and taken long distances from
home finally to reach a rubber property. There they are given a corner of a
hut to sleep in, a few cheap clothes, a rubber-picking outfit, and a name. In
return for these articles the unwilling Indian is charged any fanciful price
that comes into the mind of his “owner,” and he must thereupon work at a
per diem wage also fixed by the owner. Since his obligations increase with
time, the Indian may die over two thousand dollars in debt!
Peonage has left frightful scars upon the country. In some places the
Indians are fugitives, cultivating little farms in secreted places but visiting

them only at night or after carefully reconnoitering the spot. They change
their camps frequently and make their way from place to place by secret
trails, now spending a night or two under the shelter of a few palm leaves
on a sandbar, again concealing themselves in almost impenetrable jungle. If
the hunter sometimes discovers a beaten track he follows it only to find it
ending on a cliff face or on the edge of a lagoon where concealment is
perfect. There are tribes that shoot the white man at sight and regard him as
their bitterest enemy. Experience has led them to believe that only a dead
white is a good white, reversing our saying about the North American
Indian; and that even when he comes among them on peaceful errands he is
likely to leave behind him a trail of syphilis and other venereal diseases
scarcely less deadly than his bullets.
However, the peonage system is not hideous everywhere and in all its
aspects. There are white owners who realize that in the long run the
friendship of the Indians is an asset far greater than unwilling service and
deadly hatred. Some of them have indeed intermarried with the Indians and
live among them in a state but little above savagery. In the Mamoré country
are a few owners of original princely concessions who have grown
enormously wealthy and yet who continue to live a primitive life among
their scores of illegitimate descendants. The Indians look upon them as
benefactors, as indeed many of them are, defending the Indians from ill
treatment by other whites, giving them clothing and ornaments, and
exacting from them only a moderate amount of labor. In some cases indeed
the whites have gained more than simple gratitude for their humane
treatment of the Indians, some of whom serve their masters with real
devotion.
When the “rubber barons” wish to discourage investigation of their
system they invite the traveler to leave and he is given a canoe and oarsmen
with which to make his way out of the district. Refusal to accept an offer of
canoes and men is a declaration of war. An agent of one of the London
companies accepted such a challenge and was promptly told that he would
not leave the territory alive. The threat would have held true in the case of a
less skilful man. Though Indians slept in the canoes to prevent their seizure,
he slipped past the guards in the night, swam to the opposite shore, and
there secured a canoe within which he made a difficult journey down river
to the nearest post where food and an outfit could be secured.

A few companies operating on or near the border of the Cordillera have
adopted a normal labor system, dependent chiefly upon people from the
plateau and upon the thoroughly willing assistance of well-paid forest
Indians. The Compañia Gomera de Mainique at Puerto Mainique just below
the Pongo is one of these and its development of the region without
violation of native rights is in the highest degree praiseworthy. In fact the
whole conduct of this company is interesting to a geographer, as it reflects
at every point the physical nature of the country.
The government is eager to secure foreign capital, but in eastern Peru
can offer practically nothing more than virgin wealth, that is, land and the
natural resources of the land. There are no roads, virtually no trails, no
telegraph lines, and in most cases no labor. Since the old Spanish grants ran
at right angles to the river so as to give the owners a cross-section of varied
resources, the up-river plantations do not extend down into the rubber
country. Hence the more heavily forested lower valleys and plains are the
property of the state. A man can buy a piece of land down there, but from
any tract within ordinary means only a primitive living can be obtained. The
pioneers therefore are the rubber men who produce a precious substance
that can stand the enormous tax on production and transportation. They do
not want the land—only the exclusive right to tap the rubber trees upon it.
Thus there has arisen the concession plan whereby a large tract is obtained
under conditions of money payment or of improvements that will attract
settlers or of a tax on the export.
The “caucho” or poorer rubber of the Urubamba Valley begins at 3,000
feet (915 m.) and the “hevea” or better class is a lower-valley and plains
product. The rubber trees thereabouts produce 60 grams (2 ozs.) of dry
rubber each week for eight months. After yielding rubber for this length of
time a tree is allowed to rest four or five years. “Caucho” is produced from
trees that are cut down and ringed with machetes, but it is from fifty to sixty
cents cheaper owing to the impurities that get into it. The wood, not the nut,
of the Palma carmona is used for smoking or “curing” the rubber. The
government had long been urged to build a road into the region in place of
the miserable track—absolutely impassable in the wet season—that
heretofore constituted the sole means of exit. About ten years ago Señor
Robledo at last built a government trail from Rosalina to Yavero about 100
miles long. While it is a wretched trail it is better than the old one, for it is
more direct and it is better drained. In the wet season parts of it are turned

into rivers and lakes, but it is probably the best that could be done with the
small grant of twenty thousand dollars.
With at least an improvement in the trail it became possible for a rubber
company to induce cargadores or packers to transport merchandise and
rubber and to have a fair chance of success. Whereupon a rubber company
was organized which obtained a concession of 28,000 hectares (69,188
acres) of land on condition that the company finish a road one and one-half
meters wide to the Pongo, connecting with the road which the government
had extended to Yavero. The land given in payment was not continuous but
was selected in lots by the company in such a way as to secure the best
rubber trees over an area several times the size of the concession. The road
was finished by William Tell after four years’ work at a cost of about
seventy-five thousand dollars. The last part of it was blasted out of slate and
limestone and in 1912 the first pack train entered Puerto Mainique.
The first rubber was taken out in November, 1910, and productive
possibilities proved by the collection of 9,000 kilos (19,841 pounds) in
eight months.
If a main road were the chief problem of the rubber company the
business would soon be on a paying basis, but for every mile of road there
must be cut several miles of narrow trail (Fig. 14), as the rubber trees grow
scattered about—a clump of a half dozen here and five hundred feet farther
on another clump and only scattered individuals between. Furthermore,
about twenty-five years ago rubber men from the Ucayali came up here in
launches and canoes and cut down large numbers of trees within reach of
the water courses and by ringing the trunks every few feet with machetes
“bled” them rapidly and thus covered a large territory in a short time, and
made huge sums of money when the price of rubber was high. Only a few
of the small trees that were left are now mature. These, the mature trees that
were overlooked, and the virgin stands farther from the rivers are the
present sources of rubber.
In addition to the trails small cabins must be built to shelter the hired
laborers from the plateau, many of whom bring along their women folk to
cook for them. The combined expense to a company of these necessary
improvements before production can begin is exceedingly heavy. There is
only one alternative for the prospective exploiter: to become a vagrant
rubber gatherer. With tents, guns, machetes, cloth, baubles for trading,

tinned food for emergencies, and with pockets full of English gold parties
have started out to seek fortunes in the rubber forests. If the friendship of a
party of Indians can be secured by adequate gifts large amounts of rubber
can be gathered in a short time, for the Indians know where the rubber trees
grow. On the other hand, many fortunes have been lost in the rubber
country. Some of the tribes have been badly treated by other adventurers
and attack the newcomers from ambush or gather rubber for a while only to
overturn the canoe in a rapid and let the river relieve them of selfish friends.
The Compañia Gomera de Mainique started out by securing the good-
will of the forest Indians, the Machigangas. They come and go in friendly
visits to the port at Yavero. If one of them is sick he can secure free
medicine from the agent. If he wishes goods on credit he has only to ask for
them, for the agent knows that the Indian’s sense of fairness will bring him
back to work for the company. Without previous notice a group of Indians
appears:
“We owe,” they announce.
“Good,” says the agent, “build me a house.”
They select the trees. Before they cut them down they address them
solemnly. The trees must not hold their destruction against the Indians and
they must not try to resist the sharp machetes. Then the Indians set to work.
They fell a tree, bind it with light ropes woven from the wild cotton, and
haul it to its place. That is all for the day. They play in the sun, do a little
hunting, or look over the agent’s house, touching everything, talking little,
exclaiming much. They dip their wet fingers in the sugar bowl and taste,
turn salt out upon their hands, hold colored solutions from the medicine
chest up to the light, and pull out and push in the corks of the bottles. At the
end of a month or two the house is done. Then they gather their women and
babies together and say:
“Now we go,” without asking if the work corresponds with the cost of
the articles they had bought. Their judgment is good however. Their work is
almost always more valuable than the articles. Then they shake hands all
around.
“We will come again,” they say, and in a moment have disappeared in
the jungle that overhangs the trail.
With such labor the Compañia Gomera de Mainique can do something,
but it is not much. The regular seasonal tasks of road-building and rubber-

picking must be done by imported labor. This is secured chiefly at Abancay,
where live groups of plateau Indians that have become accustomed to the
warm climate of the Abancay basin. They are employed for eight or ten
months at an average rate of fifty cents gold per day, and receive in addition
only the simplest articles of food.
At the end of the season the gang leaders are paid a gratificación, or
bonus, the size of which depends upon the amount of rubber collected, and
this in turn depends upon the size of the gang and the degree of willingness
to work. In the books of the company I saw a record of gratificaciónes
running as high as $600 in gold for a season’s work.
Some of the laborers become sick and are cared for by the agent until
they recover or can be sent back to their homes. Most of them have fever
before they return.
The rubber costs the company two soles ($1.00) produced at Yavero. The
two weeks’ transportation to Cuzco costs three and a half soles ($1.75) per
twenty-five pounds. The exported rubber, known to the trade as Mollendo
rubber, in contrast to the finer “Pará” rubber from the lower Amazon, is
shipped to Hamburg. The cost for transportation from port to port is $24.00
per English ton (1,016 kilos). There is a Peruvian tax of 8 per cent of the net
value in Europe, and a territorial tax of two soles ($1.00) per hundred
pounds. All supplies except the few vegetables grown on the spot cost
tremendously. Even dynamite, hoes, clothing, rice—to mention only a few
necessities—must pay the heavy cost of transportation after imposts,
railroad and ocean freight, storage and agents’ percentages are added. The
effect of a disturbed market is extreme. When, in 1911, the price of rubber
fell to $1.50 a kilo at Hamburg the company ceased exporting. When it
dropped still lower in 1912 production also stopped, and it is still doubtful,
in view of the growing competition of the East-Indian plantations with their
cheap labor, whether operations will ever be resumed. Within three years no
less than a dozen large companies in eastern Peru and Bolivia have ceased
operations. In one concession on the Madre de Dios the withdrawal of the
agents and laborers from the posts turned at last into flight, as the forest
Indians, on learning the company’s policy, rapidly ascended the river in
force, committing numerous depredations. The great war has also added to
the difficulties of production.

Facts like these are vital in the consideration of the future of the Amazon
basin and especially its habitability. It was the dream of Humboldt that great
cities should arise in the midst of the tropical forests of the Amazon and that
the whole lowland plain of that river basin should become the home of
happy millions. Humboldt’s vision may have been correct, though a
hundred years have brought us but little nearer its realization. Now, as in the
past four centuries, man finds his hands too feeble to control the great
elemental forces which have shaped history. The most he can hope for in
the next hundred years at least is the ability to dodge Nature a little more
successfully, and here and there by studies in tropical hygiene and
medicine, by the substitution of water-power for human energy, to carry a
few of the outposts and prepare the way for a final assault in the war against
the hard conditions of climate and relief. We hear of the Madeira-Mamoré
railroad, 200 miles long, in the heart of a tropical forest and of the
commercial revolution it will bring. Do we realize that the forest which
overhangs the rails is as big as the whole plain between the Rockies and the
Appalachians, and that the proposed line would extend only as far as from
St. Louis to Kansas City, or from Galveston to New Orleans?
Even if twenty whites were eager to go where now there is but one
reluctant pioneer, we should still have but a halting development on account
of the scarcity of labor. When, three hundred years ago, the Isthmus of
Panama stood in his way, Gomara wrote to his king: “There are mountains,
but there are also hands,” as if men could be conjured up from the tropical
jungle. From that day to this the scarcity of labor has been the chief
difficulty in the lowland regions of tropical South America. Even when
medicine shall have been advanced to the point where residence in the
tropics can be made safe, the Amazon basin will lack an adequate supply of
workmen. Where Humboldt saw thriving cities, the population is still less
than one to the square mile in an area as large as fifteen of our Mississippi
Valley states. We hear much about a rich soil and little about intolerable
insects; the climate favors a good growth of vegetation, but a man can
starve in a tropical forest as easily as in a desert; certain tributaries of the
Negro are bordered by rich rubber forests, yet not a single Indian hut may
be found along their banks. Will men of the white race dig up the rank
vegetation, sleep in grass hammocks, live in the hot and humid air, or will
they stay in the cooler regions of the north and south? Will they rear
children in the temperate zones, or bury them in the tropics?

What Gorgas did for Panama was done for intelligent people. Can it be
duplicated in the case of ignorant and stupid laborers? Shall the white man
with wits fight it out with Nature in a tropical forest, or fight it out with his
equals under better skies?
The tropics must be won by strong hands of the lowlier classes who are
ignorant or careless of hygiene, and not by the khaki-clad robust young men
like those who work at Panama. Tropical medicine can do something for
these folk, but it cannot do much. And we cannot surround every laborer’s
cottage with expensive screens, oiled ditches, and well-kept lawns. There is
a practical optimism and a sentimental optimism. The one is based on facts;
the other on assumptions. It is pleasant to think that the tropical forest may
be conquered. It is nonsense to say that we are now conquering it in any
comprehensive and permanent way. That sort of conquest is still a dream, as
when Humboldt wrote over a hundred years ago.

CHAPTER IV

THE FOREST INDIANS
THE people of a tropical forest live under conditions not unlike those of
the desert. The Sahara contains 2,000,000 persons within its borders, a
density of one-half to the square mile. This is almost precisely the density
of population of a tract of equivalent size in the lowland forests of South
America. Like the oases groups in the desert of aridity are the scattered
groups along the river margins of the forest. The desert trails run from
spring to spring or along a valley floor where there is seepage or an
intermittent stream; the rivers are the highways of the forest, the flowing
roads, and away from them one is lost in as true a sense as one may be lost
in the desert.
A man may easily starve in the tropical forest. Before starting on even a
short journey of two or three days a forest Indian stocks his canoe with
sugar cane and yuca and a little parched corn. He knows the settlements as
well as his desert brother knows the springs. The Pahute Indian of Utah
lives in the irrigated valleys and makes annual excursions across the desert
to the distant mountains to gather the seeds of the nut pine. The Machiganga
lives in the hills above the Urubamba and annually comes down through the
forest to the river to fish during the dry season.

The Machigangas are one of the important tribes of the Amazon basin.
Though they are dispersed to some extent upon the plains their chief groups
are scattered through the heads of a large number of valleys near the eastern
border of the Andes. Chief among the valleys they occupy are the Pilcopata,
Tono, Piñi-piñi, Yavero, Yuyato, Shirineiri, Ticumpinea, Timpia, and
Camisea (Fig. 203). In their distribution, in their relations with each other,
in their manner of life, and to some extent in their personal traits, they
display characteristics strikingly like those seen in desert peoples. Though
the forest that surrounds them suggests plenty and the rivers the possibility
of free movement with easy intercourse, the struggle of life, as in the desert,
is against useless things. Travel in the desert is a conflict with heat and
aridity; but travel in the tropic forest is a struggle against space, heat, and a
superabundant and all but useless vegetation.
The Machigangas are one of the subtribes of the Campas Indians, one of
the most numerous groups in the Amazon Valley. It is estimated that there
are in all about 14,000 to 16,000 of them. Each subtribe numbers from one
to four thousand, and the territory they occupy extends from the limits of
the last plantations—for example, Rosalina in the Urubamba Valley—
downstream beyond the edge of the plains. Among them three subtribes are
still hostile to the whites: the Cashibos, the Chonta Campas, and the
Campas Bravos.
In certain cases the Cashibos are said to be anthropophagous, in the
belief that they will assume the strength and intellect of those they eat. This
group is also continuously at war with its neighbors, goes naked, uses stone
hatchets, as in ages past, because of its isolation and unfriendliness, and
defends the entrances to the tribal huts with dart and traps. The Cashibos are
diminishing in numbers and are now scattered through the valley of the
Gran Pajonal, the left bank of the Pachitea, and the Pampa del Sacramento.
[2]

The friendliest tribes live in the higher valley heads, where they have
constant communication with the whites. The use of the bow and arrow has
not, however, been discontinued among them, in spite of the wide
introduction of the old-fashioned muzzle-loading shotgun, which they prize
much more highly than the latest rifle or breech-loading shotgun because of
its simplicity and cheapness. Accidents are frequent among them owing to
the careless use of fire-arms. On our last day’s journey on the Urubamba
above the mouth of the Timpia one of our Indian boys dropped his canoe

pole on the hammer of a loaded shotgun, and not only shot his own fingers
to pieces, but gravely wounded his father (Fig. 2). In spite of his suffering
the old chief directed our work at the canoe and even was able to tell us the
location of the most favorable channel. Though the night that followed was
as black as ink, with even the stars obscured by a rising storm, his
directions never failed. We poled our way up five long rapids without
special difficulties, now working into the lee of a rock whose location he
knew within a few yards, now paddling furiously across the channel to
catch the upstream current of an eddy.
The principal groups of Machigangas live in the middle Urubamba and
its tributaries, the Yavero, Yuyato, Shirineiri, Ticumpinea, Timpia, Pachitea,
and others. There is a marked difference in the use of the land and the mode
of life among the different groups of this subtribe. Those who live in the
lower plains and river “playas,” as the patches of flood plain are called,
have a single permanent dwelling and alternately fish and hunt. Those that
live on hill farms have temporary reed huts on the nearest sandbars and
spend the best months of the dry season—April to October—in fishing and
drying fish to be carried to their mountain homes (Fig. 21). Some families
even duplicate chacras or farms at the river bank and grow yuca and sugar
cane. In latter years smallpox, malaria, and the rubber hunters have
destroyed many of the river villages and driven the Indians to permanent
residence in the hills or, where raids occur, along secret trails to hidden
camps.
Their system of agriculture is strikingly adapted to some important
features of tropical soil. The thin hillside soils of the region are but poorly
stocked with humus, even in their virgin condition. Fallen trees and foliage
decay so quickly that the layer of forest mold is exceedingly thin and the
little that is incorporated in the soil is confined to a shallow surface layer.
To meet these special conditions the Indian makes new clearings by girdling
and burning the trees. When the soil becomes worn out and the crops
diminish, the old clearing is abandoned and allowed to revert to natural
growth and a new farm is planted to corn and yuca. The population is so
scattered and thin that the land assignment system current among the
plateau Indians is not practised among the Machigangas. Several families
commonly live together and may be separated from their nearest neighbors
by many miles of forested mountains. The land is free for all, and, though
some heavy labor is necessary to clear it, once a small patch is cleared it is

easy to extend the tract by limited annual cuttings. Local tracts of naturally
unforested land are rarely planted, chiefly because the absence of shade has
allowed the sun to burn out the limited humus supply and to prevent more
from accumulating. The best soil of the mountain slopes is found where
there is the heaviest growth of timber, the deepest shade, the most humus,
and good natural drainage. It is the same on the playas along the river; the
recent additions to the flood plain are easy to cultivate, but they lack humus
and a fine matrix which retains moisture and prevents drought or at least
physiologic dryness. Here, too, the timbered areas or the cane swamps are
always selected for planting.
The traditions of the Machigangas go back to the time of the Inca
conquest, when the forest Indians, the “Antis,” were subjugated and
compelled to pay tribute.[3] When the Inca family itself fled from Cuzco
after the Spanish Conquest and sought refuge in the wilderness it was to the
Machiganga country that they came by way of the Vilcabamba and
Pampaconas Valleys. Afterward came the Spaniards and though they did not
exercise governmental authority over the forest Indians they had close
relations with them. Land grants were made to white pioneers for special
services or through sale and with the land often went the right to exploit the
people on it. Some of the concessions were owned by people who for
generations knew nothing save by hearsay of the Indians who dwelt in the
great forests of the valleys. In later years they have been exploring their
lands and establishing so-called relations whereby the savage “buys” a
dollar’s worth of powder or knives for whatever number of dollars’ worth of
rubber the owner may care to extract from him.
The forest Indian is still master of his lands throughout most of the
Machiganga country. He is cruelly enslaved at the rubber posts, held by the
loose bonds of a desultory trade at others, and in a few places, as at Pongo
do Mainique, gives service for both love and profit, but in many places it is
impossible to establish control or influence. The lowland Indian never falls
into the abject condition of his Quechua brother on the plateau. He is self-
reliant, proud, and independent. He neither cringes before a white nor looks
up to him as a superior being. I was greatly impressed by the bearing of the
first of the forest tribes I met in August, 1911, at Santo Anato. I had built a
brisk fire and was enjoying its comfort when La Sama returned with some
Indians whom he had secured to clear his playa. The tallest of the lot,
wearing a colored band of deer skin around his thick hair and a gaudy

bunch of yellow feathers down his back, came up, looked me squarely in
the eye, and asked
“Tatiry payta?” (What is your name?)
When I replied he quietly sat down by the fire, helping himself to the
roasted corn I had prepared in the hot ashes. A few days later when we
came to the head of a rapid I was busy sketching-in my topographic map
and did not hear his twice repeated request to leave the boat while the party
reconnoitered the rapid. Watching his opportunity he came alongside from
the rear—he was steersman—and, turning just as he was leaving the boat,
gave me a whack in the forehead with his open palm. La Sama saw the
motion and protested. The surly answer was:
“I twice asked him to get out and he didn’t move. What does he think we
run the canoe to the bank for?”
To him the making of a map was inexplicable; I was merely a stupid
white person who didn’t know enough to get out of a canoe when told!
The plateau Indian has been kicked about so long that all his
independence has been destroyed. His goods have been stolen, his services
demanded without recompense, in many places he has no right to land, and
his few real rights are abused beyond belief. The difference between him
and the forest Indian is due quite largely to differences of environment. The
plateau Indian is agricultural, the forest Indian nomadic and in a hunting
stage of development; the unforested plateau offers no means for
concealment of person or property, the forest offers hidden and difficult
paths, easy means for concealment, for ambush, and for wide dispersal of
an afflicted tribe. The brutal white of the plateau follows altogether
different methods when he finds himself in the Indian country, far from
military assistance, surrounded by fearless savages. He may cheat but he
does not steal, and his brutality is always carefully suited to both time and
place.
The Machigangas are now confined to the forest, but the limits of their
territory were once farther upstream, where they were in frequent conflict
with the plateau Indians. As late as 1835, according to General Miller,[4]
they occupied the land as far upstream as the “Encuentro” (junction) of the
Urubamba and the Yanatili (Fig. 53). Miller likewise notes that the
Chuntaguirus, “a superior race of Indians” who lived “toward the

Marañon,” came up the river “200 leagues” to barter with the people
thereabouts.
“They bring parrots and other birds, monkeys, cotton robes white and
painted, wax balsams, feet of the gran bestia, feather ornaments for the
head, and tiger and other skins, which they exchange for hatchets, knives,
scissors, needles, buttons, and any sort of glittering bauble.”
On their yearly excursions they traveled in a band numbering from 200
to 300, since at the mouth of the Paucartambo (Yavero) they were generally
set upon by the Pucapacures. The journey upstream required three months;
with the current they returned home in fifteen days.
Their place of meeting at the mouth of the Yanatili was a response to a
long strip of grassland that extends down the deep and dry Urubamba
Valley, as shown in Figs. 53-B and 55. The wet forests, in which the
Machigangas live, cover the hills back of the valley plantations; the belt of
dry grassland terminates far within the general limits of the red man’s
domain and only 2,000 feet above the sea. It is in this strip of low grassland
that on the one hand the highland and valley dwellers, and on the other the
Indians of the hot forested valleys and the adjacent lowland found a
convenient place for barter. The same physiographic features are repeated in
adjacent valleys of large size that drain the eastern aspect of the Peruvian
Andes, and in each case they have given rise to the periodic excursions of
the trader.
These annual journeys are no longer made. The planters have crept down
valley. The two best playas below Rosalina are now being cleared. Only a
little space remains between the lowest valley plantations and the highest
rubber stations. Furthermore, the Indians have been enslaved by the rubber
men from the Ucayali. The Machigangas, many of whom are runaway
peons, will no longer take cargoes down valley for fear of recapture. They
have the cautious spirit of fugitives except in their remote valleys. There
they are secure and now and then reassert their old spirit when a lawless
trader tries to browbeat them into an unprofitable trade. Also, they are
yielding to the alluring call of the planter. At Santo Anato they are clearing
a playa in exchange for ammunition, machetes, brandy, and baubles. They
no longer make annual excursions to get these things. They have only to
call at the nearest plantation. There is always a wolf before the door of the
planter—the lack of labor. Yet, as on every frontier, he turns wolf himself

when the lambs come, and without shame takes a week’s work for a penny
mirror, or, worse still, supplies them with firewater, for that will surely
bring them back to him. Since this is expensive they return to their tribal
haunts with nothing except a debauched spirit and an appetite from which
they cannot run away as they did from their task masters in the rubber
forest. Hence the vicious circle: more brandy, more labor; more labor, more
cleared land; more cleared land, more brandy; more brandy, less Indian. But
by that time the planter has a large sugar estate. Then he can begin to buy
the more expensive plateau labor, and in turn debauch it.
Nature as well as man works against the scattered tribes of Machigangas
and their forest kinsmen. Their country is exceedingly broken by ramifying
mountain spurs and valleys overhung with cliffs or bordered by bold, wet,
fern-clad slopes. It is useless to try to cut your way by a direct route from
one point to another. The country is mantled with heavy forest. You must
follow the valleys, the ancient trails of the people. The larger valleys offer
smooth sand-bars along the border of which canoes may be towed
upstream, and there are little cultivated places for camps. But only a few of
the tribes live along them, for they are also more accessible to the
rubbermen. The smaller valleys, difficult of access, are more secure and
there the tribal remnants live today. While the broken country thus offers a
refuge to fugitive bands it is the broken country and its forest cover that
combine to break up the population into small groups and keep them in an
isolated and quarrelsome state. Chronic quarreling is not only the product of
mere lack of contact. It is due to many causes, among which is a union of
the habit of migration and divergent tribal speech. Every tribe has its own
peculiar words in addition to those common to the group of tribes to which
it belongs. Moreover each group of a tribe has its distinctive words. I have
seen and used carefully prepared vocabularies—no two of which are alike
throughout. They serve for communication with only a limited number of
families. These peculiarities increase as experiences vary and new situations
call for additions to or changes in their vocabularies, and when migrating
tribes meet their speech may be so unlike as to make communication
difficult. Thus arise suspicion, misunderstanding, plunder, and chronic war.
Had they been a united people their defense of their rough country might
have been successful. The tribes have been divided and now and again, to
get firearms and ammunition with which to raid a neighbor, a tribe has
joined its fortunes to those of vagrant rubber pickers only to find in time

that its women were debased, its members decimated by strange and deadly
diseases, and its old morality undermined by an insatiable desire for strong
drink.[5] The Indian loses whether with the white or against him.
The forest Indian is held by his environment no less strongly than the
plateau Indian. We hear much about the restriction of the plateau dweller to
the cool zone in which the llama may live. As a matter of fact he lives far
below the cool zone, where he no longer depends upon the llama but rather
upon the mule for transport. The limits of his range correspond to the limits
of the grasslands in the dry valley pockets already described (p. 42), or on
the drier mountain slopes below the zone of heaviest rainfall (Fig. 54). It is
this distribution that brought him into such intimate contact with the forest
Indian. The old and dilapidated coca terraces of the Quechuas above the
Yanatili almost overlook the forest patches where the Machigangas for
centuries built their rude huts. A good deal has been written about the
attempts of the Incas to extend their rule into this forest zone and about the
failure of these attempts on account of the tropical climate. But the forest
Indian was held by bonds equally secure. The cold climate of the plateau
repelled him as it does today. His haunts are the hot valleys where he need
wear only a wild-cotton shirt or where he may go naked altogether. That he
raided the lands of the plateau Indian is certain, but he could never displace
him. Only along the common borders of their domains, where the climates
of two zones merged into each other, could the forest Indian and the plateau
Indian seriously dispute each other’s claims to the land. Here was endless
conflict but only feeble trade and only the most minute exchanges of
cultural elements.
Even had they been as brothers they would have had little incentive to
borrow cultural elements from each other. The forest dweller requires bow
and arrow; the plateau dweller requires a hoe. There are fish in the warm
river shallows of the forested zone; llamas, vicuña, vizcachas, etc., are a
partial source of food supply on the plateau. Coca and potatoes are the chief
products of the grassy mountain slopes; yuca, corn, bananas, are the chief
vegetable foods grown on the tiny cultivated patches in the forest. The
plateau dweller builds a thick-walled hut; the valley dweller a cane shack.
So unlike are the two environments that it would be strange if there had
been a mixture of racial types and cultures. The slight exchanges that were
made seem little more than accidental. Even today the Machigangas who
live on the highest slopes own a few pigs obtained from Quechuas, but they

never eat their flesh; they keep them for pets merely. I saw not a single
woolen article among the Indians along the Urubamba whereas Quechuas
with woolen clothing were going back and forth regularly. Their baubles
were of foreign make; likewise their few hoes, likewise their guns.
They clear the forest about a mid-cotton tree and spin and weave the
cotton fiber into sacks, cords for climbing trees when they wish to chase a
monkey, ropes for hauling their canoes, shirts for the married men and
women, colored head-bands, and fish nets. The slender strong bamboo is
gathered for arrows. The chunta palm, like bone for hardness, supplies them
with bows and arrow heads. The brilliant red and yellow feathers of forest
birds, also monkey bones and teeth, are their natural ornaments. Their life is
absolutely distinct from that of their Quechua neighbors. Little wonder that
for centuries forest and plateau Indians have been enemies and that their
cultures are so distinct, for their environment everywhere calls for unlike
modes of existence and distinct cultural development.

CHAPTER V

THE COUNTRY OF THE SHEPHERDS
THE lofty mountain zones of Peru, the high bordering valleys, and the
belts of rolling plateau between are occupied by tribes of shepherds. In that
cold, inhospitable region at the top of the country are the highest permanent
habitations in the world—17,100 feet (5,210 m.)—the loftiest pastures, the
greatest degree of adaptation to combined altitude and frost. It is here only a
step from Greenland to Arcady. Nevertheless it is Greenland that has the
people. Why do they shun Arcady? To the traveler from the highlands the
fertile valleys between 5,000 and 8,000 feet (1,500 to 2,500 m.) seem like
the abode of friendly spirits to whose charm the highland dweller must
yield. Every pack-train from valley to highland carries luxury in the form of
fruit, coca, cacao, and sugar. One would think that every importation of
valley products would be followed by a wave of migration from highland to
valley. On the contrary the highland people have clung to their lofty
pastures for unnumbered centuries. Until the Conquest the last outposts of
the Incas toward the east were the grassy ridges that terminate a few
thousand feet below the timber line.

In this natural grouping of the people where does choice or blind
prejudice or instinct leave off? Where does necessity begin? There are
answers to most of these questions to be found in the broad field of
geographic comparison. But before we begin comparisons we must study
the individual facts upon which they rest. These facts are of almost every
conceivable variety. They range in importance from a humble shepherd’s
stone corral on a mountain slope to a thickly settled mountain basin. Their
interpretation is to be sought now in the soil of rich playa lands, now in the
fixed climatic zones and rugged relief of deeply dissected, lofty highlands
in the tropics. Some of the controlling factors are historical, others
economic; still other factors have exerted their influence through obscure
psychologic channels almost impossible to trace. The why of man’s
distribution over the earth is one of the most complicated problems in
natural science, and the solution of it is the chief problem of the modern
geographer.
At first sight the mountain people of the Peruvian Andes seem to be
uniform in character and in mode of life. The traveler’s first impression is
that the same stone-walled, straw-thatched type of hut is to be found
everywhere, the same semi-nomadic life, the same degrees of poverty and
filth. Yet after a little study the diversity of their lives is seen to be, if not a
dominating fact, at least one of surprising importance. Side by side with this
diversity there runs a corresponding diversity of relations to their physical
environment. Nowhere else on the earth are greater physical contrasts
compressed within such small spaces. If, therefore, we accept the
fundamental theory of geography that there is a general, necessary, varied,
and complex relation between man and the earth, that theory ought here to
find a really vast number of illustrations. A glance at the accompanying
figures discloses the wide range of relief in the Peruvian Andes. The
corresponding range in climate and in life therefore furnishes an ample field
for the application of the laws of human distribution.
In analyzing the facts of distribution we shall do well to begin with the
causes and effects of migration. Primitive man is in no small degree a
wanderer. His small resources often require him to explore large tracts. As
population increases the food quest becomes more intense, and thus there
come about repeated emigrations which increase the food supply, extend its
variety, and draw the pioneers at last into contact with neighboring groups.
The farther back we go in the history of the race the clearer it becomes that

migrations lie at the root of much of human development. The raid for
plunder, women, food, beasts, is a persistent feature of the life of those
primitive men who live on the border of unlike regions.
The shepherd of the highland and the forest hunter of the plains perforce
range over vast tracts, and each brings back to the home group news that
confirms the tribal choice of habitation or sets it in motion toward a more
desirable place. Superstitions may lead to flight akin to migration.
Epidemics may be interpreted as the work of a malignant spirit from which
men must flee. War may drive a defeated group into the fastnesses of a
mountain forest where pursuit by stream or trail weakens the pursuer and
confines his action, thereby limiting his power. Floods may come and
destroy the cultivated spots. Want or mere desire in a hundred forms may
lead to movement.
Even among forest tribes long stationary the facile canoe and the light
household necessities may easily enable trivial causes to develop the spirit
of restlessness. Pressure of population is a powerful but not a general cause
of movement. It may affect the settled groups of the desert oases, or the
dense population of fertile plains that is rooted in the soil. On the other hand
mere whims may start a nomadic group toward a new goal. Often the goal
is elusive and the tribe turns back to the old haunts or perishes in the shock
of unexpected conflict.
In the case of both primitive societies and those of a higher order the
causes and the results of migration are often contradictory. These will
depend on the state of civilization and the extremes of circumstance. When
the desert blooms the farmer of the Piura Valley in northwestern Peru turns
shepherd and drives his flocks of sheep and goats out into the short-lived
pastures of the great pampa on the west. In dry years he sends them
eastward into the mountains. The forest Indian of the lower Urubamba is a
fisherman while the river is low and lives in a reed hut beside his cultivated
patch of cane and yuca. When the floods come he is driven to the higher
ground in the hills where he has another cultivated patch of land and a rude
shelter. To be sure, these are seasonal migrations, yet through them the
country becomes better known to each new generation of men. And each
generation supplies its pioneers, who drift into the remoter places where
population is scarce or altogether wanting.

Fig. 24—This stone hut, grass-thatched, is the highest permanent
habitation in Peru, and is believed to be the highest in the world.
Altitude of 17,100 feet (5,210 m.) determined by instrumental survey.
The general geographic relationships of the region in which the hut is
situated are shown in Fig. 25. For location see the topographic map,
204 .

Dry years and extremely dry years may have opposite effects. When
moderate dryness prevails the results may be endurable. The oases become
crowded with men and beasts just when they can ill afford to support them.
The alfalfa meadows become overstocked and cattle become lean and
almost worthless. But there is at least bare subsistence. By contrast, if
extreme and prolonged drought prevails, some of the people are driven
forth to more favored spots. At Vallenar in central Chile some of the
workmen in extreme years go up to the nitrate pampa; in wet years they
return. When the agents of the nitrate companies hear of hard times in a
desert valley they offer employment to the stricken people. It not
infrequently happens that when there are droughts in desert Chile there are
abundant rains in Argentina on the other side of the Cordillera. There has
therefore been for many generations an irregular and slight, though definite,
shifting of population from one side of the mountains to the other as periods
of drought and periods of rain alternated in the two regions. Some think
there is satisfactory evidence to prove that a number of the great Mongolian
emigrations took place in wet years when pasture was abundant and when
the pastoral nomad found it easy to travel. On the other hand it has been
urged that the cause of many emigrations was prolonged periods of drought
when the choice lay between starvation and flight. It is evident from the

foregoing that both views may be correct in spite of the fact that identical
effects are attributed to opposite causes.

Fig. 25—Regional diagram for the Maritime Cordillera to show the
physical relations in the district where the highest habitation in the
world are located. For location, see Fig. 20. It should be remembered
that the orientation of these diagrams is generalized. By reference to 20
it will be seen that some portions of the crest of the Maritime
Cordillera run east and west and others north and south. The same is
true of the Cordillera Vilcapampa, Fig. 36.

Note on regional diagrams.—For the sake of clearness I have classified the accompanying facts
of human distribution in the country of the shepherds and represented them graphically in “regional”
diagrams, Figs. 17, 25, 26, 32, 34, 36, 42, 65. These diagrams are constructed on the principle of
dominant control. Each brings out the factors of greatest importance in the distribution of the people
in a given region. Furthermore, the facts are compressed within the limits of a small rectangle. This
compression, though great, respects all essential relations. For example, every location on these
diagrams has a concrete illustration but the accidental relations of the field have been omitted; the
essential relations are preserved. Each diagram is, therefore, a kind of generalized type map. It bears
somewhat the same relation to the facts of human geography that a block diagram does to
physiography. The darkest shading represents steep snow-covered country; the next lower grade
represents rough but snow-free country; the lightest shading represents moderate relief; unshaded
parts represent plain or plateau. Small circles represent forest or woodland; small open-spaced dots,
grassland. Fine alluvium is represented by small closely spaced dots; coarse alluvium by large
closely spaced dots.
To take an illustration. In Figure 32 we have the Apurimac region near Pasaje (see location map,
20 ). At the lower edge of the rectangle is a snow-capped outlier of the Cordillera Vilcapampa. The
belt of rugged country represents the lofty, steep, exposed, and largely inaccessible ridges at the mid-
elevations of the mountains below the glaciated slopes at the heads of tributary valleys. The villages
in the belt of pasture might well be Incahuasi and Corralpata. The floors of the large canyons on
either hand are bordered by extensive alluvial fans. The river courses are sketched in a diagrammatic
way only, but a map would not be different in its general disposition. Each location is justified by a
real place with the same essential features and relations. In making the change there has been no
alteration of the general relation of the alluvial lands to each other or to the highland. By suppressing
unnecessary details there is produced a diagram whose essentials have simple and clear relations.
When such a regional diagram is amplified by photographs of real conditions it becomes a sort of
generalized picture of a large group of geographic facts. One could very well extend the method to
the whole of South America. It would be a real service to geography to draw up a set of, say, twelve
to fifteen regional diagrams, still further generalized, for the whole of the continent. As a broad
classification they would serve both the specialist and the general student. As the basis for a regional
map of South America they would be invaluable if worked out in sufficient detail and constructed on
the indispensable basis of field studies.

It is still an open question whether security or insecurity is more
favorable for the broad distribution of the Peruvian Indians of the mountain
zone which forms the subject of this chapter. Certainly both tend to make
the remoter places better known. Tradition has it that, in the days of
intertribal conflict before the Conquest, fugitives fled into the high
mountain pastures and lived in hidden places and in caves. Life was
insecure and relief was sought in flight. On the other hand peace has
brought security to life. The trails are now safe. A shepherd may drive his
flock anywhere. He no longer has any one to fear in his search for new
pastures. It would perhaps be safe to conclude that there is equally broad
distribution of men in the mountain pastures in time of peace and in time of
war. There is, however, a difference in the kind of distribution. In time of
peace the individual is safe anywhere; in time of unrest he is safe only when

isolated and virtually concealed. By contrast, the group living near the trails
is scattered by plundering bands and war parties. The remote and isolated
group may successfully oppose the smaller band and the individuals that
might reach the remoter regions. The fugitive group would have nothing to
fear from large bands, for the limited food supply would inevitably cause
these to disintegrate upon leaving the main routes of travel. Probably the
fullest exploration of the mountain pastures has resulted from the
alternation of peace and war. The opposite conditions which these establish
foster both kinds of distribution; hence both the remote group life
encouraged by war and the individual’s lack of restraint in time of peace are
probably in large part responsible for the present widespread occupation of
the Peruvian mountains.
The loftiest habitation in the world (Fig. 24) is in Peru. Between
Antabamba and Cotahuasi occur the highest passes in the Maritime
Cordillera. We crossed at 17,400 feet (5,300 m.), and three hundred feet
lower is the last outpost of the Indian shepherds. The snowline, very steeply
canted away from the sun, is between 17,200 and 17,600 feet (5,240 to
5,360 m.). At frequent intervals during the three months of winter,
snowfalls during the night and terrific hailstorms in the late afternoon drive
both shepherds and flocks to the shelter of leeward slopes or steep canyon
walls. At our six camps, between 16,000 and 17,200 feet (4,876 and 5,240
m.), in September, 1911, the minimum temperature ranged from 4° to 20°F.
The thatched stone hut that we passed at 17,100 feet and that enjoys the
distinction of being the highest in the world was in other respects the same
as the thousands of others in the same region. It sheltered a family of five.
As we passed, three rosy-cheeked children almost as fat as the sheep about
them were sitting on the ground in a corner of the corral playing with balls
of wool. Hundreds of alpacas and sheep grazed on the hill slopes and valley
floor, and their tracks showed plainly that they were frequently driven up to
the snowline in those valleys where a trickle of water supported a band of
pasture. Less than a hundred feet below them were other huts and flocks.
Here we have the limits of altitude and the limits of resources. The
intervalley spaces do not support grass. Some of them are quite bare, others
are covered with mosses. It is too high for even the tola bush—that pioneer
of Alpine vegetation in the Andes. The distance[6] to Cotahuasi is 75 miles
(120 km.), to Antabamba 50 miles (80 km.). Thence wool must be shipped
by pack-train to the railroad in the one case 250 miles (400 km.) to

Arequipa, in the other case 200 miles (320 km.) to Cuzco. Even the
potatoes and barley, which must be imported, come from valleys several
days’ journey away. The question naturally arises why these people live on
the rim of the world. Did they seek out these neglected pastures, or were
they driven to them? Do they live here by choice or of necessity? The
answer to these questions introduces two other geographic factors of prime
importance, the one physical, the other economic.
The main tracts of lofty pasture above Antabamba cover mountain slopes
and valley floor alike, but the moist valley floors supply the best grazing.
Moreover, the main valleys have been intensively glaciated. Hence, though
their sides are steep walls, their floors are broad and flat. Marshy tracts,
periodically flooded, are scattered throughout, and here and there are
overdeepened portions where lakes have gathered. There is a thick carpet of
grass, also numerous huts and corrals, and many flocks. At the upper edge
of the main zone of pasture the grasses become thin and with increasing
altitude give out altogether except along the moist valley floors or on
shoulders where there is seepage.
If the streams head in dry mountain slopes without snow the grassy
bands of the valley floor terminate at moderate elevations. If the streams
have their sources in snowfields or glaciers there is a more uniform run-off,
and a ribbon of pasture may extend to the snowline. To the latter class
belong the pastures that support these remote people.
In the case of the Maritime Andes the great elevation of the snowline is
also a factor. If, in Figure 25, we think of the snowline as at the upper level
of the main zone of pasture then we should have the conditions shown in
Figure 36, where the limit of general, not local, occupation is the snowline,
as in the Cordillera Vilcapampa and between Chuquibambilla and
Antabamba.
A third factor is the character of the soil. Large amounts of volcanic ash
and lapilli were thrown out in the late stages of volcanic eruption in which
the present cones of the Maritime Andes were formed. The coarse texture of
these deposits allows the ready escape of rainwater. The combination of
extreme aridity and great elevation results in a double restraint upon
vegetation. Outside of the moist valley floors, with their film of ground
moraine on whose surface plants find a more congenial soil, there is an
extremely small amount of pasture. Here are the natural grazing grounds of

the fleet vicuña. They occur in hundreds, and so remote and little disturbed
are they that near the main pass one may count them by the score. As we
rode by, many of them only stared at us without taking the trouble to get
beyond rifle shot. It is not difficult to believe that the Indians easily shoot
great numbers in remote valleys that have not been hunted for years.
The extreme conditions of life existing on these lofty plateaus are well
shown by the readiness with which even the hardy shepherds avail
themselves of shelter. Wherever deep valleys bring a milder climate within
reach of the pastures the latter are unpopulated for miles on either side. The
sixty-mile stretch between Chuquibamba and Salamanca is without even a
single hut, though there are pastures superior to the ones occupied by those
loftiest huts of all. Likewise there are no permanent homes between
Salamanca and Cotahuasi, though the shepherds migrate across the belt in
the milder season of rain. Eastward and northward toward the crest of the
Maritime Cordillera there are no huts within a day’s journey of the
Cotahuasi canyon. Then there is a group of a dozen just under the crest of
the secondary range that parallels the main chain of volcanoes. Thence
northward there are a number of scattered huts between 15,500 and 16,500
feet (4,700 and 5,000 m.), until we reach the highest habitations of all at
17,100 feet (5,210m.).

