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Title: The Geologic Story of Arches National Park

Author: Stanley William Lohman

Illustrator: John R. Stacy

Release date: February 3, 2016 [eBook #51116]
Most recently updated: October 22, 2024

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK THE GEOLOGIC
STORY OF ARCHES NATIONAL PARK ***

BALANCED ROCK, guarding The Windows section of Arches National Park. Rock is
Slick Rock Member of Entrada Sandstone resting upon crinkly bedded Dewey Bridge
Member of the Entrada. White rock in foreground is Navajo Sandstone. La Sal
Mountains on right skyline. (Frontispiece)

The Geologic Story of
Arches
NATIONAL PARK
By S. W. Lohman
Graphics by
John R. Stacy

GEOLOGICAL SURVEY BULLETIN 1393

UNITED STATES DEPARTMENT OF THE INTERIOR
ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY
V. E. McKelvey, Director

U.S. GOVERNMENT PRINTING OFFICE: 1975

Library of Congress Cataloging in Publication Data
Lohman, Stanley William, 1907-
The geologic story of Arches National Park.
(Geological Survey Bulletin 1393)
Bibliography: p.
Includes index.
Supt. of Docs. no.: I 19.3:1393
1. Geology—Utah—Arches National Park—Guide-books.
2. Arches National Park, Utah—Guide-books.
I. Title. II. Series: United States Geological Survey
Bulletin 1393.
QE75.B9 No. 1393 [QE170.A7] 557.3′08s [557.92′58]
74-23324

For sale by the Superintendent of Documents, U. S. Government Printing
Office
Washington, D. C. 20402
Stock Number 024-001-02598-1

VII

Contents
Page
Beginning of a monument 1
Graduation to a park 5
Early history 9
Prehistoric people 9
Late arrivals 12
Geographic setting 18
Deposition of the rock materials 20
Bending and breaking of the rocks 24
Uplift and erosion of the Plateau 33
Origin and development of the arches 37
Examples of arches 46
How to see the park 50
A trip through the park 52
Colorado River canyon 52
Headquarters area 57
Courthouse Towers area 63
The Windows section 68
Delicate Arch area 74
Fiery Furnace 79
Salt Valley and Klondike Bluffs 82
Devils Garden 83
Summary of geologic history 98
Additional reading 104
Acknowledgments 105
Selected references 105
Index 109

VIII

Figures
Page
Frontispiece. Balanced Rock.
1. Arches National Park 6
2. Rock art in Arches National Park 11
3. Wolfe’s Bar-DX Ranch 14
4. Rock column of Arches National Park 21
5. Common types of rock folds 25
6. Common types of rock faults 26
7. Paradox basin 27
8. Geologic section across northwest end of Arches National Park 28
9. Index map of northwestern part of Arches National Park 28
10. Gravity anomalies over Salt Valley 31
11. Tilted block of rocks in Cache Valley graben 34
12. Jointed northeast flank of Salt Valley anticline 36
13. Index map 38
14. Tunnel Arch 43
15. “Baby Arch” 44
16. Broken Arch 45
17. Double Arch 47
18. Pothole Arch 48
19. Glen Canyon Group 53
20. Navajo Sandstone cliffs 54
21. Mouth of Salt Wash 55
22. Southeast end of faulted Cache Valley anticline 56
23. Faulted Seven Mile-Moab Valley anticline 58
24. Three Penguins 59
25. Moab Valley 60
26. Faulted wall of Entrada Sandstone 61
27. Park Avenue 62
28. Balanced rocks on south wall of Park Avenue 64

29. Courthouse Towers 65
30. The Three Gossips 66
31. Sheep Rock 66
32. Petrified sand dunes 67
33. “Hoodoos and goblins” 68
34. Eye of The Whale 69
35. Intricate crossbeds in Navajo Sandstone 70
36. Cove Arch and Cove of Caves 71
37. North Window 72
38. Looking southwestward through North Window 73
39. South Window 74
40. Turret Arch 75
41. Parade of Elephants 76
42. Suspension foot bridge across Salt Wash 78
43. Delicate Arch 78
44. Fiery Furnace 80
45. Trail to Sand Dune Arch 81
46. Sand Dune Arch 82
47. Tower Arch 84
48. Skyline Arch 85
49. Campground in Devils Garden 86
50. View north from campground 87
51. Southeastern part of Devils Garden trail 88
52. Pine Tree Arch 89
53. Landscape Arch 91
54. Navajo Arch 92
55. Partition Arch 93
56. Double O Arch 93
57. Dark Angel 94
58. “Indian-Head Arch” 95
59. Geologic time spiral 96

1

Beginning of a Monument

According to former Superintendent Bates Wilson (1956), Prof. Lawrence
M. Gould, of the University of Michigan, was the first to recognize the
geologic and scenic values of the Arches area in eastern Utah and to urge its
[1]
creation as a national monument. Mrs. Faun McConkie Tanner told me
that Professor Gould, who had done a thesis problem in the nearby La Sal
Mountains, was first taken through the area by Marv Turnbow, third owner
of Wolfe cabin. (See p. 12.) When Professor Gould went into ecstasy over
the beautiful scenery, Turnbow replied, “I didn’t know there was anything
unusual about it.”

Dr. J. W. Williams, generally regarded as father of the monument, and L. L.
(Bish) Taylor, of the Moab Times-Independent, were the local leaders in
following up on Gould’s suggestion and, with the help of the Moab Lions

Club, their efforts finally succeeded on April 12, 1929, when President
Herbert Hoover proclaimed Arches National Monument, then 2
[2]
comprising only 7 square miles. It was enlarged to about 53 square
miles by President Franklin D. Roosevelt’s Proclamation of November 25,
1938, and remained at nearly that size, with some boundary adjustments on
July 22, 1960, until it was enlarged to about 130 square miles by President
Lyndon B. Johnson’s Proclamation of January 20, 1969.

According to Breed (1947), Harry Goulding, of Monument Valley, in a
specially equipped car, traversed the rugged sand and rocks of the Arches
region in the fall of 1936 and, thus, became the first person to drive a car
into The Windows section of Arches National Monument. Soon after, a
bulldozer followed Harry’s tracks and made a passable trail.

When my family and I visited the monument in 1946, the entrance was about
12 miles northwest of Moab on U.S. Highway 163 (then U.S. 160), where
Goulding’s old tire tracks led eastward past a small sign reading “Arches
National Monument 8 miles.” This primitive road crossed the sandy,
normally dry Courthouse Wash and ended in what is now called The
Windows section. At that time there was no water or ranger station, nor were
there any picnic tables or other improvements within the monument proper,
and the custodian was housed in an old barracks of the Civilian Conservation
Corps near what is now the entrance, 5 miles northwest of Moab.

Former Custodian Russell L. Mahan reported (oral commun., May 1973)
that soon after our initial visit in 1946 a 500-gallon tank was installed near
Double Arch in The Windows section and connected to a drinking fountain
and that two picnic tables and a pit toilet were added. At that time the only
access to Salt Valley and what is now called Devils Garden was a primitive
dirt road which, according to Breed (1947, p. 175), left old U.S. Highway
160 (now U.S. 163) 24 miles northwest of Moab, went 22 miles east, 3
then followed Salt Valley Wash down to Wolfe cabin (fig. 1).

According to Abbey (1971), who served as a seasonal ranger beginning
about 1958, a sign had by then been erected at the crossing of Courthouse
Wash which read:

WARNING: QUICKSAND
DO NOT CROSS WASH
WHEN WATER IS RUNNING

The ranger station, his home for 6 months of the year, was what Abbey
described as “a little tin housetrailer.” Nearby was an information display
under a “lean-to shelter.” He had propane fuel for heat, cooking, and
refrigeration, and a small gasoline-engine-driven generator for lights at
night. His water came from the 500-gallon tank, which was filled at intervals
from a tank truck. At that time there were three small dry campgrounds, each
with tables, fireplaces, garbage cans, and pit toilets. By that time an
extension of the dirt road led northward to Devils Garden, and some trails
had been built and marked.

Bates Wilson became Custodian of the monument in 1949 and later became
Superintendent not only of Arches but also of the nearby new Canyonlands
National Park (Lohman, 1974) and the more distant Natural Bridges
National Monument. In the fall of 1969, Bates told me of some of his early
experiences in the undeveloped monument, including the evening when 22
cars were marooned on the wrong (northeast) side of Courthouse Wash after
a flash flood. Bates and his “lone” ranger brought ropes, coffee, and what
food they could obtain in town after closing time, threw a line across the
swollen stream, had a tourist pull a rope across, then took turns wading the
stream with one hand on the rope and the other balancing supplies on his
shoulder. After a fire had been built and hot coffee and food passed around,
the spirits of the stranded group rose considerably, except for one irate
woman from the East, who refused to budge from her car. Bates and his
helper finally got the last car out about 1 a.m., after the flood had subsided,
and Mrs. Wilson then supplied lodging and more food and coffee for those
who needed it.

During and for sometime after World War II and the Korean War, lack 4
of maintenance funds and personnel had prevented improvement of the
facilities in many of our national parks and monuments, particularly in
undeveloped ones like Arches. The day was saved through the wisdom and
foresight of former Park Service Director Conrad L. Wirth, who saw the
need and desirability of putting the whole “want” list into one attractive,
marketable package. In the words of Everhart (1972, p. 36):

Selection of a name is of course recognized as the most important decision
in any large-scale enterprise, and here Wirth struck pure gold. In 1966 the
Park Service would be celebrating its fiftieth anniversary. What a God-
given target to shoot for! Why not produce a ten-year program, which
would begin in 1956, aimed to bring every park up to standard by 1966—
and call it Mission 66?

The ensuing well-documented and cost-estimated plan for Mission 66 was
enthusiastically backed by President Dwight D. Eisenhower and approved
and well supported by Congress to the tune of more than $1 billion during
the 10-year period. For Arches, this included a new entrance, Park
Headquarters, Visitor Center, a museum boasting a bust of founder Dr.
Williams, and modern housing for park personnel, all 5 miles northwest of
Moab. By 1958 (Pierson, 1960) a fine new paved road between Park
Headquarters and Balanced Rock (frontispiece) was completed. These badly
needed improvements were followed by the completion of the paved road all
the way to Devils Garden, the building of the modern campground, picnic
facilities, and amphitheater in the Devils Garden, and the construction of
turnouts and marked trails.

5

Graduation to a Park

Arches graduated to a full-fledged national park when President Richard M.
Nixon signed a Congressional Bill on November 16, 1971. The change in
status was accompanied by boundary changes that reduced the area to about
114 square miles. The loss of most of Dry Mesa, just east of the present
boundary (fig. 1), was offset in part by gains of new land northwest of
Devils Garden. The present (1974) boundaries, roads, trails, and named
features of the park are shown in figure 1.

The park was virtually completed at graduation time, and so far this change
in status has shown up mainly in new entrance signs, a new 1972 brochure
and map, and a very informative “Guide to an Auto Tour of Arches National
Park,” keyed to numbered signs at parking spaces. About all that remain to
be added are new wayside exhibits, some boundary fences, and spur roads
and trails.

6

ARCHES NATIONAL PARK, showing location in Utah, boundaries, streams, highways
and roads, trails, landforms, principal named features, and the city of Moab. The
reader is referred to figure 7 and to road maps issued by the State or by oil companies
for the locations of other nearby towns and features. Visitors also may obtain
pamphlets, from the entrance station or from the National Park Service office in Moab,

which contain up-to-date maps of the park and the latest available information on
roads, trails, campsites, and picnic sites. (Fig. 1)
High-resolution Map

Although Arches had officially become a park in November 1971, it 8
was not formally dedicated until May 15, 1972. The ceremony began by
having the Federal, State, and local dignitaries and other guests totaling 140
persons board the Canyon King, a 93-foot replica of a Mississippi River
sternwheeler (Lansford, 1972; Lohman, 1974, fig. 69), for its maiden voyage
down the Colorado River. After about half an hour, the heavily laden boat
became stuck on a sandbar, and after a 90-minute wait the passengers were
rescued by jet boats. This delayed a luncheon at the Visitor Center put on by
the Moab Lions Club. Following the luncheon, Park Superintendent Bates
Wilson made a brief welcoming address, then introduced J. Leonard Volz,
Director of the Midwest Region of the National Park Service, who served as
master of ceremonies. Speakers included Utah Governor Calvin L. Rampton,
Senator Frank E. Moss, a representative of Senator Wallace F. Bennett,
Representatives Sherman P. Lloyd of Utah and Wayne Aspinall of Colorado,
and Mitchell Melich, Solicitor General of the Department of Interior,
representing Secretary Rogers C. B. Morton. After the speeches, a
commemorative plaque, donated by the Canyonlands Natural History
Association, was unveiled by Senator Moss and Mr. Melich.