Fig. 26—Regional diagram to show the physical relations in the lava
plateau of the Maritime Cordillera west of the continental divide. For
location, see Fig. 20. Trails lead up the intrenched tributaries. If the
irrigated bench (lower right corner) is large, a town will be located on
it. Shepherds’ huts are scattered about the edge of the girdle of spurs.
There is also a string of huts in the deep sheltered head of each
tributary. See also Fig. 29 for conditions on the valley or canyon floor.

The unpopulated belts of lava plateau bordering the entrenched valleys
are, however, as distinctly “sustenance” spaces, to use Penck’s term, as the

irrigated and fertile alluvial fans in the bottom of the valley. This is well
shown when the rains come and flocks of llamas and sheep are driven forth
from the valleys to the best pastures. It is equally well shown by the
distribution of the shepherds’ homes. These are not down on the warm
canyon floor, separated by a half-day’s journey from the grazing. They are
in the intrenched tributary valleys of Figure 26 or just within the rim of the
canyon. It is not shelter from the cold but from the wind that chiefly
determines their location. They are also kept near the rim of the canyon by
the pressure of the farming population from below. Every hundred feet of
descent from the arid plateau (Fig. 29) increases the water supply. Springs
increase in number and size; likewise belts of seepage make their
appearance. The gradients in many places diminish, and flattish spurs and
shoulders interrupt the generally steep descents of the canyon wall. Every
change of this sort has a real value to the farmer and means an enhanced
price beyond the ability of the poor shepherd to pay. If you ask a wealthy
hacendado on the valley floor (Fig. 29), who it is that live in the huts above
him, he will invariably say “los Indios,” with a shrug meant to convey the
idea of poverty and worthlessness. Sometimes it is “los Indios pobres,” or
merely “los pobres.” Thus there is a vertical stratification of society
corresponding to the superimposed strata of climate and land.
At Salamanca (Fig. 62) I saw this admirably displayed under
circumstances of unusual interest. The floor and slopes of the valley are
more completely terraced than in any other valley I know of. In the
photograph, 30 , which shows at least 2,500 feet of descent near the town,
one cannot find a single patch of surface that is not under cultivation. The
valley is simply filled with people to the limit of its capacity. Practically all
are Indians, but with many grades of wealth and importance. When we rode
out of the valley before daybreak, one September morning in 1911, there
was a dead calm, and each step upward carried us into a colder stratum of
air. At sunrise we had reached a point about 2,000 feet above the town, or
14,500 feet (4,420 m.) above sea level. We stood on the frost line. On the
opposite wall of the valley the line was as clearly marked out as if it had
been an irrigating canal. The light was so fully reflected from the millions
of frost crystals above it that both the mountainside and the valley slopes
were sparkling like a ruffled lake at sunrise. Below the frost line the slopes
were dark or covered with yellow barley and wheat stubble or green alfalfa.

It happened that the frost line was near the line of division between corn
and potato cultivation and also near the line separating the steep rough
upper lands from the cultivable lower lands. Not a habitation was in sight
above us, except a few scattered miserable huts near broken terraces,
gullied by wet-weather streams and grown up to weeds and brush. Below us
were well-cultivated fields, and the stock was kept in bounds by stone
fences and corrals; above, the half-wild burros and mules roamed about
everywhere, and only the sheep and llamas were in rude enclosures. Thus in
a half hour we passed the frontier between the agricultural folk below the
frost line and the shepherd folk above it.

Fig. 27—Terraced valley slopes at Huaynacotas, Cotahuasi Valley,
Peru. Elevation 11,500 feet (3,500 m.).
Fig. 28—The highly cultivated and thoroughly terraced floor of the
Ollantaytambo Valley at Ollantaytambo. This is a tributary of the
Urubamba; elevation, 11,000 feet.

Fig. 29—Cotahuasi on the floor of the Cotahuasi canyon. The even
skyline of the background is on a rather even-topped lava plateau. The
terrace on the left of the town is formed on limestone, which is overlain
by lava flows. A thick deposit of terraced alluvium may be seen on the
valley floor, and it is on one of the lower terraces that the city of
Cotahuasi stands. The higher terraces are in many cases too dry for
cultivation. The canyon is nearly 7,000 feet (2,130 m.) deep and has
been cut through one hundred principal lava flows.

In a few spots the line followed an irregular course, as where flatter
lands were developed at unusual elevations or where air drainage altered the
normal temperature. And at one place the frost actually stood on the young
corn, which led us to speculate on the possibility of securing from
Salamanca a variety of maize that is more nearly resistant to light frosts
than any now grown in the United States. In the endless and largely
unconscious experimentation of these folk perched on the valley walls a
result may have been achieved ahead of that yet reached by our professional
experimenters. Certain it is that nowhere else in the world has the potato
been grown under such severe climatic conditions as in its native land of
Peru and Bolivia. The hardiest varieties lack many qualities that we prize.
They are small and bitter. But at least they will grow where all except very
few cultivated plants fail, and they are edible. Could they not be imported
into Canada to push still farther northward the limits of cultivation?
Potatoes are now grown at Forts Good Hope and McPherson in the lower

Mackenzie basin. Would not the hardiest Peruvian varieties grow at least as
far north as the continental timber line? I believe they could be grown still
farther north. They will endure repeated frosts. They need scarcely any
cultivation. Prepared in the Peruvian manner, as chuño, they could be kept
all winter. Being light, the meal derived from them could be easily packed
by hunters and prospectors. An Indian will carry in a pouch enough to last
him a week. Why not use it north of the continental limit of other cultivated
plants since it is the pioneer above the frost line on the Peruvian mountains?
The relation between farmer and shepherd or herdsman grows more
complex where deeper valleys interrupt the highlands and mountains. The
accompanying sketch, 32 , represents typical relations, though based chiefly
on the Apurimac canyon and its surroundings near Pasaje. First there is the
snow-clad region at the top of the country. Below it are grassy slopes, the
homes of mountain shepherds, or rugged mountain country unsuited for
grazing. Still lower there is woodland, in patches chiefly, but with a few
large continuous tracts. The shady sides of the ravines and the mountains
have the most moisture, hence bear the densest growths. Finally, the high
country terminates in a second belt of pasture below the woodland.

Fig. 32—Regional diagram representing the deep canyoned country
west of the Eastern Cordillera in the region of the Apurimac. For
photograph see Fig. 94. For further description see note on regional
diagrams, p. 51. Numbers 1, 2, and 3 correspond in position to the same
numbers in Fig. 33.

Fig. 30—Terraced hill slopes Fig. 31—Alpine pastures in the
near Salamanca. There is no part mountain valley between
of the photograph which is not Chuquibambilla and Lambrama.
covered with terraces save a few Huge stone corrals are built on
places where bushy growths are either slope, sheltered from the
visible or where torrents descend night winds that blow down-valley.
through artificial canals.

Whenever streams descend from the snow or woodland country there is
water for the stock above and for irrigation on the alluvial fan below. But
the spur ends dropping off abruptly several thousand feet have a limited
area and no running streams, and the ground water is hundreds of feet
down. There is grass for stock, but there is no water. In some places the
stock is driven back and forth every few days. In a few places water is
brought to the stock by canal from the woodland streams above, as at
Corralpata.[7] In the same way a canal brings water to Pasaje hacienda from
a woodland strip many miles to the west. The little canal in the figure is
almost a toy construction a few inches wide and deep and conveying only a
trickle of water. Yet on it depends the settlement at the spur end, and if it
were cut the people would have to repair it immediately or establish new
homes.

Fig. 33—Valley climates of the canyoned region shown in Fig. 32.

The canal and the pasture are possible because the slopes are moderate.
They were formed in an earlier cycle of erosion when the land was lower.
They are hung midway between the rough mountain slopes above and the
steep canyon walls below (Fig. 32). Their smooth descents and gentle
profiles are in very pleasing contrast to the rugged scenery about them. The
trails follow them easily. Where the slopes are flattest, farmers have settled
and produce good crops of corn, vegetables, and barley. Some farmers have
even developed three-and four-story farms. On an alluvial fan in the main
valley they raise sugar cane and tropical and subtropical fruits; on the flat
upper slopes they produce corn; in the moister soil near the edge of the
woodland are fields of mountain potatoes; and the upper pastures maintain
flocks of sheep. In one district this change takes place in a distance that may
be covered in five hours. Generally it is at least a full and hard day’s
journey from one end of the series to the other.
Wherever these features are closely associated they tend to be controlled
by the planter in some deep valley thereabouts. Where they are widely
scattered the people are independent, small groups living in places nearly
inaccessible. Legally they are all under the control of the owners of princely
tracts that take in the whole country, but the remote groups are left almost
wholly to themselves. In most cases they are supposed to sell their few
commercial products to the hacendado who nominally owns their land, but
the administration of this arrangement is left largely to chance. The
shepherds and small farmers near the plantation are more dependent upon
the planter for supplies, and also their wants are more varied and numerous.
Hence they pay for their better location in free labor and in produce sold at
a discount.
So deep are some of the main canyons, like the Apurimac and the
Cotahuasi, that their floors are arid or semi-arid. The fortunes of Pasaje are
tied to a narrow canal from the moist woodland and a tiny brook from a
hollow in the valley wall. Where the water has thus been brought down to
the arable soil of the fans there are rich plantations and farms. Elsewhere,
however, the floor is quite dry and uncultivated. In small spots here and
there is a little seepage, or a few springs, or a mere thread of water that will
not support a plantation, wherefore there have come into existence the
valley herdsmen and shepherds. Their intimate knowledge of the moist
places is their capital, quite as much as are the cattle and sheep they own. In
a sense their lands are the neglected crumbs from the rich man’s table. So

we find the shepherd from the hills invading the valleys just as the valley
farmer has invaded the country of the shepherd.

Fig. 34—Regional diagram to show the typical physical conditions
and relations in an intermont basin in the Peruvian Andes. The Cuzco
basin (see Fig. 37) is an actual illustration; it should, however, be
emphasized that the diagram is not a “map” of that basin, for whilst
conditions there have been utilized as a basis, the generalization has
been extended to illustrate many basins.

The basin type of topography calls into existence a set of relations quite
distinct from either of those we have just described. Figure 34 represents
the main facts. The rich and comparatively flat floor of the basin supports
most of the people. The alluvial fans tributary thereto are composed of fine
material on their outer margin and of coarse stony waste at their heads.
Hence the valley farms also extend over the edges of the fans, while only
pasture or dense chaparral occupies the upper portions. Finally there is the
steep margin of the basin where the broad and moderate slopes of the
highland break down to the floor of the basin.

Fig. 35—Climatic cross-section showing the location of various
zones of cultivation and pasture in a typical intermont basin in the
Peruvian Andes. The thickness of the dark symbols on the right is

proportional to the amount of each staple that is produced at the
corresponding elevation. See also the regional diagram Fig. 34.

If a given basin lies at an elevation exceeding 14,000 feet (4,270 m.),
there will be no cultivation, only pasture. If at 10,000 or 11,000 feet (3,000
or 3,350 m.), there will be grain fields below and potato fields above (Figs.
34 and 35). If still lower, fruit will come in and finally sugar cane and many
other subtropical products, as at Abancay. Much will also depend upon the
amount of available water and the extent of the pasture land. Thus the
densely populated Cuzco basin has a vast mountain territory tributary to it
and is itself within the limits of barley and wheat cultivation. Furthermore
there are a number of smaller basins, like the Anta basin on the north, which
are dependent upon its better markets and transportation facilities. A
dominance of this kind is self-stimulating and at last is out of all proportion
to the original differences of nature. Cuzco has also profited as the gateway
to the great northeastern valley region of the Urubamba and its big
tributaries. All of the varied products of the subtropical valleys find their
immediate market at Cuzco.
The effect of this natural conspiracy of conditions has been to place the
historic city of Cuzco in a position of extraordinary importance. Hundreds
of years before the Spanish Conquest it was a center of far-reaching
influence, the home of the powerful Inca kings. From it the strong arm of
authority and conquest was extended; to it came tribute of grain, wool, and
gold. To one accustomed to look at such great consequences as having at
least some ultimate connection with the earth, the situation of Cuzco would
be expected to have some unique features. With the glorious past of that
city in mind, no one can climb to the surrounding heights and look down
upon the fertile mountain-rimmed plain as at an ordinary sight (Fig. 37).
The secret of those great conquests lies not only in mind but in matter. If the
rise of the Incas to power was not related to the topography and climate of
the Cuzco basin, at least it is certain that without so broad and noble a stage
the scenes would have been enacted on a far different scale.
The first Inca king and the Spanish after the Incas found here no mobile
nomadic tribes melting away at the first touch, no savages hiding in forest
fastnesses, but a well-rooted agricultural race in whose center a large city
had grown up. Without a city and a fertile tributary plain no strong system
of government could be maintained or could even arise. It is a great

advantage in ruling to have subjects that cannot move. The agricultural
Indians of the Andean valleys and basins, in contrast to the mobile
shepherd, are as fixed as the soil from which they draw their life.
The full occupation of the pasture lands about the Cuzco basin is in
direct relation to the advantages we have already enumerated. Every part of
the region feels the pressure of population. Nowhere else in the Peruvian
Andes are the limits between cultivation and grazing more definitely drawn
than here. Moreover, there is today a marked difference between the types
that inhabit highland and basin. The basin Indian is either a debauched city
dweller or, as generally, a relatively alert farmer. The shepherds are
exceedingly ignorant and live for the most part in a manner almost as
primitive as at the time of the Conquest. They are shy and suspicious. Many
of them prefer a life of isolation and rarely go down to the town. They live
on the fringe of culture. The new elements of their life have come to them
solely by accident and by what might be called a process of ethnic seepage.
The slight advances that have been made do not happen by design, they
merely happen. Put the highland shepherd in the basin and he would starve
in competition with the basin type. Undoubtedly he would live in the basin
if he could. He has not been driven out of the basin; he is kept out.
And thus it is around the border of the Abancay basin and others like it.
Only, the Abancay basin is lower and more varied as to resources. The
Indian is here in competition with the capitalistic white planter. He lives on
the land by sufferance alone. Farther up the slopes are the farms of the
Indians and above them are the pastures of the ignorant shepherds. Whereas
the Indian farmer who raises potatoes clings chiefly to the edge of the
Cuzco basin where lie the most undesirable agricultural lands, the Indian
farmers of Abancay live on broad rolling slopes like those near the pass
northward toward Huancarama. They are unusually prosperous, with fields
so well cultivated and fenced, so clean and productive, that they remind one
somewhat of the beautiful rolling prairies of Iowa.
It remains to consider the special topographic features of the mountain
environments we are discussing, in the Vilcapampa region on the eastern
border of the Andes (Fig. 36). The Cordillera Vilcapampa is snow-crested,
containing a number of fine white peaks like Salcantay, Soray, and
Soiroccocha (Fig. 140). There are many small glaciers and a few that are
several miles long. There was here in glacial times a much larger system of
glaciers, which lived long enough to work great changes in the topography.

The floors of the glaciated valleys were smoothed and broadened and their
gradients flattened (Figs. 137 and 190). The side walls were steepened and
precipitous cirques were formed at the valley heads. Also, there were built
across the valleys a number of stony morainic ridges. With all these changes
there was, however, but little effect upon the main masses of the big
intervalley spurs. They remain as before—bold, wind-swept, broken, and
nearly inaccessible.

Fig. 36—Regional diagram for the Eastern Cordillera or Cordillera
Vilcapampa. Note the crowded zones on the right (east and north) in
contrast to the open succession on the left. In sheltered places woodland
extends even higher than shown. At several points patches of it grow
right under the snowline. Other patches grow on the floors of the
glaciated valley troughs.

The work of the glaciers aids the mountain people. The stony moraines
afford them handy sizable building material for their stone huts and their
numerous corrals. The thick tufts of grass in the marshy spots in the
overdeepened parts of the valleys furnish them with grass for their thatched
roofs. And, most important of all, the flat valley floors have the best pasture
in the whole mountain region. There is plenty of water. There is seclusion,
and, if a fence be built from one valley wall to another as can be done with
little labor, an entire section of the valley may be inclosed. A village like
Choquetira, located on a bench on the valley side, commands an extensive
view up and down the valley—an important feature in a grazing village
where the corrals cannot always be built near the houses of the owners.

Long, finger-like belts of highland-shepherd population have thus been
extended into the mountain valleys. Sheep and llamas drift right up to the
snowline.
There is, however, a marked difference between the people on opposite
sides of the Cordillera Vilcapampa. On the west the mountains are bordered
by a broad highland devoted to grazing. On the east there is a narrower
grazing belt leading abruptly down to tropical valleys. The eastern or
leeward side is also the warmer and wetter side of the Cordillera. The
snowline is several hundred feet lower on the east. The result is that patches
of scrub and even a little woodland occur almost at the snowline in favored
places. Mist and storms are more frequent. The grass is longer and fresher.
Vegetation in general is more abundant. The people make less of wool than
of cattle, horses, and mules. Vilcabamba pueblo is famous for its horses,
wiry, long-haired little beasts, as hardy as Shetland ponies. We found cattle
grazing only five hundred feet below the limit of perpetual snow. There are
cultivated spots only a little farther down, and only a thousand feet below
the snow are abandoned terraces. At the same elevation are twisted quenigo
trees, at least two hundred years old, as shown by their rings of growth.
Thus the limits of agriculture are higher on the east; likewise the limits of
cattle grazing that naturally goes with agriculture. Sheep would thrive, but
llamas do better in drier country, and the shepherd must needs mix his
flocks, for the wool which is his chief product requires transportation and
only the cheap and acclimated llama is at the shepherd’s disposal. From
these facts it will be seen that the anthropo-geographic contrasts between
the eastern and western sides of the Cordillera Vilcapampa are as definite as
the climatic and vegetal contrasts. This is especially well shown in the
differences between dry Arma, deep-sunk in a glaciated valley west of the
crest of the mountains, and wet Puquiura, a half-day’s journey east of the
crest. There is no group on the east at all comparable to the shepherds of
Choquetira, either in the matter of thorough-going dependence upon
grazing or in that of dependence upon glacial topography.

Fig. 37—Cuzco and a portion of the famous Cuzco basin with
bordering grassy highlands.
Fig. 38—Terraced valley slopes and floor, Urubamba Valley between
Urubamba and Ollantaytambo.

Fig. 39—Huichihua, near Chuquibambilla, a typical mountain
village, in the valleys of the Central Ranges, Peruvian Andes.

Fig. 40—Potato fluid above Vilcabamba at 12,000 feet (3,660 m.).
The natural sod is broken by a steel-shod stick and the seed potato
dropped into a mere puncture. It receives no attention thereafter until
harvest time.

Topography is not always so intimately related to the life of the people
as here. In our own country the distribution of available water is a far
greater factor. The Peruvian Andes therefore occupy a distinctive place in
geography, since, more nearly than in most mountains, their physical
conditions have typical human relations that enable one clearly to
distinguish the limits of control of each feature of climate or relief.

CHAPTER VI

THE BORDER VALLEYS OF THE EASTERN ANDES
On the northeastern border of the Peruvian Andes long
mountain spurs trail down from the regions of snow to the
forested plains of the Amazon. Here are the greatest
contrasts in the physical and human geography of the
Andean Cordillera. So striking is the fact that every serious
student of Peru finds himself compelled to cross and
recross this natural frontier. The thread of an investigation
runs irregularly now into one border zone, now into
Fig. 41—
another. Out of the forest came the fierce marauders who
Regional diagram in the early period drove back the Inca pioneers. Down
of the eastern into the forest to escape from the Spaniards fled the last
aspect of the
Cordillera
Inca and his fugitive court. Here the Jesuit fathers sowed
Vilcapampa. See their missions along the forest margin, and watched over
also 17 of which them for two hundred years. From the mountain border one
this is an
enlarged section. rubber project after another has been launched into the vast
swampy lowlands threaded by great rivers. As an ethnic
boundary the eastern mountain border of Peru and Bolivia
has no equal elsewhere in South America. From the earliest antiquity the
tribes of the grass-covered mountains and the hordes of the forested plains
have had strongly divergent customs and speech, that bred enduring hatred
and led to frequent and bloody strife.

Fig. 42—Rug weaver at Cotahuasi. The industry is limited to a small
group of related families, living in the Cotahuasi Canyon near
Cotahuasi. The rugs are made of alpaca wool. Pure black, pure white,
and various shades of mixed gray wool are employed. The result is that
the rugs have “fast” colors that always retain their original contrasts.
They are made only to order at the homes of the purchasers. The
money payment is small, but to it is added board and lodging, besides
tobacco, liqueurs, and wine. Before drinking they dip their finger-tips
in the wine and sprinkle the earth “that it may be fruitful,” the air
“that it may be warm,” the rug “that it may turn out well,” and finally
themselves, making the sign of the cross. Then they set to work.

Fig. 43—The floor of the Urubamba Valley from Tarai. The work of
the glaciers was not confined to the lofty situations. Mountain débris

was delivered to all the streams, many of which aggraded their floors to
a depth of several hundred feet, thus increasing the extent of arable soil
at elevations where a less rigorous climate permits the production of
crops and encourages intensive cultivation.

On the steepest spurs of the Pampaconas Valley the traveler may go from
snow to pasture in a half day and from pasture to forest in the same time.
Another day he is in the hot zone of the larger valley floors, the home of the
Machigangas. The steep descents bring out the superimposed zones with
diagrammatic simplicity. The timber line is as sharply marked as the edge
of a cultivated field. At a point just beyond the huts of Pampaconas one may
stand on a grassy spur that leads directly up—a day’s journey—to the white
summits of the Cordillera Vilcapampa. Yet so near him is the edge of the
forest that he is tempted to try to throw a stone into it. In an hour a bitter
wind from the mountains may drive him to shelter or a cold fog come
rolling up from the moist region below. It is hard to believe that oppressive
heat is felt in the valley just beneath him.
In the larger valleys the geographic contrasts are less sharp and the
transition from mountains to plain, though less spectacular, is much more
complex and scientifically interesting. The forest types interfinger along the
shady and the sunny slopes. The climate is so varied that the forest takes on
a diversified character that makes it far more useful to man. The forest
Indians and the valley planters are in closer association. There are many
islands and peninsulas of plateau population on the valley floor. Here the
zones of climate and the belts of fertile soil have larger areas and the land
therefore has greater economic value. Much as the valley people need easier
and cheaper communication with the rest of Peru it is no exaggeration to
say that the valley products, are needed far more by the coast and plateau
peoples to make the republic self-supporting. Coca, wood, sugar, fruit, are
in such demand that their laborious and costly transportation from the
valleys to the plateau is now carried on with at least some profit to the
valley people. Improved transportation would promote travel and friendship
and supply a basis for greater political unity.
A change in these conditions is imminent. Years ago the Peruvian
government decreed the construction of a railway from Cuzco to Santa Ana
and preliminary surveys were made but without any immediate practical
effect. By June, 1914, 12.4 miles (20 km.) had been opened to traffic. The
total length of the proposed line is 112 miles (180 km.), the gauge is to be

only 2.46 feet (75 cm.),[8] and the proposed cost several millions of dollars.
The financial problem may be solved either by a diversion of local
revenues, derived from taxes on coca and alcohol, or by borrowed foreign
capital guaranteed by local revenues.
A shrubby vegetation is scattered along the valley from the village of
Urubamba, 12,000 feet (3,658 m.) above sea level, to the Canyon of
Torontoy. It is local and of little value. Trees appear at Ollantaytambo,
11,000 feet (3,353 m.), and here too are more extensive wheat and maize
fields besides throngs of cacti and great patches of wild geraniums. On our
valley journey we camped in pleasant fields flanked by steep hills whose
summits each morning were tipped with snow. Enormous alluvial fans have
partly filled up the valleys and furnished broad tracts of fertile soil. The
patient farmers have cleared away the stones on the flatter portions and
built retaining walls for the smooth fields required for irrigation. In places
the lower valley slopes are terraced in the most regular manner (Fig. 38).
Some of the fans are too steep and stony for cultivation, exposing bare
tracts which wash down and cover the fields. Here and there are stone walls
built especially to retain the rush of mud and stones that the rains bring
down. Many of them were overthrown or completely buried. Unless the
stream channels on the fans are carefully watched and effective works kept
up, the labor of years may be destroyed in a single slide from the head of a
steep fan.
Each group of fans has a population proportioned to its size and fertility.
If there are broad expanses a town like Urubamba or a great hacienda like
Huadquiña is sure to be found. One group of huge stony fans below
Urubamba (Fig. 180) has only a thin population, for the soil is coarse and
infertile and the rivers deeply intrenched. In some places the tiny fans
perched high upon the flanks of the mountains where little tributaries burst
out of steep ravines are cultivated by distant owners who also till parts of
the larger fans on the main valley floors. Between the fans of the valley
bottoms and the smooth slopes of the high plateaus are the unoccupied
lands—the steep canyon walls. Only in the most highly favored places
where a small bench or a patch of alluvium occurs may one find even an
isolated dwelling. The stair-like trails, in some places cut in solid rock,
zigzag up the rocky slopes. An ascent of a thousand feet requires about an
hour’s travel with fresh beasts. The valley people are therefore walled in. If
they travel it is surely not for pleasure. Even business trips are reduced to

the smallest number. The prosperity and happiness of the valley people are
as well known among the plateau people as is their remarkable bread. Their
climate has a combination of winter rain and winter cold with light frosts
that is as favorable for good wheat as the continuous winter cold and snow
cover of our northern Middle West. The colder grainfields of the plateau are
sowed to barley chiefly, though there is also produced some wheat.
Urubamba wheat and bread are exported in relatively large quantities, and
the market demands greater quantities than the valley can supply. Oregon
and Washington flour are imported at Cuzco, two days’ muleback journey
from the wheat fields of Urubamba.
Such are the conditions in the upper Urubamba Valley. The lower valley,
beginning at Huadquiña, is 8,000 feet (2,440 m.) above sea level and
extends down to the two-thousand-foot contour at Rosalina and to one
thousand feet (305 m.) at Pongo de Mainique. The upper and lower sections
are only a score of miles (30 km.) apart between Huadquiña and Torontoy,
but there is a difference in elevation of three thousand feet (915 m.) at just
the level where the maximum contrasts are produced. The cold timber line
is at 10,500 feet (3,200 m.).[9] Winter frosts are common at the one place;
they are absent altogether at the other. Torontoy produces corn; Huadquiña
produces sugar cane.
These contrasts are still further emphasized by the sharp topographic
break between the two unlike portions of the valley. A few miles below
Torontoy the Urubamba plunges into a mile-deep granite canyon. The walls
are so close together that it is impossible from the canyon floor to get into
one photograph the highest and steepest walls. At one place there is over a
mile of descent in a horizontal distance of 2,000 feet. Huge granite slabs fall
off along joint planes inclined but 15° from the vertical. The effect is
stupendous. The canyon floor is littered with coarse waste and the gradient
of the river greatly steepened. There is no cultivation. The trees cling with
difficulty to patches of rock waste or to the less-inclined slopes. There is a
thin crevice vegetation that outlines the joint pattern where seepage supplies
the venturesome roots with moisture. Man has no foothold here, save at the
top of the country, as at Machu Picchu, a typical fortress location
safeguarded by the virtually inaccessible canyon wall and connected with
the main ridge slopes only by an easily guarded narrow spur. Toward the
lower end of the canyon a little finer alluvium appears and settlement
begins. Finally, after a tumble of three thousand feet over countless rapids

the river emerges at Colpani, where an enormous mass of alluvium has been
dumped. The well-intrenched river has already cut a large part of it away. A
little farther on is Huadquiña in the Salcantay Valley, where a tributary of
the Urubamba has built up a sheet of alluvial land, bright green with cane.
From the distant peaks of Salcantay and its neighbors well-fed streams
descend to fill the irrigation channels. Thus the snow and rock-waste of the
distant mountains are turned into corn and sugar on the valley lowlands.

Fig. 44—The snow-capped Cordillera Vilcapampa north of Yucay
and the upper canyon of the Urubamba from the wheat fields near
Chinchero. In the foreground is one of the well-graded mature slopes of
Fig. 123. The crests of the mountains lie along the axis of a granite
intrusion. The extent of the snowfields is extraordinary in view of the
low latitude, 13° S.
Fig. 45—Rounded slopes due to glacial action at Pampaconas in the
Pampaconas Valley near Vilcabamba. A heavy tropical forest extends
up the Pampaconas Valley to the hill slopes in the background. Its
upper limit of growth is about 10,000 feet (3,050 m.). The camera is
pointed slightly downhill.

Fig. 46—Hacienda Huadquiña in the Salcantay Valley a short
distance above its junction with the Urubamba, elevation 8,000 feet
(2,440 m.). The cultivated fields are all planted to sugar cane. The
mountain slopes are devoted to grazing.

The Cordillera Vilcapampa is a climatic as well as a topographic barrier.
The southwestern aspect is dry; the northeastern aspect forested. The gap of
the canyon, it should be noticed, comes at a critical level, for it falls just
above the upper border of the zone of maximum precipitation. The result is
that though mists are driven through the canyon by prolonged up-valley
winds, they scatter on reaching the plateau or gather high up on the flanks
of the valley or around the snowy peaks overlooking the trail between
Ollantaytambo and Urubamba. The canyon walls are drenched with rains
and even some of the lofty spurs are clothed with dense forest or scrub.
Farther down the valley winds about irregularly, now pushed to one side
by a huge alluvial fan, now turned by some resistant spur of rock. Between
the front range of the Andes and the Cordillera Vilcapampa there is a broad
stretch of mountain country in the lee of the front range which rises to 7,000
feet (2,134 m.) at Abra Tocate (Fig. 15), and falls off to low hills about
Rosalina. It is all very rough in that there are nowhere any flats except for
the narrow playa strips along the streams. The dense forest adds to the
difficulty of movement. In general appearance it is very much like the
rugged Cascade country of Oregon except that the Peruvian forest is much
more patchy and its trees are in many places loaded with dense dripping
moss which gives the landscape a somber touch quite absent from most of
the forests of the temperate zone.

The fertility of the eastern valleys of Peru—the result of a union of
favorable climate and alluvial soil—has drawn the planter into this remote
section of the country, but how can he dispose of his products? Even today
with a railway to Cuzco from the coast it is almost impossible for him to get
his sugar and cacao to the outside world.[10] How did he manage before
even this railway was built? How could the eastern valley planter live
before there were any railways at all in Peru? In part he has solved the
problem as the moonshiner of Kentucky tried to solve it, and from cane
juice makes aguardiente (brandy). The latter is a much more valuable
product than sugar, hence (1) it will bear a higher rate of transportation, or
(2) it will at the same rate of transportation yield a greater net profit. In a
remote valley where sugar could not be exported on account of high freight
rates brandy could still be profitably exported.
The same may be said for coca and cacao. They are condensed and
valuable products. Both require more labor than sugar but are lighter in bulk
and thus have to bear, in proportion to their value, a smaller share of the
cost of transportation. At the end of three years coca produces over a ton of
leaves per acre per year, and it can be made to produce as much as two tons
to the acre. The leaves are picked four times a year. They are worth from
eight to twelve cents gold a pound at the plantation or sixteen cents a pound
at Cuzco. An orchard of well-cultivated and irrigated cacao trees will do
even better. Once they begin to bear the trees require relatively little care
except in keeping out weeds and brush and maintaining the water ditches.
However, the pods must be gathered at just the right time, the seeds must be
raked and dried with expert care, and after that comes the arduous labor of
the grinding. This is done by hand on an inclined plane with a heavy round
stone whose corners fit the hand. The chocolate must then be worked into
cakes and dried, or it must be sacked in heavy cowhide and sewed so as to
be practically air tight. When eight or ten years old the trees are mature and
each may then bear a thousand pounds of seed.

Fig. 47—The Urubamba Valley Fig 48—Coca seed beds near
below Paltaybamba. Harder rocks Quillabamba, Urubamba Valley.
intruded into the schists that in The young plants are grown under
general compose the valley walls shade and after attaining a height
here form steep scarps. It has been of a foot or more are gradually
suggested (Davis) that such a accustomed to sunlight and finally
constricted portion of a valley be transplanted to the fields that are
called a “shut-in.” The old trail to become coca orchards.
climbed to the top of the valley
and over the back of a huge spur.
The new road is virtually a tunnel
blasted along the face of a cliff.

If labor were cheap and abundant the whole trend of tropical agriculture
in the eastern valleys would be toward intensive cultivation and the
production of expensive exports. But labor is actually scarce. Every planter
must have agents who can send men down from the plateau towns. And the
planter himself must use his labor to the best advantage. Aguardiente
requires less labor than cacao and coca. The cane costs about as much in
labor the first year as the coca bush or the cacao tree, but after that much
less. The manufacture of brandy from the cane juice requires little labor
though much expensive machinery. For chocolate, a storehouse, a grinding
stone, and a rake are all that are required. So the planter must work out his
own salvation individually. He must take account of the return upon
investments in machinery, of the number of hands he can command from
among the “faena” or free Indians, of the cost and number of imported
hands from the valley and plateau towns, and, finally, of the transportation
rates dependent upon the number of mules in the neighborhood, and
distance from the market. If in addition the labor is skilfully employed so as

to have the tasks which the various products require fall at different periods
of the year, then the planter may expect to make money upon his time and
get a return upon his initial investment in the land.[11]

Fig. 49—Fig tree formerly Fig. 50—A tiny rubber plant is
attached to a host but now left growing under the tripod made of
standing on its stilt-like aërial yuca stems tied with banana
roots owing to the decay of the leaves. Growing yuca is shown by
host. the naked stalks to the left and
right of this canopy, and banana
plants fill the background. A
plantation scene at Echarati.

The type of tropical agriculture which we have outlined is profitable for
the few planters who make up the white population of the valleys, but it has
a deplorable effect upon the Indian population. Though the planters, one
and all, complain bitterly of the drunken habits of their laborers, they
themselves put into the hands of the Indians the means of debauchery.
Practically the whole production of the eastern valleys is consumed in Peru.
What the valleys do not take is sent to the plateau, where it is the chief
cause of vicious conduct. Two-thirds of the prisoners in the city jails are
drunkards, and, to be quite plain, they are virtually supplied with brandy by
the planter, who could not otherwise make enough money. So although the
planter wants more and better labor he is destroying the quality of the little
there is, and, if not actually reducing the quantity of it, he is at least very
certainly reducing the rate of increase.
The difficulties of the valley planter could be at least partly overcome in
several ways. The railway will reduce transportation costs, especially when

the playas of the valleys are all cleared and the exports increased. Moreover
the eastern valleys are capable of producing things of greater utility than
brandy and coca leaves. So far as profits are increased by cheaper
transportation we may expect the planter to produce more rather than less of
brandy and coca, his two most profitable exports, unless other products can
be found that are still more profitable. The ratio of profits on sugar and
brandy will still be the same unless the government increases the tax on
brandy until it becomes no more profitable than sugar. That is what ought to
be done for the good of the Indian population. It cannot be done safely
without offering in its place the boon of cheaper railway transportation for
the sugar crop. Furthermore, with railway improvements should go the
blessings that agricultural experiments can bestow. A government farm in a
suitable place would establish rice and cotton cultivation. Many of the
playas or lower alluvial lands along the rivers can be irrigated. Only a small
fraction of the water of the Rio Urubamba is now turned out upon the fields.
For a large part of the year the natural rainfall would suffice to keep rice in
good condition. Six tons a year are now grown on Hacienda Sahuayaco for
local use on account of the heavy rate on rice imported on muleback from
Cuzco, whither it comes by sea and by trail from distant coastal valleys.
The lowland people also need rice and it could be sent to them down river
by an easier route than that over which their supplies now come. It should
be exported to the highlands, not imported therefrom. There are so many
varieties adapted to so many kinds of soil and climate that large amounts
should be produced at fair profits.
The cotton plant, on the other hand, is more particular about climate and
especially the duration of dry and wet seasons; in spite of this its
requirements are all met in the Santa Ana Valley. The rainfall is moderate
and there is an abundance of dry warm soil. The plant could make most of
its growth in the wet season, and the four months of cooler dry season with
only occasional showers would favor both a bright staple and a good
picking season. More labor would be required for cotton and rice and for
the increased production of cacao than under the present system. This
would not be a real difficulty if the existing labor supply were conserved by
the practical abolition, through heavy taxation, of the brandy that is the
chief cause of the laborer’s vicious habits. This is the first step in securing
the best return upon the capital invested in a railway. Economic progress is
here bound up with a very practical morality. Colonization in the eastern

valleys, of which there have been but a few dismal attempts, will only
extend the field of influence, it will not solve the real problem of bringing
the people of the rich eastern territory of Peru into full and honorable
possession of their natural wealth.
The value of the eastern valleys was known in Inca times, for their
stone-faced terraces and coca-drying patios may still be seen at Echarati and
on the border of the Chaupimayu Valley at Sahuayaco. Tradition has it that
here were the imperial coca lands, that such of the forest Indians as were
enslaved were obliged to work upon them, and that the leaves were sent to
Cuzco over a paved road now covered with “montaña” or forest. The
Indians still relate that at times a mysterious, wavering, white light appears
on the terraces and hills where old treasure lies buried. Some of the Indians
have gold and silver objects which they say were dug from the floors of hill
caves. There appears to have been an early occupation of the best lands by
the Spaniards, for the long extensions down them of Quechua population
upon which the conquerors could depend no doubt combined with the
special products of the valley to draw white colonists thither.[12] General
Miller,[13] writing in 1836, mentions the villages of Incharate (Echarati) and
Sant’ Ana (Santa Ana) but discourages the idea of colonization “... since the
river ... has lofty mountains on either side of it, and is not navigable even
for boats.”
In the “Itinerario de los viajes de Raimondi en el Peru”[14] there is an
interesting account of the settlement by the Rueda family of the great estate
still held by a Rueda, the wife of Señor Duque. José Rueda, in 1829, was a
government deputy representative and took his pay in land, acquiring
valuable territory on which there was nothing more than a mission. In 1830
Rueda ceded certain lands in “arriendo” (rent) and on these were founded
the haciendas Pucamoco, Sahuayaco, etc.
Señor Gonzales, the present owner of Hacienda Sahuayaco, recently
obtained his land—a princely estate, ten miles by forty—for 12,000 soles
($6,000). In a few years he has cleared the best tract, built several miles of
canals, hewed out houses and furniture, planted coca, cacao, cane, coffee,
rice, pepper, and cotton, and would not sell for $50,000. Moreover, instead
of being a superintendent on a neighboring estate and keeping a shop in
Cuzco, where his large family was a source of great expense, he has
become a wealthy landowner. He has educated a son in the United States.
He is importing machinery, such as a rice thresher and a distilling plant. His

son is looking forward to the purchase of still more playa land down river.
He pays a sol a day to each laborer, securing men from Cotabambas and
Abancay, where there are many Indians, a low standard of wages, little
unoccupied land, and a hot climate, so that the immigrants do not need to
become acclimatized.
The deepest valleys in the Eastern Andes of Peru have a semi-arid
climate which brings in its train a variety of unusual geographic relations.
At first as one descends the valley the shady and sunny slopes show sharply
contrasted vegetation.

Fig. 51—Robledo’s mountain-side trail in the Urubamba Valley
below Rosalina.
Fig. 52—An epiphyte partly supported by a dead host at Rosalina,
elevation 2,000 feet. The epiphyte bears a striking resemblance to a
horned beast whose arched back, tightly clasped fingers, and small eyes
give it a peculiarly malignant and life-like expression.

Fig. 53A—The smooth grassy slopes at the junction of the Yanatili
(left) and Urubamba (right) rivers near Pabellon.
Fig. 53B—Distribution of vegetation in the Urubamba Valley near
Torontoy. The patches of timber in the background occupy the shady
sides of the spurs; the sunny slopes are grass-covered; the valley floor is
filled with thickets and patches of woodland but not true forest.

The one is forested, the other grass-covered. Slopes that receive the noon
and afternoon sun the greater part of the year are hottest and therefore
driest. For places in 11° south latitude the sun is well to the north six
months of the year, nearly overhead for about two months, and to the south
four months. Northwesterly aspects are therefore driest and warmest, hence
also grass-covered. In many places the line between grass and forest is
developed so sharply that it seems to be the artificial edge of a cut-over
tract. This is true especially if the relief is steep and the hill or ridge-crests
sharp.[15]

Fig. 54—Climatic cross-section from the crest of the Cordillera
Vilcapampa down the eastern mountain valleys to the tropical plains.

At Santa Ana this feature is developed in an amazingly clear manner, and
it is also combined with the dry timber line and with productivity in a way I
have never seen equaled elsewhere. The diagram will explain the relation. It
will be seen that the front range of the mountains is high enough to shut off
a great deal of rainfall. The lower hills and ridges just within the front range
are relatively dry. The deep valleys are much drier. Each broad expansion of
a deep valley is therefore a dry pocket. Into it the sun pours even when all
the surrounding hills and mountains are wrapped in cloud. The greater
number of hours of sunshine hastens the rate of evaporation and still further
increases the dryness. Under the spur of much sunlight and of ample
irrigation water from the wetter hill slopes, the dry valley pockets produce
huge crops of fruit and cane.
The influence of the local climate upon tree growth is striking. Every
few days, even in the relatively dry winter season, clouds gather about the
hills and there are local showers. The lower limit of the zone of clouds is
sharply marked and at both Santa Ana and Echarati it is strikingly constant
in elevation—about five thousand feet above sea level. From the upper
mountains the forest descends, with only small patches of glade and prairie.
At the lower edge of the zone of cloud it stops abruptly on the warmer and
drier slopes that face the afternoon sun and continues on the moister slopes
that face the forenoon sun or that slope away from the sun.
But this is not the only response the vegetation makes. The forest
changes in character as well as in distribution. The forest in the wet zone is
dense and the undergrowth luxuriant. In the selective slope forest below the
zone of cloud the undergrowth is commonly thin or wanting and the trees
grow in rather even-aged stands and by species. Finally, on the valley floor
and the tributary fans, there is a distinct growth of scrub with bands of trees
along the water courses. Local tracts of coarse soil, or less rain on account
of a deep “hole” in a valley surrounded by steeper and higher mountains, or
a change in the valley trend that brings it into less free communication with
the prevailing winds, may still further increase the dryness and bring in a
true xerophytic or drought-resisting vegetation. Cacti are common all
through the Santa Ana Valley and below Sahuayaco there is a patch of tree
cacti and similar forms several square miles in extent. Still farther down and
about half-way between Sahuayaco and Pabellon are immense tracts of
grass-covered mountain slopes (Fig. 53). These extend beyond Rosalina, the
last of them terminating near Abra Tocate (Fig. 15). The sudden interruption

is due to a turn in the valley giving freer access to the up-valley winds that
sweep through the pass at Pongo de Mainique.
Northward from Abra Tocate (Fig. 55) the forest is
practically continuous. The break between the two
vegetal regions is emphasized by a corral for cattle and
mules, the last outpost of the plateau herdsmen. Not three
miles away, on the opposite forested slope of the valley, is
the first of the Indian clearings where several families of
Machigangas spend the wet season when the lower river
is in flood (Fig. 21). The grass lands will not yield corn
and coca because the soil is too thin, infertile, and dry. Fig. 55—Map to
The Indian farms are therefore all in the forest and begin show the relation
of the grasslands of
almost at its very edge. Here finally terminates a long the dry lower
peninsula of grass-covered country. Below this point the portion of the
heat and humidity rapidly increase; the rains are heavier Urubamba Valley
(unshaded) to the
and more frequent; the country becomes almost forested lands at
uninhabitable for stock; transportation rates double. Here higher elevations
is the undisputed realm of the forest with new kinds of (shaded). See Fig.
54 for climatic
trees and products and a distinctive type of forest- conditions. Patches
dwelling Indian. and slender
tongues of
At the next low pass is the skull of an Italian who had woodland occur
murdered his companions and stolen a season’s picking of below the main
rubber, attempting to escape by canoe to the lower timber line and
patches of
Urubamba from the Pongo de Mainique. The grassland above it.
Machigangas overtook him in their swiftest dugouts,
spent a night with him, and the next morning shot him in
the back and returned with their rightful property—a harvest of rubber. For
more than a decade foreigners have been coming down from the plateau to
exploit them. They are an independent and free tribe and have simple yet
correct ideas of right and wrong. Their chief, a man of great strength of
character and one of the most likeable men I have known, told me that he
placed the skull in the pass to warn away the whites who came to rob honest
Indians.
The Santa Ana Valley between the Canyon of Torontoy and the heavy
forest belt below Rosalina is typical of many of the eastern valleys of Peru,
both in its physical setting and in its economic and labor systems. Westward
are the outliers of the Vilcapampa range; on the east are the smaller ranges

that front the tropical lowlands. Steep valleys descend from the higher
country to join the main valley and at the mouth of every tributary is an
alluvial fan. If the alluvium is coarse and steeply inclined there is only
pasture on it or a growth of scrub. If fine and broad it is cleared and tilled.
The sugar plantations begin at Huadquiña and end at Rosalina. Those of
Santa Ana and Echarati are the most productive. It takes eighteen months
for the cane to mature in the cooler weather at Huadquiña (8,000 feet). Less
than a year is required at Santa Ana (3,400 feet). Patches of alluvium or
playas, as they are locally called, continue as far as Santo Anato, but they
are cultivated only as far as Rosalina. The last large plantation is Pabellon;
the largest of all is Echarati. All are irrigated. In the wet months, December
to March inclusive, there is little or no irrigation. In the four months of the
dry season, June to September inclusive, there is frequent irrigation. Since
the cane matures in about ten months the harvest seasons fall irregularly
with respect to the seasons of rain. Therefore the land is cleared and planted
at irregular intervals and labor distributed somewhat through the year. There
is however a concentration of labor toward the end of the dry season when
most of the cane is cut for grinding.
The combined freight rate and government tax on coca, sugar, and
brandy take a large part of all that the planter can get for his crop. It is 120
miles (190 km.) from Santa Ana to Cuzco and it takes five days to make the
journey. The freight rate on coca and sugar for mule carriage, the only kind
to be had, is two cents per pound. The national tax is one cent per pound
(0.45 kg.). The coca sells for twenty cents a pound. The cost of production
is unknown, but the paid labor takes probably one-half this amount. The
planter’s time, capital, and profit must come out of the rest. On brandy there
is a national tax of seven cents per liter (0.26 gallon) and a municipal tax of
two and a half cents. It costs five cents a liter for transport to Cuzco. The
total in taxes and transport is fourteen and a half cents a liter. It sells for
twenty cents a liter. Since brandy (aguardiente), cacao (for chocolate), and
coca leaves (for cocaine) are the only precious substances which the valleys
produce it takes but a moment’s inspection to see how onerous these taxes
would be to the planter if labor did not, as usual, pay the penalty.
Much of the labor on the plantations is free of cost to the owner and is
done by the so-called faena or free Indians. These are Quechuas who have
built their cabins on the hill lands of the planters, or on the floors of the
smaller valleys. The disposition of their fields in relation to the valley

plantations is full of geographic interest. Each plantation runs at right
angles to the course of the valley. Hacienda Sahuayaco is ten miles (16 km.)
in extent down valley and forty miles (64 km.) from end to end across the
valley, and it is one of the smaller plantations! It follows that about ten
square miles lie on the valley floor and half of this can ultimately be
planted. The remaining three hundred and ninety square miles include some
mountain country with possible stores of mineral wealth, and a great deal of
“fells” country—grassy slopes, graded though steep, excellent for pasture,
with here and there patches of arable land. But the hill country can be
cultivated only by the small farmer who supplements his supply of food
from cultivated plants like potatoes, corn, and vegetables, by keeping cattle,
mules, pigs, and poultry, and by raising coca and fruit.
The Indian does not own any of the land he tills. He has the right merely
to live on it and to cultivate it. In return he must work a certain number of
days each year on the owner’s plantation. In many cases a small money
payment is also made to the planter. The planter prefers labor to money, for
hands are scarce throughout the whole eastern valley region. No Indian
need work on the planter’s land without receiving pay directly therefor.
Each also gets a small weekly allotment of aguardiente while in the
planter’s employ.
The scene every Saturday night outside the office of the contador
(treasurer) of a plantation is a novel one. Several hundred Indians gather in
the dark patio in front of the office. Within the circle of the feeble
candlelight that reaches only the margin of the crowd one may see a pack of
heavy, perspiring faces. Many are pock-marked from smallpox; here and
there an eye is missing; only a few are jovial. A name is shouted through the
open door and an Indian responds. He pulls off his cap and stands stupid
and blinking, while the contador asks:
“Faena” (free)?
“Si, Señor,” he answers.
“Un sol” (one “sol” or fifty cents gold). The assistant hands over the
money and the man gives way to the next one on the list. If he is a laborer
in regular and constant employ he receives five soles (two fifty gold) per
week. There are interruptions now and then. A ragged, half-drunken man
has been leaning against the door post, suspiciously impatient to receive his
money. Finally his name is called.

“Faena?” asks the contador.
“No, Señor, cinco (five) soles.”
At that the field superintendente glances at his time card and speaks up
in protest.
“You were the man that failed to show up on Friday and Saturday. You
were drunk. You should receive nothing.”
“No, mi patrón,” the man contends, “I had to visit a sick cousin in the
next valley. Oh, he was very sick, Señor,” and he coughs harshly as if he too
were on the verge of prostration. The sick cousin, a faena Indian, has been
at work in another cane field on the same plantation for two days and now
calls out that he is present and has never had a sick day in his life. Those
outside laugh uproariously. The contador throws down two soles and the
drunkard is pushed back into the sweating crowd, jostled right and left, and
jeered by all his neighbors as he slinks away grumbling.
Another Indian seems strangely shy. He scarcely raises his voice above a
whisper. He too is a faena Indian. The contador finds fault.
“Why didn’t you come last month when I sent for you?”
The Indian fumbles his cap, shuffles his feet, and changes his coca cud
from one bulging cheek to the other before he can answer. Then huskily:
“I started, Señor, but my woman overtook me an hour afterward and said
that one of the ewes had dropped a lamb and needed care.”
“But your woman could have tended it!”
“No, Señor, she is sick.”
“How, then, could she have overtaken you?” he is asked.
“She ran only a little way and then shouted to me.”
“And what about the rest of the month?” persists the contador.
“The other lambs came, Señor, and I should have lost them all if I had
left.”
The contador seems at the end of his complaint. The Indian promises to
work overtime. His difficulties seem at an end, but the superintendent looks
at his old record.
“He always makes the same excuse. Last year he was three weeks late.”
So the poor shepherd is fined a sol and admonished that his lands will be
given to some one else if he does not respond more promptly to his patron’s

call for work. He leaves behind him a promise and the rank mixed smell of
coca and much unwashed woolen clothing.
It is not alone at the work that they grumble. There is malaria in the
lower valleys. Some of them return to their lofty mountain homes prostrated
with the unaccustomed heat and alternately shaking with chills and burning
with fever. Without aid they may die or become so weakened that
tuberculosis carries them off. Only their rugged strength enables the greater
number to return in good health.
A plantation may be as large as a principality and draw its laborers from
places fifty miles away. Some of the more distant Indians need not come to
work in the canefields. Part of their flock is taken in place of work. Or they
raise horses and mules and bring in a certain number each year to turn over
to the patron. Hacienda Huadquiña (Fig. 46) takes in all the land from the
snow-covered summits of the Cordillera Vilcapampa to the canefields of the
Urubamba. Within the broad domain are half the climates and occupations
characteristic of Peru. It is difficult to see how a thousand Indians can be
held to even a mixed allegiance. It seems impossible that word can be got to
them. However the native “telegraph” is even more perfect than that among
the forest Indians. From one to the other runs the news that they are needed
in the canefields. On the trail to and from a mountain village, in their
ramblings from one high pasture to another, within the dark walls of their
stone and mud huts when they gather for a feast or to exchange drinks of
brandy and chicha—the word is passed that has come up from the valleys.
For every hundred faena Indians there are five or six regular laborers on
the plantations, so with the short term passed by the faena Indians their
number is generally half that of the total laborers at work at any one time.
They live in huts provided for them by the planter, and in the houses of their
friends among the regular laborers. Here there are almost nightly carousals.
The regular laborer comes from the city or the valley town. The faena
laborer is a small hill farmer or shepherd. They have much to exchange in
the way of clothing, food, and news. I have frequently had their
conversations interpreted for me. They ask about the flocks and the
children, who passed along the trails, what accidents befell the people.
“Last year,” droned one to another over their chicha, “last year we lost
three lambs in a hailstorm up in the high fields near the snow. It was very
cold. My foot cracked open and, though I have bound it with wet coca

leaves every night, it will not cure,” and he displays his heel, the skin of
which is like horn for hardness and covered with a crust of dirt whose
layers are a record of the weather and of the pools he has waded for years.
Their wanderings are the main basis of conversation. They know the
mountains better than the condors do. We hired a small boy of twelve at
Puquiura. He was to build our fires, carry water, and help drive the mules.
He crossed the Cordillera Vilcapampa on foot with us. He scrambled down
into the Apurimac canyon and up the ten thousand feet of ascent on the
other side, twisted the tails of the mules, and shouted more vigorously then
the arrieros. He was engaged to go with us to Pasaje, where his father
would return with him in a month. But he climbed to Huascatay with us and
said he wanted to see Abancay. When an Indian whom we pressed into
service dropped the instruments on the trail and fled into the brush the boy
packed them like a man. The soldier carried a tripod on his back. The boy,
not to be outdone, insisted on carrying the plane table, and to his delight we
called him a soldier too. He went with us to Huancarama. When I paid him
he smiled at the large silver soles that I put into his hand; and when I
doubled the amount for his willingness to work his joy was unbounded.
Forthwith he set out, this time on muleback, on the return journey. The last I
saw of him he was holding his precious soles in a handkerchief and kicking
his beast with his bare heels, as light-hearted as a cavalier. Often I find
myself wondering whether he returned safely with his money. I should very
much like to see him again, for with him I associate cheerfulness in difficult
places and many a pleasant camp-fire.

CHAPTER VII

THE GEOGRAPHIC BASIS OF REVOLUTIONS AND OF HUMAN
CHARACTER IN THE PERUVIAN ANDES
HUMAN character as a spontaneous development has always been a great
factor in shaping historical events, but it is a striking fact that in the world
of our day its influence is exerted chiefly in the lowest and highest types of
humanity. The savage with his fetishes, his taboos, and his inherent
childlikeness and suspicion needs only whim or a slight religious pretext to
change his conduct. Likewise the really educated and the thoughtful act
from motives often wholly unrelated to economic conditions or results. But
the masses are deeply influenced by whatever affects their material welfare.

A purely idealistic impulse may influence a people, but in time its effects
are always displayed against an economic background.
There is a way whereby we may test this theory. In most places in the
world we have history in the making, and through field studies we can get
an intimate view of it. It is peculiarly the province of geography to study the
present distribution and character of men in relation to their surroundings
and these are the facts of mankind that must forever be the chief data of
economic history. It is not vain repetition to say that this means, first of all,
the study of the character of men in the fullest sense. It means, in the second
place, that a large part of the character must be really understood. Whenever
this is done there is found a geographic basis of human character that is
capable of the clearest demonstration. It is in the geographic environment
that the material motives of humanity have struck their deepest roots.
These conclusions might be illustrated from a hundred places in the field
of study covered in this book. Almost every chapter of Part I contains facts
of this character. I wish, however, to discuss the subject specifically and for
that purpose now turn to the conditions of life in the remoter mountain
valleys and to one or two aspects of the revolutions that occur now and then
in Peru. The last one terminated only a few months before our arrival and it
was a comparatively easy matter to study both causes and effects.
A caution is necessary however. It is a pity that we use the term
“revolution” to designate these little disturbances. They affect sometimes a
few, again a few hundred men. Rarely do they involve the whole country. A
good many of them are on a scale much smaller than our big strikes. Most
of them involve a loss of life smaller than that which accompanies a city
riot. They are in a sense strikes against the government, marked by local
disorders and a little violence.
Early in 1911 the Prefect of the Department of Abancay had crowned his
long career by suppressing a revolution. He had been Subprefect at
Andahuaylas, and when the rebels got control of the city of Abancay and
destroyed some of the bridges on the principal trails, he promptly organized
a military expedition, constructed rafts, floated his small force of men
across the streams, and besieged the city. The rebel force was driven at last
to take shelter in the city jail opposite the Prefectura. There, after the loss of
half their number, they finally surrendered. Seventy-five of them were sent
to the government penitentiary at Arequipa. Among the killed were sons

from nearly half the best families of Abancay. All of the rebels were young
men.
It would be difficult to give an adequate idea of the hatred felt by the
townspeople toward the government. Every precaution was taken to prevent
a renewal of the outbreak. Our coming was telegraphed ahead by
government agents who looked with suspicion upon a party of men, well
armed and provisioned, coming up from the Pasaje crossing of the
Apurimac, three days’ journey north. The deep canyon affords shelter not
only to game, but also to fugitives, rebels, and bandits. The government
generally abandons pursuit on the upper edge of the canyon, for only a
prolonged guerilla warfare could completely subdue an armed force
scattered along its rugged walls and narrow floor. The owner of the
hacienda at Pasaje is required to keep a record of all passengers rafted
across the Apurimac, but he explains significantly that some who pass are
too hurried to write their names in his book. Once he reaches the eastern
wall of the canyon a fugitive may command a view of the entire western
wall and note the approach of pursuers. Thence eastward he has the whole
Cordillera Vilcapampa in which to hide. Pursuit is out of the question.
When we arrived, the venerable Prefect, a model of old-fashioned
courtesy, greeted us with the utmost cordiality. He told us of our movements
since leaving Pasaje, and laughingly explained that since we had sent him
no friendly message and had come from a rebel retreat, he had taken it for
granted that we intended to storm the town. I assured him that we were
ready to join his troops, if necessary, whereupon, with a delightful
frankness, he explained his method of keeping the situation in hand. Several
troops of cavalry and two battalions of infantry were quartered at the
government barracks. Every evening the old gentleman, a Colonel in the
Peruvian army, mounted a powerful gray horse and rode, quite unattended,
through the principal streets of the town. Several times I walked on foot
behind him, again I preceded him, stopping in shops on the way to make
trivial purchases, to find out what the people had to say about him and the
government as he rode by. One old gentleman interested me particularly. He
had only the day before called at the Prefectura to pay his respects.
Although his manner was correct there was lacking to a noticeable degree
the profusion of sentiment that is apt to be exhibited on such an occasion.
He now sat on a bench in a shop. Both his own son and the shopkeeper’s
son had been slain in the revolution. It was natural that they should be

bitter. But the precise nature of their complaint was what interested me
most. One said that he did not object to having his son lose his life for his
country. But that his country’s officials should hire Indians to shoot his son
seemed to him sheer murder. Later, at Lambrama, I talked with a rebel
fugitive, and that was also his complaint. The young men drafted into the
army are Indians, or mixed, never whites. White men, and men with a small
amount of Indian blood, officer the army. When a revolutionary party
organizes it is of course made up wholly of men of white and mixed blood,
never Indians. The Indians have no more grievance against one white party
than another. Both exploit him to the limit of law and beyond the limit of
decency. He fights if he must, but never by choice.

Fig. 56—The type of forest in the Fig. 57—Arboreal cacti in the
moister tracts of the valley floor at mixed forest of the dry valley floor
Sahuayaco. In the center of the below Sahuayaco.
photograph is a tree known as the
“sandy matico” used in making
canoes for river navigation.

Fig. 58—Crossing the Apurimac at Pasaje. These are mountain
horses, small and wiry, with a protective coat of long hair. They are
accustomed to graze in the open without shelter during the entire
winter.
Fig. 59—Crossing the Apurimac at Pasaje. The mules are
blindfolded and pushed off the steep bank into the water and rafted
across.

Thus Indian troops killed the white rebels of Abancay.
“Tell me, Señor,” said the fugitive, “if you think that just. Tell me how
many Indians you think a white man worth. Would a hundred dead Indians
matter? But how replace a white man where there are so few? The
government assassinated my compatriots!”
“But,” I replied, “why did you fight the government? All of you were
prosperous. Your fathers may have had a grievance against the government,
but of what had you young men to complain?”
His reply was far from convincing. He was at first serious, but his long
abstract statements about taxes and government wastefulness trailed off into
vagueness, and he ended in a laughing mood, talking about adventure, the
restless spirit of young men, and the rich booty of confiscated lands and
property had the rebels won. He admitted that it was a reckless game, but
when I called him a mere soldier of fortune he grew serious once more and
reverted to the iniquitous taxation system of Peru. Further inquiry made it

quite clear that the ill-fated revolution of Abancay was largely the work of
idle young men looking for adventure. It seemed a pity that their splendid
physical energy could not have been turned into useful channels. The land
sorely needs engineers, progressive ranchmen and farmers, upright officials,
and a spirit of respect for law and order. Old men talked of the unstable
character of the young men of the time, but almost all of them had
themselves been active participants in more than one revolution of earlier
years.
Every night at dinner the Prefect sent off by government telegraph a long
message to the President of the Republic on the state of the Department,
and received similar messages from the central government about
neighboring departments. These he read to us, and, curiously enough, to the
entire party, made up of army officers and townsmen. I was surprised to
find later that the company included one government official whose son had
been among the imprisoned rebels at Arequipa. We met the young man a
week later at a mountain village, a day after a general amnesty had been
declared. His escape had been made from the prison a month before. He
forcibly substituted the mess-boy’s clothing for his own, and thus passed
out unnoticed. After a few days’ hiding in the city, he set out alone across
the desert of Vitor, thence across the lofty volcanic country of the Maritime
Andes, through some of the most deserted, inhospitable land in Peru, and at
the end of three weeks had reached Lambrama, near Abancay, the picture of
health!
Later I came to have a better notion of the economic basis of the
revolution, for obviously the planters and the reckless young men must
have had a mutual understanding. Somewhere the rebels had obtained the
sinews of war. The planters did not take an open part in the revolution, but
they financed it. When the rebels were crushed, the planters, at least
outwardly, welcomed the government forces. Inwardly they cursed them for
thwarting their scheme. The reasons have an interesting geographic basis.
Abancay is the center of a sugar region. Great irrigated estates are spread
out along the valley floor and the enormous alluvial fans built into the main
valley at the mouths of the tributary streams. There is a heavy tax on sugar
and on aguardiente (brandy) manufactured from cane juice. The
hacendados had dreamed of lighter taxes. The rebels offered the means of
securing relief. But taxes were not the real reason for the unrest, for many
other sugar producers pay the tax without serious complaint. Abancay is cut

off from the rest of Peru by great mountains. Toward the west, via
Antabamba, Cotahuasi, and Chuquibamba, two hundred miles of trail
separate its plantations from the Pacific. Twelve days’ hard riding is
required to reach Lima over the old colonial trade route. It is three days to
Cuzco at the end of the three-hundred-mile railway from the port of
Mollendo. The trails to the Atlantic rivers are impossible for trading
purposes. Deep sunk in a subtropical valley, the irrigable alluvial land of
Abancay tempts the production of sugar.
But nature offers no easy route out of the valley. For centuries the
product has been exported at almost prohibitive cost, as in the eastern valley
of Santa Ana. The coastal valleys enjoy easy access to the sea. Each has its
own port at the valley mouth, where ocean steamers call for cargo. Many
have short railway lines from port to valley head. The eastern valleys and
Abancay have been clamoring for railways, better trails, and wagon roads.
From the public fund they get what is left. The realization of their hopes has
been delayed too long. It would be both economic and military strategy to
give them the desired railway. Revolutions in Peru always start in one of
two ways: either by a coup at Lima or an unchecked uprising in an interior
province. Bolivia has shown the way out of this difficulty. Two of her four
large centers—La Paz and Oruro—are connected by rail, and the line to
Cochabamba lacks only a few kilometres of construction.[16] To Sucre a line
has been long projected. Formerly a revolution at one of the four towns was
exceedingly difficult to stamp out. Diaz had the same double motive in
encouraging railway building in the remote desert provinces of Northern
Mexico, where nine out of ten Mexican revolutions gather headway.
Argentina has enjoyed a high degree of political unity since her railway
system was extended to Córdoba and Tucumán. The last uprising, that of
1906, took place on her remotest northeastern frontier.
We had ample opportunity to see the hatred of the rebels. At nightfall of
September 25th we rode into the courtyard of Hacienda Auquibamba. We
had traveled under the worst possible circumstances. Our mules had been
enfeebled by hot valley work at Santa Ana and the lower Urubamba and the
cold mountain climate of the Cordillera Vilcapampa. The climb out of the
Apurimac canyon, even without packs, left them completely exhausted. We
were obliged to abandon one and actually to pull another along. It had been
a hard day in spite of a prolonged noon rest. Everywhere our letters of
introduction had won an outpouring of hospitality among a people to whom

hospitality is one of the strongest of the unwritten laws of society. Our
soldier escort rode ahead of the pack train.
As the clatter of his mules’ hoofs echoed through the dark buildings the
manager rushed out, struck a light and demanded “Who’s there?” To the
soldier’s cheerful “Buena noche, Señor,” he sneeringly replied “Halto!
Guardia de la República, aqui hay nada para un soldado del gobierno.”
Whereupon the soldier turned back to me and said we should not be able to
stop here, and coming nearer me he whispered “He is a revolutionary.” I
dismounted and approached the haughty manager, who was in a really
terrible mood. Almost before I could begin to ask him for accommodations
he rattled off that there was no pasture for our beasts, no food for us, and
that we had better go on to the next hacienda. “Absolutamente nada!” he
repeated over and over again, and at first I thought him drunk. Since it was
then quite dark, with no moon, but instead heavy black clouds over the
southern half of the sky and a brisk valley wind threatening rain, I mildly
protested that we needed nothing more than shelter. Our food boxes would
supply our wants, and our mules, even without fodder, could reach Abancay
the next day. Still he stormed at the government and would have none of us.
I reminded him that his fields were filled with sugar cane and that it was the
staple forage for beasts during the part of the year when pasture was scarce.
The cane was too valuable, he said. It was impossible to supply us. I was on
the point of pitching camp beside the trail, for it was impossible to reach the
next hacienda with an exhausted outfit.
Just then an older man stepped into the circle of light and amiably
inquired the purpose of our journey. When it was explained, he turned to the
other and said it was unthinkable that men should be treated so inhospitably
in a strange land. Though he himself was a guest he urged that the host
should remember the laws of hospitality, whereupon the latter at last
grudgingly asked us to join him at his table and to turn our beasts over to
his servants. It was an hour or more before he would exhibit any interest in
us. When he had learned of our object in visiting Abancay he became
somewhat more friendly, though his hostility still manifested itself.
Nowhere else in South America have I seen exhibited such boorish conduct.
Nevertheless the next morning I noticed that our mules had been well fed.
He said good-by to us as if he were glad to be rid of any one in any way
connected with the hostile government. Likewise the manager at Hacienda
Pasaje held out almost until the last before he would consent to aid us with

fresh beasts. Finally, after a day of courting I gave him a camp chair. He
was so pleased that he not only gave us beasts, but also a letter of
introduction to one of his caretakers on a farm at the top of the cuesta. Here
on a cold, stormy night we found food and fuel and the shelter of a friendly
roof.
A by-product of the revolution, as of all revolutions in thinly settled
frontier regions, was the organization of small bands of outlaws who
infested the lonely trails, stole beasts, and left their owners robbed and
helpless far from settlements. We were cautioned to beware of them, both
by Señor Gonzales, the Prefect at Abancay, and by the Subprefect of
Antabamba. Since some of the bandits had been jailed, I could not doubt the
accuracy of the reports, but I did doubt stories of murder and of raids by
large companies of mountain bandits. As a matter of fact we were robbed by
the Governor of Antabamba, but in a way that did not enable us to find
redress in either law or lead. The story is worth telling because it illustrates
two important facts: first, the vile so-called government that exists in some
places in the really remote sections of South America, and second, the
character of the mountain Indians.
The urgent letter from the Prefect of Abancay to the Subprefect of
Antabamba quickly brought the latter from his distant home. When we
arrived we found him drinking with the Governor. The Subprefect was most
courteous. The Governor was good-natured, but his face exhibited a rare
combination of cruelty and vice. We were offered quarters in the municipal
building for the day or two that we were obliged to stop in the town. The
delay enabled us to study the valley to which particular interest attaches
because of its situation in the mountain zone between the lofty pastures of
the Alpine country and the irrigated fields of the valley farmers.
Antabamba itself lies on a smooth, high-level shoulder of the youthful
Antabamba Valley. The valley floor is narrow and rocky, and affords little
cultivable land. On the valley sides are steep descents and narrow benches,
chiefly structural in origin, over which there is scattered a growth of scrub,
sufficient to screen the deer and the bear, and, more rarely, vagrant bands of
vicuña that stray down from their accustomed haunts in the lofty Cordillera.
Three thousand feet above the valley floor a broad shoulder begins (Fig. 60)
and slopes gently up to the bases of the true mountains that surmount the
broad rolling summit platform. Here are the great pasture lands of the
Andes and their semi-nomadic shepherds. The highest habitation in the

world is located here at 17,100 feet (5,210 m.), near a secondary pass only a
few miles from the main axis of the western chain, and but 300 feet (91 m.)
below it.
The people of Antabamba are both shepherds and farmers. The elevation
is 12,000 feet (3,658 m.), too high and exposed for anything more than
potatoes. Here is an Indian population pure-blooded, and in other respects,
too, but little altered from its original condition. There is almost no
communication with the outside world. A deep canyon fronts the town and a
lofty mountain range forms the background.
At nightfall, one after another, the Indians came in from the field and
doffed their caps as they passed our door. Finally came the “Teniente
Gobernador,” or Lieutenant Governor. He had only a slight strain of white
blood. His bearing was that of a sneak, and he confirmed this impression by
his frank disdain for his full-blooded townsmen. “How ragged and ugly
they are! You people must find them very stupid,” etc. When he found that
we had little interest in his remarks, he asked us if we had ever seen Lima.
We replied that we had, whereupon he said, “Do you see the gilded cross
above the church yonder? I brought that on muleback all the way from
Lima! Think of it! These ignorant people have never seen Lima!” His whole
manner as he drew himself up and hit his breast was intended to make us
think that he was vastly superior to his neighbors. The sequel shows that our
first estimate of him was correct.
We made our arrangements with the Governor and departed. To inspire
confidence, and at the Governor’s urgent request, we had paid in advance
for our four Indians and our fresh beasts—and at double the usual rates, for
it was still winter in the Cordillera. They were to stay with us until we
reached Cotahuasi, in the next Department beyond the continental divide,
where a fresh outfit could be secured. The Lieutenant Governor
accompanied us to keep the party together. They appeared to need it. Like
our Indian peons at Lambrama the week before, these had been taken from
the village jail and represented the scum of the town. As usual they behaved
well the first day. On the second night we reached the Alpine country where
the vegetation is very scanty and camped at the only spot that offered fuel
and water. The elevation was 16,000, and here we had the lowest
temperature of the whole journey, +6° F. (-14.4° C.). Ice covered the brook
near camp as soon as the sun went down and all night long the wind blew
down from the lofty Cordillera above us, bringing flurries of snow and

tormenting our unprotected beasts. It seemed to me doubtful if our Indians
would remain. I discussed with the other members of the party the
desirability of chaining the peons to the tent pole, but this appeared so
extreme a measure that we abandoned the idea after warning the Teniente
that he must not let them escape.
At daybreak I was alarmed at the unusual stillness about camp. A glance
showed that half our hobbled beasts had drifted back toward Antabamba
and no doubt were now miles away. The four Indian peons had left also, and
their tracks, half buried by the last snowfall, showed that they had left hours
before and that it was useless to try to overtake them. Furthermore we were
making a topographic map across the Cordillera, and, in view of the
likelihood of snow blockading the 17,600-foot (5,360 m.) pass which we
had to cross, the work ought not to be delayed. With all these disturbing
conditions to meet, and suffering acutely from mountain sickness, I could
scarcely be expected to deal gently with our official. I drew out the sleeping
Teniente and set him on his feet. To my inquiry as to the whereabouts of the
Indians that he had promised to guard, he blinked uncertainly, and after a
stupid “Quien sabe?” peered under the cover of a sheepskin near by as if the
peons had been transformed into insects and had taken refuge under a blade
of grass. I ordered him to get breakfast and after that to take upon his back
the instruments that two men had carried up to that time, and accompany
the topographer. Thus loaded, the Lieutenant Governor of Antabamba set
out on foot a little ahead of the party. Hendriksen, the topographer, directed
him to a 17,000-foot peak near camp, one of the highest stations occupied
in the traverse. When the topographer reached the summit the instruments
were there but the Teniente had fled. Hendriksen rapidly followed the tracks
down over the steep snow-covered wall of a deeply recessed cirque, but
after a half-hour’s search could not get sight of the runaway, whereupon he
returned to his station and took his observations, reaching camp in the early
afternoon.
In the meantime I had intercepted two Indians who had come from
Cotahuasi driving a llama train loaded with corn. They held a long
conversation at the top of the pass above camp and at first edged
suspiciously away. But the rough ground turned them back into the trail and
at last they came timidly along. They pretended not to understand Spanish
and protested vigorously that they had to keep on with their llamas. I
thought from the belligerent attitude of the older, which grew rapidly more

threatening as he saw that I was alone, that I was in for trouble, but when I
drew my revolver he quickly obeyed the order to sit down to breakfast,
which consisted of soup, meat, and army biscuits. I also gave them coca and
cigarettes, the two most desirable gifts one can make to a plateau Indian,
and thereupon I thought I had gained their friendship, for they at last talked
with me in broken Spanish. The older one now explained that he must at all
hazards reach Matará by nightfall, but he would be glad to leave his son to
help us. I agreed, and he set out forthwith. The arriero (muleteer) had now
returned with the lost mules and with the assistance of the Indian we soon
struck camp and loaded our mules. I cautioned the arriero to keep close
watch of the Indian, for at one time I had caught on his face an expression
of hatred more intense than I had ever seen before. The plateau Indian of
South America is usually so stupid and docile that the unexpectedly
venomous look of the man after our friendly conversation and my good
treatment alarmed me. At the last moment, and when our backs were turned,
our Indian, under the screen of the packs, slipped away from us. The arriero
called out to know where he had gone. It took us but a few moments to gain
the top of a hill that commanded the valley. Fully a half-mile away and
almost indistinguishable against the brown of the valley floor was our late
assistant, running like a deer. No mule could follow over that broken
ground at an elevation of 16,000 feet, and so he escaped.
Fortunately that afternoon we passed a half-grown boy riding back
toward Antabamba and he promised to hand the Governor a note in
Spanish, penciled on a leaf of my traverse book. I dropped all the polite
phrases that are usually employed and wrote as follows:
“Señor Gobernador:
“Your Indians have escaped, likewise the Lieutenant Governor. They have taken two beasts. In
the name of the Prefect of Abancay, I ask you immediately to bring a fresh supply of men and
animals. We shall encamp near the first pass, three days west of Antabamba, until you come.”

We were now without Indians to carry the instruments, which had
therefore to be strapped to the mules. Without guides we started westward
along the trail. At the next pass the topographer rode to the summit of a
bluff and asked which of the two trails I intended to follow. Just then a
solitary Indian passed and I shouted back that I would engage the Indian
and precede the party, and he could tell from my course at the fork of the
trail how to direct his map and where to gain camp at nightfall. But the
Indian refused to go with us. All my threatening was useless and I had to

force myself to beat him into submission with my quirt. Several repetitions
on the way, when he stubbornly refused to go further, kept our guide with
us until we reached a camp site. I had offered him a week’s pay for two
hours’ work, and had put coca and cigarettes into his hands. When these
failed I had to resort to force. Now that he was about to leave I gave him
double the amount I had promised him. He could scarcely believe his eyes.
He rushed up to the side of my mule, and reaching around my waist
embraced me and thanked me again and again. The plateau Indian is so
often waylaid in the mountains and impressed for service, then turned loose
without pay or actually robbed, that a promise to pay holds no attraction for
him. I had up to the last moment resembled this class of white. He was
astonished to find that I really meant to pay him well.
Then he set out upon the return, faithfully delivering my note to the
topographer about the course of the trail and the position of the camp. He
had twelve miles to go to the first mountain hut, so that he could not have
traveled less than that distance to reach shelter. The next morning a mantle
of snow covered everything, yet when I pushed back the tent flap there
stood my scantily clad Indian of the night before, shivering, with sandaled
feet in the snow, saying that he had come back to work for me!
This camp was number thirteen out of Abancay, and here our
topographer was laid up for three days. Heretofore the elevation had had no
effect upon him, but the excessively lofty stations of the past few days and
the hard climbing had finally prostrated him. We had decided to carry him
out by the fourth day if he felt no better, but happily he recovered
sufficiently to continue the work. The delay enabled the Governor to
overtake us with a fresh outfit. On the morning of our third day in camp he
overtook us with a small escort of soldiers accompanied by the fugitive
Teniente. He said that he had come to arrest me on the charge of maltreating
an official of Peru. A few packages of cigarettes and a handful of raisins and
biscuits so stirred his gratitude that we parted the best of friends. Moreover
he provided us with four fresh beasts and four new men, and thus equipped
we set out for a rendezvous about ten miles away. But the faithless
Governor turned off the trail and sought shelter at the huts of a company of
mountain shepherds. That night his men slept on the ground in a bitter wind
just outside our camp at 17,200 feet. They complained that they had no
food. The Governor had promised to join us with llama meat for the peons.
We fed them that night and also the next day. But we had by that time

passed the crest of the western Cordillera and were outside the province of
Antabamba. The next morning not only our four men but also our four
beasts were missing. We were stranded and sick just under the pass. To add
to our distress the surgeon, Dr. Erving, was obliged to leave us for the
return home, taking the best saddle animal and the strongest pack mule. It
was impossible to go on with the map. That morning I rode alone up a side
valley until I reached a shepherd’s hut, where I could find only a broken-
down, shuffling old mule, perfectly useless for our hard work.
Then there happened a piece of good luck that seems almost
providential. A young man came down the trail with three pack mules
loaded with llama meat. He had come from the Cotahuasi Valley the week
before and knew the trail. I persuaded him to let us hire one of his mules. In
this way and by leaving the instruments and part of our gear in the care of
two Indian youths we managed to get to Cotahuasi for rest and a new outfit.
The young men who took charge of part of our outfit interested me very
greatly. I had never seen elsewhere so independent and clear-eyed a pair of
mountain Indians. At first they would have nothing to do with us. They
refused us permission to store our goods in their hut. To them we were
railroad engineers. They said that the railway might come and when it did it
would depopulate the country. The railway was a curse. Natives were
obliged to work for the company without pay. Their uncle had told them of
frightful abuses over at Cuzco and had warned them not to help the railway
people in any way. They had moved out here in a remote part of the
mountains so that white men could not exploit them.
In the end, however, we got them to understand the nature of our work.
Gifts of various sorts won their friendship, and they consented to guard the
boxes we had to leave behind. Two weeks later, on his return, the
topographer found everything unmolested.
I could not but feel that the spirit of those strong and independent young
men was much better for Peru than the cringing, subservient spirit of most
of the Indians that are serfs of the whites. The policy of the whites has been
to suppress and exploit the natives, to abuse them, and to break their spirit.
They say that it keeps down revolution; it keeps the Indian in his place. But
certainly in other respects it is bad for the Indian and it is worse for the
whites. Their brutality toward the natives is incredible. It is not so much the

white himself as the vicious half-breed who is often allied with him as his
agent.
I shall never forget the terror of two young girls driving a donkey before
them when they came suddenly face to face with our party, and we at the
same time hastily scrambled off our beasts to get a photograph of a
magnificent view disclosed at the bend of the steep trail. They thought we
had dismounted to attack them, and fled screaming in abject fear up the
mountain side, abandoning the donkey and the pack of potatoes which must
have represented a large part of the season’s product. It is a kind of highway
robbery condoned because it is only robbing an Indian. He is considered to
be lawful prey. His complaint goes unnoticed. In the past a revolution has
offered him sporadic chances to wreak vengeance. More often it adds to his
troubles by scattering through the mountain valleys the desperate refugees
or lawless bands of marauders who kill the flocks of the mountain
shepherds and despoil their women.
There are still considerable numbers of Indians who shun the white man
and live in the most remote corners of the mountains. I have now and again
come upon the most isolated huts, invisible from the valley trails. They
were thatched with grass; the walls were of stone; the rafters though light
must have required prodigious toil, for all timber stops at 12,000 feet on the
mountain borders. The shy fugitive who perches his hut near the lip of a
hanging valley far above the trail may look down himself unseen as an
eagle from its nest. When the owner leaves on a journey, or to take his flock
to new pastures, he buries his pottery or hides it in almost inaccessible
caves. He locks the door or bars it, thankful if the spoiler spares rafters and
thatch.
At length we reached Cotahuasi, a town sprawled out on a terrace just
above the floor of a deep canyon (Fig. 29). Its flower gardens and pastures
are watered by a multitude of branching canals lined with low willows. Its
bright fields stretch up the lower slopes and alluvial fans of the canyon to
the limits of irrigation where the desert begins. The fame of this charming
oasis is widespread. The people of Antabamba and Lambrama and even the
officials of Abancay spoke of Cotahuasi as practically the end of our
journey. Fruits ripen and flowers blossom every month of the year. Where
we first reached the canyon floor near Huaynacotas, elevation 11,500 feet
(3,500 m.), there seemed to be acres of rose bushes. Only the day before at
an elevation of 16,800 feet (5,120 m.) we had broken thick ice out of a

mountain spring in order to get water; now we were wading a shallow river,
and grateful for the shade along its banks. Thus we came to the town
prepared to find the people far above their plateau neighbors in character.
Yet, in spite of friendly priests and officials and courteous shopkeepers,
there was a spirit strangely out of harmony with the pleasant landscape.
Inquiries showed that even here, where it seemed that only sylvan peace
should reign, there had recently been let loose the spirit of barbarism. We
shall turn to some of its manifestations and look at the reasons therefor.
In the revolution of 1911 a mob of drunken, riotous citizens gathered to
storm the Cotahuasi barracks and the jail. A full-blooded Indian soldier, on
duty at the entrance, ordered the rioters to stop and when they paid no heed
he shot the leader and scattered the crowd. The captain thereupon ordered
the soldier to Arequipa because his life was no longer safe outside the
barracks. A few months later he was assigned to Professor Bingham’s
Coropuna expedition. Professor Bingham reached the Cotahuasi Valley as I
was about to leave it for the coast, and the soldier was turned over to me so
that he might leave Cotahuasi at the earliest possible moment, for his
enemies were plotting to kill him.
He did not sleep at all the last night of his stay and had us called at three
in the morning. He told his friends that he was going to leave with us, but
that they were to announce his leaving a day later. In addition, the
Subprefect was to accompany us until daybreak so that no harm might
befall me while under the protection of a soldier who expected to be shot
from ambush.
At four o’clock our whispered arrangements were made, we opened the
gates noiselessly, and our small cavalcade hurried through the pitch-black
streets of the town. The soldier rode ahead, his rifle across his saddle, and
directly behind him rode the Subprefect and myself. The pack mules were
in the rear. We had almost reached the end of the street when a door opened
suddenly and a shower of sparks flew out ahead of us. Instantly the soldier
struck spurs into his mule and turned into a side street. The Subprefect drew
his horse back savagely and when the next shower of sparks flew out
pushed me against the wall and whispered: “Por Dios, quien es?” Then
suddenly he shouted: “Sopla no mas, sopla no mas” (stop blowing).
Thereupon a shabby penitent man came to the door holding in his hand a
large tailor’s flatiron. The base of it was filled with glowing charcoal and he

was about to start his day’s work. The sparks were made in the process of
blowing through the iron to start the smoldering coals. We greeted him with
more than ordinary friendliness and passed on.
At daybreak we had reached the steep western wall of the canyon where
the real ascent begins, and here the Subprefect turned back with many
felicidades for the journey and threats for the soldier if he did not look
carefully after the pack train. From every angle of the zigzag trail that
climbs the “cuesta” the soldier scanned the valley road and the trail below
him. He was anxious lest news of his escape reach his enemies who had
vowed to take his life. Half the day he rode turned in his saddle so as to see
every traveler long before he was within harm’s reach. By nightfall we
safely reached Salamanca, fifty miles away (Fig. 62).
The alertness of the soldier was unusual and I quite enjoyed his close
attention to the beasts and his total abstinence, for an alert and sober soldier
on detail is a rare phenomenon in the interior of Peru. But all Salamanca
was drunk when we arrived—Governor, alcaldes, citizens. Even the peons
drank up in brandy the money that we gave them for forage and let the
beasts starve. The only sober person I saw was the white telegraph operator
from Lima. He said that he had to stay sober, for the telegraph office—the
outward sign of government—was the special object of attack of every
drink-crazed gang of rioters. They had tried to break in a few nights before
and he had fired his revolver point-blank through the door. The town
offered no shelter but the dark filthy hut of the Gobernador and the tiny
telegraph office. So I made up my bed beside that of the operator. We
shared our meals and chatted until a late hour, he recounting the glories of
Lima, to which he hoped to return at the earliest possible moment, and
cursing the squalid town of Salamanca. His operator’s keys were old, the
batteries feeble, and he was in continual anxiety lest a message could not be
received. In the night he sprang out of bed shouting frantically:
“Estan llamando” (they are calling), only to stumble over my bed and
awaken himself and offer apologies for walking in his sleep.
Meanwhile my soldier, having regained his courage, began drinking. It
was with great difficulty that I got started, after a day’s delay, on the trail to
Chuquibamba. There his thirst quite overcame him. To separate him from
temptation it became necessary to lock him up in the village jail. This I did
repeatedly on the way to Mollendo, except beyond Quilca, where we slept

in the hot marshy valley out of reach of drink, and where the mosquitoes
kept us so busy that either eating or drinking was almost out of the question.
The drunken rioters of Cotahuasi and their debauched brothers at
Salamanca are chiefly natives of pure or nearly pure Indian blood. They are
a part of the great plateau population of the Peruvian Andes. Have they
degenerated to their present low state, or do they display merely the normal
condition of the plateau people? Why are they so troublesome an element?
To this as to so many questions that arise concerning the highland
population we find our answer not chiefly in government, or religion, or
inherited character, but in geography. I doubt very much if a greater relative
difference would be seen if two groups of whites were set down, the one in
the cold terrace lands of Salamanca, the other in the warm vineyards of
Aplao, in the Majes Valley. The common people of these two towns were
originally of the same race, but the lower valley now has a white element
including even most of those having the rank of peons. Greater differences
in character could scarcely be found between the Aztecs and the Iroquois. In
the warm valley there is of coarse drunkenness, but it is far from general;
there is stupidity, but the people are as a whole alert; and finally, the climate
and soil produce grapes from which famous wines are made, they produce
sugar cane, cotton, and alfalfa, so that the whites have come in, diluted the
Indian blood, and raised the standard of life and behavior. Undoubtedly
their influence would tend to have the same general effect if they mixed in
equal numbers with the plateau groups. There is, however, a good reason
for their not doing so.

Fig. 62—Salamanca, on the floor of the deep Arma Valley (a
tributary of one of the major coast valleys, the Ocoña), which is really a
canyon above this point and which, in spite of its steepness, is
thoroughly terraced and intensively cultivated up to the frost line.