Most of the color photographs were taken by me on 4- × 5-inch film in a
tripod-mounted press camera, using lenses of several focal lengths, but a few
were taken on 35-mm film, using lenses of various focal lengths. I am
grateful to several friends for the color photographs credited to them in the
figure captions. The black and white photographs were kindly loaned from
the Moab and Arches files of the National Park Service. The points from
which most of the photographs were taken are shown in figure 13.

9

Early History

Prehistoric People

The Canyon lands in and south of Arches were inhabited by cliff dwellers
centuries before the first visits of the Spaniards and fur trappers. Projectile
points and other artifacts found in the nearby La Sal and Abajo Mountains
indicate occupation by aborigines during the period from about 3000-2000
B.C. to about A.D. 1 (Hunt, Alice, 1956). The Fremont people occupied the
area around A.D. 850 or 900, and the Pueblo or Anasazi people from about
A.D. 1075 to their departure in the late 12th century (Jennings, 1970). Most
of the evidence for these early occupations has been found in and south of
Canyonlands National Park (Lohman, 1974), but some traces of these and
possibly earlier cultures have been found also within Arches National Park.

Ross A. Maxwell (National Park Service, written commun., 1941)
investigated two caves in the Entrada Sandstone in the upper reaches of Salt
Wash that contain Anasazi ruins. He mentioned that perhaps a dozen or more
other caves should be checked for evidence of former occupation and, also,
that he found several ancient campsites littered with flint chips and broken
tools.

One cave Maxwell explored some 5 miles north of Wolfe Ranch and north of
the park is about 300 feet long and 100 to 150 feet deep. It contains the
remains of one or more ruins of a structure he thought may have covered
much of the floor. The remaining parts of walls now are only two to four
tiers of stones in height, although originally they may have been more than
one story high. Maxwell explored a second cave on the east side of Salt 10
Wash, about 2 miles north of Wolfe Ranch, which contains 16 storage
cists of adobe.

The faces of many older sandstone cliffs or ledges are darkened by desert
varnish—a natural pigment of iron and manganese oxides. The prehistoric
inhabitants of the Plateau learned that effective and enduring designs, called
petroglyphs, could be created simply by chiseling or pecking through the
thin dark layer to reveal the buff or tan sandstone beneath. Most petroglyphs
were created by the Anasazi, but those showing men mounted on horses
were done by Ute tribesmen after the Spaniards brought in horses in the
1500’s. The Fremont people and some earlier people painted figures on rock
faces, called pictographs, and some of these had pecked outlines.

The so-called “Moab panel” was described by Beckwith (1934, p. 177) as a
petroglyph, but, as pointed out by Schaafsma (1971, p. 72, 73), it comprises
figures having pecked outlines and painted bodies, which actually are
combinations of petroglyphs and pictographs. This beautifully preserved
group of paintings is shown in the upper photograph of figure 2. Mrs.
Schaafsma goes on to say, concerning the “Moab panel”:

The long tapered body, the antenna like headdresses, and the staring eyes
are characteristic features of Barrier Canyon style figures elsewhere * * *.
Of special interest here are the large shields held by certain figures. A visit
to this site indicated that the shields, although apparently of some
antiquity, have been superimposed over some of the Barrier Canyon
figures. Whether or not this was done by the Barrier Canyon style artists
themselves or later comers to the site is impossible to tell.

Although definite proof seems lacking, she suggested (written commun.,
[3]
Nov. 3, 1973) that the “‘Barrier Canyon style’ * * * is earlier than the
work in the same region clearly attributable to the Fremont.” Note the three

bullet holes in and near the right-hand shield. A ledge above the panel that
contained petroglyphs during her earlier visit had fallen to the base of the
cliff by the time my wife and I inspected the panel in September 1973.

11

ROCK ART IN ARCHES NATIONAL PARK. A (above), “Moab panel,” on cliff of Wingate
Sandstone above U.S. Highway 163 between Courthouse Wash and Colorado River,
believed to be the work of “Barrier Canyon” style people. B (below), Petroglyphs on
ledge of sandstone in Morrison Formation on east side of Salt Wash just north of
Wolfe Ranch, believed to have been cut by Ute tribesmen. (Fig. 2)

Mrs. Schaafsma believes the petroglyphs in the lower photograph of 12
figure 2 to be the work of Ute tribesmen, not only because of the
horses, but also because of the stiff-legged appearance of the mountain
sheep. Note the bullet hole above the panel.

Late Arrivals

Later arrivals in and near Arches National Park included first Spanish
explorers, then trappers, cattlemen, cattle rustlers and horse thieves,
followed in the present century by oil drillers, uranium hunters, jeepsters,
and tourists. Butch Cassidy, the Sundance Kid, and other members of The
Wild Bunch are known to have frequented parts of what is now Canyonlands
National Park (Baker, Pearl, 1971), but it is not certain whether or not any of
them traversed what is now Arches National Park.

The first settler in what is now Arches National Park was a Civil War veteran
named John Wesley Wolfe, who was discharged from the Union Army about
3 weeks before the Battle of Bull Run because he suffered from varicose
veins. In 1888 his doctor told him he had to leave Ohio for a dryer climate or
he would not live 6 months, so he took his son Fred west and settled on a
tract of 150 acres along the west bank of Salt Wash, where his “Wolfe cabin”
still stands (figs. 1, 3). From family letters and newspaper clippings
compiled by Mrs. Maxine Newell and other members of the National Park
Service (Maxine Newell, written commun., 1971), we learn what life in the
area was like:

We have started a cattle spread on a desert homestead. We call it the Bar-
DX Ranch. Fred and I live in a little log house on the bank of a creek that
is sometimes dry, sometimes flooded from bank to bank with roaring
muddy water. We are surrounded with rocks—gigantic red rock
formations, massive arches and weird figures, the like of which youve
[sic] never seen. The desert is a hostile, demanding country, hot in
summer, cold in winter. The Bar-DX Ranch is a day’s ride from the
nearest store, out of the range of schools.