Fig. 60—View across the Antabamba canyon just above
Huadquirca.
Fig. 61—Huancarama, west of Abancay, on the famous Lima to
Buenos Aires road. Note the smooth slopes in the foreground. See
Chapter XI.

The lofty towns of the plateau have a really wretched climate. White
men cannot live comfortably at Antabamba and Salamanca. Further, they
are so isolated that the modest comforts and the smallest luxuries of
civilization are very expensive. To pay for them requires a profitable
industry managed on a large scale and there is no such industry in the
higher valleys. The white who goes there must be satisfied to live like an
Indian. The result is easy to forecast. Outside of government officers, only
the dissolute or unsuccessful whites live in the worst towns, like Salamanca
and Antabamba. A larger valley with a slightly milder climate and more
accessible situation, like Chuquibamba, will draw a still better grade of
white citizen and in the largest of all—Cuzco and the Titicaca basin—we
find normal whites in larger numbers, though they nowhere live in such
high ratios to the Indian as on the coast and in the lower valleys near the
coast. With few exceptions the white population of Peru is distributed in
response to favorable combinations of climate, soil, accessibility, and
general opportunities to secure a living without extreme sacrifice.
These facts are stated in a simple way, for I wish to emphasize the
statement that the Indian population responds to quite other stimuli. Most of
the luxuries and comforts of the whites mean nothing to the Indian. The
machine-made woolens of the importers will probably never displace his
homespun llama-wool clothing. His implements are few in number and
simple in form. His tastes in food are satisfied by the few products of his
fields and his mountain flocks. Thus he has lived for centuries and is quite
content to live today. Only coca and brandy tempt him to engage in
commerce, to toil now and then in the hot valleys, and to strive for more
than the bare necessities of life. Therefore it matters very little to him if his
home town is isolated, or the resources support but a small group of people.
He is so accustomed to a solitary existence in his ramblings with his flocks
that a village of fifty houses offers social enjoyments of a high order. Where
a white perishes for lack of society the Indian finds himself contented.
Finally, he is not subject to the white man’s exploitation when he lives in
remote places. The pastures are extensive and free. The high valley lands
are apportioned by the alcalde according to ancient custom. His life is
unrestricted by anything but the common law and he need have no care for
the morrow, for the seasons here are almost as fixed as the stars.
Thus we have a sort of segregation of whites in the lower places where a
modern type of life is maintained and of Indians in the higher places where

they enjoy advantages that do not appeal to the whites. Above 8,000 feet the
density of the white population bears a close inverse proportion to the
altitude, excepting in the case of the largest valleys whose size brings
together such numbers as to tempt the commercial and exploiting whites to
live in them. Furthermore, we should find that high altitude, limited size,
and greater isolation are everywhere closely related to increasing
immorality or decreasing character among the whites. So to the low Indian
population there is thus added the lowest of the white population.
Moreover, because it yields the largest returns, the chief business of these
whites is the sale of coca and brandy and the downright active debauchery
of the Indian. This is all the easier for them because the isolated Indian, like
the average isolated white, has only a low and provincial standard of
morality and gets no help from such stimulation as numbers usually excite.
For example, the Anta basin at harvest time is one of the fairest sights in
Peru. Sturdy laborers are working diligently. Their faces are bright and
happy, their skin clear, their manner eager and animated. They sing at their
work or gather about their mild chicha and drink to the patron saints of the
harvest. The huts are filled with robust children; all the yards are turned into
threshing floors; and from the stubbly hillslopes the shepherd blows shrill
notes upon his barley reeds and bamboo flute. There is drinking but there is
little disorder and there is always a sober remnant that exercises a
restraining influence upon the group.
In the most remote places of all one may find mountain groups of a high
order of morality unaffected by the white man or actually shunning him.
Clear-eyed, thick-limbed, independent, a fine, sturdy type of man this
highland shepherd may be. But in the town he succumbs to the temptation
of drink. Some writers have tried to make him out a superior to the plains
and low valley type. He is not that. The well-regulated groups of the lower
elevations are far superior intellectually and morally in spite of the fact that
the poorly regulated groups may fall below the highland dweller in
morality. The coca-chewing highlander is a clod. Surely, as a whole, the
mixed breed of the coastal valleys is a far worthier type, save in a few cases
where a Chinese or negroid element or both have led to local inferiority.
And surely, also, that is the worst combination which results in adding the
viciousness of the inferior or debased white to the stupidity of the highland
Indian. It is here that the effects of geography are most apparent. If the
white is tempted in large numbers because of exceptional position or

resources, as at La Paz, the rule of altitude may have an exception. And
other exceptions there are not due to physical causes, for character is
practically never a question of geography alone. There is the spiritual factor
that may illumine a strong character and through his agency turn a weak
community into a powerful one, or hold a weakened group steadfast against
the forces of disintegration. Exceptions arise from this and other causes and
yet with them all in mind the geographic factor seems predominant in the
types illustrated herewith.[17]
CHAPTER VIII

THE COASTAL DESERT
TO the wayfarer from the bleak mountains the warm green valleys of the
coastal desert of Peru seem like the climax of scenic beauty. The streams
are intrenched from 2,000 to 4,000 feet, and the valley walls in some places
drop 500 feet by sheer descents from one level to another. The cultivated
fields on the valley floors look like sunken gardens and now and then one
may catch the distant glint of sunlight on water. The broad white path that
winds through vineyards and cotton-fields, follows the foot of a cliff, or fills
the whole breadth of a gorge is the waste-strewn, half-dry channel of the
river. In some places almost the whole floor is cultivated from one valley
wall to the other. In other places the fields are restricted to narrow bands
between the river and the impending cliffs of a narrow canyon. Where
tributaries enter from the desert there may be huge banks of mud or broad
triangular fans covered with raw, infertile earth. The picture is generally
touched with color—a yellow, haze-covered horizon on the bare desert
above, brown lava flows suspended on the brink of the valley, gray-brown
cliffs, and greens ranging from the dull shade of algarrobo, olive and fig
trees, to the bright shade of freshly irrigated alfalfa pastures.
After several months’ work on the cold highlands, where we rode almost
daily into hailstorms or wearisome gales, we came at length to the border of
the valley country. It will always seem to me that the weather and the sky
conspired that afternoon to reward us for the months of toil that lay behind.
And certainly there could be no happier place to receive the reward than on
the brink of the lava plateau above Chuquibamba. There was promise of an
extraordinary view in the growing beauty of the sky, and we hurried our
tired beasts forward so that the valley below might also be included in the

picture. The head of the Majes Valley is a vast hollow bordered by cliffs
hundreds of feet high, and we reached the rim of it only a few minutes
before sunset.

Fig. 63—The deep fertile Majes Valley below Cantas. Compare with
6 showing the Chili Valley at Arequipa.
Fig. 64—The Majes Valley, desert coast, western Peru. The lighter
patches on the valley floor are the gravel beds of the river at high
water. Much of the alluvial land is still uncleared.

I remember that we halted beside a great wooden cross and that our
guide, dismounting, walked up to the foot of it and kissed and embraced it
after the custom of the mountain folk when they reach the head of a steep
“cuesta.” Also that the trail seemed to drop off like a stairway, which indeed
it was.[18] Everything else about me was completely overshadowed by
snowy mountains, colored sky, and golden-yellow desert. One could almost
forget the dark clouds that gather around the great mass of Coropuna and
the bitter winds that creep down from its glaciers at night—it seemed so
friendly and noble. Behind it lay bulky masses of rose-tinted clouds. We
had admired their gay colors only a few minutes, when the sun dropped
behind the crest of the Coast Range and the last of the sunlight played upon
the sky. It fell with such marvelously swift changes of color upon the
outermost zone of clouds as these were shifted with the wind that the eye

had scarcely time to comprehend a tint before it was gone and one more
beautiful still had taken its place. The reflected sunlight lay warm and soft
upon the white peaks of Coropuna, and a little later the Alpine glow came
out delicately clear.
When we turned from this brilliant scene to the deep valley, we found
that it had already become so dark that its greens had turned to black, and
the valley walls, now in deep shadow, had lost half their splendor. The color
had not left the sky before the lights of Chuquibamba began to show, and
candles twinkled from the doors of a group of huts close under the cliff. We
were not long in starting the descent. Here at last were friendly habitations
and happy people. I had worked for six weeks between 12,000 and 17,000
feet, constantly ill from mountain sickness, and it was with no regret that I
at last left the plateau and got down to comfortable altitudes. It seemed
good news when the guide told me that there were mosquitoes in the
marshes of Camaná. Any low, hot land would have seemed like a health
resort. I had been in the high country so long that, like the Bolivian mining
engineer, I wanted to get down not only to sea level, but below it!

Fig. 65—Regional diagram to show the physical relations in the
coastal desert of Peru. For location, see Fig. 20.

If the reader will examine Figs. 65 and 66, and the photographs that
accompany them, he may gain an idea of the more important features of the
coastal region. We have already described, in Chapters V and VII, the
character of the plateau region and its people. Therefore, we need say little
in this place of the part of the Maritime Cordillera that is included in the
figure. Its unpopulated rim (see p. 54), the semi-nomadic herdsmen and
shepherds from Chuquibamba that scour its pastures in the moist vales
about Coropuna, and the gnarled and stunted trees at 13,000 feet (3,960 m.)
which partly supply Chuquibamba with firewood, are its most important
features. A few groups of huts just under the snowline are inhabited for only

a part of the year. The delightful valleys are too near and tempting. Even a
plateau Indian responds to the call of a dry valley, however he may shun the
moist, warm valleys on the eastern border of the Cordillera.

Fig. 66—Irrigated and irrigable land of the coastal belt of Peru. The
map exhibits in a striking manner how small a part of the whole Pacific
slope is available for cultivation. Pasture grows over all but the steepest
and the highest portions of the Cordillera to the right of (above) the
dotted line. Another belt of pasture too narrow to show on the map,
grows in the fog belt on the seaward slopes of the Coast Range. Scale,
170 miles to the inch.

The greater part of the coastal region is occupied by the desert. Its outer
border is the low, dry, gentle, eastward-facing slope of the Coast Range. Its
inner border is the foot of the steep descent that marks the edge of the lava
plateau. This descent is a fairly well-marked line, here and there broken by
a venturesome lava flow that extends far out from the main plateau. Within
these definite borders the desert extends continuously northwestward for
hundreds of miles along the coast of Peru from far beyond the Chilean
frontier almost to the border of Ecuador. It is broken up by deep tranverse
valleys and canyons into so-called “pampas,” each of which has a separate
name; thus west of Arequipa between the Vitor and Majes valleys are the
“Pampa de Vitor” and the “Pampa de Sihuas,” and south of the Vitor is the
“Pampa de Islay.”
The pampa surfaces are inclined in general toward the sea. They were
built up to their present level chiefly by mountain streams before the

present deep valleys were cut, that is to say, when the land was more than a
half-mile lower. Some of their material is wind-blown and on the walls of
the valleys are alternating belts of wind-blown and water-laid strata from
one hundred to four hundred feet thick as if in past ages long dry and long
wet periods had succeeded each other. The wind has blown sand and dust
from the desert down into the valleys, but its chief work has been to drive
the lighter desert waste up partly into the mountains and along their
margins, partly so high as to carry it into the realm of the lofty terrestrial
winds, whence it falls upon surfaces far distant from the fields of origin.
There are left behind the heavier sand which the wind rolls along on the
surfaces and builds into crescentic dunes called médanos, and the pebbles
that it can sandpaper but cannot remove bodily. Thus there are belts of
dunes, belts of irregular sand drifts, and belts of true desert “pavement” (a
residual mantle of faceted pebbles and irregular stones).

Yet another feature of the desert pampa are the “dry” valleys that join the
through-flowing streams at irregular intervals, as shown in the

accompanying regional diagram. If one follow a dry valley to its head he
will find there a set of broad and shallow tributaries. Sand drifts may clog
them and appear to indicate that water no longer flows through them. They
are often referred to by unscientific travelers as evidences of a recent
change of climate. I had once the unusual opportunity (in the mountains of
Chile) of seeing freshly fallen snow melted rapidly and thus turned
suddenly into the streams. In 1911 this happened also at San Pedro de
Atacama, northern Chile, right in the desert at 8,000 feet (2,440 m.)
elevation, and in both places the dry, sand-choked valleys were cleaned out
and definite channels reëstablished. From a large number of facts like these
we know that the dry valleys represent the work of the infrequent rains. No
desert is absolutely rainless, although until recently it was the fashion to say
so. Naturally the wind, which works incessantly, partly offsets the work of
the water. Yet the wind can make but little impression upon the general
outlines of the dry valleys. They remain under the dominance of the
irregular rains. These come sometimes at intervals of three or four years,
again at intervals of ten to fifteen years, and some parts of the desert have
probably been rainless for a hundred years. Some specific cases are
discussed in the chapter on Climate.
The large valleys of the desert zone have been cut by snow-fed streams
and then partly filled again so that deep waste lies on their floors and abuts
with remarkable sharpness against the bordering cliffs (Fig. 155). Extensive
flats are thus available for easy cultivation, and the through-flowing streams
furnish abundant water to the irrigating canals. The alluvial floor begins
almost at the foot of the steep western slope of the lava plateau, but it is
there stony and coarse—hence Chuquibamba, or plain of stones (chuqui =
stone; bamba = plain). Farther down and about half-way between
Chuquibamba and Aplao (Camaná Quadrangle) it is partly covered with
fresh mud and sand flows from the bordering valley walls and the stream is
intrenched two hundred feet. A few miles above Aplao the stream emerges
from its narrow gorge and thenceforth flows on the surface of the alluvium
right to the sea. Narrow places occur between Cantas and Aplao, where
there is a projection of old and hard quartzitic rock, and again above
Camaná, where the stream cuts straight across the granite axis of the Coast
Range. Elsewhere the rock is either a softer sandstone or still unindurated
sands and gravels, as at the top of the desert series of strata that are exposed

on the valley wall. The changing width of the valley is thus a reflection of
the changing hardness of the rock.
There is a wide range of products between Chuquibamba at 10,000 feet
(3,050 m.) at the head of the valley and Camaná near the valley mouth. At
the higher levels fruit will not grow—only alfalfa, potatoes, and barley. A
thousand feet below Chuquibamba fruit trees appear. Then follows a barren
stretch where there are mud flows and where the river is intrenched. Below
this there is a wonderful change in climate and products. The elevation falls
off 4,000 feet and the first cultivated patches below the middle unfavorable
section are covered with grape vines. Here at 3,000 feet (900 m.) elevation
above the sea begin the famous vineyards of the Majes Valley, which
support a wine industry that dates back to the sixteenth century. Some of the
huge buried earthenware jars for curing the wine at Hacienda Cantas were
made in the reign of Philip II.
The people of Aplao and Camaná are among the most hospitable and
energetic in Peru, as if these qualities were but the reflection of the bounty
of nature. Nowhere could I see evidences of crowding or of the degeneracy
or poverty that is so often associated with desert people. Water is always
plentiful; sometimes indeed too plentiful, for floods and changes in the bed
of the river are responsible for the loss of a good deal of land. This
abundance of water means that both the small and the large landowners
receive enough. There are none of the troublesome official regulations, as in
the poorer valleys with their inevitable favoritism or downright graft. Yet
even here the valley is not fully occupied; at many places more land could
be put under cultivation. The Belaunde brothers at Cantas have illustrated
this in their new cotton plantation, where clearings and new canals have
turned into cultivated fields tracts long covered with brush.
The Majes Valley sorely lacks an adequate port. Its cotton, sugar, and
wine must now be shipped to Camaná and thence to Mollendo, either by a
small bi-weekly boat, or by pack-train over the coast trail to Quilca, where
ocean steamers call. This is so roundabout a way that the planters of the
mid-valley section and the farmers of the valley head now export their
products over the desert trail from Cantas to Vitor on the Mollendo-
Arequipa railroad, whence they can be sent either to the cotton mills or the
stores of Arequipa, the chief distributing market of southern Peru, or to the
ocean port.

The foreshore at Camaná is low and marshy where the salt water covers
the outer edge of the delta. In the hollow between two headlands a broad
alluvial plain has been formed, through which the shallow river now
discharges. Hence the natural indentation has been filled up and the river
shoaled. To these disadvantages must be added a third, the shoaling of the
sea bottom, which compels ships to anchor far off shore. Such shoals are so
rare on this dry and almost riverless coast as to be a menace to navigation.
The steamer Tucapelle, like all west-coast boats, was sailing close to the
unlighted shore on a very dark night in April, 1911, when the usual fog
came on. She struck the reef just off Camaná. Half of her passengers
perished in trying to get through the tremendous surf that broke over the
bar. The most practicable scheme for the development of the port would
seem to be a floating dock and tower anchored out of reach of the surf, and
connected by cable with a railway on shore. Harbor works would be
extraordinarily expensive. The valley can support only a modest project.
The relations of 65 , representing the Camaná-Vitor region, are typical of
southern Peru, with one exception. In a few valleys the streams are so small
that but little water is ever found beyond the foot of the mountains, as at
Moquegua. In the Chili Valley is Arequipa (8,000 feet), right at the foot of
the big cones of the Maritime Cordillera (see Fig. 6). The green valley floor
narrows rapidly and cultivation disappears but a few miles below the town.
Outside the big valleys cultivation is limited to the best spots along the foot
of the Coast Range, where tiny streams or small springs derive water from
the zone of clouds and fogs on the seaward slopes of the Coast Range. Here
and there are olive groves, a vegetable garden, or a narrow alfalfa meadow,
watered by uncertain springs that issue below the hollows of the bordering
mountains.

Fig. 67—Irrigated and irrigable Fig. 68—The projected canal to
land in the Ica Valley of the convey water from the Atlantic
coastal desert of Peru. slope to the Pacific slope of the
Maritime Cordillera.[19]

In central and northern Peru the coastal region has aspects quite different
from those about Camaná. At some places, for example north of Cerro Azul,
the main spurs of the Cordillera extend down to the shore. There is neither a
low Coast Range nor a broad desert pampa. In such places flat land is found
only on the alluvial fans and deltas. Lima and Callao are typical. 66 ,
compiled from Adams’s reports on the water resources of the coastal region
of Peru, shows this distinctive feature of the central region. Beyond
Salaverry extends the northern region, where nearly all the irrigated land is
found some distance back from the shore. The farther north we go the more
marked is this feature, because the coastal belt widens. Catacaos is several
miles from the sea, and Piura is an interior place. At the extreme north,
where the rains begin, as at Tumbez, the cultivated land once more extends
to the coast.

Fig. 69—A stream of the intermittent type in the coastal desert of
Peru. Depth of water in the Puira River at Puira, 1905. (Bol. de Minas
del Perú, 1906, No. 45, p. 2.)

Fig. 70—A stream of the perennial type in the coastal desert of Peru.
Depth of water in the Chira River at Sullana, 1905. Data from May to
September are approximate. (Bol. de Minas del Perú, 1906, No. 45, p.
2.)

These three regions contain all the fertile coastal valleys of Peru. The
larger ones are impressive—with cities, railways, ports, and land in a high
state of cultivation. But they are after all only a few hundred square miles in
extent. They contain less than a quarter of the people. The whole Pacific

slope from the crest of the Cordillera has about 15,000 square miles (38,850
sq. km.), and of this only three per cent is irrigated valley land, as shown in
66 . Moreover, only a small additional amount may be irrigated, perhaps
one half of one per cent. Even this amount may be added not only by a
better use of the water but also by the diversion of streams and lakes from
the Atlantic to the Pacific. Figs. 67 and 68 represent such a project, in which
it is proposed to carry the water of Lake Choclococha through a canal and
tunnel under the continental divide and so to the head of the Ica Valley. A
little irrigation can be and is carried on by the use of well water, but this
will never be an important source because of the great depth to the ground
water, and the fact that it, too, depends ultimately upon the limited rains.
The inequality of opportunity in the various valleys of the coastal region
depends in large part also upon inequality of river discharge. This is
dependent chiefly upon the sources of the streams, whether in snowy peaks
of the main Cordillera with fairly constant run-off, or in the western spurs
where summer rains bring periodic high water. A third type has high water
during the time of greatest snow melting, combined with summer rains, and
to this class belongs the Majes Valley with its sources in the snow-cap of
Coropuna. The other two types are illustrated by the accompanying
diagrams for Puira and Chira, the former intermittent in flow, the latter
fairly constant.[20]

CHAPTER IX

CLIMATOLOGY OF THE PERUVIAN ANDES
CLIMATIC BELTS
The noble proportions of the Peruvian Andes and their position in
tropical latitudes have given them climatic conditions of great diversity.
Moreover, their great breadth and continuously lofty summits have
distributed the various climatic types over spaces sufficiently ample to
affect large and important groups of people. When we add to this the fact
that the topographic types developed on a large scale are distributed at
varying elevations, and that upon them depend to a large degree the chief
characteristics of the soil, another great factor in human distribution, we are
prepared to see that the Peruvian Andes afford some striking illustrations of
combined climatic and topographic control over man.
The topographic features in their relations to the people have been
discussed in preceding chapters. We shall now examine the corresponding

effects of climate. It goes without saying that the topographic and climatic
controls cannot and need not be kept rigidly apart. Yet it seems desirable,
for all their natural interdependence, to give them separate treatment, since
the physical laws upon which their explanations depend are of course
entirely distinct. Further, there is an independent group of human responses
to detailed climatic features that have little or no connection with either
topography or soil.
The chief climatic belts of Peru run roughly from north to south in the
direction of the main features of the topography. Between 13° and 18° S.,
however, the Andes run from northwest to southeast, and in short stretches
nearly west-east, with the result that the climatic belts likewise trend
westward, a condition well illustrated on the seventy-third meridian. Here
are developed important climatic features not found elsewhere in Peru. The
trade winds are greatly modified in direction and effects; the northward-
trending valleys, so deep as to be secluded from the trades, have floors that
are nearly if not quite arid; a restricted coastal region enjoys a heavier
rainfall; and the snowline is much more strongly canted from west to east
than anywhere else in the long belt of mountains from Patagonia to
Venezuela. These exceptional features depend, however, upon precisely the
same physical laws as the normal climatic features of the Peruvian Andes.
They can, therefore, be more easily understood after attention has been
given to the larger aspects of the climatic problem of which they form a
part.
The critical relations of trade winds, lofty mountains, and ocean currents
that give distinction to Peruvian climate are shown in Figs. 71 to 73. From
them and 74 it is clear that the two sides of the Peruvian mountains are in
sharp contrast climatically. The eastern slopes have almost daily rains, even
in the dry season, and are clothed with forest. The western leeward slopes
are so dry that at 8,000 feet even the most drought-resisting grasses stop—
only low shrubs live below this level, and over large areas there is no
vegetation whatever. An exception is the Coast Range, not shown on these
small maps, but exhibited in the succeeding diagram. These have moderate
rains on their seaward (westerly) slopes during some years and grass and
shrubby vegetation grow between the arid coastal terraces below them and
the parched desert above. The greatest variety of climate is enjoyed by the
mountain zone. Its deeper valleys and basins descend to tropical levels; its
higher ranges and peaks are snow-covered. Between are the climates of half

the world compressed, it may be, between 6,000 and 15,000 feet of
elevation and with extremes only a day’s journey apart.

Fig. 71—The three chief topographic regions of Peru.
Fig. 72—The wind belts of Peru and ocean currents of adjacent waters.
Fig. 73—The climatic belts of Peru.
Fig. 74—Belts of vegetation in Peru.

In the explanation of these contrasts we have to deal with relatively
simple facts and principles; but the reader who is interested chiefly in the
human aspects of the region should turn to p. 138 where the effects of the
climate on man are set forth. The ascending trades on the eastern slopes
pass successively into atmospheric levels of diminishing pressure; hence
they expand, deriving the required energy for expansion from the heat of
the air itself. The air thereby cooled has a lower capacity for the retention of
water vapor, a function of its temperature; the colder the air the less water
vapor it can take up. As long as the actual amount of water vapor in the air
is less than that which the air can hold, no rain falls. But the cooling process
tends constantly to bring the warm, moist, ascending air currents to the limit
of their capacity for water vapor by diminishing the temperature. Eventually
the air is saturated and if the capacity diminishes still further through
diminishing temperature some of the water vapor must be condensed from a
gaseous to a liquid form and be dropped as rain.

The air currents that rise thousands of feet per day on the eastern slopes
of the Andes pass again and again through this practically continuous
process and the eastern aspect of the mountains is kept rain-soaked the
whole year round. For the trades here have only the rarest reversals.
Generally they blow from the east day after day and repeat a fixed or
average type of weather peculiar to that part of the tropics under their
steady domination. During the southern summer, when the day-time
temperature contrasts between mountains and plains are strongest, the force
of the trade wind is greatly increased and likewise the rapidity of the rain-
making processes. Hence there is a distinct seasonal difference in the
rainfall—what we call, for want of a better name, a “wet” and a “dry”
season.
On the western or seaward slopes of the Peruvian Andes the trade winds
descend, and the process of rain-making is reversed to one of rain-taking.
The descending air currents are compressed as they reach lower levels
where there are progressively higher atmospheric pressures. The energy
expended in the process is expressed in the air as heat, whence the
descending air gains steadily in temperature and capacity for water vapor,
and therefore is a drying wind. Thus the leeward, western slopes of the
mountains receive little rain and the lowlands on that side are desert.
THE CLIMATE OF THE COAST
A series of narrow but pronounced climatic zones coincide with the
topographic subdivisions of the western slope of the country between the
crest of the Maritime Cordillera and the Pacific Ocean. This belted
arrangement is diagrammatically shown in 75 . From the zone of lofty
mountains with a well-marked summer rainy season descent is made by
lower slopes with successively less and less precipitation to the desert strip,
where rain is only known at irregular intervals of many years’ duration.
Beyond lies the seaward slope of the Coast Range, more or less constantly
enveloped in fog and receiving actual rain every few years, and below it is
the very narrow band of dry coastal terraces.

Fig. 75—Topographic and climatic provinces in the coastal region of
Peru. The broadest division, into the zones of regular annual rains and
of irregular rains, occurs approximately at 8,000 feet but is locally
variable. To the traveler it is always clearly defined by the change in
architecture, particularly of the house roofs. Those of the coast are flat;
those of the sierra are pitched to facilitate run off.

The basic cause of the general aridity of the region has already been
noted; the peculiar circumstances giving origin to the variety in detail can
be briefly stated. They depend upon the meteorologic and hydrographic
features of the adjacent portion of the South Pacific Ocean and upon the
local topography.
The lofty Andes interrupt the broad sweep of the southeast trades passing
over the continent from the Atlantic; and the wind circulation of the
Peruvian Coast is governed to a great degree by the high pressure area of
the South Pacific. The prevailing winds blow from the south and the
southeast, roughly paralleling the coast or, as onshore winds, making a
small angle with it. When the Pacific high pressure area is best developed
(during the southern winter), the southerly direction of the winds is
emphasized, a condition clearly shown on the Pilot Charts of the South
Pacific Ocean, issued by the U.S. Hydrographic Office.
The hydrographic feature of greatest importance is the
Humboldt Current. To its cold waters is largely due the
remarkably low temperatures of the coast.[21] In the latitude
of Lima its mean surface temperature is about 10° below
normal. Lima itself has a mean annual temperature 4.6° F.
below the theoretical value for that latitude, (12° S.). An
accompanying curve shows the low temperature of Callao
Fig. 76—
Temperatures at
during the winter months. From mid-June to mid-
Callao, June- September the mean was 61° F., and the annual mean is
September, 1912, only 65.6° F. (18° C.). The reduction in temperature is
from
observations accompanied by a reduction in the vapor capacity of the
taken by Captain super-incumbent air, an effect of which much has been
A. Taylor, of made in explanation of the west-coast desert. That it is a
Callao. Air
temperatures are contributing though not exclusive factor is demonstrated in
shown by heavy Fig. 77. Curve A represents the hypothetical change of
lines; sea temperature on a mountainous coast with temporary
temperatures by
light lines. In afternoon onshore winds from a warm sea. Curve B
view of the scant

record for
represents the change of temperature if the sea be cold
comparative
land and water (actual case of Peru). The more rapid rise of curve B to the
temperatures right of X-X′, the line of transition, and its higher elevation
along the
above its former saturation level, as contrasted with A,
Peruvian coast
indicates greater dryness (lower relative humidity). There
this record, short
as it is, has has been precipitation in case A, but at a higher
special interest.temperature, hence more water vapor remains in the air
after precipitation has ceased. Curve B ultimately rises
nearly to the level of A, for with less water vapor in the air of case B the
temperature rises more rapidly (a general law). Moreover, the higher the
temperature the greater the radiation. To summarize, curve A rises more
slowly than curve B, (1) because of the greater amount of water vapor it
contains, which must have its temperature raised with that of the air, and
thus absorbs energy which would otherwise go to increase the temperature
of the air, and (2) because its loss of heat by radiation is more rapid on
account of its higher temperature. We conclude from these principles and
deductions that under the given conditions a cold current intensifies, but
does not cause the aridity of the west-coast desert.

Fig. 77—To show progressive lowering of saturation temperature in
a desert under the influence of the mixing process whereby dry and
cool air from aloft sinks to lower levels thus displacing the warm
surface air of the desert. The evaporated moisture of the surface air is
thus distributed through a great volume of upper air and rain becomes
increasingly rarer. Applied to deserts in general it shows that the effect
of any cosmic agent in producing climatic change from moist to dry or
dry to moist will be disproportionately increased. The shaded areas C
and C’ represent the fog-covered slopes of the Coast Range of Peru as
shown in Fig. 92. X-X’ represents the crest of the Coast Range.

Curves a and b represent the rise of temperature in two contrasted cases
of warm and cold sea with the coastal mountains eliminated, so as to
simplify the principle applied to A and B. The steeper gradient of b also
represents the fact that the lower the initial temperature the dryer will the air
become in passing over the warm land. For these two curves the transition

line X-X’ coincides with the crest of the Coast Range. It will also be seen
that curve a is never so far from the saturation level as curve b. Hence,
unusual atmospheric disturbances would result in heavier and more frequent
showers.

Fig. 78—Wind roses for Callao. The figures for the earlier period
(1897-1900) are drawn from data in the Boletín de la Sociedad
Geográfica de Lima, Vols. 7 and 8, 1898-1900: for the latter period data
from observations of Captain A. Taylor, of Callao. The diameter of the
circle represents the proportionate number of observations when calm
was registered.

Fig. 79—Wind roses for Mollendo. The figures are drawn from data
in Peruvian Meteorology (1892-1895), Annals of the Astronomical

Observatory of Harvard College, Vol. 30, Pt. 2, Cambridge, Mass.,
1906. Observations for an earlier period, Feb. 1889-March 1890, (Id.
Vol. 39, Pt. 1, Cambridge, Mass. 1890) record S. E. wind at 2 p. m. 97
per cent of the observation time.

Fig. 80—Wind roses for the summer and winter seasons of the years
1911-1913. The diameter of the circle in each case shows the proportion
of calm. Figures are drawn from data in the Anuario Meteorológico de
Chile, Publications No. 3, (1911), 6 (1912) and 13 (1913), Santiago,
1912, 1914, 1914.

Turning now to local factors we find on the west coast a regional
topography that favors a diurnal periodicity of air movement. The strong
slopes of the Cordillera and the Coast Range create up-slope or eastward air
gradients by day and opposite gradients by night. To this circumstance, in
combination with the low temperature of the ocean water and the direction
of the prevailing winds, is due the remarkable development of the sea-
breeze, without exception the most important meteorological feature of the
Peruvian Coast. Several graphic representations are appended to show the
dominance of the sea-breeze (see wind roses for Callao, Mollendo, Arica,
and Iquique), but interest in the phenomenon is far from being confined to
the theoretical. Everywhere along the coast the virazon, as the sea-breeze is
called in contradistinction to the terral or land-breeze, enters deeply into the
affairs of human life. According to its strength it aids or hinders shipping;
sailing boats may enter port on it or it may be so violent, as, for example, it
commonly is at Pisco, that cargo cannot be loaded or unloaded during the
afternoon. On the nitrate pampa of northern Chile (20° to 25° S.) it not
infrequently breaks with a roar that heralds its coming an hour in advance.
In the Majes Valley (12° S.) it blows gustily for a half-hour and about noon
(often by eleven o’clock) it settles down to an uncomfortable gale. For an
hour or two before the sea-breeze begins the air is hot and stifling, and dust

clouds hover about the traveler. The maximum temperature is attained at
this time and not around 2.00 P. M. as is normally the case. Yet so
boisterous is the noon wind that the laborers time their siesta by it, and not
by the high temperatures of earlier hours. In the afternoon it settles down to
a steady, comfortable, and dustless wind, and by nightfall the air is once
more calm.

Fig. 81—Wind roses for Iquique for the summer and winter seasons
of the years 1911-1913. The diameter of the circle in each case shows
the proportion of calm. For source of data see Fig. 80.

Of highest importance are the effects of the sea-breeze on precipitation.
The bold heights of the Coast Range force the nearly or quite saturated air
of the sea-wind to rise abruptly several thousand feet, and the adiabatic
cooling creates fog, cloud, and even rain on the seaward slope of the
mountains. The actual form and amount of precipitation both here and in
the interior region vary greatly, according to local conditions and to season
and also from year to year. The coast changes height and contour from place
to place. At Arica the low coastal chain of northern Chile terminates at the
Morro de Arica. Thence northward is a stretch of open coast, with almost no
rainfall and little fog. But in the stretch of coast between Mollendo and the
Majes Valley a coastal range again becomes prominent. Fog enshrouds the
hills almost daily and practically every year there is rain somewhere along
their western aspect.

Fig. 82—The wet and dry Fig. 83—During the southern
seasons of the Coast Range and summer the seaward slopes of the

the Cordillera are complementary Coast Range are comparatively
in time. The “wet” season of the clear of fog. Afternoon cloudiness
former occurs during the southern is characteristic of the desert and
winter; the cloud bank on the increases eastward (compare 86 ),
seaward slopes of the hills is best the influence of the strong sea
developed at that time and actual winds as well as that of the trades
rains may occur. (compare 93 B) being felt on the
lower slopes of the Maritime
Cordillera.

During the southern winter the cloud bank of the coast is best developed
and precipitation is greatest. At Lima, for instance, the clear skies of March
and April begin to be clouded in May, and the cloudiness grows until, from
late June to September, the sun is invisible for weeks at a time. This is the
period of the garua (mist) or the “tiempo de lomas,” the “season of the
hills,” when the moisture clothes them with verdure and calls thither the
herds of the coast valleys.
During the southern summer on account of the greater
relative difference between the temperatures of land and
water, the sea-breeze attains its maximum strength. It then
accomplishes its greatest work in the desert. On the pampa
of La Joya, for example, the sand dunes move most rapidly
in the summer. According to the Peruvian Meteorological
Records of the Harvard Astronomical Observatory the
average movement of the dunes from April to September,
1900, was 1.4 inches per day, while during the summer
months of the same year it was 2.7 inches. In close
agreement are the figures for the wind force, the record for Fig. 84—
Cloudiness at
which also shows that 95 per cent of the winds with Callao. Figures
strength over 10 miles per hour blew from a southerly are drawn from
direction. Yet during this season the coast is generally data in the
Boletín de la
clearest of fog and cloud. The explanation appears to lie in Sociedad
the exceedingly delicate nature of the adjustments between Geográfica de
the various rain-making forces. The relative humidity of Lima, Vols. 7 and
8, 1898-1900.
the air from the sea is always high, but on the immediate They represent
coast is slightly less so in summer than in winter. Thus in the conditions at
Mollendo the relative humidity during the winter of 1895 three observation
hours during the
was 81 per cent; during the summer 78 per cent. Moreover, summers (Dec.,
the temperature of the Coast Range is considerably higher Jan.) of 1897-

in summer than in winter, and there is a tendency to 1898, 1898-1899,
1899-1900 and
reëvaporation of any moisture that may be blown against the winters (June,
it. The immediate shore, indeed, may still be cloudy as is July) of 1898 and
the case at Callao, which actually has its cloudiest season 1899.
in the summer but the hills are comparatively clear. In
consequence the sea-air passes over into the desert, where the relative
increase in temperature has not been so great (compare Mollendo and La
Joya in the curve for mean monthly temperature), with much higher vapor
content than in winter. The relative humidity for the winter season at La
Joya, 1895, was 42.5 per cent; for the summer season 57 per cent. The
influence of the great barrier of the Maritime Cordillera, aided doubtless by
convectional rising, causes ascent of the comparatively humid air and the
formation of cloud. Farther eastward, as the topographic influence is more
strongly felt, the cloudiness increases until on the border zone, about 8,000
feet in elevation, it may thicken to actual rain. Data have been selected to
demonstrate this eastern gradation of meteorological phenomena.

Fig. 85—Temperature curves for Mollendo (solid lines) and La Joya
(broken lines) April, 1894, to December, 1895, drawn from data in
Peruvian Meteorology, 1892-1895, Annals of the Astronomical
Observatory of Harvard College, Vol. 49, Pt. 2, Cambridge, Mass.,
1908. The approximation of the two curves of maximum temperature
during the winter months contrasts with the well-maintained difference
in minimum temperatures throughout the year.

Fig. 86—Mean monthly cloudiness for Mollendo (solid line) and La
Joya (broken line) from April, 1892, to December, 1895. Mollendo, 80
feet elevation, has the maximum winter cloudiness characteristic of the
seaward slope of the Coast Range (compare Fig. 82) while the desert
station of La Joya, 4,140 feet elevation, has typical summer cloudiness
(compare Fig. 83). Figures are drawn from data in Peruvian

Meteorology, 1892-1895, Annals of the Astronomical Observatory of
Harvard College, Vol. 49, Pt. 2, Cambridge, Mass., 1908.

Fig. 87—Wind roses for La Joya for the period April, 1892, to
December, 1895. Compare the strong afternoon indraught from the
south with the same phenomenon at Mollendo, Fig. 79. Figures drawn
from data in Peruvian Meteorology, 1892-1895, Annals of the
Astronomical Observatory of Harvard College, Vol. 39, Pt. 2,
Cambridge, Mass., 1906.

At La Joya, a station on the desert northeast of Mollendo at an elevation
of 4,140 feet, cloudiness is always slight, but it increases markedly during
the summer. Caraveli, at an altitude of 5,635 feet,[22] and near the eastern
border of the pampa, exhibits a tendency toward the climatic characteristics
of the adjacent zone. Data for a camp station out on the pampa a few
leagues from the town, were collected by Mr. J. P. Little of the staff of the
Peruvian Expedition of 1912-13. They relate to the period January to
March, 1913. Wind roses for these months show the characteristic light
northwesterly winds of the early morning hours, in sharp contrast with the
strong south and southwesterly indraught of the afternoon. The daily march
of cloudiness is closely coördinated. Quotations from Mr. Little’s field
notes follow:
“In the morning there is seldom any noticeable wind. A breeze starts at
10 A. M., generally about 180° (i. e. due south), increases to 2 or 3 velocity
at noon, having veered some 25° to the southwest. It reaches a maximum
velocity of 3 to 4 at about 4.00 P. M., now coming about 225° (i. e.
southwest). By 6 P. M. the wind has died down considerably and the
evenings are entirely free from it. The wind action is about the same every
day. It is not a cold wind and, except with the fog, not a damp one, for I
have not worn a coat in it for three weeks. It has a free unobstructed sweep
across fairly level pampas.... At an interval of every three or four days a
dense fog sweeps up from the southwest, dense enough for one to be easily
lost in it. It seldom makes even a sprinkle of rain, but carries heavy

moisture and will wet a man on horseback in 10 minutes. It starts about 3
P.M. and clears away by 8.00 P. M..... During January, rain fell in camp
twice on successive days, starting at 3.00 P. M. and ceasing at 8.00 P. M. It
was merely a light, steady rain, more the outcome of a dense fog than a
rain-cloud of quick approach. In Caraveli, itself, I am told that it rains off
and on all during the month in short, light showers.” This record is dated
early in February and, in later notes, that month and March are recorded
rainless.

Fig. 88—Wind roses for a station on the eastern border of the Coast
Desert near Caraveli during the summer (January to March) of 1913.
Compare with Fig. 87. The diameter of the circle in each case
represents the proportion of calm. Note the characteristic morning
calm.

Chosica (elevation 6,600 feet), one of the meteorological stations of the
Harvard Astronomical Observatory, is still nearer the border. It also lies
farther north, approximately in the latitude of Lima, and this in part may
help to explain the greater cloudiness and rainfall. The rainfall for the year
1889-1890 was 6.14 inches, of which 3.94 fell in February. During the
winter months when the principal wind observations were taken, over 90
per cent showed noon winds from a southerly direction while in the early
morning northerly winds were frequent. It is also noteworthy that the
“directions of the upper currents of the atmosphere as recorded by the
motion of the clouds was generally between N. and E.” Plainly we are in
the border region where climatic influences are carried over from the
plateau and combine their effects with those from Pacific sources. Arequipa,
farther south, and at an altitude of 7,550 feet, resembles Chosica. For the
years 1892 to 1895 its mean rainfall was 5.4 inches.

Fig. 89—Cloudiness at the desert station of Fig. 88 (near Caraveli),
for the summer (January to March) of 1913.

Besides the seasonal variations of precipitation there are longer periodic
variations that are of critical importance on the Coast Range. At times of
rather regular recurrence, rains that are heavy and general fall there. Every
six or eight years is said to be a period of rain, but the rains are also said to
occur sometimes at intervals of four years or ten years. The regularity is
only approximate. The years of heaviest rain are commonly associated with
an unusual frequency of winds from the north, and an abnormal
development of the warm current, El Niño, from the Gulf of Guayaquil.
Such was the case in the phenomenally rainy year of 1891. The connection
is obscure, but undoubtedly exists.
The effects of the heavy rains are amazing and appear the more so
because of the extreme aridity of the country east of them. During the
winter the desert traveler finds the air temperature rising to uncomfortable
levels. Vegetation of any sort may be completely lacking. As he approaches
the leeward slope of the Coast Range, a cloud mantle full of refreshing
promise may be seen just peeping over the crest (Fig. 91). Long, slender
cloud filaments project eastward over the margin of the desert. They are
traveling rapidly but they never advance far over the hot wastes, for their
eastern margins are constantly undergoing evaporation. At times the top of
the cloud bank rises well above the crest of the Coast Range, and it seems
to the man from the temperate zone as if a great thunderstorm were rising in
the west. But for all their menace of wind and rain the clouds never get
beyond the desert outposts. In the summer season the aspect changes, the
heavy yellow sky of the desert displaces the murk of the coastal mountains
and the bordering sea.
It is an age-old strife renewed every year and limited to a narrow field of
action, wonderfully easy to observe. We saw it in its most striking form at
the end of the winter season in October, 1911, and for more than a day
watched the dark clouds rise ominously only to melt into nothing where the

desert holds sway. At night we camped beside a scum-
coated pool of alkali water no larger than a wash basin. It
lay in a valley that headed in the Coast Range, and carried
down into the desert a mere trickle that seeped through the
gravels of the valley floor. A little below the pool the
valley cuts through a mass of granite and becomes a steep-
Fig. 90— walled gorge. The bottom is clogged with waste, here
Cloudiness at
Chosica, July, boulders, there masses of both coarse and fine alluvium.
1889, to The water in the valley was quite incapable of
September, 1890. accomplishing any work except that associated with
Chosica, a station
on the Oroya solution and seepage, and we saw it in the wet season of an
railroad east of unusually wet year. Clearly there has been a diminution in
Lima, is situated the water supply. But time prevented us from exploring
on the border
region between this particular valley to its head, to see if the reduction
the desert zone of were due to a change of climate, or only to capture of the
the coast and the
mountain zone of
head-waters by the vigorous rain-fed streams that enjoy a
yearly rains. The favorable position on the wet seaward slopes and that are
minimum extending their watershed aggressively toward the east at
cloudiness
recorded about 11
the expense of their feeble competitors in the dry belt.
a. m. is shown by An early morning start enabled me to witness the whole
a broken line; the
maximum
series of changes between the clear night and the murky
cloudiness, about day, and to pass in twelve hours from the dry desert belt
7 p. m., by a through the wet belt, and emerge again into the sunlit
dotted line, and
the mean for the
terraces at the western foot of the Coast Range. Two hours
24 hours by a before daylight a fog descended from the hills and the
heavy solid line. going seemed to be curiously heavy for the beasts. At
The curves are
drawn from data daybreak my astonishment was great to find that it was due
in Peruvian to the distinctly moist sand. We were still in the desert.
Meteorology, There was not a sign of a bush or a blade of grass. Still, the
1889-1890,
Annals of the surface layer, from a half inch to an inch thick, was really
Astronomical wet. The fog that overhung the trail lifted just before
Observatory of sunrise, and at the first touch of the sun melted away as
Harvard College,
Vol. 39, Pt. 1, swiftly as it had come. With it went the surface moisture
Cambridge, and an hour after sunrise the dust was once more rising in
Mass., 1899. clouds around us.
We had no more than broken camp that morning when a
merchant with a pack-train passed us, and shouted above the bells of the

leading animals that we ought to hurry or we should get caught in the rain at
the pass. My guide, who, like many of his kind, had never before been over
the route he pretended to know, asked him in heaven’s name what drink in
distant Camaná whence he had come produced such astonishing effects as
to make a man talk about rain in a parched desert. We all fell to laughing
and at our banter the stranger stopped his pack-train and earnestly urged us
to hurry, for, he said, the rains beyond the pass were exceptionally heavy
this year. We rode on in a doubtful state of mind. I had heard about the
rains, but I could not believe that they fell in real showers!
About noon the cloud bank darkened and overhung the border of the
desert. Still the sky above us was clear. Then happened what I can yet
scarcely believe. We rode into the head of a tiny valley that had cut right
across the coast chain. A wisp of cloud, an outlier of the main bank, lay
directly ahead of us. There were grass and bushes not a half-mile below the
bare dry spot on which we stood. We were riding down toward them when
of a sudden the wind freshened and the cloud wisp enveloped us, shutting
out the view, and ten minutes later the moisture had gathered in little beads
on the manes of our beasts and the trail became slippery. In a half-hour it
was raining and in an hour we were in the midst of a heavy downpour. We
stopped and pastured our famished beasts in luxuriant clover. While they
gorged themselves a herd of cattle drifted along, and a startled band of
burros that suddenly confronted our beasts scampered out of sight in the
heavy mist. Later we passed a herdsman’s hut and long before we reached
him he shouted to us to alter our course, for just ahead the old trail was wet
and treacherous at this time of year. The warning came too late. Several of
our beasts lost their footing and half rolled, half slid, down hill. One turned
completely over, pack and all, and lay in the soft mud calmly taking
advantage of the delay to pluck a few additional mouthfuls of grass. We
were glad to reach firmer ground on the other side of the valley.
The herdsmen were a hospitable lot. They had come from Camaná and
rarely saw travelers. Their single-roomed hut was mired so deeply that one
found it hard to decide whether to take shelter from the rain inside or escape
the mud by standing in the rain outside. They made a little so-called cheese,
rounded up and counted the cattle on clear days, drove them to the springs
from time to time, and talked incessantly of the wretched rains in the hills
and the delights of dry Camaná down on the coast. We could not believe
that only some hours’ traveling separated two localities so wholly unlike.

The heavy showers and luxuriant pastures of the wet years and the light
local rains of the dry years endow the Coast Range with many peculiar
geographic qualities. The heavy rains provide the desert people at the foot
of the mountains such a wealth of pasture for their burdensome stock as
many oases dwellers possess only in their dreams. From near and far cattle
are driven to the wet hill meadows. Some are even brought in from distant
valleys by sea, yet only a very small part of the rich pastures can be used. It
is safe to say that they could comfortably support ten times the number of
cattle, mules, and burros that actually graze upon them. The grass would be
cut for export if the weather were not so continually wet and if there were
not so great a mixture of weeds, flowers, and shrubs.
Then come the dry years. The surplus stock is sold, and what remains is
always maintained at great expense. In 1907 I saw stock grazing in a small
patch of dried vegetation back of Mollendo, although they had to be driven
several miles to water. They looked as if they were surviving with the
greatest difficulty and their restless search for pasture was like the search of
a desperate hunter of game. In 1911 the same tract was quite devoid of
grass, and except for the contour-like trails that completely covered the hills
no one would even guess that this had formerly been a cattle range. The
same year, but five months later, a carpet of grass, bathed in heavy mist,
covered the soil; a trickle of water had collected in pools on the valley
floor; several happy families from the town had laid out a prosperous-
looking garden; there were romping children who showed me where to pick
up the trail to the port; on every hand was life and activity because the rains
had returned bringing plenty in their train. I asked a native how often he
was prosperous.
“Segun el temporal y la Providencia” (according to the weather and to
Providence), he replied, as he pointed significantly to the pretty green hills
crowned with gray mist.
It, therefore, seems fortunate that the Coast Range is so placed as to
intercept and concentrate a part of the moisture that the sea-winds carry, and
doubly fortunate that its location is but a few miles from the coast, thereby
giving temporary relief to the relatively crowded people of the lower
irrigated valleys and the towns. The wet years formerly developed a crop of
prospectors. Pack animals are cheaper when there is good pasture and they
are also easier to maintain. So when the rains came the hopeful pick-and-
shovel amateurs began to emigrate from the towns to search for ore among

the discolored bands of rock intruded into the granite masses of the coastal
hills. However, the most likely spots have been so thoroughly and so
unsuccessfully prospected for many years that there is no longer any
interest in the “mines.”
Transportation rates are still most intimately related to the rains. My
guide had two prices—a high price if I proposed to enter a town at night
and thus require him to buy expensive forage; a low price if I camped in the
hills and reached the town in time for him to return to the hills with his
animals. Inquiry showed that this was the regular custom. I also learned that
in packing goods from one part of the coast to another forage must be
carried in dry years or the beasts required to do without. In wet years by a
very slight detour the packer has his beasts in good pasture that is free for
all. The merchant who dispatches the goods may find his charges nearly
doubled in extremely dry years. Goods are more expensive and there is a
decreased consumption. The effects of the rains are thus transmitted from
one to another, until at last nearly all the members of a community are
bearing a share of the burdens imposed by drought. As always there are a
few who prosper in spite of the ill wind. If the pastures fail, live stock must
be sold and the dealers ship south to the nitrate ports or north to the large
coast towns of Peru, where there is always a demand. Their business is most
active when it is dry or rather at the beginning, of the dry period. Also if
transport by land routes becomes too expensive the small traders turn to the
sea routes and the carriers have an increased business. But so far as I have
been able to learn, dry years favor only a few scattered individuals.
To the traveler on the west coast it is a source of constant surprise that
the sky is so often overcast and the ports hidden by fog, while on every
hand there are clear evidences of extreme aridity. Likewise it is often
inquired why the sunsets there should be often so superlatively beautiful
during the winter months when the coast is fog bound. Why a desert when
the air is so humid? Why striking sunsets when so many of the days are
marked by dull skies? As we have seen in the first part of this chapter, the
big desert tracts lie east of the Coast Range, and there, excepting slight
summer cloudiness, cloudless skies are the rule. The desert just back of the
coast is in many parts of Peru only a narrow fringe of dry marine terraces
quite unlike the real desert in type of weather and in resources. The fog
bank overhanging it forms over the Humboldt Current which lies off shore;
it drifts landward with the onshore wind; it forms over the upwelling cold

water between the current and the shore; it gathers on the seaward slopes of
the coastal hills as the inflowing air ascends them in its journey eastward.
Sometimes it lies on the surface of the land and the water; more frequently
it is some distance above them. On many parts of the coast its characteristic
position is from 2,000 to 4,000 feet above sea level, descending at night
nearly or quite to the surface, ascending by day and sometimes all but
disappearing except as rain-clouds on the hills.[23] Upon the local behavior
of the fog bank depends in large measure the local climate. A general
description of the coastal climate will have many exceptions. The physical
principles involved are, however, the same everywhere. I take for
discussion therefore the case illustrated by 92 , since this also displays with
reasonable fidelity the conditions along that part of the Peruvian coast
between Camaná and Mollendo which lies in the field of work of the Yale
Peruvian Expedition of 1911.
Three typical positions of the fog bank are shown in the figure, and a
fourth—that in which the bank extends indefinitely westward—may be
supplied by the imagination.
If the cloud bank be limited to C only the early morning hours at the port
are cloudy. If it extend to B the sun is obscured until midday. If it reach as
far west as A only a few late afternoon hours are sunny. Once in a while
there is a sudden splash of rain—a few drops which astonish the traveler
who looks out upon a parched landscape. The smaller drops are evaporated
before reaching the earth. In spite of the ever-present threat of rain the coast
is extremely arid. Though the vegetation appears to be dried and burned up,
the air is humid and for months the sky may be overcast most of the time.
So nicely are the rain-making conditions balanced that if one of our
ordinary low-pressure areas, or so-called cyclonic storms, from the
temperate zone were set in motion along the foot of the mountains, the
resulting deluge would immediately lay the coast in ruins. The cane-
thatched, mud-walled huts and houses would crumble in the heavy rain like
a child’s sand pile before a rising sea; the alluvial valley land would be
coated with infertile gravel; and mighty rivers of sand, now delicately
poised on arid slopes, would inundate large tracts of fertile soil.

Fig. 91—Looking down the canyon of the Majes River to the edge of
the cloud bank formed against the Coast Range back of Camaná.
Fig. 92—Topographic and climatic cross-section to show the varying
positions of the cloud bank on the coast of Peru, the dry terrace region,
and the types of stream profiles in the various belts.

If the fog and cloud bank extend westward indefinitely, the entire day
may be overcast or the sun appear for a few moments only through
occasional rifts. Generally, also, it will make an appearance just before
sunset, its red disk completely filling the narrow space between the under
surface of the clouds and the water. I have repeatedly seen the ship’s
passengers and even the crew leave the dinner table and collect in
wondering groups about the port-holes and doorways the better to see the
marvelous play of colors between sky and sea. It is impossible not to be
profoundly moved by so majestic a scene. A long resplendent path of light
upon the water is reflected in the clouds. Each cloud margin is tinged with
red and, as the sun sinks, the long parallel bands of light are shortened
westward, changing in color as they go, until at last the full glory of the
sunset is concentrated in a blazing arc of reds, yellows, and purples, that to
most people quite atones for the dull gray day and its humid air.
At times the clouds are broken up by the winds and scattered helter-
skelter through the west. A few of them may stray into the path of the sun
temporarily to hide it and to reflect its primary colors when the sun
reappears. From the main cloud masses there reach out slender wind-blown
streamers, each one delicately lighted as the sun’s rays filter through its
minute water particles. Many streamers are visible for only a short distance,

but when the sun catches them their filmy invisible fingers become delicate
bands of light, some of which rapidly grow out almost to the dome of the
sky. Slowly they retreat and again disappear as the rays of the sun are
gradually shut off by the upturning curve of the earth.
The unequal distribution of precipitation in the climatic zones of western
Peru has important hydrographic consequences. These will now be
considered. In the preceding figure four types of stream profiles are
displayed and each has its particular relation to the cloud bank. Stream 1 is
formed wholly upon the coastal terraces beneath the cloud bank. It came
into existence only after the uplift of the earth’s crust that brought the wave-
cut platforms above sea level. It is extremely youthful and on account first
of the small seepage at its headquarters—it is elsewhere wholly without a
tributary water supply—and, second, of the resistant granite that occurs
along this part of the coast, it has very steep and irregular walls and an
ungraded floor. Many of these “quebradas” are difficult to cross. A few of
them have fences built across their floors to prevent the escape of cattle and
burros that wander down from the grassy hills into the desert zone. Others
are partitioned off into corrals by stone fences, the steep walls of the gorge
preventing the escape of the cattle. To these are driven the market cattle, or
mules and burros that are required for relays along the shore trail.
Stream 2 heads in the belt of rains. Furthermore it is a much older stream
than 1, since it dates back to the time when the Coast Range was first
formed. It has ample tributary slopes and a large number of small valleys. A
trickle of water flows down to become lost in the alluvium of the lower part
of the valley or to reappear in scattered springs. Where springs and seepage
occur together, an olive grove or a garden marks the spot, a corral or two
and a mud or stone or reed hut is near by, and there is a tiny oasis. Some of
these dots of verdure become so dry during a prolonged drought that the
people, long-established, move away. To others the people return
periodically. Still others support permanent settlements.
Stream 3 has still greater age. Its only competitors are the feeble, almost
negligible, streams that at long intervals flow east toward the dry zone.
Hence it has cut back until it now heads in the desert. Its widely branched
tributaries gather moisture from large tracts. There is running water in the
valley floor even down in the terrace zone. At least there are many
dependable springs and the permanent homes that they always encourage. A
valley of this type is always marked by a well-defined trail that leads from

settlement to settlement and eastward over the “pass” to the desert and the
Andean towns.
Stream 4 is a so-called “antecedent” stream. It existed before the Coast
Range was uplifted and cut its channel downward as the mountains rose in
its path. The stretch where it crosses the mountains may be a canyon with a
narrow, rocky, and uncultivable floor, so that the valley trails rise to a pass
like that at the head of stream 3, and descend again to the settlements at the
mouth of 4. There is in this last type an abundance of water, for the sources
of the stream are in the zone of permanent snows and frequent winter rains
of the lofty Cordillera of the Andes. The settlements along this stream are
continuous, except where shut-ins occur—narrow, rocky defiles caused by
more resistant rock masses in the path of the stream. Here and there are
villages. The streams have fish. When the water rises the river may be
unfordable and people on opposite sides must resort to boats or rafts.[24]
EASTERN BORDER CLIMATES
On windward mountain slopes there is always a belt of maximum
precipitation whose elevation and width vary with the strength of the wind,
with the temperature, and with the topography. A strong and constant wind
will produce a much more marked concentration of the rainfall. The belt is
at a low elevation in high latitudes and at a high elevation in low latitudes,
with many irregularities of position dependent upon the local and especially
the minimum winter temperature. The topographic controls are important,
since the rain-compelling elevation may scatter widely the localities of
maximum precipitation or concentrate them within extremely narrow limits.
The human effects of these climatic conditions are manifold. Wherever the
heaviest rains are, there, too, as a rule, are the densest forests and often the
most valuable kinds of trees. If the general climate be favorable and the
region lie near dense and advanced populations, exploitation of the forest
and progress of the people will go hand in hand. If the region be remote and
some or all of the people in a primitive state, the forest may hinder
communication and retard development, especially if it lie in a hot zone
where the natural growth of population is slow.... These are some of the
considerations we shall keep in mind while investigating the climate of the
eastern border of the Peruvian Andes.

Fig. 93A—Cloud types and rainfall belts on the eastern border of
the Peruvian Andes in the dry season, southern winter. The zone of
maximum rainfall extends approximately from 4,000 to 10,000 feet
elevation.

Fig. 93B—Cloud types and rainfall belts on the eastern border of
the Peruvian Andes in the wet season, southern summer.

The belt of maximum precipitation on the eastern border of the Andean
Cordillera in Peru lies between 4,000 and 10,000 feet. Judging by the
temporary records of the expedition and especially by the types of forest
growth, the heaviest rains occur around 8,000 feet. It is between these
elevations that the densest part of the Peruvian montaña (forest) is found.
The cold timber line is at 10,500 feet with exceptional extensions of a few
species to 12,500 feet. In basins or deep secluded valleys near the mountain
border, a dry timber line occurs at 3,000 feet with many variations in
elevation due to the variable declivity and exposure of the slopes and
degree of seclusion of the valleys. Elsewhere, the mountain forest passes
without a break into the plains forest with change in type but with little
change in density. The procumbent and suppressed trees of the cold timber
line in regions of heavy winter snows are here absent, for the snows rarely
reach below 14,000 feet and even at that elevation they are only light and
temporary. The line of perpetual snow is at 15,000 feet. This permanent gap
of several thousand feet vertical elevation between the zone of snow and the
zone of forest permits the full extension of many pioneer forest species,
which is to say, there is an irregular development of the cold timber line. It
also permits the full use of the pasture belt above the timber (Fig. 97),
hence permanent habitations exist but little below the snowline and a group
of distinctive high-mountain folk enjoys a wide distribution. There is a
seasonal migration here, but it is not wholesale; there are pastures snow-
covered in the southern winter, but, instead of the complete winter burial of

the Alpine meadows of our western mountains, we have here only a buried
upper fringe. All the rest of the pasture belt is open for stock the year round.
This climatic distinction between the lofty grazing lands of the tropics
and those of the temperate zones is far-reaching. Our mountain forests are
not utilized from above but from below. Furthermore, the chief ways of
communication lead around our forests, or, if through them, only for the
purpose of putting one population group in closer touch with another. In the
Peruvian Andes the largest population groups live above the forest, not
below it or within it. It must be and is exploited from above.
Hence railways to the eastern valleys of Peru have two chief objects, (1)
to get the plantation product to the dense populations above the forest and
(2) to bring timber from the montaña to the treeless plateau. The mountain
prospector is always near a habitation; the rubber prospector goes down into
the forested valleys and plains far from habitations. The forest separates the
navigable streams from the chief towns of the plateau; it does not lead down
to rich and densely populated valley floors.
Students in eastern Peru should find it a little difficult to understand
poetical allusions to silent and lonely highlands in contrast to the busy life
of the valleys. To them Shelley’s description of the view from the Euganean
Hills of northern Italy,
“Beneath is spread like a green sea
The waveless plain of Lombardy, ...
Islanded by cities fair,”

might well seem to refer to a world that is upside down.
There is much variation in the forest types between the mountains and
the plains. At the top of the forest zone the warm sunny slopes have a forest
cover; the shady slopes are treeless. At the lower edge of the grassland, only
the shady slopes are forested (Fig. 53B). Cacti of arboreal size and form
grow on the lofty mountains far above the limits of the true forest; they also
appear at 3,000 feet in modified form, large, rank, soft-spined, and in dense
stands on the semi-arid valley floors below the dry timber line. Large tracts
between 8,000 and 10,000 feet are covered with a forest growth distributed
by species—here a dense stand of one type of tree, there another. This is the
most accessible part of the Peruvian forest and along the larger valleys it is
utilized to some extent. The number of species is more limited, however,
and the best timber trees are lower down. Though often referred to as

jungle, the lowlier growths at the upper edge of the forest zone have no
resemblance to the true jungle that crowds the lowland forest. They are
merely an undergrowth, generally open, though in some places dense. They
are nowhere more dense than many examples from New England or the
West.
Where deep valleys occur near the border of the mountains there is a
semi-arid climate below and a wet climate above, with a correspondingly
greater number of species within short distances of each other. This is a far
more varied forest than at the upper edge of the timber zone or down on the
monotonous plains. It has a higher intrinsic value than any other. That part
of it between the Pongo and Yavero (1,200 to 4,000 feet) is very beautiful,
with little undergrowth except a light ground-cover of ferns. The trees are
from 40 to 100 feet in height with an average diameter of about 15 inches.
It would yield from 3,000 to 5,000 board feet per acre exclusive of the
palms. There are very few vines suspended from the forest crown and the
trunks run clear from 30 to 60 feet above the ground. Were there plenty of
labor and a good transportation line, these stands would have high
economic value. Among the most noteworthy trees are the soft white cedar,
strong and light; the amarillo and the sumbayllo, very durable in water; the
black nogal, and the black balsam, straight and easy to work; the heavy
yunquero, which turns pink when dry; the chunta or black palm, so hard and
straight and easy to split that wooden nails are made from it; and the rarer
sandy matico, highly prized for dug-out canoes. Also from the chunta palm,
hollow except for a few central fibers, easily removed, pipes are made to
convey water. The cocobolo has a rich brown color and a glossy surface and
is very rare, hence is much sought after for use in furniture making. Most of
these woods take a brilliant polish and exhibit a richness and depth of color
and a beauty of grain that are rare among our northern woods.

Fig. 94—Cloud belt at 11,000 feet in the Apurimac Canyon near
Incahuasi. For a regional diagram and a climatic cross-section see Figs.
32 and 33.
Fig. 95—The tropical forest near Pabellon on the slopes of the
Urubamba Valley. Elevation 3,000 feet (915 m.).

The plains forest northeast of the mountains is in the zone of moderate
rainfall where there is one long dry season and one long wet season. When
it is dry the daytime temperatures rise rapidly to such high levels that the
relative humidity of the air falls below 50 per cent (Fig. 110). The effect on
the vegetation is so marked that many plants pass into a distinctly wilted
condition. On clear days the rapid fall in the relative humidity is
astonishing. By contrast the air on the mountain border heats more slowly
and has a higher relative humidity, because clouds form almost constantly
in the ascending air currents and reflect and absorb a large part of the heat
of the sun’s rays. It is striking to find large tracts of cane and bamboo on the
sand bars and on wet shady hillslopes in the slope belt, and to pass out of
them in going to the plains with which we generally associate a swamp
vegetation. They exist on the plains, but only in favored, that is to say wet,
spots. Larger and more typical tracts grow farther north where the heavier
rains of the Amazon basin fall.
The floods of the wet tropical season also have a restricting influence
upon the tropical forest. They deliver such vast quantities of water to the

low-gradient lowland streams that the plains rivers double, even treble, their
width and huge pools and even temporary lakes form in the shallow
depressions back of the natural levees. Of trees in the flooded areas there
are only those few species that can grow standing in water several months
each year. There are also cane and bamboo, ferns in unlimited numbers, and
a dense growth of jungle. These are the haunts of the peccary, the red forest
deer, and the jungle cat. Except along the narrow and tortuous animal trails
the country is quite impassable. Thus for the sturdiest and most useful forest
growth the one-wet-one-dry season zone of the plains has alternately too
much and too little water. The rubber tree is most tolerant toward these
conditions. Some of the best stands of rubber trees in Amazonia are in the
southwestern part of the basin of eastern Peru and Bolivia, where there is
the most typical development of the habitat marked by the seasonal
alternation of floods and high temperatures.
When tropical agriculture is extended to the plains the long dry season
will be found greatly to favor it. The southwestern quadrant of the Amazon
basin, above referred to, is the best agricultural area within it. The northern
limits of the tract are only a little beyond the Pongo. Thence northward the
climate becomes wetter. Indeed the best tracts of all extend from Bolivia
only a little way into southeastern Peru, and are coincident with the patchy
grasslands that are there interspersed with belts of woodland and forest.
Sugar-cane is favored by a climate that permits rapid growth with a heavy
rainfall and a dry season is required for quality and for the harvest. Rice and
a multitude of vegetable crops are also well suited to this type of climate.
Even corn can be grown in large quantities.
At the present time tropical agriculture is almost wholly confined to the
mountain valleys. The reasons are not wholly climatic, as the above
enumeration of the advantages of the plains suggests. The consuming
centers are on the plateau toward the west and limitation to mule pack
transport always makes distance in a rough country a very serious problem.
The valleys combine with the advantage of a short haul a climate
astonishingly like the one just described. In fact it is even more extreme in
its seasonal contrasts. The explanation is dependent upon precisely the same
principles we have hitherto employed. The front range of the Andes and the
course of the Urubamba run parallel for some distance. Further, the front
range is in many places somewhat higher than the mountain spurs and
knobs directly behind it. Even when these relations are reversed the front

range still acts as a barrier to the rains for all the deep valleys behind it
whose courses are not directly toward the plains. Thus, one of the largest
valleys in Peru, the Urubamba, drops to 3,400 feet at Santa Ana and to
2,000 feet at Rosalina, well within the eastern scarp of the Andes. The
mountains immediately about it are from 6,000 to 10,000 feet high. The
result is a deep semi-arid pocket with only a patchy forest (Fig. 54, p. 79).
[25] In places the degree of seclusion from the wind is so great that the
scrub, cacti, and irrigation remind one strongly of the desert on the border
of an oasis, only here the transition is toward forests instead of barren
wastes. The dense forest, or montaña, grows in the zone of clouds and
maximum precipitation between 4,000 and 10,000 feet. At the lower limit it
descends a thousand feet farther on shady slopes than it does on sunny
slopes. The continuous forest is so closely restricted to the cloud belt that in
99 the two limits may be seen in one photograph. All these sharply defined
limits and contrasts are due to the fact that the broad valley, discharging
through a narrow and remote gorge, is really to leeward of all the mountains
around it. It is like a real desert basin except in a lesser degree of exclusion
from the rains. If it were narrow and small the rains formed on the
surrounding heights would be carried over into it. Rain on the hills and
sunshine in the valley is actually the day-by-day weather of the dry season.
In the wet season the sky is overcast, the rains are general, though lighter in
the valley pocket, and plants there have then their season of most rapid
growth. The dry season brings plants to maturity and is the time of harvest.
Hence sugar and cacao plantations on a large scale, hence a varied life in a
restricted area, hence a distinct geographic province unique in South
America.
INTER-ANDEAN VALLEY CLIMATES
Not all the deep Andean valleys lie on or near the eastern border. Some,
like the Apurimac and the Marañon, extend well into the interior of the
Cordillera. Besides these deep remote valleys with their distinct climatic
belts are basins, most of them with outlets to the sea—broad structural
depressions occurring in some cases along large and in others along small
drainage lines. The Cuzco basin at 11,000 feet and the Abancay basin at
6,000 to 8,000 feet are typical. Both have abrupt borders, narrow outlets,
large bordering alluvial fans, and fertile irrigable soil. Their difference of
elevation occurs at a critical level. Corn will ripen in the Cuzco basin, but

cane will not. Barley, wheat, and potatoes are the staple crops in the one;
sugar-cane, alfalfa, and fruit in the other. Since both are bordered by high
pastures and by mineralized rocks, the deeper Abancay basin is more
varied. If it were not so difficult to get its products to market by reason of
its inaccessibility, the Abancay basin would be the more important. In both
areas there is less rainfall on the basin floor than on the surrounding hills
and mountains, and irrigation is practised, but the deeper drier basin is the
more dependent upon it. Many small high basins are only within the limits
of potato cultivation. They also receive proportionately more rain. Hence
irrigation is unnecessary. According as the various basins take in one or
another of the different product levels (Fig. 35) their life is meager and
unimportant or rich and interesting.
The deep-valley type of climate has the basin factors more strongly
developed. Below the Canyon of Choqquequirau, a topographic feature
comparable with the Canyon of Torontoy, the Apurimac descends to 3,000
feet, broadens to several miles, and has large alluvial fans built into it. Its
floor is really arid, with naked gravel and rock, cacti stands, and gnarled
shrubs as the chief elements of the landscape. Moreover the lower part of
the valley is the steeper. A former erosion level is indicated in 125 . When it
was in existence the slopes were more moderate than now and the valley
broad and open. Thereupon came uplift and the incision of the stream to its
present level. As a result, a steep canyon was cut in the floor of a mature
valley. Hence the slopes are in a relation unlike that of most of the slopes in
our most familiar landscapes. The gentle slopes are above, the steep below.
The break between the two, a topographic unconformity, may be distinctly
traced.

Fig. 96—Snow-capped Fig. 97—Shrubby vegetation
mountain, Soiroccocha, north of mixed with grass at 14,000 feet
Arma, Cordillera Vilcapampa. (4,270 m.) on the northern or
The blue glacier ice descends sunny slopes of the Cordillera
almost to the edge of a belt of Vilcapampa above Pampaconas, a
extraordinary woodland growing thousand feet below the snowline.
just under the snowline. The The grass is remarkably profuse
glacier is seen to overhang the and supports the flocks and herds
valley and to have built on the of a pastoral population.
steep valley wall terminal
moraines whose outer slopes are
almost precipitous.

Fig. 98—Dense ground cover, Fig. 99—The Urubamba Valley
typical trees, epiphytes, and below Santa Ana. On the dry
parasites of the tropical rain forest valley floor is a mixed growth of
at 2,500-3,000 feet between Pongo scattered trees, shrubs and grass,
de Mainique and Rosalina. with shrubs predominating.
Higher up a more luxuriant ravine
vegetation appears. On the upper
spurs true forest patches occupy
the shady slopes. Finally, in the
zone of clouds at the top of the
picture is a continuous forest. See
17 , for regional applications.

Combined with these topographic features are certain climatic features
of equal precision. Between 7,000 and 13,000 feet is a zone of clouds
oftentimes marked out as distinctly as the belt of fog on the Peruvian coast.
[26] Rarely does it extend across the valley. Generally it hangs as a white
belt on the opposite walls. When the up-valley winds of day begin to blow

it drifts up-valley, oftentimes to be dissolved as it strikes the warmer slopes
of the upper valley, just as its settling under surface is constantly being
dissolved in the warm dry air of the valley floor. Where the precipitation is
heaviest there is a belt of woodland—dark, twisted trees, moss-draped, wet
—a Druid forest. Below and above the woodland are grassy slopes. At
Incahuasi a spur runs out and down until at last it terminates between two
deep canyons. No ordinary wells could be successful. The ground water
must be a thousand feet down, so a canal, a tiny thing only a few inches
wide and deep, has been cut away up to a woodland stream. Thence the
water is carried down by a contour-like course out of the woodland into the
pasture, and so down to the narrow part of the spur where there is pasture
but no springs or streams.
Corn fields surround the few scattered habitations that have been built
just above the break or shoulder on the valley wall where the woodland
terminates, and there are fine grazing lands. The trails follow the upper
slopes whose gentler contours permit a certain liberty of movement. Then
the way plunges downward over a staircase trail, over steep boulder-strewn
slopes to the arid floor of a tributary where nature has built a graded route.
And so to the still more arid floor of the main valley, where the ample and
moderate slopes of the alluvial fans with their mountain streams permit
plantation agriculture again to come in.
To these three climates, the western border type, the eastern border type,
and the inter-Andean type, we have given chief attention because they have
the most important human relations. The statistical records of the expedition
as shown in the curves and the discussion that accompanies them give
attention to those climatic features that are of theoretical rather than
practical interest, and are largely concerned with the conventional
expression of the facts of weather and climate. They are therefore combined
in the following chapter which is devoted chiefly to a technical discussion
of the meteorology as distinguished from the climatology of the Peruvian
Andes.
CHAPTER X

METEOROLOGICAL RECORDS FROM THE PERUVIAN ANDES
Introduction

The data in this chapter, on the weather and climate of the Peruvian
Andes, were gathered under the usual difficulties that accompany the
collection of records at camps scarcely ever pitched at the same elevation or
with the same exposure two days in succession. Some of them, and I may
add, the best, were contributed by volunteer observers at fixed stations. The
observations are not confined to the field of the Yale Peruvian Expedition of
1911, but include also observations from Professor Hiram Bingham’s
Expeditions of 1912 and 1914-15, together with data from the Yale South
American Expedition of 1907. In addition I have used observations supplied
by the Morococha Mining Company through J. P. Little. Some hitherto
unpublished observations from Cochabamba, Bolivia, gathered by Herr
Krüger at considerable expense of money for instruments and of time from
a large business, are also included, and he deserves the more credit for his
generous gift of these data since they were collected for scientific purposes
only and not in connection with enterprises in which they might be of
pecuniary value. My only excuse to Herr Krüger for this long delay in
publication (they were put into my hands in 1907) is that I have wanted to
publish his data in a dignified form and also to use them for comparison
with the data of other climatic provinces.
A further word to the reader seems necessary before he examines the
following curves and tables. It would be somewhat audacious to assume
that these short-term records have far-reaching importance. Much of their
value lies in their organization with respect to the data already published on
the climate of Peru. But since this would require a delay of several years in
their publication it seems better to present them now in their simplest form.
After all, the professional climatologist, to whom they are chiefly of
interest, scarcely needs to have such organization supplied to him. Then,
too, we hope that there will become available in the next ten or fifteen years
a vastly larger body of climatological facts from this region. When these
have been collected we may look forward to a volume or a series of
volumes on the “Climate of Peru,” with full statistical tables and a complete
discussion of them. That would seem to be the best time for the
reproduction of the detailed statistics now on hand. It is only necessary that
there shall be sufficient analysis of the data from time to time to give a
general idea of their character and to indicate in what way the scope of the
observations might profitably be extended. I have, therefore, taken from the
available facts only such as seem to me of the most importance because of

their unusual character or their special relations to the boundaries of plant
provinces or of the so-called “natural regions” of geography.
Machu Picchu [27]
The following observations are of special interest in that they illustrate
the weather during the southern winter and spring at the famous ruins of
Machu Picchu in the Canyon of Torontoy. The elevation is 8,500 feet. The
period they cover is too short to give more than a hint of the climate or of
the weather for the year. It extends from August 20, 1912, to November 6,
1912 (79 days).
ANALYTICAL TABLE OF WIND DIRECTIONS, MACHU PICCHU,
1912
Number of Observations
Direction of wind Aug. 20 — Sept. 30 Oct. 1 — Nov. 6
7 a. m. 1 p. m. 7 p. m. 7 a. m. 1 p. m. 7 p. m.
N. 5 2 5 2 — —
N.W. 9 10 14 4 6 11
W. — 1 2 2 2 4
S. W. — — 1 1 1 6
S. — — 1 — — 2
S. E. 4 2 1 — — 3
E. 6 3 3 12 4 4
N. E. 8 7 6 4 1 3
CALM — — 2 5 3 3
Percentages of Total Observation[28]
Direction of wind Aug. 20 — Sept. 30 Oct. 1 — Nov. 6
7 a. m. 1 p. m. 7 p. m. 7 a. m. 1 p. m. 7 p. m.
N. 15.6 8.0 14.2 6.7 —— ——
N. W. 28.1 40.0 40.0 13.3 35.3 30.7
W. —— 4.0 5.7 6.7 11.8 11.1
S. W. —— —— 2.8 3.3 5.9 16.7
S. —— —— 2.8 —— —— 5.5
S. E. 12.5 8.0 2.8 —— —— 8.3
E. 18.8 12.0 8.6 40.0 23.5 11.1

N. E. 25.0 28.0 17.1 13.3 5.9 8.3
CALM —— —— 5.7 16.7 17.6 8.3

Fig. 100—Wind roses for Machu Picchu, August 20 to November 6,
1912.

The high percentage of northwest winds during afternoon hours is due to
the up-valley movement of the air common to almost all mountain borders.
The air over a mountain slope is heated more than the free air at the same
elevation over the plains (or lower valley); hence a barometric gradient
towards the mountain becomes established. At Machu Picchu the Canyon of
Torontoy trends northwest, making there a sharp turn from an equally sharp
northeast bend directly upstream. The easterly components are unrelated to
the topography. They represent the trades. If a wind rose were made for still
earlier morning hours these winds would be more faithfully represented.
That an easterly and northeasterly rather than a southeasterly direction
should be assumed by the trades is not difficult to believe when we consider
the trend of the Cordillera—southeast to northwest. The observations from
here down to the plains all show that there is a distinct change in wind
direction in sympathy with the larger features of the topography, especially
the deep valleys and canyons, the trades coming in from the northeast.
CLOUDINESS
It will be seen that the sky was overcast or a fog lay in the valley 53 per
cent of the time at early morning hours. Even at noon the sky was at no time
clear, and it was more than 50 per cent clear only 18 per cent of the time.
Yet this is the so-called “dry” season of the valleys of the eastern Andes.
The rainfall record is in close sympathy. In the 79 days’ observations rain is
recorded on 50 days with a greater proportion from mid-September to the
end of the period (November 6), a distinct transition toward the wet period
that extends from December to May. The approximate distribution of the
rains by hours of observation (7 A. M., 1 P. M., 7 P. M.) was in the ratio
4:3:6. Also the greatest number of heavy showers as well as the greatest

number of showers took place in the evening. The rainfall was apparently
unrelated to wind direction in the immediate locality, though undoubtedly
associated with the regional movement of the moist plains air toward the
mountains. All these facts regarding clouds and rain plainly show the
location of the place in the belt of maximum precipitation. There is,
therefore, a heavy cover of vegetation. While the situation is admirable for
defence, the murky skies and frequent fogs somewhat offset its topographic
surroundings as a lookout.
ANALYTICAL TABLE OF THE STATE OF THE SKY, MACHU
PICCHU, 1912
Morning Total Noon Total Evening Total
Aug.- Oct.- Aug.- Oct.- Aug.- Oct.-
Days % Days % Days %
Sept. Nov. Sept. Nov. Sept. Nov.
Foggy 3.0 14.0 17.0 28.4 1.0 — 1.0 2.6 1.0 2.0 3.0 4.3
Overcast 12.0 3.0 15.0 25.0 6.0 8.0 14.036.8 13.0 11.0 24.0 34.8
50-100%
4.0 10.0 14.0 23.3 0.0 7.0 16.042.2 8.0 15.0 23.0 33.3
cloudy
0-50%
6.0 4.0 10.0 16.7 5.0 2.0 7.018.4 9.0 4.0 13.0 18.8
cloudy
Clear 3.0 1.0 4.0 6.6 0.0 0.0 0.0 0.0 3.0 3.0 6.0 8.8
Santa Lucia [29]
Santa Lucia is a mining center in the province of Puno (16° S.), at the
head of a valley here running northeast towards Lake Titicaca. Its elevation,
15,500 feet above sea level, confers on it unusual interest as a
meteorological station. A thermograph has been installed which enables a
closer study of the temperature to be made than in the case of the other
stations. It is unfortunate, however, that the observations upon clouds, wind
directions, etc., should not have been taken at regular hours. The time
ranges from 8.30 to 11.30 for morning hours and from 2.30 to 5.30 for
afternoon. The observations cover portions of the years 1913 and 1914.
TEMPERATURE
Perhaps the most striking features of the weather of Santa Lucia are the
highly regular changes of temperature from night to day or the uniformly
great diurnal range and the small differences of temperature from day to day

or the low diurnal variability. For the whole period of nearly a year the
diurnal variability never exceeds 9.5° F. (5.3° C.) and for days at a time it
does not exceed 2-3° F. (1.1°-1.7° C.). The most frequent variation,
occurring on 71 per cent of the total number of days, is from 0-3° F., and
the mean for the year gives the low variability of 1.9° F. (1.06° C.). These
facts, illustrative of a type of weather comparable in uniformity with low
stations on the Amazon plains, are shown in the table following as well as
in the accompanying curves.
FREQUENCY OF THE DIURNAL VARIABILITY, SANTA LUCIA,
1913-14
Total
Degrees
May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March No.
F.
of days
0 — 2 6 3 4 6 2 — 1 — 2 26
0-1 2 7 7 5 6 4 8 12 14 9 5 79
1-2 11 5 7 11 7 8 5 5 4 9 13 85
2-3 2 8 8 9 3 7 7 5 5 4 6 64
3-4 4 4 2 1 4 1 3 6 2 4 2 33
4-5 1 3 1 — 2 1 3 — 2 1 1 15
Over 5 — 1 — 2 4 4 2 2 3 1 — 19
Days per
20 30 31 31 30 31 30 30 31 28 29 321
month
If we take the means of the diurnal variations by months we have a still
more striking curve showing how little change there is between successive
days. June and December are marked by humps in the curve. They are the
months of extreme weather when for several weeks the temperatures drop
to their lowest or climb to their highest levels. Moreover, there is at these
lofty stations no pronounced lag of the maximum and minimum
temperatures for the year behind the times of greatest and least heating such
as we have at lower levels in the temperate zone. Thus we have the highest
temperature for the year on December 2, 70.4° F. (21.3° C.), the lowest on
June 3, 0.2° F. (—17.7° C.). The daily maxima and minima have the same
characteristic. Radiation is active in the thin air of high stations and there is
a very direct relation between the times of greatest heat received and
greatest heat contained. The process is seen at its best immediately after the

sun is obscured by clouds. In five minutes I have observed the temperature
drop 20° F. (11.1° C.) at 16,000 feet (4,877 m.); and a drop of 10° F. (5.6°
C.) is common anywhere above 14,000 feet (4,267 m.). In the curves of
daily maximum and minimum temperatures we have clearly brought out the
uniformity with which the maxima of high-level stations rise to a mean
level during the winter months (May-August). Only at long intervals is
there a short series of cloudy days when the maximum is 10°-12° F.
(5.6°-6.7° C.) below the normal and the minimum stands at abnormally
high levels. Since clouds form at night in quite variable amounts—in
contrast to the nearly cloudless days—there is a far greater variability
among the minimum temperatures. Indeed the variability of the winter
minima is greater than that of the summer minima, for at the latter season
the nightly cloud cover imposes much more stable atmospheric
temperatures. The summer maxima have a greater degree of variability.
Several clear days in succession allow the temperature to rise from 5°-10°
F. (2.8°-5.6° C.) above the winter maxima. But such extremes are rather
strictly confined to the height of the summer season—December and
January. For the rest of the summer the maxima rise only a few degrees
above those of the winter. This feature of the climate combines with a
December maximum of rainfall to limit the period of most rapid plant
growth to two months. Barley sown in late November could scarcely
mature by the end of January, even if growing on the Argentine plains and
much less at an elevation which carries the night temperatures below
freezing at least once a week and where the mean temperature hovers about
47° F. (8.3° C.). The proper conditions for barley growing are not
encountered above 13,000 to 13,500 feet and the farmer cannot be certain
that it will ripen above 12,500 feet in the latitude of Santa Lucia.
The curve of mean monthly temperatures expresses a fact of great
importance in the plant growth at high situations in the Andes—the sharp
break between the winter and summer seasons. There are no real spring and
autumn seasons. This is especially well shown in the curve for non-periodic
mean monthly range of temperature for the month of October. During the
half of the year that the sun is in the southern hemisphere the sun’s noonday
rays strike Santa Lucia at an angle that varies between 0° and 16° from the
vertical. The days and nights are of almost equal length and though there is
rapid radiation at night there is also rapid insolation by day. When the sun is
in the northern hemisphere the days are shortened from one to two hours

and the angle of insolation decreased, whence the total amount of heat
received is so diminished that the mean monthly temperature lies only a
little above freezing point. In winter the quiet pools beside the springs
freeze over long before dark as the hill shadows grow down into the high-
level valleys, and by morning ice also covers the brooks and marshes. Yet
the sun and wind-cured ichu grass lives here, pale green in summer, straw-
yellow in winter. The tola bush also grows rather abundantly. But we are
almost at the upper limit of the finer grasses and a few hundred feet higher
carries one into the realm of the snowline vegetation, mosses and lichens
and a few sturdy flowering plants.
For convenience in future comparative studies the absolute extremes are
arranged in the following table:

ABSOLUTE MONTHLY EXTREMES, SANTA LUCIA, 1913-14
Date Highest Lowest Date
May[30] (12) 62° F. 9° F. May (25, 26)
June (4 days) 60° F. 0.2° F. June (3)
July (4 days, 31) 60° F. 5° F. July (8)
Aug. (8, 26) 62° F. 4° F. Aug. (4, 5)
Sept. (several days) 62° F. 7° F. Sept. (4 days)
Oct. (24) 63° F. 10° F. Oct. (12, 13)
Nov. (11)[31] 63° F. 24.0° F. Nov. (29)
Dec. (2) 70.4° F. 22.2° F. Dec. (14)
Jan. (19) 69.5° F. 26.5° F. Jan. (3, 15)
Feb. (16, 18) 63.2° F. 30.5° F. Feb. (23)
March (8) 68.4° F. 28.5° F. March (6)
RAINFALL
The rainfall record for Santa Lucia is for the year beginning November,
1913. For this period the precipitation amounts to 24.9 inches of which over
85 per cent fell in the rainy season from November to March. Most of the
rain fell during the violent afternoon tempests that characterize the summer
of these high altitudes.
The rainfall of Santa Lucia for this first year of record approximates
closely to the yearly mean of 23.8 inches for the station of Caylloma in the
adjacent province of that name. Caylloma is the center of a mining district
essentially similar to Santa Lucia though the elevation of its meteorological

station, 14,196 feet (4,330 m.), is lower. It is one of the few Peruvian
stations for which a comparatively long series of records is available. The
Boletín de la Sociedad Geográfica de Lima[32] contains a résumé of rainfall
and temperature for seven years, 1896-7 to 1902-3. Later data may be found
in subsequent volumes of the same publication but they have not been
summarized or in any way prepared for analysis and they contain several
typographical errors. A graphic representation of the monthly rainfall for the
earlier period is here reproduced from the Boletín de minas del Perú.[33]
The amount of precipitation fluctuates considerably from year to year. For
the earlier period, with a mean of 23.8 inches the minimum (1896-7) was 8
inches and the maximum (1898-9) 36 inches. For the later period, 1903-4 to
1910-11, with a mean of 29.5 inches the minimum (1904-5) was 17.5
inches and the maximum (1906-7) was 43 inches.