Although John Wolfe had promised his wife and his other children that 13
he would return home the first fall that his cattle sales netted enough
money, he and Fred stayed on and on, and his wife refused to go west and
join her husband and son. Eighteen years later he sent money from his
pension check to his daughter, Mrs. Flora Stanley, his son-in-law, Ed
Stanley, and his two grandchildren, Esther and Ferol, to join him and Fred at
the ranch. Their train was met at Thompson Springs (now Thompson), Utah
(fig. 7), by John Wolfe for the 30-mile ride to the ranch by horse and wagon.
Sight of the tiny log cabin with only a dirt floor brought tears to his
daughter’s eyes, but her spirits rose considerably after John Wolfe promised
to build a new log cabin with a wooden floor. But the children were
enchanted with this strange country, with the building of the new cabin, and,
especially, with getting to go rabbit hunting with Grandpa Wolfe. The
Stanleys stayed at the ranch until Esther was 10, then moved to Moab to
await the arrival of their third child, Volna.

In 1910 John Wolfe sold the Bar-DX Ranch, and the entire family moved to
Kansas. John Wolfe later moved back to Ohio, and died at Etna, Licking

County, on October 22, 1913, at the age of 84, 25 years after his doctor had
warned him to move to a dryer climate or face an early death.

Wolfe had sold his spread to Tommy Larson, who later sold it to J. Marv
Turnbow and his partners, Lester Walker and Stib Beeson. The old log cabin
gradually came to be known as the “Turnbow cabin,” and this name
appeared on early maps of the area by the U.S. Geological Survey and on
early pamphlets by the National Park Service, partly because Marv Turnbow
served as a camphand in 1927 assisting in the first detailed geologic
mapping of the area (Dane, 1935, p. 4). In 1947 the ranch was sold to
Emmett Elizondo, who later sold it to the Government for inclusion in what
was then the monument.

From information supplied by Wolfe’s granddaughter, Mrs. Esther Stanley
Rison, and his great-granddaughter, Mrs. Hazel Wolfe Hastler, who visited
the cabin in July 1970, the original name Wolfe cabin, or Wolfe Ranch, 14
has been restored, and appears on the newer maps and pamphlets. (See
fig. 1.) What remains of Wolfe’s Bar-DX Ranch is shown in figure 3.

WOLFE’S BAR-DX RANCH, on west bank of Salt Wash at start of trail to Delicate Arch.
Left to right: Corral, wagon, “new” cabin, and root cellar. “Old” cabin, which formerly

was to right of photograph, was washed away by a flood in 1906. (Fig. 3)

Arches National Park is surrounded by active uranium and vanadium mines
and by many test wells for oil, gas, and potash; it is underlain by extensive
salt and potash deposits. Oil and gas are produced a few miles to the north
and east, and potash is being produced about 12 miles to the south (Lohman,
1974).

Uranium and vanadium have been mined on the Colorado Plateau since
1898 (Dane, 1935, p. 176) and in the Yellow Cat area (also called
Thompson’s area), just north of the park (fig. 1), since about 1911 (Stokes,
1952, p. 7). The deposits in the Yellow Cat area occur in the Salt Wash
Sandstone Member of the Morrison Formation (fig. 4). According to Pete
Beroni (U.S. Atomic Energy Commission, oral commun., August 6, 1973),
some ore is still being produced in the Yellow Cat area, and the production
of vanadium ore will increase as soon as the uranium mill at Moab is
converted to also handle vanadium ore. The Corral and so-called 15
Shinarump mines along the southwest side of Moab Canyon just north
of Sevenmile Canyon (fig. 1) are still actively producing uranium ore from
the Moss Back Member of the Chinle Formation, according to Mr. Beroni.

The occurrences of salt and potash in and near the park and the attempts to
find oil and gas nearby are discussed in a recent report (Hite and Lohman,
1973), and the deposits beneath Moab, Salt, and Cache Valleys are discussed
in later chapters.

In 1955 and 1956 the Pacific Northwest Pipeline, known also as the “Scenic
Inch,” was constructed by the Pacific Northwest Pipeline Corp. to transmit
natural gas from wells in the San Juan Basin of northwestern New Mexico
for a total of 1,487 miles to the Pacific Northwest, with additional pickups
from gas fields in northeastern Utah, northwestern Colorado, and
southwestern Wyoming (Walters, 1956). This 26-inch pipeline follows the
general route of U.S. Highway 163 from Cortez, Colo., past Moab to
Sevenmile Canyon 10 miles northwest of Moab, where it turns abruptly to
the northeast and crosses about the middle of Arches National Park. It
crosses the park road and the flat area between the Fiery Furnace and the
southeast end of Devils Garden, but the scars are so well healed that most

visitors are unaware of its existence unless they happen to look
southwestward across Salt Valley, where the filled excavation is still visible.
The filled trench also appears in the lower middle of figure 23.

Unlike Canyonlands National Park a few miles to the south, Arches was not
on the route of the famous early-day river expeditions of John Wesley
Powell or of most of those that followed; however, the southeastern
boundary of the park is the Colorado River, formerly the Grand, which was
traversed by the first leg of the ill-fated Brown-Stanton expedition
(Dellenbaugh, 1902, p. 343-369; Lohman, 1974).

The canyon of the Colorado River along the southeastern park boundary is
deep and beautiful and is a favorite stretch of quiet water for boaters and
floaters. Partly paved State Highway 128 on the east bank is a part of a 16
most scenic drive from Moab to Cisco—a small railroad town about 32
miles northeast of the eastern border of figure 1 (fig. 7). This road has been
variously called the “Moab Mail Road,” the “Cisco Cutoff,” the “Dewey
Road,” or the “Dewey Bridge Road” after an old suspension bridge (fig. 7)
across the Colorado River at the old townsite of Dewey about 12 miles south
of Cisco. During the summer this deep colorful canyon may be viewed at
night by artificial illumination. Each evening one-half hour after sundown,
an 80-passenger jet boat leaves a dock north of the highway bridge, carries
passengers several miles upstream, then floats slowly downstream followed
by a truck on the highway carrying 40,000 watts of searchlights which play
back and forth on the colorful red canyon walls, while the passengers listen
to a taped discourse. The entire trip requires about 2 hours.

The spectacular arches and red rocks of Arches and vicinity have been used
to advantage in making color movies and color TV shows. Parts of the recent
Walt Disney film “Run, Cougar, Run” were filmed beneath Delicate Arch
(fig. 43), in Professor Valley of the Colorado River just east of the park (fig.
7), and in other sections of the canyon country.