Fig. 102—Monthly rainfall of Santa Lucia for the year November,
1913, to October, 1914. No rain fell in July and August.
Fig. 103A—Maximum, mean and minimum monthly rainfall of
Caylloma for the period 1896-7 to 1902-3. July was absolutely rainless.
Caylloma is situated immediately east of the crest of the Maritime
Cordillera in a position similar to that of Santa Lucia (see Fig. 66).
Fig. 103B—Annual rainfall of Caylloma for the periods 1896-7 to
1902-3; 1903-4 to 1910-11 and for 1915-6 (incomplete: May and June,
months of low rainfall, are missing). Means for the respective seven and
eight year periods are shown and the rainfall of Santa Lucia for the
single observation year is inserted for comparison.

RAINFALL, SANTA LUCIA, NOV. 1913 TO OCT. 1914
No of fine No. of rainy Max. for single Total rainfall in
days days day inches
November 9 21 1.150 4.264[34]
December 16 15 .700 6.439
January 17 14 .610 3.313
February 9 17 .910 2.975
March 11 20 1.102 4.381
April 17 13 0.31 0.92
May 8 23 0.35 1.63
June 27 3 0.05 0.07
July 31 0 0.00 0.00
August 31 0 0.00 0.00
September 23 7 0.05 0.35
October 21 10 0.14 0.56
Total 24.902
WIND
An analysis of the wind at Santa Lucia shows an excess of north and
south winds over those of all other directions. The wind-rose for the entire
period of observation (Fig. 104) clearly expresses this fact. When this
element is removed we observe a strongly seasonal distribution of the wind.
The winter is the time of north and south winds. In summer the winds are
chiefly from the northeast or the southwest. Among single months, August
and February show this fact clearly as well as the less decisive character of
the summer (February) wind.
The mean wind velocity for the month of February was 540 meters per
minute for the morning and 470 meters per minute for the afternoon. The
higher morning rate, an unusual feature of the weather of high stations, or
indeed of wind-phenomena in general, is due, however, to exceptional
changes in wind strength on two days of the month, the 16th and 25th,
when the velocity decreased from a little less than a thousand meters per
minute in the morning to 4 and 152 meters respectively in the afternoon.
More typical is the March record for 1914 at Santa Lucia, when the wind

was always stronger in the afternoon than in the morning, their ratios being
550 to 510.

Fig. 104—Monthly wind roses for Santa Lucia, June, 1913, to July,
1914, and composite rose for the whole period of observation.

CLOUD
The greater strength of the afternoon wind would lead us to suppose that
the cloudiness, which in the trade-wind belt, is to so great an extent
dependent on the wind, is greatest in the afternoon. The diagrams bring out
this fact. Barely is the sky quite clear after the noon hour. Still more striking
is the contrast between the morning and afternoon if we combine the two
densest shadings of the figures. Light, high-lying cirrus clouds are most
characteristic of early morning hours. They produce some very striking sky
effects just before sunrise as they catch the sun’s rays aloft. An hour or two
after sunrise they disappear and small cumulus clouds begin to form. These
grow rapidly as the winds begin and by afternoon become bulky and
numerous. In the wet season they grow into the nimbus and stratus types
that precede a sudden downpour of water or a furious hailstorm. This is best
seen from the base of a mountain range looking towards the crest, where the
cloud-and rain-making processes of this type are most active.
CLOUD ANALYSIS, SANTA LUCIA

Nov. Dec. Jan. Feb. March Total
Type of cloud
a.m. p.m. a.m. p.m. a.m. p. m. a.m. p.m. a.m. p.m. a.m. p.m.
Cirrus 6 º 2 15 2 9 2 5 3 6 3 41 12
Cirro-stratus — — — — — — — — — — — —
Cirro-cumulus 4 4 7 11 3 5 6 8 17 10 37 38
Cumulus 3 4 4 7 10 9 15 13 5 13 37 46
Strato-cumulus 2 6 3 10 7 14 2 3 — 3 14 36
Stratus — — — 1 — — — 1 1 2 2 4
Nimbus — — — — — — — — — — — —
Clear — — 2 — 2 1 — — 2 — 6 1
UNUSUAL WEATHER PHENOMENA, SANTA LUCIA, 1913-14

Fig. 105—Monthly cloudiness of Santa Lucia from January to July,
1914. Mean cloudiness for the whole period is also shown.

The following abstracts are selected because they give some important
features of the weather not included in the preceding tables and graphs. Of
special interest are the strong contrasts between the comparatively high
temperatures of midday and the sudden “tempests” accompanied by rain or
hail that follow the strong convectional movements dependent upon rapid
and unequal heating. The furious winds drive the particles of hail like shot.
It is sometimes impossible to face them and the pack train must be halted
until the storm has passed. Frequently they leave the ground white with
hailstones. We encountered one after another of these “tempestades” on the
divide between Lambrama and Antabamba in 1911. They are among the
most impetuous little storms I have ever experienced. The longest of them

raged on the divide from two-o’clock until dark, though in the valleys the
sun was shining. Fortunately, in this latitude they do not turn into heavy
snowstorms as in the Cordillera of northwestern Argentina, where the
passes are now and then blocked for weeks at a time and loss of human life
is no infrequent occurrence.[35] They do, however, drive the shepherds
down from the highest slopes to the mid-valley pastures and make travel
uncomfortable if not unsafe.
ABSTRACT FROM DAILY WEATHER OBSERVATIONS, SANTA LUCIA, 1913-14
NOVEMBER
“Tempest” recorded 11 times, distant thunder and lightning 9 times. Unusual weather records:
“clear sky, scorching sun, good weather” (Nov. 29); “morning sky without a single cloud, weather
agreeable” (Nov. 30).
DECEMBER
Clear morning sky 6 times. Starry night or part of night 7 times. Beginning of rain and strong
wind frequently observed at 5-6 P.M. “Tempest” mentioned 19 times—5 times at midnight, 8 times at
5-6 P.M.
JANUARY
Clear morning sky 5 times. Starry night 3 times. Rain, actual or threatening, characteristic of
afternoons. “Tempest,” generally about 5-6 P.M., 7 times. Sun described 4 times as scorching and,
when without wind, heat as stifling. Weather once “agreeable.”
FEBRUARY
Constant cloud changes, frequent afternoon or evening rains. “Tempest,” generally 4 P.M. and
later, 16 times.
MARCH
Twice clear morning skies, once starry night. Scorching sun and stifling heat on one occasion.
“Tempest,” generally in late afternoon and accompanied by hail, 19 times. Observed 3 or 4 times a
strong, “land breeze” (terral) of short duration (15-20 mins.) and at midnight.

Morococha
Morococha, in the Department of Ancachs, Peru, lies in 76° 11′ west
longitude and 11° 45′ south latitude and immediately east of the crest line of
the Maritime Cordillera. It is 14,300 feet above sea level, and is surrounded
by mountains that extend from 1,000 to 3,000 feet higher. The weather
records are of special interest in comparison with those of Santa Lucia.
Topographically the situations of the two stations are closely similar hence
we may look for climatic differences dependent on the latitudinal
difference. This is shown in the heavier rainfall of Morococha, 4° nearer the
equatorial climatic zone. (For location see Fig. 66.)
The meteorological data for 1908-09 were obtained from records kept by
the Morococha Mining Company for use in a projected hydro-electric

installation. Other data covering the years 1906-11 have appeared in the
bulletins of the Sociedad Geográfica de Lima. These are not complete but
they have supplied rainfall data for the years 1910-11;[36] those for 1906
and 1907 have been obtained from the Boletín de Minas.[37]
Temperature
The most striking facts expressed by the various temperature curves are
the shortness of the true winter season—its restriction to June and July—
and its abrupt beginning and end. This is well known to anyone who has
lived from April to October or November at high elevations in the Central
Andes. Winter comes on suddenly and with surprising regularity from year
to year during the last few days of May and early June. In the last week of
July or the first week of August the temperatures make an equally sudden
rise. During 1908 and 1909 the mean temperature reached the freezing
point but once each year—July 24 and July 12 respectively. The absolute
minimum for the two years was -22° C. July of 1908 and June of 1909 are
also the months of smallest diurnal variability, showing that the winter
temperatures are maintained with great regularity. Like all tropical high-
level stations, Morococha exhibits winter maxima that are very high as
compared with the winter maxima of the temperate zone. In both June and
July of 1908 and 1909 the maximum was maintained for about a week
above 55° F. (12.8° C.), and in 1909 above 60° F. (15.6° C.), the mean
maximum for the year being only 4.7° F. higher. For equal periods,
however, the maxima fell to levels about 10° F. below those for the period
from December to May, 1908.
It is noteworthy that the lowest maximum for 1909 was in October, 44°
F. (6.7° C.); and that other low maxima but little above those of June and
July occur in almost all the other months of the year. While 1909 was in this
respect an exceptional year, it nevertheless illustrates a fact that may occur
in any month of any year. Its occurrence is generally associated with
cloudiness. One of the best examples of this is found in the January
maximum curve for 1909, where in a few days the maxima fell 12° F. Cloud
records are absent, hence a direct comparison cannot be made, but a
comparison of the maximum temperature curve with the graphic
representation of mean monthly rainfall, will emphasize this relation of
temperature and cloudiness. February was the wettest month of both 1908
and 1909. In sympathy with this is the large and sharp drop from the

January level of the maxima—the highest for the year—to the February
level. The mean temperatures are affected to a less degree because the
cloudiness retards night radiation of heat, thus elevating the maxima. Thus
in 1908 the lowest minimum for both January and February was 28.4° F.
(-2° C.). For 1909 the minima for January and February were 27.5° F. (-2.5°
C.) and 29.3° F. (-1.5° C.) respectively.

The extent to which high minima may hold up the mean temperature is
shown by the fact that the mean monthly temperature for January, 1908,
was lower than for February. Single instances illustrate this relation equally
well. For example, on March 5th, 1908, there occurred the heaviest rainfall
of that year. The maximum and minimum curves almost touch. The middle
of April and late September, 1909, are other illustrations. The relationship is
so striking that I have put the two curves side by side and have had them
drawn to the same scale.
FREQUENCY OF THE DIURNAL VARIABILITY, MOROCOCHA,
1908 AND 1909
1908
Total No.
Degrees F. J. F. M. A. M. J. J. A. S. O. N. D.
of days
0 — 3 2 3 — — 2 1 3 1 1 3 19
0-1 6 5 6 10 9 10 13 10 8 6 6 5 94
1-2 4 1 3 7 5 3 7 7 8 6 6 4 61
2-3 6 1 3 4 9 2 2 4 4 7 7 4 53
3-4 5 3 2 3 3 4 2 9 4 5 3 5 48

4-5 2 3 1 1 2 5 5 — 1 1 6 3 30
Over 5 3 4 3 2 3 6 — — 2 5 1 5 34
Days per
26 20 20 30 31 30 31 31 30 31 30 20 339
month

1909
Total No. Mean for
Degrees F. J. F. M. A. M. J. J. A. S. O. N. D.
of days 1908-1909
0 6 1 4 2 1 2 4 4 3 6 2 1 36 27.5
0-1 9 8 5 6 6 7 813 9 4 11 10 96 95
1-2 4 6 8 3 11 14 3 3 5 3 9 6 75 68
2-3 3 7 4 8 4 3 6 6 4 6 1 3 55 54
3-4 4 5 3 6 4 4 4 3 6 3 2 5 49 48.5
4-5 1 1 5 1 2— 2 1 1 2— 2 18 24
Over 5 4 — 2 4 3— 4 1 2 7 5 3 35 34.5
Days per
31 28 3130 3130313130313030 364 351.5
month
RAINFALL
The annual rainfall of Morococha is as follows:
190628inches ( 712 mm.)
[38] 190740 " (1,011 mm.)
190857 " (1,450 mm.)
190945 " (1,156 mm.)
191047 " (1,195 mm.)
1911 25 " ( 622 mm.)

Fig. 107—Rainfall of Morococha. 107 A shows daily rainfall during
the rainy (summer) season, 1908-1909. 107 B shows monthly rainfall
from July, 1905, to December, 1911, and 107 C the annual and mean
rainfall for the same period.

The mean for the above six years amounts to 40 inches (1,024 mm.).
This is a value considerably higher than that for Caylloma or Santa Lucia.
The greater rainfall of Morococha is probably due in part to its more
northerly situation. An abnormal feature of the rainfall of 1908, the rainiest
year, is the large amount that fell in June. Ordinarily June and July, the
coldest months, are nearly or quite rainless. The normal concurrence of
highest temperatures and greatest precipitation is of course highly favorable
to the plant life of these great altitudes. Full advantage can be taken of the
low summer temperatures if the growing temperatures are concentrated and
are accompanied by abundant rains. Since low temperatures mean
physiologic dryness, whether or not rains are abundant, the dryness of the
winter months has little effect in restricting the range of Alpine species.
The seasonal distribution of rain helps the plateau people as well as the
plateau plants. The transportation methods are primitive and the trails mere
tracks that follow the natural lines of topography and drainage. Coca is
widely distributed, likewise corn and barley which grow at higher
elevations, and wool must be carried down to the markets from high-level
pastures. In the season of rains the trails are excessively wet and slippery,
the streams are often in flood and the rains frequent and prolonged. On the
other hand the insignificant showers of the dry or non-growing season
permit the various products to be exchanged over dry trails.
The activities of the plateau people have had a seasonal expression from
early times. Inca chronology counted the beginning of the year from the

middle of May, that is when the dry season was well started and it was
inaugurated with the festivals of the Sun. With the exception of June when
the people were entirely busied in the irrigation of their fields, each month
had its appropriate feasts until January, during which month and February
and March no feasts were held. April, the harvest month, marked the
recommencement of ceremonial observances and a revival of social life.[39]
In Spanish times the ritualistic festivals, incorporated with fairs,
followed the seasonal movement. Today progress in transportation has
caused the decadence of many of the fairs but others still survive. Thus two
of the most famous fairs of the last century, those of Vilque (province of
Puno) and Yunguyo (province of Chucuito), were held at the end of May
and the middle of August respectively. Copacavana, the famous shrine on
the shores of Titicaca, still has a well-attended August fair and Huari, in the
heart of the Bolivian plateau, has an Easter fair celebrated throughout the
Andes.
Cochabamba
Cochabamba, Bolivia, lies 8,000 feet above sea level in a broad basin in
the Eastern Andes. The Cerro de Tunari, on the northwest, has a snow and
ice cover for part of the year. The tropical forests lie only a single long
day’s journey to the northeast. Yet the basin is dry on account of an eastern
front range that keeps out the rain-bearing trade winds. The Rio Grande has
here cut a deep valley by a roundabout course from the mountains to the
plains so that access to the region is over bordering elevations. The basin is
chiefly of structural origin.
The weather records from Cochabamba are very important. I could
obtain none but temperature data and they are complete for 1906 only. Data
for 1882-85 were secured by von Boeck[40] and they have been quoted by
Sievers and Hann. The mean annual temperature for 1906 was 61.9° F.
(16.6° C.), a figure in close agreement with von Boeck’s mean of 60.8° F.
(16° C.). The monthly means indicate a level of temperature favorable to
agriculture. The basin is in fact the most fertile and highly cultivated area of
its kind in Bolivia. Bananas, as well as many other tropical and subtropical
plants, grow in the central plaza. The nights of midwinter are
uncomfortably cool; and the days of midsummer are uncomfortably hot but
otherwise the temperatures are delightful. The absolute extremes for 1906
were 81.5° F. (27.5° C.) on December 11, and 39.9° F. (4.4° C.) on July 15

and 16. The (uncorrected) readings of von Boeck give a greater range. High
minima rather than high maxima characterize the summer. The curve for
1906 shows the maxima for June and July cut off strikingly by an abrupt
drop of the temperature and indicates a rather close restriction of the depth
of the season to these two months, which are also those of greatest diurnal
range.

The rainfall of about 18 inches is concentrated in the summer season, 85
per cent falling between November and March. During this time the town is
somewhat isolated by swollen streams and washed out trails: hence here, as
on the plateau, there is a distinct seasonal distribution of the work of
planting, harvesting, moving goods, and even mining, and of the general
commerce of the towns. There is an approach to our winter season in this
respect and in respect of a respite from the almost continuously high
temperatures of summer. The daytime temperatures of summer are however
mitigated by the drainage of cool air from the surrounding highlands. This,
indeed, prolongs the period required for the maturing of plants, but there are
no harmful results because freezing temperatures are not reached, even in
winter.
MONTHLY TEMPERATURES, COCHABAMBA, 1906
Month Mean Min. Mean Max. Mean Range Daily Mean
January 55.7 72.25 16.65 63.3
February 61.2 71.3 10.1 65.5
March 59.8 72.6 12.8 65.5
April 55.06 70.8 15.74 62.2
May 50.9 68.7 17.8 59.1
June 47.1 65.6 18.5 55.6

July 44.8 64.9 20.1 54.1
August 49.9 68.0 18.1 58.2
September 55.6 73.2 17.6 63.7
October 56.1 73.4 17.3 64.0
November 58.1 75.7 17.6 66.2
December 58.6 73.9 15.3 65.8

Figs. 109-113—Temperature curves for locations in the montaña,
July and August, 1911. The curves are based on hourly readings with
interpolated readings for such critical occurrences as the appearance of
cloud or rain. Dry bulb readings are shown by solid lines, wet bulb by
dotted lines, and breaks in the continuity of the observations by heavy
broken lines. 109 is for Pongo de Mainique, August 20 and 21; Fig. 110
for Yavero; Fig. 111 for Santo Anato, August 11 and 12; Fig. 112 for
Sahuayaco, August 20, and Fig. 113 for Santa Ana, July 30 to August 1.

Fig. 114—Typical afternoon cloud composition at Santa Ana during
the dry season.
Fig. 115—Temperature curve for Abancay drawn from data
obtained by hourly readings on September 27, 1911. Dry bulb readings
are shown by a heavy solid line, wet bulb readings by a dotted line. The
heavy broken line shows the normal curve when the sky is unobscured
by cloud. The reduction in temperature with cloud is very marked.

FREQUENCY OF DIURNAL VARIABILITY AT
COCHABAMBA, 1906
Total No.
Degrees F. J. F. M. A. M. J. J. A. S. O. N. D. of
days
0 1 3 10 12 6 10 9 6 9 6 3 4 79
0-1 5 — 3 5 3 3 — 4 — 3 1 1 28
1-2 10 10 13 11 15 7 14 11 15 10 14 13 143
2-3 7 11 3 1 5 8 7 4 3 6 7 6 68
3-4 6 2 2 1 2 2 1 6 3 4 3 5 37
4-5 — — — — — — — — — 1 1 1 3
Over 5 2 2 — — — — — — — 1 1 1 7

A series of curves shows the daily march of temperature at various
locations along the seventy-third meridian. Figs. 109 to 113 are for the

Urubamba Valley. Respectively they relate to Pongo de Mainique, 1,200
feet elevation (365 m.), the gateway to the eastern plains; Yavero, 1,600 feet
(488 m.), where the tributary of this name enters the main stream; Santo
Anato, 1,900 feet (580 m.); Sahuayaco, 2,400 feet (731 m.), and Santa Ana,
3,400 feet (1,036 m.), one of the outposts of civilization beyond the Eastern
Cordillera. The meteorological conditions shown are all on the same order.
They are typical of dry season weather on the dry floor of a montaña valley.
The smooth curves of clear days are marked by high mid-day temperatures
and great diurnal range. Santo Anato is a particularly good illustration: the
range for the 24 hours is 38° F. (21.1° C.). This site, too, is remarkable as
one of the most unhealthful of the entire valley. The walls of the valley here
make a sharp turn and free ventilation of the valley is obstructed. During
the wet season tertian fever prevails to a degree little known east of the
Cordillera, though notorious enough in the deep valleys of the plateau. The
curves show relative humidity falling to a very low minimum on clear days.
At Santo Anato and Santa Ana, for example, it drops below 30 per cent
during the heat of the day. Afternoon cloudiness, however, is a common
feature even of the dry season. A typical afternoon cloud formation is
shown in 114 . The effect on temperature is most marked. It is well shown
in the curve for August 20 and 22 at Yavero. Cloudiness and precipitation
increase during the summer months. At Santa Ana the rainfall for the year
1894-95 amounted to 50 inches, of which 60 per cent fell between
December and March. For a discussion of topographic features that have
some highly interesting climatic effects in the eastern valleys of Peru see
Chapter VI.

Figs. 116-118—Temperature curves for locations in the Maritime
Cordillera and its western valleys, October, 1911. For construction of
curves see Figs. 109-113. 116 is for Camp 13 on the northern slope of
the Maritime Cordillera (which here runs from east to west), October
13-15; 117 for Cotahuasi, October 26; 118 for Salamanca, October 31.

Fig. 119. Fig. 120. Figs. 119-120—Temperature curves for the Coast
Desert, November, 1911. Fig. 119 is for Aplao, November 4 and 5; and
Fig. 120 for Camaná, November 9 and 10. For construction of curves
see Figs. 109 to 113.

Abancay, 8,000 feet (2,440 m.), in one of the inter-Andean basins, is
situated in the zone of marked seasonal precipitation. The single day’s
record shows the characteristic effect of cloud reducing the maximum
temperature of the day and maintaining the relative humidity.
Camp 13, 15,400 feet (4,720 m.), lies near the crest of the Maritime
Cordillera a little south of Antabamba. Afternoon storms are one of its most
significant features. Cotahuasi, 9,100 feet (2,775 m.) is near the head of a
west-coast valley. Its low humidity is worthy of note. That for Salamanca,
12,700 feet (3,870 m.), is similar but not so marked.

Aplao, 3,100 feet (945 m.), and Camaná at the seacoast are stations in
the west-coast desert. The interior location of the former gives it a greater
range of temperature than Camaná, yet even here the range is small in
comparison with the diurnal extremes of the montaña, and the tempering
effect of the sea-breeze is clearly apparent. Camaná shows a diurnal
temperature range of under 10° F. and also the high relative humidity, over
70 per cent, characteristic of the coast.

PART II

PHYSIOGRAPHY OF THE PERUVIAN ANDES
CHAPTER XI

THE PERUVIAN LANDSCAPE
FROM the west coast the great Andean Cordillera appears to have little of
the regularity suggested by our relief maps. Steep and high cliffs in many
places form the border of the land and obstruct the view; beyond them
appear distant summits rising into the zone of clouds. Where the cliffs are
absent or low, one may look across a sun-baked, yellow landscape,
generally broken by irregular foothills that in turn merge into the massive
outer spurs and ranges of the mountain zone. The plain is interrupted by
widely separated valleys whose green lowland meadows form a brilliant
contrast to the monotonous browns and yellows of the shimmering desert.
In rare situations the valley trenches enable one to look far into the
Cordillera and to catch memorable glimpses of lofty peaks capped with
snow.
If the traveler come to the west-coast landscape from the well-molded
English hills or the subdued mountains of Vermont and New Hampshire
with their artistic blending of moderate profiles, he will at first see nothing
but disorder. The scenery will be impressive and, in places, extraordinary,
but it is apparently composed of elements of the greatest diversity. All the
conceivable variations of form and color are expressed, with a
predominance of bold rugged aspects that give a majestic appearance to the
mountain-bordered shore. One looks in vain for some sign of a quiet view,
for some uniformity of features, for some landscape that will remind him of
the familiar hills of home. The Andes are aggressive mountains that front
the sea in formidable spurs or desert ranges. Could we see in one view their
entire elevation from depths of over 20,000 feet beneath sea level to snowy
summits, a total altitude of 40,000 feet (12,200 m.), their excessive
boldness would be more apparent. No other mountains in the world are at

once so continuously lofty and so near a coast which drops off to abyssal
depths.
The view from the shore is, however, but one of many which the Andes
exhibit. Seen from the base the towering ranges display a stern aspect, but,
like all mountains, their highest slopes and spurs must be crossed and re-
crossed before the student is aware of other aspects of a quite different
nature. The Andes must be observed from at least three situations: from the
floors of the deep intermontane valleys, from the intermediate slopes and
summits, and from the uppermost levels as along the range crests and the
highest passes. Strangely enough it is in the summit views that one sees the
softest forms. At elevations of 14,000 to 16,000 feet (4,270 to 4,880 m.),
where one would expect rugged spurs, serrate chains, and sharp needles and
horns, one comes frequently upon slopes as well graded as those of a city
park—grass-covered, waste-cloaked, and with gentle declivity (Figs. 121-
124).
The graded, waste-cloaked slopes of the higher levels are interpreted as
the result of prolonged denudation in an erosion cycle which persisted
through the greater part of the Tertiary period, and which was closed by
uplifts aggregating at least several thousands of feet. Above the level of the
mature slopes rise the ragged profiles and steep, naked declivities of the
snow-capped mountains which bear residual relations to the softer forms at
their bases. They are formed upon rock masses of greater original elevation
and of higher resistance to denudation. Though they are dominating
topographic features, they are much less extensive and significant than the
tame landscape which they surmount.

Fig. 121—Looking north from the hill near Anta in the Anta basin
north of Cuzco. Typical composition of slopes and intermont basins in
the Central Andes. Alluvial fill in the foreground; mature slopes in the
background; in the extreme background the snow-capped crests of the
Cordillera Vilcapampa.
Fig. 122—Showing topographic conditions before the formation of
the deep canyons in the Maritime Cordillera. The view, looking across
a tributary canyon of the Antabamba river, shows in the background
the main canyon above Huadquirca. Compare with Fig. 60.

Below the level of the mature slopes are topographic features of equal
prominence: gorges and canyons up to 7,000 feet deep. The deeply
intrenched streams are broken by waterfalls and almost continuous rapids,
the valley walls are so abrupt that one may, in places, roll stones down a
4,000 foot incline to the river bed, and the tortuous trail now follows a
stream in the depths of a profound abyss, now scales the walls of a
labyrinthine canyon.

Fig. 123—Mature slopes Fig. 124—Dissected mature
between Ollantaytambo and slopes north of Anta in the Anta
Urubamba. basin north of Cuzco.

The most striking elements of scenery are not
commonly the most important in physiography. The oldest
and most significant surface may be at the top of the
country, where it is not seen by the traveler or where it
cannot impress him, except in contrast to features of
greater height or color. The layman frequently seizes on a Fig. 125—
Mature upper
piece of bad-land erosion or an outcrop of bright-colored and young lower
sandstone or a cliff of variegated clays or a snow-covered slopes at the
mountain as of most interest. All we can see of a beautiful outlet of
Cuzco basin.
the

snow-clad peak is mere entertainment compared with what
subdued waste-cloaked hill-slopes may show. We do not
wish to imply that everywhere the tops of the Andes are meadows, that
there are no great scenic features in the Peruvian mountains, or that they are
not worth while. But we do wish to say that the bold features are far less
important in the interpretation of the landscape.
Amid all the variable forms of the Peruvian Cordillera certain strongly
developed types recur persistently. That their importance and relation may
be appreciated we shall at once name them categorically and represent them
in the form of a block diagram (Fig. 126). The principal topographic types
are as follows:
1. An extensive system of high-level, well-graded, mature slopes, below which are:
2. Deep canyons with steep, and in places, cliffed sides and narrow floors, and above which are:

3. Lofty residual mountains composed of resistant, highly deformed rock, now sculptured into a
maze of serrate ridges and sharp commanding peaks.
4. Among the forms of high importance, yet causally unrelated to the other closely associated
types, are the volcanic cones and plateaus of the western Cordillera.
5. At the valley heads are a full complement of glacial features, such as cirques, hanging valleys,
reversed slopes, terminal moraines, and valley trains.
6. Finally there is in all the valley bottoms a deep alluvial fill formed during the glacial period
and now in process of dissection.

Though there are in many places special features either remotely related
or quite unrelated to the principal enumerated types, they belong to the class
of minor forms to which relatively small attention will be paid, since they
are in general of small extent and of purely local interest.

Fig. 126—Block diagram of the typical physiographic features of the
Peruvian Andes.

The block diagram represents all of these features, though of necessity
somewhat more closely associated than they occur in nature. Reference to
the photographs, Figs. 121-124, will make it clear that the diagram is
somewhat ideal: on the other hand the photographs together include all the
features which the diagram displays. In descending from any of the higher
passes to the valley floor one passes in succession down a steep, well-like
cirque at a glaciated valley head, across a rocky terminal moraine, then
down a stair-like trail cut into the steep scarps which everywhere mark the
descent to the main valley floors, over one after another of the confluent
alluvial fans that together constitute a large part of the valley fill, and finally
down the steep sides of the inner valley to the boulder-strewn bed of the
ungraded river.
We shall now turn to each group of features for description and
explanation, selecting for first consideration the forms of widest
development and greatest significance—the high-level mature slopes lying
between the lofty mountains which rise above them and the deep, steep-
walled valleys sunk far below them. These are the great pasture lands of the

Cordillera; their higher portions constitute the typical puna of the Indian
shepherds. In many sections it is possible to pasture the vagrant flocks
almost anywhere upon the graded slopes, confident that the ichu, a tufted
forage grass, will not fail and that scattered brooks and springs will supply
the necessary water. At nightfall the flocks are driven down between the
sheltering walls of a canyon or in the lee of a cliff near the base of a
mountain, or, failing to reach either of these camps, the shepherd confines
his charge within the stone walls of an isolated corral.
In those places where the graded soil-covered slopes lie within the zone
of agriculture—below 14,000 feet—they are cultivated, and if the soil be
deep and fertile they are very intensively cultivated. Between Anta and
Urubamba, a day’s march north of Cuzco, the hill slopes are covered with
wheat and barley fields which extend right up to the summits (Fig. 134). In
contrast are the uncultivated soil-less slopes of the mountains and the bare
valley walls of the deeply intrenched streams. The distribution of the fields
thus brings out strongly the principal topographic relations. Where the
softer slopes are at too high a level, the climatic conditions are extreme and
man is confined to the valley floors and lower slopes where a laborious
system of terracing is the first requirement of agriculture.
The appearance of the country after the mature slopes had been formed
is brought out in 122 . The camera is placed on the floor of a still
undissected, mature valley which shows in the foreground of the
photograph. In the middle distance is a valley whose great depth and
steepness are purposely hidden; beyond the valley are the smoothly graded,
catenary curves, and interlocking spurs of the mature upland. In
imagination one sees the valleys filled and the valley slopes confluent on
the former (now imaginary) valley floor which extends without important
change of expression to the border of the Cordillera. No extensive cliffs
occur on the restored surface, and none now occur on large tracts of the still
undissected upland. Since the mature slopes represent a long period of
weathering and erosion, their surfaces were covered with a deep layer of
soil. Where glaciation at the higher levels and vigorous erosion along the
canyons have taken place, the former soil cover has been removed;
elsewhere it is an important feature. Its presence lends a marked softness
and beauty to these lofty though subdued landscapes.
The graded mountain slopes were not all developed (1) at the same
elevation, nor (2) upon rock of the same resistance to denudation, nor (3) at

the same distance from the major streams, nor (4) upon rock of the same
structure. It follows that they will not all display precisely the same form.
Upon the softer rocks at the lowest levels near the largest streams the
surface was worn down to extremely moderate slopes with a local relief of
not more than several hundred feet. Conversely, there are quite unreduced
portions whose irregularities have mountainous proportions, and between
these extremes are almost all possible variations. Though the term mature in
a broad way expresses the stage of development which the land had
reached, post mature should be applied to those portions which suffered the
maximum reduction and now exhibit the softest profiles. At no place along
the 73rd meridian was denudation carried to the point of even local
peneplanation. All of the major and some of the minor divides bear residual
elevations and even approximately plane surfaces do not exist.

Among the most important features of the mature slopes are (1) their
great areal extent—they are exhibited throughout the whole Central Andes,
(2) their persistent development upon rocks of whatever structure or degree

of hardness, and (3) their present great elevation in spite of moderate grades
indicative of their development at a much lower altitude. Mature slopes of
equivalent form are developed in widely separated localities in the Central
Andes: in every valley about Cochabamba, Bolivia, at 10,000 feet (3,050
m.); at Crucero Alto in southern Peru at 14,600 feet (4,450 m.); several
hundred miles farther north at Anta near Cuzco, 11,000 feet to 12,000 feet
(3,600 to 3,940 m.), and 129 shows typical conditions in the Vilcabamba
Valley along the route of the Yale Peruvian Expedition of 1911. The
characteristic slopes so clearly represented in these four photographs are the
most persistent topographic elements in the physiography of the Central
Andes.

Fig. 127—Topographic profiles across typical valleys of southern
Peru. They are drawn to scale and the equality of gradient of the
gentler upper slopes is so close that almost any curve would serve as a
composite of the whole. These curves form the basis of the diagram,
Fig. 128, whereby the amount of elevation of the Andes in late geologic
time may be determined. The approximate locations of the profiles are
as follows: 1, Antabamba; 2, Chuquibambilla; 3, upland south of
Antabamba; 4, Apurimac Canyon above Pasaje; 5, Abancay; 6, Arma
(Cordillera Vilcapampa); 7, divide above Huancarama; 8, Huascatay;
9, Huasentay, farther downstream; 10, Rio Pampas. The upper valley
in 8 is still undissected; 7 is practically the same; 8a is at the level which
8 must reach before its side slopes are as gentle as at the end of the
preceding interrupted cycle.

The rock masses upon which the mature slopes were formed range from
soft to hard, from stratified shales, slates, sandstones, conglomerates, and
limestones to volcanics and intrusive granites. While these variations
impose corresponding differences of form, the graded quality of the slopes
is rarely absent. In some places the highly inclined strata are shown thinly

veiled with surface débris, yet so even as to appear artificially graded. The
rock in one place is hard granite, in another a moderately hard series of lava
flows, and again rather weak shales and sandstones.
Proof of the rapid and great uplift of certain now lofty mountain ranges
in late geologic time is one of the largest contributions of physiography to
geologic history. Its validity now rests upon a large body of diversified
evidence. In 1907 I crossed the Cordillera Sillilica of Bolivia and northern
Chile and came upon clear evidences of recent and great uplift. The
conclusions presented at that time were tested in the region studied in 1911,
500 miles farther north, with the result that it is now possible to state more
precisely the dates of origin of certain prominent topographic forms, and to
reconstruct the conditions which existed before the last great uplift in which
the Central Andes were born. The relation to this general problem of the
forms under discussion will now be considered.
The gradients of the mature slopes, as we have already seen, are
distinctly moderate. In the Anta region, over an area several hundred square
miles in extent, they run from several degrees to 20° or 30°. Ten-degree
slopes are perhaps most common. If the now dissected slopes be
reconstructed on the basis of many clinometer readings, photographs, and
topographic maps, the result is a series of profiles as in 127 . If, further, the
restored slopes be coördinated over an extensive area the gradients of the
resulting valley floors will run from 3° to 10°. Finally, if these valley floors
be extended westward to the Pacific and eastward to the Amazon basin,
they will be found about 5,000 feet above sea level and 4,000 feet above the
eastern plains. (For explanation of method and data employed, see the
accompanying figures 127-128). It is, therefore, a justifiable conclusion that
since the formation of the slopes the Andes have been uplifted at least a
mile, or, to put it in another way, the Andes at the time of formation of the
mature slopes were at least a mile lower than they are at present.

Fig. 128—Composition of slopes and profiles in the Peruvian Andes.
By superimposing the cross profiles of typical valleys as shown in 127 a
restoration is possible of the longitudinal profiles of the earlier cycle of
erosion. The difference in elevation of the two profiles gives less than
the minimum amount of uplift that must have occurred. Case A
represents a valley in which recent cutting has not yet reached the
valley head. Below the point 1 the profile has been steepened and
lowered by erosion in the current cycle. Above point 1 the profile is still
in the stage it reached in the preceding cycle. In case B the renewed
erosion of the current cycle has reached to the valley head. Case C
represents conditions similar to those in the preceding cases save that
the stream is typical of those that lie nearest the steep flexed or faulted
margins of the Cordillera and discharge to the low levels of the desert
pampa on the west or the tropical plains on the east.

Further proof of recent and great uplift is afforded by the deeply
intrenched streams. After descending the long graded slopes one comes
upon the cliffed canyons with a feeling of consternation. The effect of
powerful erosion, incident upon uplift, is heightened by the ungraded
character of the river bed. Falls and rapids abound, the river profiles suggest
tumultuous descents, and much time will elapse before the river beds have
the regular and moderate gradients of the streams draining the mature
surface before uplift as shown in the profiles by the dotted lines
representing the restored valley floors of the older cycle. Since the smooth-
contoured landscape was formed great changes have taken place. The
streams have changed from completely graded to almost completely
ungraded profiles; in place of a subdued landscape we now have upland
slopes intersected by mile-deep canyons; the high-level slopes could not
have been formed under existing conditions, for they are being dissected by
the present streams.

Since the slopes of the land in general undergo progressive changes in
the direction of flatter gradients during a given geographical cycle, it
follows that with the termination of one cycle and the beginning of another,
two sets of slopes will exist and that the gradients of the two will be unlike.
The result is a break in the descent of the slopes from high to low levels to
which the name “topographic unconformity” is now applied. It will be a
prominent feature of the landscape if the higher, older, and flatter gradients
have but little declivity, and the gradients of the lower younger slopes are
very steep. In those places where the relief of the first cycle was still great
at the time of uplift, the erosion forms of the second cycle may not be
differentiated from those of the first, since both are marked by steep
gradients. In the Central Andes the change in gradient between the higher
and lower slopes is generally well marked. It occurs at variable heights
above the valley floors, though rarely more than 3,000 feet above them. In
the more central tracts, far from the main streams and their associated
canyons, dissection in the present erosion cycle has not yet been initiated,
the mature slopes are still intact, and a topographic unconformity has not

yet been developed. The higher slopes are faced with rock and topped with
slowly moving waste. Ascent of the spur end is by steep zigzag trails; once
the top is gained the trail runs along the gentler slopes without special
difficulties.
It is worth noting at this point that the surface of erosion still older than
the mature slopes herewith described appears not to have been developed
along the seventy-third meridian of Peru, or if developed at one time,
fragments of it no longer remain. The last well-developed remnant is
southwest of Cuzco, 130 . I have elsewhere described the character and
geographic distribution of this oldest recognizable surface of the Central
Andes.[41] Southern Peru and Bolivia and northern Chile display its features
in what seems an unmistakable manner. The best locality yet found is in the
Desaguadero Valley between Ancoaqui and Concordia. There one may see
thousands of feet of strongly inclined sediments of varying resistance
beveled by a well-developed surface of erosion whose preserval is owing to
a moderate rainfall and to location in an interior basin.[42]
The highest surface of a region, if formed during a prolonged period of
erosion, becomes a surface of reference in the determination of the
character and amount of later crustal deformations, having somewhat the
same functions as a key bed in stratigraphic geology. Indeed, concrete
physiographic facts may be the only basis for arguments as to both
epeirogenic and orogenic movements. The following considerations may
show in condensed form the relative value of physiographic evidence:
1. If movements in the earth’s crust are predominantly downward,
sedimentation may be carried on continuously, and a clear geologic record
may be made.
2. Even if crustal movements are alternately downward and upward,
satisfactory conclusions may be drawn from both (a) the nature of the
buried surfaces of erosion, and (b) the alternating character of the
sediments.
3. If, however, the deformative processes effect steady or intermittent
uplifts, there may be no sediments, at least within the limits of the positive
crustal units, and a geologic record must be derived not from sedimentary
deposits but from topographic forms. We speak of the lost intervals
represented by stratigraphic breaks or unconformities and commonly
emphasize our ignorance concerning them. The longest, and, from the

human standpoint, the most important, break in the sedimentary record is
that of the present wherever degradation is the predominant physiographic
process. Unlike the others the lost interval of the present is not lost, if we
may so put it, but is in our possession, and may be definitely described as a
concrete thing. It is the physiography of today.
Even where long-buried surfaces of erosion are exposed to view, as in
northern Wisconsin, where the Pre-Cambrian paleo-plain projects from
beneath the Paleozoic sediments, or, as in New Jersey and southeastern
Pennsylvania, where the surface developed on the crystalline rocks became
by depression the floor of the Triassic and by more recent uplift and erosion
has been exposed to view,—even in such cases the exposures are of small
extent and give us at best but meager records. In short, many of the breaks
in the geologic record are of such long duration as to make imperative the
use of physiographic principles and methods. The great Appalachian
System of eastern North America has been a land area practically since the
end of the Paleozoic. In the Central Andes the “lost interval,” from the
standpoint of the sedimentary, record, dates from the close of the
Cretaceous, except in a few local intermont basins partially filled with
Tertiary or Pleistocene deposits. Physiographic interpretations, therefore,
serve the double purpose of supplying a part of the geologic record while at
the same time forming a basis for the scientific study of the surface
distribution of living forms.
The geologic dates of origin of the principal topographic forms of the
Central Andes may be determined with a fair degree of accuracy. Geologic
studies in Peru and Bolivia have emphasized the wide distribution of the
Cretaceous formations. They consist principally of thick limestones above
and sandstones and conglomerates below, and thus represent extensive
marine submergence of the earth’s crust in the Cretaceous where now there
are very lofty mountains. The Cretaceous deposits are everywhere strongly
deformed or uplifted to a great height, and all have been deeply eroded.
They were involved, together with other and much older sediments, in the
erosion cycle which resulted in the development of the widely extended
series of mature slopes already described. From low scattered island
elevations projecting above sea level, as in the Cretaceous period, the Andes
were transformed by compression and uplift to a rugged mountain belt
subjected to deep and powerful erosion. The products of erosion were in

part swept into the adjacent seas, in part accumulated on the floors of
intermont basins, as in the great interior basins of Titicaca and Poopó.
Since the early Tertiary strata are themselves deformed from once simple
and approximately horizontal structures and subjected to moderate tilting
and faulting, it follows that mountain-making movements again affected the
region during later Tertiary. They did not, however, produce extreme
effects. They did stimulate erosion and bring about a reorganization of all
the slopes with respect to the new levels.
This agrees closely with a second line of evidence which rests upon an
independent basis. The alluvial fill which lies upon all the canyon and
valley floors is of glacial origin, as shown by its interlocking relations with
morainal deposits at the valley heads. It is now in process of dissection and
since its deposition in the Pleistocene had been eroded on the average about
200 feet. Clearly, to form a 3,000-foot canyon in hard rock requires much
more time than to deposit and again partially to excavate an alluvial fill
several hundred feet deep. Moreover, the glacial material is coarse
throughout, and was built up rapidly and dissected rapidly. In most cases,
furthermore, coarse material at the bottom of the glacial series rests directly
upon the rock of a narrow and ungraded valley floor. From these and allied
facts it is concluded that there is no long time interval represented by the
transitions from degrading to aggrading processes and back again. The early
Pleistocene, therefore, seems quite too short a period in which to produce
the bold forms and effect the deep erosion which marks the period between
the close of the mature cycle and the beginnings of deposition in the
Pleistocene.
The alternative conclusion is that the greater part of the canyon cutting
was effected in the late Tertiary, and that it continued into the early
Pleistocene until further erosion was halted by changed climatic conditions
and the augmented delivery of land waste to all the streams. The final
development of the well-graded high-level slopes is, therefore, closely
confined to a small portion of the Tertiary. The closest estimate which the
facts support appears to be Miocene or early Pliocene. It is clear, however,
that only the culmination of the period can be definitely assigned. Erosion
was in full progress at the close of the Cretaceous and by middle Tertiary
had effected vast changes in the landscape. The Tertiary strata are marked
by coarse basal deposit and by thin and very fine top deposits. Though their
deformed condition indicates a period of crustal disturbance, the Tertiary

beds give no indication of wholesale transformations. They indicate chiefly
tilting and moderate and normal faulting. The previously developed effects
of erosion were, therefore, not radically modified. The surface was thus in
large measure prepared by erosion in the early Tertiary for its final
condition of maturity reached during the early Pliocene.
It seems appropriate, in concluding this chapter, to summarize in its main
outlines the physiography of southern Peru, partly to condense the extended
discussion of the preceding paragraphs, and partly to supply a background
for the three chapters that follow. The outstanding features are broad plateau
areas separated by well-defined “Cordilleras.” The plateau divisions are not
everywhere of the same origin. Those southwest of Cuzco (Fig. 130), and in
the Anta Basin (Fig. 124), northwest of Cuzco, are due to prolonged erosion
and may be defined as peneplane surfaces uplifted to a great height. They
are now bordered on the one hand by deep valleys and troughs and basins
of erosion and deformation; and, on the other hand, by residual elevations
that owe their present topography to glacial erosion superimposed upon the
normal erosion of the peneplane cycle. The residuals form true mountain
chains like the Cordillera Vilcanota and Cordillera Vilcapampa; the
depressions due to erosion or deformation or both are either basins like
those of Anta and Cuzco or valleys of the canyon type like the Urubamba
canyon; the plateaus are broad rolling surfaces, the punas of the Peruvian
Andes.
There are two other types of plateaus. The one represents a mature stage
in the erosion cycle instead of an ultimate stage; the other is volcanic in
origin. The former is best developed about Antabamba (Figs. 122 and 123),
where again deep canyons and residual ranges form the borders of the
plateau remnants. The latter is well developed above Cotahuasi and in its
simplest form is represented in 133 . Its surface is the top of a vast
accumulation of lavas in places over a mile thick. While rough in detail it is
astonishingly smooth in a broad view (Fig. 29). Above it rise two types of
elevations: first, isolated volcanic cones of great extent surrounded by huge
lava flows of considerable relief; and second, discontinuous lines of peaks
where volcanic cones of less extent are crowded closely together. The
former type is displayed on the Coropuna Quadrangle, the latter on the
Cotahuasi and La Cumbre Quadrangles.
So high is the elevation of the lava plateau, so porous its soil, so dry the
climate, that a few through-flowing streams gather the drainage of a vast

territory and, as in the Grand Canyon country of our West, they have at long
intervals cut profound canyons. The Arma has cut a deep gorge at
Salamanca; the Cotahuasi runs in a canyon in places 7,000 feet deep; the
Majes heads at the edge of the volcanic field in a steep amphitheatre of
majestic proportions.
Finally, we have the plateaus of the coastal zone. These are plains with
surfaces several thousand feet in elevation separated by gorges several
thousand feet deep. The Pampa de Sihuas is an illustration. The post-
maturely dissected Coast Range separates it from the sea. The pampas are
in general an aggradational product formed in a past age before uplift
initiated the present canyon cycle of erosion. Other plateaus of the coastal
zone are erosion surfaces. The Tablazo de Ica appears to be of this type.
That at Arica, Chile, near the southern boundary of Peru, is demonstrably of
this type with a border on which marine planation has in places given rise to
a broad terrace effect.[43]
CHAPTER XII

THE WESTERN ANDES: THE MARITIME CORDILLERA OR
CORDILLERA OCCIDENTAL
THE Western or Maritime Cordillera of Peru forms part of the great
volcanic field of South America which extends from Argentina to Ecuador.
On the walls of the Cotahuasi Canyon (Fig. 131), there are exposed over
one hundred separate lava flows piled 7,000 feet deep. They overflowed a
mountainous relief, completely burying a limestone range from 2,000 to
4,000 feet high. Finally, upon the surface of the lava plateau new mountains
were formed, a belt of volcanoes 5,000 feet (1,520 m.) high and from
15,000 to 20,000 feet (4,570 to 6,100 m.) above the sea. There were vast
mud flows, great showers of lapilli, dust, and ashes, and with these violent
disturbances also came many changes in the drainage. Sixty miles northeast
of Cotahuasi the outlet of an unnamed deep valley was blocked, a lake was
formed, and several hundred feet of sediments were deposited. They are
now wasting rapidly, for they lie in the zone of alternate freezing and
thawing, a thousand feet and more below the snowline. Some of their bad-
land forms look like the solid bastions of an ancient fortress, while others
have the delicate beauty of a Japanese temple.