Ever since military jet aircraft broke the sound barrier, there has been a
growing number of protests from concerned citizens, organizations, and
National Park Service officials concerning the dangers sonic booms have
posed to Indian ruins and delicate erosional forms in our national parks and
monuments, such as natural bridges, arches and windows, balanced rocks,

and natural spires or towers. Many instances of damaged ruins, roads,
erosional forms, and broken windows were reported. My wife and I can
vouch for the destructive power of such booms, for in October 1969, while
we were having breakfast at Squaw Flat Campground in The Needles section
of Canyonlands National Park, a particularly severe blast from a low-flying
jet not only violently rocked our jack-supported trailer but broke the
windshield of our car.

At Arches National Park, particular fear was felt for Landscape Arch (fig.
53), thought to be the longest natural stone arch in the world, and many 17
a special round trip from headquarters involving 47 road miles and 2
trail miles was made to check on the condition of this arch after especially
loud sonic booms were heard. Finally, in April 1972, following a rash of
newspaper and magazine articles that spread across the nation, the Secretary
of the Air Force put a virtual stop to this danger by ruling that, except in an
emergency (Moab Times-Independent, April 12, 1972):

Supersonic flights must not only avoid passing over national parks, they
also may not fly near them, according to the new regulation. For each
1,000 feet of altitude, the pilot must allow one-half mile between the flight
path and the park boundary. The regulation also prohibits supersonic
flights below 30,000 feet (over land) so the high speed planes must allow
15 miles between the nearest park boundary and the flight path.

Let us hope that with the aid of this long-needed regulation and cooperation
from visitors, the arches will remain intact for many more generations to see.

18

Geographic Setting

Geologists have divided the United States into many provinces, each of
which has distinctive geologic and topographic characteristics that set it
apart from the others. One of the most intriguing and scenic of these is the
Colorado Plateaus province, referred to in this report simply as the Colorado
Plateau, or the Plateau (Hunt, C. B., 1956, fig. 1). This province, which
covers some 150,000 square miles and is not all plateaus, as we shall see,
extends from Rifle, Colo., at the northeast to a little beyond Flagstaff, Ariz.,
at the southwest, and from Cedar City, Utah, at the west nearly to
Albuquerque, N. Mex., at the southeast. Arches National Park occupies part
of the Canyon Lands Section, one of the six subdivisions of the Plateau. As
the names imply, the Canyon Lands Section of the Plateau comprises a high
plateau generally ranging in altitude from 5,000 to 7,000 feet, which has
been intricately dissected by literally thousands of canyons.

Arches National Park is drained entirely by the Colorado River, whose deep
canyon borders the park on the southeast (fig. 1). Most of the park is drained
by Salt Wash, which enters the Colorado River just southeast of The
Windows section, but the southwestern part is drained by Courthouse Wash

and Moab Canyon, whose flows join the Colorado just west of the bridge on
which U.S. Highway 163 crosses the river.

When viewed at a distance of 1 foot, the shaded relief map (fig. 1) shows the
general shape of the land surface in and near Arches National Park to the
same horizontal scale as it would appear to a person in a spacecraft flying at
a height of 250,000 feet, or about 47.5 miles. This map was prepared 19
[4]
from part of the reverse side of a plastic-relief map at a scale of
1:250,000 by the U.S. Army Map Service of the Moab quadrangle, using a
simple time- and money-saving method (Stacy, 1962).

20

Deposition of The Rock Materials

The vivid and varied colors of the bare rocks and the fantastic buttes, spires,
columns, alcoves, caves, arches, and other erosional forms of Arches
National Park result from a fortuitous combination of geologic and climatic
circumstances and events unequalled in most other parts of the world.

First among these events was the piling up, layer upon layer, of thousands of
feet of sedimentary rocks under a wide variety of environments.
Sedimentary rocks of the region are composed of clay, silt, sand, and gravel
carried and deposited by moving water; silt and sand transported by wind;
and some materials precipitated from water solutions, such as limestone
(calcium carbonate), dolomite (calcium and magnesium carbonate), gypsum
(calcium sulfate with some water), anhydrite (calcium sulfate alone),
common salt (sodium chloride), potash minerals, such as potassium chloride,
and a few other less common types. Some of the beds were laid down in
shallow seas that once covered the area or in lagoons and estuaries near the
sea. Other beds were deposited by streams in inland basins or plains, a few
were deposited in lakes, and the constituents of deposits like the Navajo
Sandstone, were carried in by the wind. The character and thickness of the

exposed sedimentary rocks and the names and ages assigned to them by
geologists are shown in the rock column (fig. 4) and in the cross section (fig.
8). The history of their deposition is summarized on pages 98-102. Figure 4
was compiled mainly from generalized sections given by A. A. Baker
(1933), Dane (1935), McKnight (1940), and Wright, Shawe, and Lohman
(1962), and, in part, from Hite and Lohman (1973).

21

ROCK COLUMN OF ARCHES NATIONAL PARK. Average thickness of units 250-1,000
feet is exaggerated two times; those less than 250 feet, four times. 1 foot = 0.305
meter. (Fig. 4)

AGE (millions of yrs ago)
GEOLOGIC AGE
NAME OF ROCK UNIT
KIND OF ROCK AND HOW IT IS SCULPTURED BY EROSION
THICKNESS (feet)
NAMED FOR OCCURRENCE AT OR NEAR

100
Late Cretaceous
Mancos Shale
Lead-gray fossiliferous marine shale. Forms slopes.

?
Mancos, Colo.
Dakota Sandstone
Conglomeratic sandstone, gray shale, carbonaceous shale, and coal. Forms
ledge.
100
Dakota, Nebr.
Unconformity
Late Jurassic
Morrison Fm.
700
Morrison, Colo.
Brushy Basin Member
Variegated shale, some sandstone and conglomerate, petrified wood, chert,
and dinosaur bones. May contain some beds of Burro Canyon (Early
Cretaceous) age.
Salt Wash Member
Crossbedded white and gray conglomeratic sandstone beds and lenses,
locally carnotite bearing, and red and gray sandy mudstone. Forms
slopes.
Unconformity
160
San Rafael Group
(San Rafael Swell, Utah)
Summerville Fm.
Thin bedded red sandstone and shale. Some cherty limestone concretions.
Forms slopes.
0-40
Summerville Point, Utah
Entrada Ss.
(Entrada Point, Utah)
Moab Member
White, crossbedded fine-grained sandstone. Caps Slick Rock Member north
of Devils Garden and Fiery Furnace and on Klondike Bluffs.
0-100
Moab, Utah
Slick Rock Member
Salmon-colored to pink and white fine-grained generally crossbedded
sandstone, containing some medium- to coarse-grained sand.
Generally forms cliffs or narrow fins many of which contain arches or
windows.
0-240
Slick Rock, Colo.
Dewey Bridge Member
Red muddy sandstone and sandy mudstone, with contorted bedding.
Forms easily eroded bases to arches in Windows Section, hence
aided in their development.
0-175
Dewey Bridge, Utah
Unconformity
190

Jurassic and Triassic(?);
Glen Canyon Group
Navajo Sandstone
Massive crossbedded buff, gray, and white fine-grained sandstone, and
local beds of gray limestone. Forms cliffs along Colorado River,
floors Windows Section.
0-350
Navajo Country, Four Corners (Glen Canyon, U.)
Late Triassic(?)
Kayenta Formation
Lavender, gray, and white lenses of sandstone, red sandy shale, and
conglomerate. Contains some freshwater shells. Caps and protects
cliffs of Wingate Sandstone.
0-250
Kayenta, Ariz.
Late Triassic
Wingate Sandstone
Massive, horizontally bedded and crossbedded reddish buff fine-grained
sandstone. Forms vertical cliffs along Colorado River, Cache Valley,
Salt Wash, and Courthouse Wash.
0-350
Fort Wingate, N. Mex.
200
Chinle Formation
Irregularly bedded buff to red sandstone, red mudstone, limestone, and
conglomerate. Lenticular sandstone and conglomerate (Moss Back
Member) locally at base. Freshwater shells, petrified wood, reptile
bones. Forms slopes.
0-700
Chinle Valley, Ariz.
Moss Back Ridge, Utah Unconformity
Middle(?) and Early Triassic
Moenkopi Formation
Thin-bedded brown shale, gray and brown sandstone, arkosic grit, and
conglomerate. Crops out on southwest side of Moab Valley and in
several places in Salt and Cache Valleys. Forms slopes.
0-1,300
Moenkopi Wash, Ariz.
Unconformity
250
Permian
Cutler Formation
Chocolate brown and red sandy shale, maroon and pinkish-gray arkose and
conglomerate. Lower part probably equivalent in age to Rico
Formation in areas to south and east. Crops out in Moab Canyon
west of Moab fault. Forms slopes.
0-2,500
Cutler Creek, Colo.
Pennsylvanian
Hermosa Formation
Unnamed upper member

Gray marine fossiliferous sandy limestone, gray and greenish-gray
sandstone and sandy shale, and red sandy shale. Exposed in ledges
southwest of Moab fault in highway cut west of park entrance.
0-1,500
Hermosa Creek, Animas River Valley, Colo.
300
Paradox Member
Salt, gypsum, and anhydrite, with black and gray shale and limestone. Few
exposures in Salt and Cache Valleys. Forms slopes.
0-11,000
Paradox Valley, Colo.
Unconformity
Pennsylvanian(?)
Unnamed conglomerate
Yellow sandstone with boulders of limestone and chert containing
Mississippian fossils. Exposed at two places in Salt Valley.
?
22
Not exposed in the area but present far beneath the sedimentary cover
and exposed in several places a few miles to the northeast are examples of
the other two principal types of rocks—(1) igneous rocks, solidified from
molten rock forced into or above preexisting rocks along cracks, joints, and
faults, and (2) much older metamorphic rocks, formed from other preexisting
rock types by great heat and pressure at extreme depths. Igneous rocks of
Tertiary age (fig. 59) form the nearby La Sal Mountains. The particles
comprising the sedimentary rocks in the area were derived by weathering
and erosion of all three types of rocks in various source areas.

Arches National Park and nearby Canyonlands National Park are both in the
heart of the Canyon Lands Section of the Plateau; therefore, it is only
reasonable to wonder why the differences in their general character
seemingly outweigh their similarities. First, let us consider the similarities.
Both parks are underlain by dominantly red sedimentary rocks, both parks
feature unusual erosional forms of sandstone, and both contain beautiful
natural arches, although the arches in Canyonlands are restricted almost
entirely to the southeastern part of The Needles section and are in much
older rocks than those in Arches.

To be sure, differences in the rocks themselves play a part in the
dissimilarity of the two parks, and these differences are of two types. First,
there are lateral changes in the character of the strata, known to geologists as
facies changes, brought about by differences in the environment, in the type

of materials, and in the mode of deposition even within relatively short
distances. Thus, during parts of the Permian Period while sand, later to be
known as the Cedar Mesa and White Rim Sandstone Members of the 23
Cutler Formation, was being deposited in the southern part of
Canyonlands, red mud, silt, and sand of the Cutler were laid down farther
north in Canyonlands (Lohman, 1974, fig. 9), and similar, though somewhat
coarser, beds of the Cutler were laid down at Arches (fig. 4). Further
comparisons of the rock columns in the two parks show that while
limestones of the Rico Formation were being deposited in a shallow sea in
the southern part of Canyonlands, additional red mud, silt, and sand of the
Cutler were being laid down above sea level in areas to the northeast. The
source of the coarser materials was the ancient Uncompahgre Highland,
which stood above sea level from Late Pennsylvanian time to Late Triassic
time (figs. 7, 59). Although wider and longer, it occupied about the same
position as the present Uncompahgre Plateau between Grand Junction and
Gateway, Colo. Streams eroded the hard igneous and metamorphic rocks
from this ancient landmass and dumped the material into basins to the
northeast and southwest. The basin to the southwest, now called the Paradox
basin (after Paradox Valley, Colo.), at intervals contained shallow seas and
lagoons, which I will discuss later.

Comparison of the rock columns for the two parks also reveals other
differences. Both parks contain exposures of rocks as old as the
Pennsylvanian Paradox Member of the Hermosa Formation. However, only
in the Horseshoe Canyon Detached Unit of Canyonlands are rocks as young
as the Jurassic Entrada Sandstone, whereas all the spectacular natural arches
that make Arches famous were formed in the Entrada Sandstone, and Arches
also contains several younger formations of Jurassic and Cretaceous age (fig.
4).

A commonly asked question is “Why are most of the rocks so red,
particularly those in which the arches were formed?” This can be answered
with one word—iron, the same pigment used in rouge and in paint for barns
and boxcars. Various oxides of iron, some including water, produce not only
brick red but also pink, salmon, brown, buff, yellow, and even green or
bluish green. This does not imply that the rocks could be considered as
sources of iron ore, for the merest trace, generally only 1 to 3 percent, 24
is enough to produce even the darkest shades of red. The white or

nearly white Navajo Sandstone and the Moab Member of the Entrada
Sandstone contain little or no iron.