Not all the striking effects of vulcanism belong to the remote geologic
past. A day’s journey northeast of Huaynacotas are a group of lakes only
recently hemmed in by flows from the small craters thereabouts. The fires
in some volcanic craters of the Peruvian Andes are still active, and there is
no assurance that devastating flows may not again inundate the valleys. In
the great Pacific zone or girdle of volcanoes the earth’s crust is yet so
unstable that earthquakes occur every year, and at intervals of a few years
they have destructive force. Cotahuasi was greatly damaged in 1912;
Abancay is shaken every few years; and the violent earthquakes of Cuzco
and Arequipa are historic.
On the eastern margin of the volcanic country the flows thin out and
terminate on the summit of a limestone (Cretaceous) plateau. On the
western margin they descend steeply to the narrow west-coast desert. The
greater part of the lava dips beneath the desert deposits; there are a few
intercalated flows in the deposits themselves, and the youngest flows—
limited in number—have extended down over the inner edge of the desert.
The immediate coast of southern Peru is not volcanic. It is composed of
a very hard and ancient granite-gneiss which forms a narrow coastal range
(Fig. 171). It has been subjected to very long and continued erosion and
now exhibits mature erosion forms of great uniformity of profile and
declivity.
From the outcrops of older rocks beneath the lavas it is possible to
restore in a measure the pre-volcanic topography of the Maritime
Cordillera, In its present altitude it ranges from several thousand to 15,000
feet above sea level. The unburied topography has been smoothed out; the
buried topography is rough (Figs. 29 and 166). The contact lines between
lavas and buried surfaces in the deep Majes and Cotahuasi valleys are in
places excessively serrate. From this, it seems safe to conclude that the
period of vulcanism was so prolonged that great changes in the unburied
relief were effected by the agents of erosion. Thus, while the dominant
process of volcanic upbuilding smoothed the former rough topography of
the Maritime Cordillera, erosion likewise measurably smoothed the present
high extra-volcanic relief in the central and eastern sections. The effect has
been to develop a broad and sufficiently smooth aspect to the summit
topography of the entire Andes to give them a plateau character. Afterward
the whole mountain region was uplifted about a mile above its former level
so that at present it is also continuously lofty.

The zone of most intense volcanic action does not coincide with the
highest part of the pre-volcanic topography. If the pre-volcanic relief were
even in a very general way like that which would be exhibited if the lavas
were now removed, we should have to say that the chief volcanic outbursts
took place on the western flank of an old and deeply dissected limestone
range.

Fig. 129—Composition of slopes at Puquiura, Vilcabamba Valley,
elevation 9,000 feet (2,740 m.). The second prominent spur entering the
valley on the left has a flattish top unrelated to the rock structure. Like
the spurs on the right its blunt end and flat top indicate an earlier
erosion cycle at a lower elevation.
Fig. 130—Inclined Paleozoic strata truncated by an undulating
surface of erosion at 15,000 feet, southwest of Cuzco.

Fig. 131—Terraced valley slopes at Huaynacotas, Cotahuasi Valley,
at 11,500 feet (3,500 m.). Solimana is in the background. On the floor of
the Cotahuasi Canyon fruit trees grow. At Huaynacotas corn and
potatoes are the chief products. The section is composed almost entirely
of lava. There are over a hundred major flows aggregating 5,000 to
7,000 feet thick.

The volume of the lavas is enormous. They are a mile and a half thick,
nearly a hundred miles wide, and of indefinite extent north and south. Their
addition to the Andes, therefore, has greatly broadened the zone of lofty
mountains. Their passes are from 2,000 to 3,000 feet higher than the passes
of the eastern Andes. They have a much smaller number of valleys
sufficiently deep to enjoy a mild climate. Their soil is far more porous and
dry. Their vegetation is more scanty. They more than double the difficulties
of transportation. And, finally, their all but unpopulated loftier expanses are
a great vacant barrier between farms in the warm valleys of eastern Peru
and the ports on the west coast.
The upbuilding process was not, of course, continuous. There were at
times intervals of quiet, and some of them were long enough to enable
streams to become established. Buried valleys may be observed in a number
of places on the canyon walls, where subsequently lava flows displaced the
streams and initiated new drainage systems. In these quiet intervals the
weathering agents attacked the rock surfaces and formed soil. There were at

least three or four such prolonged periods of weathering and erosion
wherein a land surface was exposed for many thousands of years, stream
systems organized, and a cultivable soil formed. No evidence has been
found, however, that man was there to cultivate the soil.
The older valleys cut in the quiet period are mere pygmies beside the
giant canyons of today. The present is the time of dominant erosion. The
forces of vulcanism are at last relatively quiet. Recent flows have occurred,
but they are limited in extent and in effects. They alter only the minor
details of topography and drainage. Were it not for the oases set in the now
deep-cut canyon floors, the lava plateau of the Maritime Cordillera would
probably be the greatest single tract of unoccupied volcanic country in the
world.
The lava plateau has been dissected to a variable degree. Its high eastern
margin is almost in its original condition. Its western margin is only a
hundred miles from the sea, so that the streams have steep gradients. In
addition, it is lofty enough to have a moderate rainfall. It is, therefore,
deeply and generally dissected. Within the borders of the plateau the degree
of dissection depends chiefly upon position with respect to the large
streams. These were in turn located in an accidental manner. The repeated
upbuilding of the surface by the extensive outflow of liquid rock obliterated
all traces of the earlier drainage. In the Cotahuasi Canyon the existing
stream, working down through a mile of lavas, at last uncovered and cut
straight across a mountain spur 2,000 feet high. Its course is at right angles
to that pursued by the stream that once drained the spur. It is noteworthy
that the Cotahuasi and adjacent streams take northerly courses and join
Atlantic rivers. The older drainage was directly west to the Pacific. Thus,
vulcanism not only broadened the Andes and increased their height, but also
moved the continental divide still nearer the west coast.
The glacial features of the western or Maritime Cordillera are of small
extent, partly because vulcanism has added a considerable amount of
material in post-glacial time, partly because the climate is so exceedingly
dry that the snowline lies near the top of the country. The slopes of the
volcanic cones are for the most part deeply recessed on the southern or
shady sides. Above 17,500 feet (5,330 m.) the process of snow and ice
excavation still continues, but the tracts that exceed this elevation are
confined to the loftiest peaks or their immediate neighborhood. There is a
distinct difference between the glacial forms of the eastern or moister and

the western or dryer flanks of this Cordillera. Only peaks like Coropuna and
Solimana near the western border now bear or ever bore snowfields and
glaciers. By contrast the eastern aspect is heavily glaciated. On La Cumbre
Quadrangle, there is a huge glacial trough at 16,000 feet (4,876 m.), and
this extends with ramifications up into the snowfields that formerly
included the highest country. Prolonged glacial erosion produced a full set
of topographic forms characteristic of the work of Alpine glaciers. Thus,
each of the main mountain chains that make up the Andean system has, like
the system as a whole, a relatively more-dry and a relatively less-dry aspect.
The snowline is, therefore, canted from west to east on each chain as well
as on the system. However, this effect is combined with a solar effect in an
unequal way. In the driest places the solar factor is the more efficient and
the snowline is there canted from north to south.
CHAPTER XIII

THE EASTERN ANDES: THE CORDILLERA VILCAPAMPA
THE culminating range of the eastern Andes is the so-called Cordillera
Vilcapampa. Its numerous, sharp, snow-covered peaks are visible in every
summit view from the central portion of the Andean system almost to the
western border of the Amazon basin. Though the range forms a water
parting nearly five hundred miles long, it is crossed in several places by
large streams that flow through deep canyons bordered by precipitous cliffs.
The Urubamba between Torontoy and Colpani is the finest illustration. For
height and ruggedness the Vilcapampa mountains are among the most
noteworthy in Peru. Furthermore, they display glacial features on a scale
unequaled elsewhere in South America north of the ice fields of Patagonia.
GLACIERS AND GLACIAL FORMS
One of the most impressive sights in South America is a tropical forest
growing upon a glacial moraine. In many places in eastern Bolivia and Peru
the glaciers of the Ice Age were from 5 to 10 miles long—almost the size of
the Mer de Glace or the famous Rhone glacier. In the Juntas Valley in
eastern Bolivia the tree line is at 10,000 feet (3,050 m.), but the terminal
moraines lie several thousand feet lower. In eastern Peru the glaciers in
many places extended down nearly to the tree line and in a few places well
below it. In the Cordillera Vilcapampa vast snowfields and glacier systems

were spread out over a summit area as broad as the Southern Appalachians.
The snowfields have since shrunk to the higher mountain recesses; the
glaciers have retreated for the most part to the valley heads or the cirque
floors; and the lower limit of perpetual snow has been raised to 15,500 feet.

Fig. 132—Recessed volcanoes in the right background and eroded
tuffs, ash beds, and lava flows on the left. Maritime Cordillera above
Cotahuasi.
Fig. 133—The summit of the great lava plateau above Cotahuasi on
the trail to Antabamba. The lavas are a mile and a half in thickness.
The elevation is 16,000 feet. Hence the volcanoes in the background,
17,000 feet above sea level, are mere hills on the surface of the lofty
plateau.

Fig. 134—Southwestern aspect of the Cordillera Vilcapampa
between Anta and Urubamba from Lake Huaipo. Rugged summit
topography in the background, graded post-mature slopes in the
middle distance, and solution lake in limestone in the foreground.
Fig. 135—Summit view, Cordillera Vilcapampa. There are fifteen
glaciers represented in this photograph. The camera stands on the
summit of a minor divide in the zone of nivation.

These features are surprising because neither Whymper[44] nor Wolf[45]
mentions the former greater extent of the ice on the volcanoes of Ecuador,
only ten or twelve degrees farther north. Moreover, Reiss[46] denies that the
hypothesis of universal climatic change is supported by the facts of a
limited glaciation in the High Andes of Ecuador; and J. W. Gregory[47]
completely overlooks published proof of the existence of former more
extensive glaciers elsewhere in the Andes:
“... the absence not only of any traces of former more extensive
glaciation from the tropics, as in the Andes and Kilimandjaro, but also from
the Cape.” He says further: “In spite of the extensive glaciers now in
existence on the higher peaks of the Andes, there is practically no evidence
of their former greater extension.”(!)
Whymper spent most of his time in exploring recent volcanoes or those
recently in eruption, hence did not have the most favorable opportunities for
gathering significant data. Reiss was carried off his feet by the
attractiveness of the hypothesis[48] relating to the effect of glacial
denudation on the elevation of the snowline. Gregory appeared not to have
recognized the work of Hettner on the Cordillera of Bogotá and of
Sievers[49] and Acosta on the Sierra Nevada de Santa Marta in northern
Colombia.
The importance of the glacial features of the Cordillera Vilcapampa
developed on a great scale in very low latitudes in the southern hemisphere
is twofold: first, it bears on the still unsettled problem of the universality of
a colder climate in the Pleistocene, and, second, it supplies additional data
on the relative depression of the snowline in glacial times in the tropics.
Snow-clad mountains near the equator are really quite rare. Mount Kenia
rising from a great jungle on the equator, Kilimandjaro with its two peaks,
Kibo and Mawenzi, two hundred miles farther south, and Ingomwimbi in
the Ruwenzori group thirty miles north of the equator, are the chief African
examples. A few mountains from the East Indies, such as Kinibalu in

Borneo, latitude 6° north, have been found glaciated, though now without a
snow cover. In higher latitudes evidences of an earlier extensive glaciation
have been gathered chiefly from South America, whose extension 13° north
and 56° south of the equator, combined with the great height of its
dominating Cordillera, give it unrivaled distinction in the study of mountain
glaciation in the tropics.
Furthermore, mountain summits in tropical lands are delicate climatic
registers. In this respect they compare favorably with the inclosed basins of
arid regions, where changes in climate are clearly recorded in shoreline
phenomena of a familiar kind. Lofty mountains in the tropics are in a sense
inverted basins, the lower snowline of the past is like the higher shoreline of
an interior basin; the terminal moraines and the alluvial fans in front of
them are like the alluvial fans above the highest strandline; the present
snow cover is restricted to mountain summits of small areal extent, just as
the present water bodies are restricted to the lowest portions of the interior
basin; and successive retreatal stages are marked by terminal moraines in
the one case as they are marked in the other by flights of terraces and beach
ridges.
I made only a rapid reconnaissance across the Cordillera Vilcapampa in
the winter season, and cannot pretend from my limited observations to
solve many of the problems of the field. The data are incorporated chiefly in
the chapter on Glacial Features. In this place it is proposed to describe only
the more prominent glacial features, leaving to later expeditions the detailed
descriptions upon which the solution of some of the larger problems must
depend.
At Choquetira three prominent stages in the retreat of the ice are
recorded. The lowermost stage is represented by the great fill of morainic
and outwash material at the junction of the Choquetira, and an unnamed
valley farther south at an elevation of 11,500 feet (3,500 m.). A mile below
Choquetira a second moraine appears, elevation 12,000 feet (3,658 m.), and
immediately above the village a third at 12,800 (3,900 m.). The lowermost
moraine is well dissected, the second is ravined and broken but
topographically distinct, the third is sharp-crested and regular. A fourth
though minor stage is represented by the moraine at the snout of the living
glacier and still less important phases are represented in some valleys—
possibly the record of post-glacial changes of climate. Each main moraine
is marked by an important amount of outwash, the first and third moraines

being associated with the greatest masses. The material in the moraines
represents only a part of that removed to form the successive steps in the
valley profile. The lowermost one has an enormous volume, since it is the
oldest and was built at a time when the valley was full of waste. It is fronted
by a deep fill, over the dissected edge of which one may descend 800 feet in
half an hour. It is chiefly alluvial in character, whereas the next higher one
is composed chiefly of bowlders and is fronted by a pronounced bowlder
train, which includes a remarkable perched bowlder of huge size. Once the
valley became cleaned out the ice would derive its material chiefly by the
slower process of plucking and abrasion, hence would build much smaller
moraines during later recessional stages, even though the stages were of
equivalent length.
There is a marked difference in the degree of dissection
of the moraines. The lowermost and oldest is so
thoroughly dissected as to exhibit but little of its original
surface. The second has been greatly modified, but still
possesses a ridge-like quality and marks the beginning of a
noteworthy flattening of the valley gradient. The third is as
sharp-crested as a roof, and yet was built so long ago that
the flat valley floor behind it has been modified by the Fig. 136—
meandering stream. From this point the glacier retreated Glacial sculpture
up-valley several miles (estimated) without leaving more on the
southwestern
than the thinnest veneer on the valley floor. The retreat flank of the
must, therefore, have been rapid and without even Cordillera
temporary halts until the glacier reached a position near Vilcapampa.
floored
Flat-
valleys
that occupied today. Both the present ice tongues and and looped
snowfields and those of a past age are emphasized by the terminal
presence of a patch of scrub and woodland that extends on moraines below
and glacial steps
the north side of the valley from near the snowline down and hanging
over the glacial forms to the lower valley levels. valleys are
characteristic.
The retreatal stages sketched above would call for no The present
special comment if they were encountered in mountains in snowfields and
northern latitudes. They would be recognized at once as glaciersshown by dotted
are

evidence of successive periodic retreats of the ice, due to contours.
successive changes in temperature. To understand their
importance when encountered in very low latitudes it is
necessary to turn aside for a moment and consider two rival hypotheses of

glacial retreat. First we have the hypothesis of periodic retreat, so generally
applied to terminal moraines and associated outwash in glaciated mountain
valleys. This implies also an advance of the ice from a higher position, the
whole taking place as a result of a climatic change from warmer to colder
and back again to warmer.

Fig. 137—Looking up a spurless flat-floored glacial trough near the
Chucuito pass in the Cordillera Vilcapampa from 14,200 feet (4,330
m.). Note the looped terminal and lateral moraines on the steep valley
wall on the left. A stone fence from wall to wall serves to inclose the
flock of the mountain shepherd.
Fig. 138—Terminal moraine in the glaciated Choquetira Valley
below Choquetira. The people who live here have an abundance of
stones for building corrals and stone houses. The upper edge of the
timber belt (cold timber line) is visible beyond the houses. Elevation
12,100 feet (3,690 m.).

But evidences of more extensive mountain glaciation in the past do not
in themselves prove a change in climate over the whole earth. In an epoch
of fixed climate a glacier system may so deeply and thoroughly erode a
mountain mass, that the former glaciers may either diminish in size or
disappear altogether. As the work of excavation proceeds, the catchment
basins are sunk to, and at last below, the snowline; broad tributary spurs
whose snows nourish the glaciers, may be reduced to narrow or skeleton

ridges with little snow to contribute to the valleys on either hand; the
glaciers retreat and at last disappear. There would be evidences of glaciation
all about the ruins of the former loftier mountain, but there would be no
living glaciers. And yet the climate might remain the same throughout.
It is this “topographic” hypothesis that Reiss and Stübel accept for the
Ecuadorean volcanoes. Moreover, the volcanoes of Ecuador are practically
on the equator—a very critical situation when we wish to use the facts they
exhibit in the solution of such large problems as the contemporaneous
glaciation of the two hemispheres, or the periodic advance and retreat of the
ice over the whole earth. This is not the place to scrutinize either their facts
or their hypothesis, but I am under obligations to state very emphatically
that the glacial features of the Cordillera Vilcapampa require the climatic
and not the topographic hypothesis. Let us see why.
The differences in degree of dissection and the flattening gradient up-
valley that we noted in a preceding paragraph leave no doubt that each
moraine of the bordering valleys in the Vilcapampa region, represents a
prolonged period of stability in the conditions of topography as well as of
temperature and precipitation. If change in topographic conditions is
invoked to explain retreat from one position to the other there is left no
explanation of the periodicity of retreat which has just been established. If a
period of cold is inaugurated and glaciers advance to an ultimate position,
they can retreat only through change of climate effected either by general
causes or by topographic development to the point where the snowfields
become restricted in size. In the case of climatic change the ice changes are
periodic. In the case of retreat due to topographic change there should be a
steady or non-periodic falling back of the ice front as the catchment basins
decrease in elevation and the snow-gathering ridges tributary to them are
reduced in height.
Further, the matterhorns of the Cordillera Vilcapampa are not bare but
snow-covered, vigorous glaciers several miles in length and large
snowfields still survive and the divides are not arêtes but broad ridges. In
addition, the last two moraines, composed of very loose material, are well
preserved. They indicate clearly that the time since their formation has
witnessed no wholesale topographic change. If (1) no important
topographic changes have taken place, and (2) a vigorous glacier lay for a
long period back of a given moraine, and (3) suddenly retreated several
miles and again became stable, we are left without confidence in the

application of the topographic hypothesis to the glacial features of the
Vilcapampa region. Glacial retreat may be suddenly begun in the case of a
late stage of topographic development, but it should be an orderly retreat
marked by a large number of small moraines, or at least a plentiful strewing
of the valley floor with débris.
The number of moraines in the various glaciated
valleys of the Cordillera Vilcapampa differ, owing to
differences in elevation and to the variable size of the
catchment basins. All valleys, however, display the same
sudden change from moraine to moraine and the same
characteristics of gradient. In all of them the lowermost
moraine is always more deeply eroded than the higher
moraines, in all of them glacial erosion was sufficiently
Fig. 139—Glacial prolonged greatly to modify the valley walls, scour out
features on the lake basins, or broad flat valley floors, develop cirques,
eastern slopes of
the Cordillera
arêtes, and pinnacled ridges in limited number. In some,
Vilcapampa. glaciation was carried to the point where only skeleton
divides remained, in most places broad massive ridges or
mountain knots persist. In spite of all these differences
successive moraines were formed, separated by long stretches either thinly
covered with till or exposing bare rock.
In examining this group of features it is important to recognize the
essential fact that though the number of moraines varies from valley to
valley, the differences in character between the moraines at low and at high
elevations in a single valley are constant. It is also clear that everywhere the
ice retreated and advanced periodically, no matter with what topographic
features it was associated, whether those of maturity or of youth in the
glacial cycle. We, therefore, conclude that topographic changes had no
significant part to play in the glacial variations in the Cordillera
Vilcapampa.
The country west of the Cordillera Vilcapampa had been reduced to
early topographic maturity before the Ice Age, and then uplifted with only
moderate erosion of the masses of the interfluves. That on the east had
passed through the same sequence of events, but erosion had been carried
much farther. The reason for this is found in a strong climatic contrast. The
eastern is the windward aspect and receives much more rain than the
western. Therefore, it has more streams and more rapid dissection. The

result was that the eastern slopes were cut to pieces rapidly after the last
great regional uplift; the broad interfluves were narrowed to ridges. The
region eastward from the crest of the Cordillera to the Pongo de Mainique
looks very much like the western half of the Cascade Mountains in Oregon
—the summit tracts of moderate declivity are almost all consumed.
The effect of these climatic and topographic contrasts is manifested in
strong contrasts in the position and character of the glacial forms on the
opposite slopes of the range. At Pampaconas on the east the lowermost
terminal moraine is at least a thousand feet below timber line. Between
Vilcabamba pueblo and Puquiura the terminal moraine lies at 11,200 feet
(3,414 m.). By contrast the largest Pleistocene glacier on the western slope,
nearly twelve miles long, and the largest along the traverse, ended several
miles below Choquetira at 11,500 feet (3,504 m.) elevation, or just at the
timber line. Thus, the steeper descents of the eastern side of the range
appear to have carried short glaciers to levels far lower than those attained
by the glaciers of the western slope.
It seems at first strange that the largest glaciers were west of the divide
between the Urubamba and the Apurimac, that is, on the relatively dry side
of the range. The reason lies in a striking combination of topographic and
climatic conditions. Snow is a mobile form of precipitation that is shifted
about by the wind like a sand dune in the desert. It is not required, like
water, to begin a downhill movement as soon as it strikes the earth. Thus, it
is a noteworthy fact that snow drifting across the divides may ultimately
cause the largest snowfields to lie where the least snow actually falls. This
is illustrated in the Bighorns of Wyoming and others of our western ranges.
It is, however, not the wet snow near the snowline, but chiefly the dry snow
of higher altitudes that is affected. What is now the dry or leeward side of
the Cordillera appears in glacial times to have actually received more snow
than the wet windward side.

The topography conspired to increase this contrast. In
place of many streams, direct descents, a dispersion of
snow in many valleys, as on the east, the western slopes
had indirect descents, gentler valley profiles, and that
higher degree of concentration of drainage which naturally
goes with topographic maturity. For example, there is
nothing in the east to compare with the big spurless valley
near the pass above Arma. The side walls were so
extensively trimmed that the valley was turned into a
trough. The floor was smoothed and deepened and all the
Fig. 140— tributary glaciers were either left high up on the bordering
Glacial sculpture
in the heart of the slopes or entered the main valley with very steep profiles;
Cordillera their lateral and terminal moraines now hang in festoons
Vilcapampa. In on the steep side walls. Moreover, the range crest is
places the
topography has trimmed from the west so that the serrate skyline is a
so high a relief feature rarely seen from eastern viewpoints. This may not
that the glaciers hold true for more than a small part of the Cordillera. It
seem almost to
overhang the was probably emphasized here less by the contrasts already
valleys. See Figs. noted than by the geologic structure. The eastward-flowing
96 and 179 for
photographs.
glaciers descended over dip slopes on highly inclined
sandstones, as at Pampaconas. Those flowing westward
worked either in a jointed granite or on the outcropping
edges of the sandstones, where the quarrying process known as glacial
plucking permitted the development of excessively steep slopes.
There are few glacial steps in the eastern valleys. The western valleys
have a marvelous display of this striking glacial feature. The accompanying
hachure maps show them so well that little description is needed. They are
from 50 to 200 feet high. Each one has a lake at its foot into which the
divided stream trickles over charming waterfalls. All of them are clearly
associated with a change in the volume of the glacier that carved the valley.
Wherever a tributary glacier entered, or the side slopes increased notably in
area, a step was formed. By retreat some of them became divided, for the
process once begun would push the step far up valley after the manner of an
extinguishing waterfall.
The retreat of the steps, the abrasion of the rock, and the sapping of the
cirques at the valley heads excavated the upper valleys so deeply that they
are nearly all, as W. D. Johnson has put it, “down at the heel.” Thus, above

Arma, one plunges suddenly from the smooth, grassy glades of the strongly
glaciated valley head down over the outer slopes of the lowermost terminal
moraine to the steep lower valley. Above the moraine are fine pastures, in
the steep valley below are thickets and rocky defiles. There are long quiet
reaches in the streams of the glaciated valley heads besides pretty lakes and
marshes. Below, the stream is swift, almost torrential. Arma itself is built
upon alluvial deposits of glacial origin. A mile farther down the valley is
constricted and steep-walled—really a canyon.
Though the glaciers have retreated to the summit region, they are by no
means nearing extinction. The clear blue ice of the glacier descending from
Mt. Soiroccocha in the Arma Valley seems almost to hang over the
precipitous valley border. In curious contrast to its suggestion of cold and
storm is the patch of dark green woodland which extends right up to its
border. An earthquake might easily cause the glacier to invade the
woodland. Some of the glaciers between Choquetira and Arma rest on
terminal moraines whose distal faces are from 200 to 300 feet high. The ice
descending southeasterly from Panta Mt. is a good illustration. Earlier
positions of the ice front are marked by equally large moraines. The one
nearest that engaged by the living glacier confines a large lake that
discharges through a gap in the moraine and over a waterfall to the marshy
floor of the valley.
Retreat has gone so far, however, that there are only a few large glacier
systems. Most of the tributaries have withdrawn toward their snowfields. In
place of the twenty distinct glaciers now lying between the pass and the
terminal moraine below Choquetira, there was in glacial times one great
glacier with twenty minor tributaries. The cirques now partly filled with
damp snow must then have been overflowing with dry snow above and ice
below. Some of the glaciers were over a thousand feet thick; a few were
nearly two thousand feet thick, and the cirques that fed them held snow and
ice at least a half mile deep. Such a remarkably complete set of glacial
features only 700 miles from the equator is striking evidence of the moist
climate on the windward eastern part of the great Andean Cordillera, of the
universal change in climate in the glacial period, and of the powerful
dominating effects of ice erosion in this region of unsurpassed Alpine relief.
THE VILCAPAMPA BATHOLITH AND ITS TOPOGRAPHIC EFFECTS

Fig. 141—Composite geologic section on the northeastern border of
the Cordillera Vilcapampa, in the vicinity of Pampaconas, to show the
deformative effects of the granite intrusion. There is a limited amount
of limestone near the border of the Cordillera. Both limestone and
sandstone are Carboniferous. See Appendix B. See also Figs. 142 and
146. The section is about 15 miles long.

The main axis of the Cordillera Vilcapampa consists of granite in the
form of a batholith between crystalline schists on the one hand (southwest),
and Carboniferous limestones and sandstones and Silurian shales and slates
on the other (northeast). It is not a domal uplift in the region in which it was
observed in 1911, but an axial intrusion, in places restricted to a narrow belt
not more than a score of miles across. As we should expect from the
variable nature of the invaded material, the granite belt is not uniform in
width nor in the character of its marginal features. In places the intrusion
has produced strikingly little alteration of the country rock; in other
localities the granite has been injected into the original material in so
intimate a manner as almost completely to alter it, and to give rise to a very
broad zone of highly metamorphosed rock. Furthermore, branches were
developed so that here and there tributary belts of granite extend from the
main mass to a distance of many miles. Outlying batholiths occur whose
common petrographic character and similar manner of occurrence leave
little doubt that they are related abyssally to a common plutonic mass.
The Vilcapampa batholith has two highly contrasted borders, whether we
consider the degree of metamorphism of the country rock, the definition of
the border, or the resulting topographic forms. On the northeastern ridge at
Colpani the contact is so sharp that the outstretched arms in some places
embrace typical granite on the one hand and almost unaltered shales and
slates on the other. Inclusions or xenoliths of shale are common, however,
ten and fifteen miles distant, though they are prominent features in a belt
only a few miles wide. The lack of more intense contact effects is a little
remarkable in view of the altered character of the inclusions, all of which
are crystalline in contrast to the fissile shales from which they are chiefly
derived. Inclusions within a few inches of the border fall into a separate
class, since they show in general but trifling alteration and preserve their

original cleavage plains. It appears that the depth of the intrusion must have
been relatively slight or the intrusion sudden, or both shallow and sudden,
conditions which produce a narrow zone of metamorphosed material and a
sharp contact.
The relation between shale and granite at
Colpani is shown in 143 . Projections of granite
extend several feet into the shale and slate and
Fig. 142—The deformative generally end in blunt barbs or knobs. In a few
effects of the Vilcapampa places there is an intimate mixture of irregular
intrusion on the northeastern slivers and blocks of crystallized sediments in a
border of the Cordillera. The
deformed strata are heavy- granitic groundmass, with sharp lines of
bedded sandstones and shales demarcation between igneous and included
and the igneous rocks are material. The contact is vertical for at least
chiefly granites with bordering
porphyries. Looking northwest several miles. It is probable that other localities
near Puquiura. For conditions on the contact exhibit much greater
near Pampaconas, looking in modification and invasion of the weak shales
the opposite direction, see Fig.
141. For conditions on the other and slates, but at Colpani the phenomena are
side of the Cordillera, see Fig. both simple and restricted in development.
146.
The highly
mineralized
character of the bordering sedimentary strata,
and the presence of numbers of complementary
dikes, nearly identical in character to those in Fig. 143—Relation of granite
the parent granite now exposed by erosion over intrusion to schist on the
northeastern border of the
a broad belt roughly parallel to the contact, Vilcapampa batholith near the
supplies a basis for the inference that the bridge of Colpani, lower end of
granite may underlie the former at a slight the granite Canyon of Torontoy.
The sections are from 15 to 25
depth, or may have had far greater feet high and represent
metamorphic effects upon its sedimentary roof conditions at different levels
than the intruded granite has had upon its along the well-defined contact.
sedimentary rim.
The physiographic features of the contact belt are of special interest. No
available physiographic interpretation of the topography of a batholith
includes a discussion of those topographic and drainage features that are
related to the lithologic character of the intruded rock, the manner of its
intrusion, or the depth of erosion since intrusion. Yet each one of these
factors has a distinct topographic effect. We shall, therefore, turn aside for a

moment from the detailed discussion of the Vilcapampa region to an
examination of several physiographic principles and then return to the main
theme for applications.
It is recognized that igneous intrusions are of many varieties and that
even batholithic invasions may take place in rather widely different ways.
Highly heated magmas deeply buried beneath the earth’s surface produce
maximum contact effects, those nearer the surface may force the strata apart
without extreme lithologic alterations of the displaced beds, while through
the stoping process a sedimentary cover may be largely absorbed and the
magmas may even break forth at the surface as in ordinary vulcanism. If the
sedimentary beds have great vertical variation in resistance, in attitude, and
in composition, there may be afforded an opportunity for the display of
quite different effects at different levels along a given contact, so that a
great variety of physical conditions will be passed by the descending levels
of erosion. At one place erosion may have exposed only the summit of the
batholith, at another the associated dikes and sheets and ramifying branches
may be exposed as in the zone of fracture, at a third point the original zone
of flowage may be reached with characteristic marginal schistosity, while at
still greater depths there may be uncovered a highly metamorphosed rim of
resistant sedimentary rock.
The mere enumeration of these variable structural features is sufficient to
show how variable we should expect the associated land forms to be. Were
the forms of small extent, or had they but slight distinction upon
comparison with other erosional effects, they would be of little concern.
They are, on the contrary, very extensively developed; they affect large
numbers of lofty mountain ranges besides still larger areas of old land
masses subjected to extensive and deep erosion, thus laying bare many
batholiths long concealed by a thick sedimentary roof.
The differences between intruded and country rock dependent upon
these diversified conditions of occurrence are increased or diminished
according to the history of the region after batholithic invasion takes place.
Regional metamorphism may subsequently induce new structures or
minimize the effects of the old. Joint systems may be developed, the planes
widely spaced in one group of rocks giving rise to monolithic masses very
resistant to the agents of weathering, while those of an adjacent group may
be so closely spaced as greatly to hasten the rate of denudation. There may
be developed so great a degree of schistosity in one rock as to give rise

(with vigorous erosion) to a serrate topography; on the other hand the forms
developed on the rocks of a batholith may be massive and coarse-textured.
To these diversifying conditions may be added many others involving a
large part of the field of dynamic geology. It will perhaps suffice to mention
two others: the stage of erosion and the special features related to climate. If
a given intrusion has been accompanied by an important amount of uplift or
marginal compression, vigorous erosion may follow, whereupon a chance
will be offered for the development of the greatest contrast in the degree of
boldness of topographic forms developed upon rocks of unequal resistance.
Ultimately these contrasts will diminish in intensity, as in the case of all
regional differences of relief, with progress toward the end of the normal
cycle of erosion. If peneplanation ensue, only feeble topographic
differences may mark the line of contact which was once a prominent
topographic feature. With reference to the effects of climate it may be said
simply that a granite core of batholithic origin may extend above the
snowline or above timber line or into the timbered belt, whereas the invaded
rock may occur largely below these levels with obvious differences in both
the rate and the kind of erosion affecting the intruded mass.

Fig. 144—Cliffed canyon wall in Fig. 145—Another aspect of the
the Urubamba Valley between canyon wall of 144 . The almost
Huadquiña and Torontoy. There is sheer descents are in contrast with
a descent of nearly 2,000 feet the cliff and platform type of
shown in the photograph and it is topography characteristic of the
developed almost wholly along Grand Canyon of Colorado.
successive joint planes.

If we apply the foregoing considerations to the Cordillera Vilcapampa,
we shall find some striking illustrations of the principles involved. The
invasion of the granite was accompanied by moderate absorption of the
displaced rock, and more especially by the marginal pushing aside of the
sedimentary rim. The immediate effect must have been to give both
intruded rock and country rock greater height and marked ruggedness.
There followed a period of regional compression and torsion, and the
development of widespread joint systems with strikingly regular features. In
the Silurian shales and slates these joints are closely spaced; in the granites
they are in many places twenty to thirty feet apart. The shales, therefore,
offer many more points of attack and have weathered down into a smooth-
contoured topography boldly overlooked along the contact by walls and
peaks of granite. In some cases a canyon wall a mile high is developed
entirely on two or three joint planes inclined at an angle no greater than
15°. The effect in the granite is to give a marked boldness of relief, nowhere
more strikingly exhibited than at Huadquiña, below Colpani, where the
foot-hill slopes developed on shales and slates suddenly become moderate.
The river flows from a steep and all but uninhabited canyon into a broad
valley whose slopes are dotted with the terraced chacras, or farms, of the
mountain Indians.
The Torontoy granite is also homogeneous while the shales and slates
together with their more arenaceous associates occur in alternating belts, a
diversity which increases the points of attack and the complexity of the
forms. Tending toward the same result is the greater hardness of the granite.
The tendency of the granite to develop bold forms is accelerated in lofty
valleys disposed about snow-clad peaks, where glaciers of great size once
existed, and where small glaciers still linger. The plucking action of ice has
an excellent chance for expression, since the granite may be quarried
cleanly without the production of a large amount of spoil which would load
the ice and diminish the intensity of its plucking action.
As a whole the Central Andes passed through a cycle of erosion in late
Tertiary time which was interrupted by uplift after the general surface had
been reduced to a condition of topographic maturity. Upon the granites
mature slopes are not developed except under special conditions (1) of
elevation as in the small batholith above Chuquibambilla, and (2) where the
granite is itself bordered by resistant schists which have upheld the surface
over a broad transitional belt. Elsewhere the granite is marked by

exceedingly rugged forms: deep steep-walled canyons, precipitous cirques,
matterhorns, and bold and extended escarpments of erosion. In the shale
belt the trails run from valley to valley in every direction without special
difficulties, but in the granite they follow the rivers closely or cross the axis
of the range by carefully selected routes which generally reach the limit of
perpetual snow. Added interest attaches to these bold topographic forms
because of the ruins now found along the canyon walls, as at Torontoy, or
high up on the summit of a precipitous spur, as at Machu Picchu near the
bridge of San Miguel.
The Vilcapampa batholith is bordered on the southwest by a series of
ancient schists with which the granite sustains quite different relations. No
sharp dividing line is visible, the granite extending along the planes of
foliation for such long distances as in places to appear almost interbedded
with the schists. The relation is all the more striking in view of the trifling
intrusions effected in the case of the seemingly much weaker shales on the
opposite contact. Nor is the metamorphism of the invaded rock limited to
simple intrusion. For several miles beyond the zone of intenser effects the
schists have been enriched with quartz to such an extent that their original
darker color has been changed to light gray or dull white. At a distance they
may even appear as homogeneous and light-colored as the granite. At
distant points the schists assume a darker hue and take on the characters of
a rather typical mica schist.
It is probable that the Vilcapampa intrusion is one of a family of
batholiths which further study may show to extend over a much larger
territory. The trail west of Abancay was followed quite closely and
accidentally crosses two small batholiths of peculiar interest. Their limits
were not closely followed out, but were accurately determined at a number
of points and the remaining portion of the contact inferred from the
topography. In the case of the larger area there may indeed be a connection
westward with a larger mass which probably constitutes the ranges distant
some five to ten miles from the line of traverse.

Fig. 146—Deformative effects on limestone strata of the granite
intrusion on the southwestern border of the Vilcapampa batholith

above Chuquibambilla. Fig. 147 is on the same border of the batholith
several miles farther northwest. The granite mass on the right is a
small outlier of the main batholith looking south. The limestone is
Cretaceous. See Appendix C for locations.

These smaller intrusions are remarkable in that they appear to have been
attended by little alteration of either invading or invaded rock, though the
granites were observed to become distinctly more acid in the contact zone.
Space was made for them by displacing the sedimentary cover and by a
marked shortening of the sedimentary rim through such structures as
overthrust faults and folds. The contact is observable in a highly
metamorphosed belt about twenty feet wide, and for several hundred feet
more the granite has absorbed the limestone in small amounts with the
production of new minerals and the development of a distinctly lighter
color. The deformative effects of the batholithic invasion are shown in their
gross details in Figs. 141, 142, and 146; the finer details of structure are
represented in 147 , which is drawn from a measured outcrop above
Chuquibambilla.
It will be seen that we have here more than a mere crinkling, such as the
mica schists of the Cordillera Vilcapampa display. The diversified
sedimentary series is folded and faulted on a large scale with broad
structural undulations visible for miles along the abrupt valley walls. Here
and there, however, the strata become weaker generally through the
thinning of the beds and the more rapid alternation of hard and soft layers,
and for short distances they have absorbed notable amounts of the stresses
induced by the igneous intrusions. In such places not only the structure but
the composition of the rock shows the effects of the intrusion. Certain
shales in the section are carbonaceous and in all observed cases the organic
matter has been transformed to anthracite, a condition generally associated
with a certain amount of minute mashing and a cementation of both
limestone and sandstone.
The granite becomes notably darker on
approach to the northeastern contact near
Colpani; the proportion of ferro-magnesian
minerals in some cases is so large as to give a
distinctly black color in sharp contrast to the
Fig. 147—Overthrust folds in
detail on the southwestern border nearly white granite typical of the central
of the Vilcapampa batholith near portion of the mass. Large masses of shale

Chuquibambilla. The section is foundered in the invading magma, and upon
fifteen feet high. Elevation,
13,100 feet (4,000 m.). For fusion gave rise to huge black masses
comparison with the structural impregnated with quartz and in places
effects of the Vilcapampa smeared or injected with granite magma.
intrusion on the northeast see
Fig. 142. Everywhere the granite is marked by numbers
of black masses which appear at first sight to
be aggregations of dark minerals normal to
the granite and due to differentiation processes at the time of crystallization.
It is, however, noteworthy that these increase rapidly in number on
approach to the contact, until in the last half-mile they appear to grade into
the shale inclusions. It may, therefore, be doubted that they are
aggregations. From their universal distribution, their uniform character, and
their marked increase in numbers on approach to lateral contacts, it may
reasonably be inferred that they represent foundered masses of country
rock. Those distant from present contacts are in almost all cases from a few
inches to a foot in diameter, while on approach to lateral contacts they are in
places ten to twenty feet in width, as if the smaller areas represented the last
remnants of large inclusions engulfed in the magma near the upper or roof
contact. They are so thoroughly injected with silica and also with typical
granite magma as to make their reference to the country rock less secure on
petrographical than on purely distributional grounds.
A parallel line of evidence relates to the distribution of complementary
dikes throughout the granite. In the main mass of the batholith the dikes are
rather evenly distributed as to kind with a slight preponderance of the dark-
colored group. Near the contact, however, aplitic dikes cease altogether and
great numbers of melanocratic dikes appear. It may be inferred that we have
in this pronounced condition suggestions of strong influence upon the final
processes of invasion and cooling of the granite magma, on the part of the
country rock detached and absorbed by the invading mass. It might be
supposed that the indicated change in the character of the complementary
dikes could be ascribed to possible differentiation of the granite magma
whereby a darker facies would be developed toward the Colpani contact. It
has, however, been pointed out already that the darkening of the granite in
this direction is intimately related to a marked increase in the number of
inclusions, leaving little doubt that the thorough digestion of the smaller
masses of detached shales is responsible for the marked increase in the
number and variety of the ferro-magnesian and special contact minerals.