As pointed out by Stokes (1970, p. 3), microscopic examination of the
colored grains of quartz or other minerals shows the pigment to be merely a
thin coating on and between white or colorless particles. Sand or silt
weathered from such rocks soon loses its color by the scouring action of
wind or water, so that most of the sand dunes and sand bars are white or
nearly so.

Bending And Breaking of The Rocks

Perhaps the greatest geologic contrast between these two closely adjacent
parks lies in their different geologic structure—the kind and amount of
bending and breaking of the once nearly flat lying strata. Consolidated rocks,
particularly brittle types, are subject to two types of fracturing by Earth
forces. Joints are fractures along which no movement has taken place. Faults
are fractures along which there has been displacement of the two sides
relative to one another (fig. 6). As noted in the report on Canyonlands
National Park (Lohman, 1974), the strata there, particularly along the valley
of the Green River, are virtually flat lying or have only very gentle dips.
Along the Colorado River above the confluence with the Green, however,
the slightly dipping strata are interrupted by several gentle anticlinal and
synclinal folds (fig. 5) and by at least one fault (fig. 6). The largest of these
folds—the Cane Creek anticline, which crosses the Colorado River north of
Canyonlands—has yielded oil in the past and is now yielding potash 25
by solution mining of salt beds in the Paradox Member of the Hermosa
Formation.

COMMON TYPES OF ROCK FOLDS. Top, Anticline, or upfold; closed anticlines are
called domes. Bottom, Syncline, or downfold; closed synclines are called basins.
From Hansen (1969, p. 31, 108). (Fig. 5)

In strong contrast to Canyonlands, Arches National Park contains three
northwesterly trending major folds and is bordered on the southwest by a
fourth. The largest and most important are the collapsed Salt Valley and
Cache Valley anticlines, which separate the two most scenic groups of arches
and other erosional forms—Eagle Park, Devils Garden, Fiery Furnace, and
Delicate Arch on the northeast, and Klondike Bluffs, Herdina Park, and The
Windows section on the southwest. Farther southwest is the Courthouse
syncline, containing the attractive group of erosional forms called
Courthouse Towers (fig. 1). Finally, near the southwest edge of the 26
park, is the Seven Mile-Moab Valley anticline (also known as the
Moab-Spanish Valley anticline), whose southwest limb is cut off by the
Moab fault (figs. 7, 23). The folds just named and the sharply contrasting
geologic structures of the two parks are well shown on sheet 2 of the
geologic map of the Moab quadrangle (Williams, 1964), and the geologic
formations are shown in color on sheet 1.

COMMON TYPES OF FAULTS. Top, Normal, or gravity fault, resulting from tension in
and lengthening of the Earth’s crust. Bottom, reverse fault, resulting from
compression in and shortening of the Earth’s crust. Low-angle reverse faults
generally are called overthrusts or overthrust faults. In both types, note amount of

displacement and repetition of strata. Displacements may range from a few inches or
feet to many thousands of feet. From Hansen (1969, p. 116). (Fig. 6)

27

PARADOX BASIN, in southeastern Utah and southwestern Colorado, showing the
extent of common salt and major potash deposits in the Paradox Member of the
Hermosa Formation, and the salt anticlines. Adapted from Hite (1972, fig. 1B). (Fig. 7)

28

GEOLOGIC SECTION ACROSS NORTHWEST END OF ARCHES NATIONAL PARK,
showing strata beneath Courthouse syncline and Salt Valley anticline. For line of
section, see figure 9. Caprock consists of gypsum and shale, from which common salt
has been leached by ground water, covered by alluvium. Heavy slanted lines near
crest of anticline are faults. Adapted from Hite and Lohman (1973, fig. 13). (Fig. 8)

INDEX MAP OF NORTHWESTERN PART OF ARCHES NATIONAL PARK, showing axes
of Courthouse syncline and Salt Valley anticline, line of section A-A′ in figure 8 and
line of section B-B′ in figure 10. Open circles along line of section are sites of test
wells for oil, gas, or potash. Adapted from Hite and Lohman (1973, fig. 12). (Fig. 9)

Arches National Park and most of nearby Canyonlands National Park 29
lie within what geologists have termed the “Paradox basin,” which
contains a remarkable assemblage of sediments called the Paradox Member
of the Hermosa Formation. These deposits were laid down in shallow seas
and lagoons during Middle Pennsylvanian time, roughly 300 million years
ago (fig. 59). As indicated in figure 4, the Paradox Member contains, in
addition to shale and limestone, minerals deposited by the evaporation and
concentration of sea water—common salt, gypsum, anhydrite, and potash
salts. For this reason such deposits are collectively called evaporites. Figure

7 also shows that the northeastern part of the Paradox basin, which is 30
the deepest part, contains a series of partly alined anticlines which have
cores of salt and, hence, are called salt anticlines. As might be expected,
roughly alined synclines intervene between the anticlines, but are not shown
because of space limitations. According to Cater (1970, p. 50): “The salt
anticlines of Utah and Colorado are unique in North America both in
structure and in mode of development.” To this may be added that they also
are relatively rare in the world.

A section across the Salt Valley anticline and the Courthouse syncline in the
northwestern part of the park is shown in figure 8, and the axes of these
structures are shown in figure 9.

Normally, a series of roughly parallel northwestward-trending folds would
result from shortening of a segment of the Earth’s crust by compressive
forces from the northeast and the southwest, but such does not seem to be
the origin of these folds. The folds occur in a relatively narrow belt along the
northeastern part of the Paradox basin, the deepest part, which was broken
by a series of northwesterly trending normal faults (fig. 6) that cut the deep-
lying Precambrian and older Paleozoic rocks (fig. 8) prior to the deposition
of the salt-bearing Paradox Member of the Hermosa Formation. Movement
along these faults continued intermittently during and after deposition of the
Paradox, however, and resulted in the formation of a series of northwesterly
trending ridges and troughs. Following Paradox time, normal sediments
derived from a rising landmass to the northeast began to fill the basin. These
sediments accumulated most rapidly and to greater thicknesses in the fault-
derived troughs. Salt differs from normal sediments in two properties critical
to the development of salt anticlines: first, salt is considerably lighter (fig.
10), and, second, salt under pressure will flow slowly by plastic deformation,
much like ice in a glacier flows slowly downstream. Thus, salt in the troughs
underlying the thicker and heavier masses of sediments was squeezed into
the adjoining ridges, causing them to rise. Once started, this process 31
tended to be self-perpetuating, as the flow of salt from beneath the
thick masses of sediments in the troughs made room for the accumulation of
still greater thicknesses of normal sediments. Consequently, the troughs
receiving most of the sediments began to form downfolds, or synclines, and
the ridges receiving little or no normal sediments began to form huge salt
rolls that later were to become the cores of the salt anticlines when finally

the ridges too were buried by sediments. Thus, the cross section (fig. 8)
shows about 12,000 feet of the Paradox Member beneath the crest of the Salt
Valley anticline and only about 2,000 feet beneath the Courthouse syncline.
Near the middle of these structures farther to the southeast, all the Paradox
Member has been squeezed out from beneath the bordering synclines.