Upon the southwestern border of the batholith the number of aplitic
dikes greatly increases. They form prominent features, not only of the
granite, but also of the schists, adding greatly to the strong contrast between
the schist of the border zone and that outside the zone of metamorphism. In
places in the border schists, these are so numerous that one may count up to
twenty in a single view, and they range in size from a few inches to ten or
fifteen feet. The greater fissility of the schists as contrasted with the shales
on the opposite or eastern margin of the batholith caused them to be
relatively much more passive in relation to the granite magma. They were
not so much torn off and incorporated in the magma, as they were
thoroughly injected and metamorphosed. Added to this is the fact that they
are petrographically more closely allied to the granite than are the shales
upon the northeastern contact.

CHAPTER XIV

THE COASTAL TERRACES
ALONG the entire coast of Peru are upraised and dissected terraces of
marine origin. They extend from sea level to 1,500 feet above it, and are
best displayed north of Mollendo and in the desert south of Payta. The
following discussion relates to that portion of the coast between Mollendo
and Camaná.
At the time of the development of the coastal terraces the land was in a
state of temporary equilibrium, for the terraces were cut to a mature stage as
indicated by the following facts: (1) the terraces have great width—from
one to five and more miles; (2) their inner border is straight, or, where
curves exist, they are broad and regular; (3) the terrace tops are planed off
smoothly so that they now have an even gradient and an almost total
absence of rock stacks or unreduced spurs; (4) the mature slopes of the
Coast Range, strikingly uniform in gradient and stage of development (Fig.
148), are perfectly organized with respect to the inner edge of the terrace.
They descend gradually to the terrace margin, showing that they were
graded with respect to sea level when the sea stood at the inner edge of the
highest terrace.
From the composition and even distribution of the thick-bedded Tertiary
deposits of the desert east of the Coast Range, it is concluded that the

precipitation of Tertiary time was greater than that of today (see p. 261).
Therefore, if the present major streams reach the sea, it may also be
concluded that those of an earlier period reached the sea, provided the
topography indicates the perfect adjustment of streams to structure.
Lacustrine sediments are absent throughout the Tertiary section. Such
through-flowing streams, discharging on a stable coast, would also have
mature valleys as a consequence of long uninterrupted erosion at a fixed
level. The Majes river must have cut through the Coast Range at Camaná
then as now. Likewise the Vitor at Quilca must have cut straight across the
Coast Range. An examination of the surface leading down from the Coast
Range to the upper edge of these valleys fully confirms this deduction.
Flowing and well-graded slopes descend to the brink of the inner valley in
each case, where they give way to the gorge walls that continue the descent
to the valley floor.
Confirmatory evidence is found in the wide Majes Valley at Cantas and
Aplao. (See the Aplao Quadrangle for details.) Though the observer is first
impressed with the depth of the valley, its width is more impressive still. It
is also clear that two periods of erosion are represented on its walls. Above
Aplao the valley walls swing off to the west in a great embayment quite
inexplicable on structural grounds; in fact the floor of the embayment is
developed across the structure, which is here more disordered than usual.
The same is true below Cantas, as seen from the trail, which drops over two
scarps to get to the valley floor. The upper, widely opened valley is
correlated with the latter part of the period in which were formed the mature
terraces of the coast and the mature slopes bordering the larger valleys
where they cross the Coast Range.
After its mature development the well-graded marine terrace was
upraised and dissected. The deepest and broadest incisions in it were made
where the largest streams crossed it. Shallower and narrower valleys were
formed where the smaller streams that headed in the Coast Range flowed
across it. Their depth and breadth was in general proportional to the height
of that part of the Coast Range in which their headwaters lay and to the size
of their catchment basins.
When the dissection of the terrace had progressed to the point where
about one-third of it had been destroyed, there came depression and the
deposition of Pliocene or early Pleistocene sands, gravels, and local clay
beds. Everywhere the valleys were partly or wholly filled and over broad

stretches, as in the vicinity of stream mouths and upon lower portions of the
terrace, extensive deposits were laid down. The largest deposits lie several
hours’ ride south of Camaná, where locally they attain a thickness of several
hundred feet. Their upper surface was well graded and they show a
prolonged period of deposition in which the former coastal terrace was all
but concealed.

Fig. 148—The Coast Range between Mollendo and Arequipa at the
end of June, 1911. There is practically no grass and only a few dry
shrubs. The fine network over the hill slopes is composed of interlacing
cattle tracks. The cattle roam over these hills after the rains which
come at long intervals. (See page 141 for description of the rains and
the transformations they effect. For example, in October, 1911, these
hills were covered with grass.)
Fig. 149—The great marine terrace at Mollendo. See Fig. 150 for
profile.

The uplift of the coast terrace and its subsequent dissection bring the
physical history down to the present. The uplift was not uniform; three
notches in the terrace show more faintly upon the granite-gneiss where the
buried rock terrace has been swept clean again, more strongly upon the
softer superimposed sands. They lie below the 700-foot contour and are
insignificant in appearance beside the slopes of the Coast Range or the
ragged bluff of the present coast.

The effect of the last uplift of the coast was to impel the Majes River
again to cut down its lower course nearly to sea level. The Pliocene terrace
deposits are here entirely removed over an area several leagues wide. In
their place an extensive delta and alluvial fan have been formed. At first the
river undoubtedly cut down to base level at its mouth and deposited the cut
material on the sea floor, now shoal, for a considerable distance from shore.
We should still find the river in that position had other agents not
intervened. But in the Pleistocene a great quantity of waste was swept into
the Majes Valley, whereupon aggradation began; and in the middle and
lower valley it has continued down to the present.

Fig. 150—Profile of the coastal terraces at Mollendo. At 1, in a
tributary gorge, fossiliferous clay occurs at 800 feet elevation above the
sea. At 2 is a characteristic change of profile marking a drop from a
higher to a lower terrace. On the extreme left is the highest terrace, just
under 1,500 feet (460 m.).

Figs. 151-154—These four diagrams represent the physical history
and the corresponding physiographic development of the coastal region
of Peru between Camaná and Mollendo. The sedimentary beds in the

background of the first diagram are hypothetical and are supposed to
correspond to the quartzites of the Majes Valley at Aplao.

The effect has been not only the general aggradation of the valley floor,
but also the development of a combined delta and superimposed alluvial fan
at the valley mouth. The seaward extension of the delta has been hastened
by the gradation of the shore between the bounding headlands, thus giving
rise to marine marshes in which every particle of contributed waste is
firmly held. The plain of Camaná, therefore, includes parts of each of the
following: a delta, a superposed alluvial fan, a salt-water marsh, a fresh-
water marsh, a series of beaches, small amounts of piedmont fringe at the
foot of Pliocene deposits once trimmed by the river and by waves, and
extensive tracts of indefinite fill. (See the Camaná Quadrangle for details.)
With the coastal conditions now before us it will be possible to attempt a
correlation between the erosion features and the deposits of the coast and
those of the interior. An understanding of the comparisons will be facilitated
by the use of diagrams, Figs. 151-154, and by a series of concise summary
statements. From the relations of the figure it appears that:
1. The Tertiary deposits bordering the Majes Valley east of the Coast
Range were in process of deposition when the sea planed the coastal terrace
(Fig. 151).
2. A broad mature marine terrace without stacks or sharply alternating
spurs and reëntrants (though the rock is a very resistant granite) is
correlated with the mature grades of the Coast Range, with which they are
integrated and with the mature profiles of the main Cordillera.
3. Such a high degree of topographic organization requires the dissection
in the late stages of the erosion cycle of at least the inner or eastern border
of the piedmont deposits of the desert, largely accumulated during the early
stages of the cycle.
4. Since the graded slopes of the Coast Range on the one side descend to
a former shore whose elevation is now but 1,500 feet above sea level, and
since only ten to twenty miles inland on the other side of the range, the
same kind of slope extends beneath Tertiary deposits 4,000 feet above sea
level, it appears that aggradation of the outer (or western) part of the
Tertiary deposits on the eastern border of the Coast Range continued down
to the end of the cycle of erosion, though

5. There must have been an outlet to the sea, since, as we have already
seen, the water supply of the Tertiary was greater than that of today and the
present streams reach the sea. Moreover, the mature upper slopes and the
steep lower slopes of the large valleys make a pronounced topographic
unconformity, showing two cycles of valley development.
6. Upon uplift of the coast and dissection of the marine terraces at the
foot of the Coast Range, the streams cut deep trenches on the floors of their
former valleys (Fig. 152) and removed (a) large portions of the coast
terrace, and (b) large portions of the Tertiary deposits east of the Coast
Range.
7. Depression of the coastal terrace and its partial burial meant the
drowning of the lower Majes Valley and its partial filling with marine and
later with terrestrial deposits. It also brought about the partial filling by
stream aggradation of the middle portion of the valley, causing the valley
fill to abut sharply against the steep valley walls. (See 155 .)
8. Uplift and dissection of both the terrace and its overlying sediments
would be accompanied by dissection of the former valley fill, provided that
the waste supply was not increased and that the uplift was regional and
approximately equal throughout—not a bowing up of the coast on the one
hand, or an excessive bowing up of the mountains on the other. But the
waste supply has not remained constant, and the uplift has been greater in
the Cordillera than on the coast. Let us proceed to the proof of these two
conclusions, since upon them depends the interpretation of the later
physical history of the coastal valleys.

Fig. 155—Steep walls in the Fig. 156—Canyon of the Majes
Majes Valley below Cantas and River through the Coast Range
the abrupt termination against north of Camaná. The rock is a
them of a deep alluvial fill. granite-gneiss capped by rather
flat-lying sedimentaries.

It is known that the Pleistocene was a time of augmented waste delivery.
At the head of the broadly opened Majes Valley there was deposited a huge
mass of extremely coarse waste several hundred feet deep and several miles
long. Forward from it, interstratified with its outer margin, and continuing
the same alluvial grade, is a still greater mass of finer material which
descends to lower levels. The fine material is deposited on the floor of a
valley cut into Tertiary strata, hence it is younger than the Tertiary. It is
now, and has been for some time past, in process of dissection, hence it was
not formed under present conditions of climate and relief. It is confidently
assigned to the Pleistocene, since this is definitely known to have been a
time of greater precipitation and waste removal on the mountains, and
deposition on the plains and the floors of mountain valleys. Such a
conclusion appears, even on general grounds, to be but a shade less reliable
than if we were able to find in the upper Majes Valley, as in so many other
Andean valleys, similar alluvial deposits interlocked with glacial moraines
and valley trains.
In regard to the second consideration—the upbowing of the Cordillera—
it may be noted that the valley and slope profiles of the main Cordillera
shown on p. 191, when extended toward the margin of the mountain belt, lie
nearly a mile above the level of the sea on the west and the Amazon plains
on the east. The evidence of regional bowing thus afforded is checked by
the depths of the mountain valleys and the stream profiles in them. The
streams are now sunk from one to three thousand feet below their former
level. Even in the case of three thousand feet of erosion the stream profiles
are still ungraded, the streams themselves are almost torrential, and from
one thousand to three thousand feet of vertical cutting must still be
accomplished before the profiles will be as gentle and regular as those of
the preceding cycle of erosion, in which were formed the mature slopes
now lying high above the valley floors.
Further evidence of bowing is afforded by the attitude of the Tertiary
strata themselves, more highly inclined in the case of the older Tertiary, less

highly inclined in the case of the younger Tertiary. It is noteworthy that the
gradient of the present valley floor is distinctly less than that of the least
highly inclined strata. This is true even where aggradation is now just able
to continue, as near the nodal point of the valley, above Aplao, where
cutting ceases and aggradation begins. (See the Aplao Quadrangle for
change of function on the part of the stream a half mile above Cosos). Such
a progressive steepening of gradients in the direction of the oldest deposits,
shows very clearly a corresponding progression in the growth of the Andes
at intervals throughout the Tertiary.
Thus we have aggradation in the Tertiary at the foot of the growing
Andes; aggradation in the Pliocene or early Pleistocene on the floor of a
deep valley cut in earlier deposits; aggradation in the glacial epoch; and
aggradation now in progress. Basin deposits within the borders of the
Peruvian Andes are relatively rare. The profound erosion implied by the
development, first of a mature topography across this great Cordillera, and
second of many deep canyons, calls for deposition on an equally great scale
on the mountain borders. The deposits of the western border are a mile
thick, but they are confined to a narrow zone between the Coast Range and
the Cordillera. Whatever material is swept beyond the immediate coast is
deposited in deep ocean water, for the bottom falls off rapidly. The deposits
of the eastern border of the Andes are carried far out over the Amazon
lowland. Those of earlier geologic periods were largely confined to the
mountain border, where they are now upturned to form the front range of
the Andes. The Tertiary deposits of the eastern border are less restricted,
though they appear to have gathered chiefly in a belt from fifty to one
hundred miles wide.
The deposits of the western border were laid down by short streams
rising on a divide only 100 to 200 miles from the Pacific. Furthermore, they
drain the dry leeward slopes of the Andes. The deposits of the wet eastern
border were made by far larger streams that carry the waste of nearly the
whole Cordillera. Their shoaling effect upon the Amazon depression must
have been a large factor in its steady growth from an inland sea to a river
lowland.
CHAPTER XV

PHYSIOGRAPHIC AND GEOLOGIC DEVELOPMENT

GENERAL FEATURES
In the preceding chapter we employed geologic facts in the
determination of the age of the principal topographic forms. These facts
require further discussion in connection with their closest physiographic
allies if we wish to show how the topography of today originated. There are
many topographic details that have a fundamental relation to structure;
indeed, without a somewhat detailed knowledge of geology only the
broader and more general features of the landscape can be interpreted. In
this chapter we shall therefore refer not to the scenic features as in a purely
topographic description, but to the rock structure and the fossils. A complete
and technical geologic discussion is not desirable, first, because it should be
based upon much more detailed geologic field work, and second because
after all our main purpose is not to discuss the geologic features per se, but
the physiographic background which the geologic facts afford. I make this
preliminary observation partly to indicate the point of view and partly to
emphasize the necessity, in a broad, geographic study, for the reconstruction
of the landscapes of the past.
The two dominating ranges of the Peruvian Andes, called the Maritime
Cordillera and the Cordillera Vilcapampa, are composed of igneous rock—
the one volcanic lava, the other intrusive granite. The chief rock belts of the
Andes of southern Peru are shown in 157 . The Maritime Cordillera is
bordered on the west by Tertiary strata that rest unconformably upon
Palaeozoic quartzites. It is bordered on the east by Cretaceous limestones
that grade downward into sandstones, shales, and basal conglomerates. At
some places the Cretaceous deposits rest upon old schists, at others upon
Carboniferous limestones and related strata, upon small granite intrusives
and upon old and greatly altered volcanic rock.
The Cordillera Vilcapampa has an axis of granitic rock which was thrust
upward through schists that now border it on the west and slates that now
border it on the east. The slate series forms a broad belt which terminates
near the eastern border of the Andes, where the mountains break down
abruptly to the river plains of the Amazon Basin. The immediate border on
the east is formed of vertical Carboniferous limestones. The narrow foothill
belt is composed of Tertiary sandstones that grade into loose sands and
conglomerates. The inclined Tertiary strata were leveled by erosion and in
part overlain by coarse and now dissected river gravels, probably of

Pleistocene age. Well east of the main border are low ranges that have never
been described. They could not be reached by the present expedition on
account of lack of time. On the extreme western border of that portion of
the Peruvian Andes herein described, there is a second distinct border chain,
the Coast Range. It is composed of granite and once had considerable relief,
but erosion has reduced its former bold forms to gentle slopes and graded
profiles.
The continued and extreme growth of the Andes in later geologic periods
has greatly favored structural and physiographic studies. Successive uplifts
have raised earlier deposits once buried on the mountain flanks and erosion
has opened canyons on whose walls and floors are the clearly exposed
records of the past. In addition there have been igneous intrusions of great
extent that have thrust aside and upturned the invaded strata exposing still
further the internal structures of the mountains. From sections thus revealed
it is possible to outline the chief events in the history of the Peruvian Andes,
though the outline is still necessarily broad and general because based on
rapid reconnaissance. However, it shows clearly that the landscape of the
present represents but a temporary stage in the evolution of a great
mountain belt. At the dawn of geologic history there were chains of
mountains where the Andes now stand. They were swept away and even
their roots deeply submerged under invading seas. Repeated uplifts of the
earth’s crust reformed the ancient chains or created new ones out of the rock
waste derived from them. Each new set of forms, therefore, exhibits some
features transmitted from the past. Indeed, the landscape of today is like the
human race—inheriting much of its character from past generations. For
this reason the philosophical study of topographic forms requires at least a
broad knowledge of related geologic structures.
Fig. 157—Outline sketch showing the principal rock belts of Peru along the seventy-third
meridian. They are: 1, Pleistocene and Recent gravels and sands, the former partly indurated
and slightly deformed, with the degree of deformation increasing toward the mountain border
(south). 2, Tertiary sandstones, inclined from 15° to 30° toward the north and unconformably
overlain by Pleistocene gravels. 3, fossil-bearing Carboniferous limestones with vertical dip. 4,
non-fossiliferous slates, shales, and slaty schists (Silurian) with great variation in degree of
induration and in type of structure. South of the parallel of 13° is a belt of Carboniferous
limestones and sandstones bordering (5), the granite axis of the Cordillera Vilcapampa. For its
structural relations to the Cordillera see Figs. 141 and 142. 6, old and greatly disturbed
volcanic agglomerates, tuffs and porphyries, and quartzitic schists and granite-gneiss. 7,
principally Carboniferous limestones north of the axis of the Central Ranges and Cretaceous
limestones south of it. Local granite batholiths in the axis of the Central Ranges. 8, quartzites
and slates predominating with thin limestones locally. South of 8 is a belt of shale, sandstone,

and limestone with a basement quartzite appearing on the valley
floors. 9, a portion of the great volcanic field of the Central Andes
and characteristically developed in the Western or Maritime
Cordillera, throughout northern Chile, western Bolivia, and Peru. At
Cotahuasi (see also Fig. 20) Cretaceous limestones appear beneath
the lavas. 10, Tertiary sandstones of the coastal desert with a
basement of old volcanics and quartzites appearing on the valley
walls. The valley floor is aggraded with Pleistocene and Recent
alluvium. 11, granite-gneiss of the Coast Range. 12, late Tertiary or
Pleistocene sands and gravels deposited on broad coastal terraces.
For rock structure and character see the other figures in this
chapter. For a brief designation of index fossils and related forms see
Appendix B. For the names of the drainage lines and the locations of
the principal towns see Figs. 20 and 204.

SCHISTS AND SILURIAN SLATES [50]
The oldest series of rocks along the seventy-third meridian of Peru
extends eastward from the Vilcapampa batholith nearly to the border of the
Cordillera, 157 . It consists of (1) a great mass of slates and shales with
remarkable uniformity of composition and structure over great areas, and
(2) older schists and siliceous members in restricted belts. They are
everywhere thoroughly jointed; near the batholith they are also mineralized
and altered from their original condition; in a few places they have been
intruded with dikes and other form of igneous rock.
The slates and shales underlie known Carboniferous strata on their
eastern border and appear to be a physical continuation of the fossiliferous
slates of Bolivia; hence they are provisionally referred to the Silurian,
though they may possibly be Devonian. Certainly the known Devonian
exceeds in extent the known Silurian in the Central Andes but its
lithological character is generally quite unlike the character of the slates
here referred to the Silurian. The schists are of great but unknown age. They
are unconformably overlain by known Carboniferous at Puquiura in the
Vilcapampa Valley (Fig. 158), and near Chuquibambilla on the opposite
side of the Cordillera Vilcapampa. The deeply weathered fissile mica schists

east of Pasaje (see Appendix C for all locations) are also unconformably
overlain by conglomerate and sandstone of Carboniferous age. While the
schists vary considerably in lithological appearance and also in structure,
they are everywhere the lowest rocks in the series and may with confidence
be referred to the early Palaeozoic, while some of them may date from the
Proteriozoic.

Fig. 158—Geologic sketch map of the lower Urubamba Valley. A
single traverse was made along the valley, hence the boundaries are not
accurate in detail. They were sketched in along a few lateral traverses
and also inferred from the topography. The country rock is schist and
the granite intruded in it is an arm of the main granite mass that
constitutes the axis of the Cordillera Vilcapampa. The structure and to
some degree the extent of the sandstone on the left are represented in
Figs. 141 and 142.

The Silurian beds are composed of shale, sandstone, shaly sandstone,
limestone, and slate with some slaty schist, among which the shales are
predominent and the limestones least important. Near their contact with the
granite the slate series is composed of alternating beds of sandstone and
shale arranged in beds from one to three feet thick. At Santa Ana they
become more fissile and slaty in character and in several places are quarried
and used for roofing. At Rosalina they consist of almost uniform beds of
shale so soft and so minutely and thoroughly jointed as to weather easily.
Under prolonged erosion they have, therefore, given rise to a well-rounded
and soft-featured landscape. Farther down the Urubamba Valley they again
take on the character of alternating beds of sandstone and shale from a few
feet to fifteen and more feet thick. In places the metamorphism of the series
has been carried further—the shales have become slates and the sandstones
have been altered to extremely resistant quartzites. The result is again
clearly shown in the topography of the valley wall which becomes bold,
inclosing the river in narrow “pongos” or canyons filled with huge bowlders
and dangerous rapids. The hills become mountains, ledges appear, and even

the heavy forest cover fails to smooth out the natural ruggedness of the
landscape.
It is only upon their eastern border that the Silurian series includes
calcareous beds, and all of these lie within a few thousand yards of the
contact with the Carboniferous limestones and shales. At first they are thin
paper-like layers; nearer the top they are a few inches wide and finally
attain a thickness of ten or twelve feet. The available limestone outcrops
were rigorously examined for fossils but none were found, although they
are lavishly distributed throughout the younger Carboniferous beds just
above them. It is also remarkable that though the Silurian age of these beds
is reasonably inferred they are not separated from the Carboniferous by an
unconformity, at least we could find none in this locality. The later beds
disconformably overlie the earlier beds, although the sharp differences in
lithology and fossils make it easy to locate the line of separation. The
limestone beds of the Silurian series are extremely compact and
unfossiliferous. At least in this region those of Carboniferous age are friable
and the fossils varied and abundant. The Silurian beds are everywhere
strongly inclined and throughout the eastern half or third of their outcrop in
the Urubamba Valley they are nearly vertical.
In view of the enormous thickness of the repeated layers of shale and
sandstone this series is of great interest. Added importance attaches to their
occurrence in a long belt from the eastern edge of the Bolivian highlands
northward through Peru and possibly farther. From the fact that their
disturbance has been on broad lines over wide areas with extreme
metamorphism, they are to be separated from the older mica-schists and the
crumpled chlorite schists of Puquiura and Pasaje. Further reasons for this
distinction lie in their lithologic difference and, to a more important degree,
in the strong unconformity between the Carboniferous and the schists in
contrast to the disconformable relations shown between the Carboniferous
and Silurian fifty miles away at Pongo de Mainique. The mashing and
crumpling that the schists have experienced at Puquiura is so intense, that
were they a part of the Silurian series the latter should exhibit at least a
slight unconformity in relation to the Carboniferous limestones deposited
upon them.
If our interpretation of the relation of the schists to the slates and shales
be correct, we should have a mountain-making period introduced in pre-
Silurian time, affecting the accumulated sediments and bringing about their

metamorphism and crumpling on a large scale. From the mountains and
uplands thus created on the schists, sediments were washed into adjacent
waters and accumulated as even-bedded and extensive sheets of sands and
muds (the present slates, shales, quartzites, etc.). Nowhere do the sediments
of the slate series show a conglomeratic phase; they are remarkably well-
sorted and consist of material disposed with great regularity. Though they
are coarsest at the bottom the lower beds do not show cross-bedding, ripple
marking, or other signs of shallow-water conditions. Toward the upper part
of the series these features, especially the ripple-marking, make their
appearance. During the deposition of the last third of the series, and again
just before the deposition of the limestone, the beds took on a
predominantly arenaceous character associated with ripple marks and cross-
bedding characteristic of shallow-water deposits.
In the persistence of arenaceous sediments throughout the series and the
distribution of the ripple marks through the upper third of the beds, we have
a clear indication that the degree of shallowness was sufficient to bring the
bottom on which the sediments accumulated into the zone of current action
and possibly wave action. It is also worth considering whether the currents
involved were not of similar origin to those now a part of the great counter-
clockwise movements in the southern seas. If so, their action would be
peculiarly effective in the wide distribution of the sediment derived from a
land mass on the eastern edge of a continental coast, since they would
spread out the material to a greater and greater degree as they flowed into
more southerly latitudes. Among geologic agents a broad ocean current of
relatively uniform flow would produce the most uniform effects throughout
a geologic period, in which many thousand feet of clastic sediments were
being accumulated. A powerful ocean current would also work on flats (in
contrast to the gradient required by near-shore processes), and at the same
time be of such deep and steady flow as to result in neither ripple marks nor
cross-bedding.
The increasing volume of shallow-water sediments of uniform character
near the end of the Silurian, indicates great crustal stability at a level which
brought about neither a marked gain nor loss of material to the region. At
any rate we have here no Devonian sediments, a characteristic shared by
almost all the great sedimentary formations of Peru. At the beginning of the
Carboniferous the water deepened, and great heavy-bedded limestones
appear with only thin shale partings through a vertical distance of several

hundreds of feet. The enormous volume of Silurian sediments indicates the
deep and prolonged erosion of the land masses then existing, a conclusion
further supported (1) by the extensive development of the Silurian
throughout Bolivia as well as Peru, (2) by the entire absence of coarse
material whether at the top or bottom of the section, and (3) by the very
limited extent of older rock now exposed even after repeated and irregular
uplift and deep dissection. Indeed, from the latter very striking fact, it may
be reasonably argued that in a general way the relief of the country was
reduced to sea level at the close of the Silurian. Over the perfected grades of
that time there would then be afforded an opportunity for the effective
transportation of waste to the extreme limits of the land.
Further evidence of the great reduction of surface during the Silurian and
Devonian is supplied by the extensive development of the Carboniferous
strata. Their outcrops are now scattered across the higher portions of the
Andean Cordillera and are prevailingly calcareous in their upper portions.
Upon the eastern border of the Silurian they indicate marine conditions
from the opening of the period, but at Pasaje in the Apurimac Valley they
are marked by heavy beds of basal conglomerate and sandstone, and an
abundance of ripple marking and other features associated with shallow-
water and possibly near-shore conditions.
CARBONIFEROUS
Carboniferous strata are distributed along the seventy-third meridian and
rival in extent the volcanic material that forms the western border of the
Andes. They range in character from basal conglomerates, sandstones, and
shales of limited development, to enormous beds of extremely resistant blue
limestone, in general well supplied with fossils. On the eastern border of the
Andes they are abruptly terminated by a great fault, the continuation
northward of the marginal fault recognized in eastern Bolivia by
Minchin[51] and farther north by the writer.[52] Coarse red sandstones with
conglomeratic phase abut sharply and with moderate inclination against
almost vertical sandstones and limestones of Carboniferous age. The break
between the vertical limestones and the gently inclined sandstones is
marked by a prominent scarp nearly four thousand feet high (Fig. 159), and
the limestone itself forms a high ridge through which the Urubamba has cut
a narrow gateway, the celebrated Pongo de Mainique.

Fig. 159—Topographic and structural section at the northeastern
border of the Peruvian Andes. The slates are probably Silurian, the
fossiliferous limestones are known Carboniferous, and the sandstones
are Tertiary grading up to Pleistocene.

At Pasaje, on the western side of the Apurimac, the Carboniferous again
appears resting upon the old schists described on p. 236. It is steeply
upturned, in places vertical, is highly conglomeratic, and in a belt a half-
mile wide it forms true badlands topography. It is succeeded by evenly
bedded sandstones of fine and coarse composition in alternate beds, then
follow shales and sandstones and finally the enormous beds of limestone
that characterize the series. The structure is on the whole relatively simple
in this region, the character and attitude of the beds indicating their
accumulation in a nearly horizontal position. Since the basal conglomerate
contains only pebbles and stones derived from the subjacent schists and
does not contain granites like those in the Cordillera Vilcapampa batholith
on the east it is concluded that the batholithic invasion was accompanied by
the compression and tilting of the Carboniferous beds and that the batholith
itself is post-Carboniferous. From the ridge summits above Huascatay and
in the deep valleys thereabouts the Carboniferous strata may be seen to
extend far toward the west, and also to have great extent north and south.
Because of their dissected, bare, and, therefore, well-exposed condition they
present exceptional opportunities for the study of Carboniferous geology in
central Peru.
Carboniferous strata again appear at Puquiura,
Vilcapampa, and Pampaconas. They are sharply
upturned against the Vilcapampa batholith and
associated volcanic material, chiefly basalt, porphyry,
and various tuffs and related breccias. The
Fig. 160—The
deformative effects of Carboniferous beds are here more arenaceous,
the granite intrusion of consisting chiefly of alternating beds of sandstone and
the Cordillera shale. The lowermost beds, as at Pongo de Mainique,
Vilcapampa are here
shown as transmitted are dominantly marine, fossiliferous limestone beds
through ancient schists having a thickness estimated to be over two miles.
to the overlying

conglomerates, From Huascatay westward and southward the
sandstones, and
limestones of Carboniferous is in part displaced by secondary
Carboniferous age, in batholiths of granite, in part cut off or crowded aside
the Apurimac Valley at by igneous intrusions of later date, and in still larger
Pasaje.
part buried under great masses of Tertiary volcanic
material. Nevertheless, it remains the dominating rock
type over the whole stretch of country from Huascatay to Huancarama. In
the northwestern part of the Abancay sheet its effect on the landscape may
be observed in the knife-like ridge extending from west to east just above
Huambo. Above Chuquibambilla it again outcrops, resting upon a thick
resistant quartzite of unknown age, 162 . It is strongly developed about
Huadquirca and Antabamba and, still associated with a quartzite floor, it
finally disappears under the lavas of the great volcanic field on the western
border of the Andes. Figs. 141 and 142 show its relation to the invading
granite batholiths and 162 shows further structural features as developed
about Antabamba where the great volcanic field of the Maritime Cordillera
begins.
Both the enormous thickness of the Carboniferous
limestone series and the absence of clastic members
over great areas in the upper portion of the series
prove the widespread extent of the Carboniferous
seas and their former occurrence in large Fig. 161—Types of
interlimestone tracts from which they have since been deformation north of
eroded. At Puquiura they extend far over the schist, in Lambrama
Sotospampa. A dark
near

fact almost completely conceal it; at Pasaje they basaltic rock has
formerly covered the mica-schists extensively, their invaded both granite-
erosion in both cases being conditioned by the gneiss and slate. Sills
and dikes occur in great
pronounced uplift and marginal deformation which numbers. The
accompanied the development of the Vilcapampa topographic depression
in the profile is the
batholith. Lambrama Valley. See
The degree of deformation the Lambrama
of the Carboniferous sediments Quadrangle.
varies between simple uplift
through moderate folding and complex disturbances
Fig. 162—Sketch resulting in nearly vertical attitudes. The simplest
sections at Antabamba structures are represented at Pasaje, where the uplift
to show (a) deformed of the intruded schists, marginal to the Vilcapampa

limestones on the upper batholith, has produced an enormous monoclinal fold
edge of the geologic
map, 163 A; and (b) the exposing the entire section from basal conglomerates
structural relations of and sandstones to the thickest limestone. Above
limestone and quartzite. Chuquibambilla the limestones have been uplifted and
See also Fig. 163.
very gently folded by the invasion of granite
associated with the main batholith and several
satellitic batholiths of limited extent. A higher degree of complexity is
shown at Pampaconas (Fig. 141), where the main monoclinal fold is
traversed almost at right angles by secondary folds of great amplitude. The
limestones are there carried to the limit of the winter snows almost at the
summit of the Cordillera. The crest of each secondary anticline rises to form
a group of conspicuous peaks and tabular ridges. Higher in the section, as at
Puquiura, the sandstones are thrown into a series of huge anticlines and
synclines, apparently by the marginal compression brought about at the
time of the intrusion of the granite core of the range. At Pongo de Mainique
the whole of the visible Carboniferous is practically vertical, and is cut off
by a great fault marking the abrupt eastern border of the Cordillera.
It is noteworthy that the farther east the Carboniferous
extends the more dominantly marine it becomes, though
marine beds of great thickness constitute a large part of the
series in whatever location. From Huascatay westward the
Fig. 163—
Geologic sketch
limestones become more and more argillaceous, and finally
section to show give way altogether to an enormous thickness of shales,
the relation of sandstones, and thin conglomerates. These were observed to
the volcanic
flows of Fig. 164
extend with strong inclination westward out of the region
to the studied and into and under the volcanoes crowning the
sandstones and western border of the Cordillera. Along the line of traverse
quartzites
beneath. opportunity was not afforded for further study of this aspect
of the series, since our route led generally along the strike
rather than along the dip of the beds. It is interesting to note,
however, that these observations as to the increasing amounts of clastic
material in a westward direction were afterwards confirmed by Señor José
Bravo, the Director of the Bureau of Mines at Lima, who had found
Carboniferous land plants in shales at Pacasmayo, the only fossils of their
kind found in Peru. Formerly it had been supposed that non-marine
Carboniferous was not represented in Peru. From the varied nature of the
flora, the great thickness of the shales in which the specimens were

collected, and the fact that the dominantly marine Carboniferous elsewhere
in Peru is of great extent, it is concluded that the land upon which the plants
grew had a considerable area and probably extended far west of the present
coast line. Since its emergence it has passed through several orogenic
movements. These have resulted in the uplift of the marine portion of the
Carboniferous, while the terrestrial deposits seem to have all but
disappeared in the down-sunken blocks of the ocean floor, west of the great
fault developed along the margin of the Cordillera. The following figures
are graphic representations of this hypothesis.

Fig. 165—The upper diagram (A) represents the
hypothetical distribution of land and sea during the
Carboniferous Period, as inferred from the present
distribution and character of Carboniferous limestones
and slates. The lower diagram (B) represents the Fig. 164—Geologic
present relief. The dotted line at the left of the two sketch map and section,
diagrams connects identical points. The fragmentation Antabamba region. The
of the former continental border is believed to have left Antabamba River has
only a small portion of a former coastal chain and to cut through almost the
have been contemporaneous with the development of entire series of bedded
ocean abysses near the present shore. strata.

The wide distribution of the Carboniferous sediments and especially the
limestones, together with the uniformity of the fossil faunas, makes it
certain that the sea extended entirely across the region now occupied by the
Andes. However, from the relation of the Carboniferous to the basal schists,
and the most conservative extension of the known Carboniferous, it may be
inferred that the Carboniferous sea did not completely cover the entire area
but was broken here and there by island masses in the form of an elongated
archipelago. The presence of land plants in the Carboniferous of Pisco
warrants the conclusion that a second island mass, possibly an island chain
parallel to the first, extended along and west of the present shore.
CRETACEOUS

The Cretaceous formations are of very limited extent in the belt of
country under consideration, in spite of their generally wide distribution in
Peru. They are exposed distinctly only on the western border of the
Cordillera and in special relations. In the gorge of Cotahuasi, over seven
thousand feet deep, about two thousand feet of Cretaceous limestones are
exposed. The series includes only a very resistant blue limestone and
terminates abruptly along a well-marked and highly irregular erosion
surface covered by almost a mile of volcanic material, chiefly lava flows.
The character of the bottom of the section is likewise unknown, since it lies
apparently far below the present level of erosion.
The Cretaceous limestones of the Cotahuasi
Canyon are everywhere greatly and irregularly
disturbed. Typical conditions are represented in the
maps and sections, Figs. 166 and 167. They are
penetrated and tilted by igneous masses, apparently
the feeders of the great lava sheets that form the
western summit of the Cordillera. From the restricted
development of the limestones along a western border
Fig. 166—Geologic
zone it might be inferred that they represent a very sketch map and cross-
limited marine invasion. It is certainly clear that great section in the Cotahuasi
deformative movements were in progress from at Canyon at Cotahuasi.
least late Palæozoic time since all the Palæozoic With a slight gap this
figure continues Fig.
deposits are broken abruptly down in this direction, 167 to the left. The
and, except for such isolated occurrences as the land section represents a
spur of the main
Carboniferous at Pacasmayo, are not found anywhere plateau about 1,500 feet
in the coastal region today. The Cretaceous is not only high in the center of the
limited within a relatively narrow shore zone, but map.
also, like the Palæozoic, it is broken down toward the
west, not reappearing from beneath the Tertiary cover of the desert region
or upon the granite-gneisses that form the foundation for all the known
sedimentary strata of the immediate coast.
From these considerations I think we have a strong suggestion of the
geologic date assignable to the development of the great fault that is the
most strongly marked structural and physiographic feature of the west coast
of South America. Since the development of this fault is so intimately
related to the origin of the Pacific Ocean basin its study is of special
importance. The points of chief interest may be summarized as follows:

(1) The character of the land Carboniferous implies
a much greater extent of the land than is now visible.
(2) The progressive coarsening of the
Carboniferous deposits westward and their land
derivation, together with the great thickness of the
series, point to an elevated land mass in process of
erosion west of the series as a whole, that is west of
Fig. 167—Geologic
sketch map and cross- the present coast.
section in the Cotahuasi (3) The restricted development of the Cretaceous
Canyon at Taurisma,
above Cotahuasi. The
seas upon the western border of the Carboniferous,
relations of limestone and the still more restricted development of the
and lava flows in the Tertiary deposits between the mountains and the
center of the map and
on a spur top near the present coast, point to increasing definition of the
canyon floor. submarine scarp through the Mesozoic and the
Thousands of feet of Tertiary.
lava extend upward
from the flows that cap (4) The Tertiary deposits are all clearly derived
the limestone. from the present mountains and have been washed
seaward down slopes with geographic relations
approximately like those of the present.
(5) From the great width, deep dissection, and subsequent burial of the
Tertiary terraces of the coast, it is clear that the greater part of the
adjustment of the crust to which the bordering ocean basin is due was
accomplished at least by mid-Tertiary time.

Fig. 168—Composite structure section representing the succession of
rocks in the Urubamba Valley from Urubamba to Torontoy.

Aside from the fossiliferous limestones of known Cretaceous age there
have been referred to the Cretaceous certain red sandstones and shales
marked, especially in the central portions of the Cordillera, by the presence
of large amounts of salt and gypsum. These beds were at first considered
Permian, but Steinmann has since found at Potosí related and similar
formations with Cretaceous fossils. In this connection it is also necessary to
add that the great red sandstone series forming the eastern border of the
Andes in Bolivia is of uncertain age and has likewise been referred to the
Cretaceous, though the matter of its age has not yet been definitely
determined. In 1913 I found it appearing in northwestern Argentina in the
Calchaquí Valley in a relation to the main Andean mass, similar to that
displayed farther north. It contains fossils and its age was, therefore, readily
determinable there.[53]
In the Peruvian field the red beds of questionable age were not examined
in sufficient detail to make possible a definite age determination. They
occur in a great and only moderately disturbed series in the Anta basin north
of Cuzco, but are there not fossiliferous. The northeastern side of the hill
back of Puqura (of the Anta basin: to be distinguished from Puquiura in the
Vilcabamba Valley) is composed largely of rocks of this class. In a few
places their calcareous members have been weathered out in such a manner
as to show karst topography. Where they occur on the well-drained brow of
a bluff the caves are used in place of houses by Indian farmers. The large
and strikingly beautiful Lake Huaipo, ten miles north of Anta, and several
smaller, neighboring lakes, appear to have originated in solution
depressions formed in these beds.

Fig. 169—The line of unconformity between the igneous basement
rocks (agglomerates at this point) and the quartzites and sandstones of
the Urubamba Valley, between the town of Urubamba and
Ollantaytambo.
Fig. 170—The inclined lower and horizontal upper sandstone on the
southeastern wall of the Majes Valley at Hacienda Cantas. The section
is a half-mile high.

The structural relation of the red sandstone series to the older rocks is
well displayed about half-way between Urubamba and Ollantaytambo in the
deep Urubamba Valley. The basal rocks are slaty schist and granite
succeeded by agglomerates and basalt porphyries upon whose eroded
surfaces (Fig. 169) are gray to yellow cross-bedded sandstones. Within a
few hundred feet of the unconformity gypsum deposits begin to appear and
increase in number to such an extent that the resulting soil is in places
rendered worthless. Copper-stained bands are also common near the bottom
of the series, but these are confined to the lower beds. Higher up in the
section, for example, just above the gorge between Urubamba and
Ollantaytambo, even-bedded sandstones occur whose most prominent
characteristic is the regular succession of coarse and fine sandstone beds.
Such alternations of character in sedimentary rocks are commonly marked
by alternating shales and sandstones, but in this locality shales are
practically absent. Toward the top of the section gypsum deposits again

appear first as beds and later, as in the case of the hill-slope on the southern
shore of Lake Huaipo, as veins and irregular masses of gypsum. The top of
the deformed Cretaceous (?) is eroded and again covered unconformably by
practically flat-lying Tertiary deposits.
TERTIARY
The Tertiary deposits of the region under discussion are limited to three
regions: (1) the extreme eastern border of the main Cordillera, (2)
intermontane basins, the largest and most important of which are (a) the
Cuzco basin and (b) the Titicaca-Poopó basin on the Peruvian-Bolivian
frontier, and (3) in the west-coast desert and in places upon the huge
terraces that form a striking feature of the topography of the coast of Peru.
It has already been pointed out that the eastern border of the Cordillera is
marked by a fault of great but undetermined throw, whose topographic
importance may be estimated from the fact that even after prolonged
erosion it stands nearly four thousand feet high. Cross-bedded and ripple-
marked features and small lenses of conglomerate are common. The beds
now dip at an angle approximately 20° to 50° northward at the base of the
scarp, but have decreasing dip as they extend farther north and east. It is
noteworthy that the deposits become distinctly conglomeratic as flatter dips
are attained, and that there seems to have been a steady accumulation of
detrital material from the mountains for a long period, since the deposits
pass in unbroken succession from the highly indurated and massive beds of
the mountain base to loose conglomerates that now weather down much
like an ordinary gravel bank. In a few places just below the mouth of the
Ticumpinea, logs about six inches in diameter were observed embeded in
the deposits, but these belong distinctly to the upper horizons.
The border deposits, though they vary in dip from nearly flat to 50°, are
everywhere somewhat inclined and now lie up to several hundred feet
above the level of the Urubamba River. Their upper surface is moderately
dissected, the degree of dissection being most pronounced where the dips
are steepest and the height greatest. In fact, the attitude of the deposits and
their progressive change in character point toward, if they do not actually
prove, the steady and progressive character of the beds first deposited and
their erosion and redeposition in beds now higher in the series.