GRAVITY ANOMALIES OVER SALT VALLEY, along line B-B′ shown in figure 9, and
relative densities and shapes of rock bodies beneath. Densities are in grams per cubic
centimeter. Gravity values are in milligals, as shown. The standard acceleration of
gravity is 980.665 centimeters per second per second; 1 gal is equal to 1 centimeter
per second per second, and 1 milligal is one thousandth of a gal. Modified from Case
and Joesting (1972, fig. 2). (Fig. 10)

The general shape of the Salt Valley anticline is shown also by cross-section
B-B′ (fig. 10), taken along the northeast-southwest line B-B′ in figure 9, 32
which is based upon so-called gravity anomalies over Salt Valley. The
lighter Paradox Member, having an average density of 2.20, has a lower
gravitational attraction than the heavier rocks on each side, which have an
average density of 2.55.

By this time you are doubtless wondering why prominent upfolds of the
rocks, such as the Salt Valley anticline and associated Cache Valley anticline
and the Seven Mile-Moab Valley anticline, now underlie relatively deep
valleys bordered by prominent ridges. The formation of these valleys was
not simple and involved many steps extending over a considerable amount
of geologic time, as portrayed by Cater (1970, fig. 13; 1972, fig. 4). For a
part of the story, let us reexamine the cross section (fig. 8); the rest of the
story will be told in the section on “Uplift and Erosion.”

Figure 8 shows that the unnamed upper member of the Hermosa Formation
and the overlying Cutler and Moenkopi Formations are thickest beneath the
Courthouse syncline but wedge out against the flanks of the anticline.
Although the Chinle Formation and younger rocks appear to extend across
the fold, and may have extended across this part of the fold, in Colorado all
rocks older than the Jurassic Morrison wedge out against the flanks of the
salt anticlines (Cater, 1970, p. 35) and also in the widest part of the Salt
Valley anticline southwest of the section in figure 8. The salt anticlines were
uplifted in a series of pulses so that some formations either were not
deposited over the rising structures or were removed by erosion before
deposition of the next younger unit. By Morrison time the supply of salt
beneath the synclines seems to have become used up; hence, the anticline
stopped rising, and the Morrison and younger formations were deposited
across the structures. Thus, in figure 4, the minimum thickness of all units
older than the Morrison is given as zero. Figure 4 shows the marine Mancos
Shale to be the youngest rock unit exposed in the park, but the Mesaverde
Group of Late Cretaceous age and possibly the early Tertiary (fig. 59)
Wasatch Formation may have been deposited and later removed by erosion.

33

Uplift And Erosion of The Plateau

Next among the main events leading to the formation of landforms in the
park was the raising and additional buckling and breaking of the Plateau by
Earth forces partly during the Late Cretaceous but mainly during the early
Tertiary. After uplift and deformation, the Plateau was vigorously attacked
by various forces of erosion, and the rock materials pried loose or dissolved
were eventually carted away to the Gulf of California by the ancestral
Colorado River. Some idea of the enormous volume of rock thus removed is
apparent when one looks down some 2,000 feet to the river from any of the
high overlooks farther south, such as Dead Horse Point (Lohman, 1974, fig.
15). Not so apparent, however, is the fact that younger Mesozoic and
Tertiary rocks more than 1 mile thick once overlaid this high plateau but
have been swept away by erosion. In all, the river has carried thousands of
cubic miles of sediment to the sea and is still actively at work on this
gigantic earth-moving project. In an earlier report (Lohman, 1965, p. 42) I
estimated that the rate of removal may have been as great as about 3 cubic
miles each century. For a few years the bulk of the sediment was dumped
into Lake Mead, but now Lake Powell is getting much of it. When these and
other reservoirs ultimately become filled with sediment—for reservoirs and
lakes are but temporary things—the Gulf of California will again become the
burial ground.

According to Cater (1970, p. 65-67), who made an intensive study of the salt
anticlines, collapse of their crests seemingly occurred in two stages—the
first stage following Late Cretaceous folding; the second following uplift of
the Plateau later in the Tertiary. Solution and removal of salt by ground 34
water played the leading role in the ultimate collapse.

TILTED BLOCK OF ROCKS IN CACHE VALLEY GRABEN, viewed to the east toward
Cache Valley from point on gravelled side road to Wolfe’s cabin, about half a mile east
of paved road. Steep slope on left composed of Jurassic Morrison Formation,
hogback on top formed by Dakota Sandstone of Late Cretaceous age, and gentle
slopes to right composed of the Mancos Shale of Late Cretaceous age. (Fig. 11)

As shown by Dane (1935, pl. 1, p. 121-126), collapse of the Salt Valley and
Cache Valley anticlines was accompanied by considerable faulting and
jointing, particularly along their northeast sides; by the upward intrusion of
two large areas of the Paradox Member of the Hermosa Formation, one just
northwest of the park and one in the middle of Salt Valley south of the
campground; and by two downdropped masses of rock known to geologists
as grabens (pronounced gräbǝns)—one just northwest of the park and one
called the Cache Valley graben, which extends both east and west from Salt

Wash. The Cache Valley graben has preserved from erosion the youngest
rock formations in the park, as shown in figure 11.

The remarkable jointing of the rocks on the northeast limb of the Salt Valley
anticline is shown in figure 12. All the arches in this section of the park were
eroded through thin fins of the Slick Rock Member of the Entrada 35
Sandstone, and some, like Broken Arch, figure 16, are capped by the
Moab Member.

Differences in the composition, hardness, arrangement, and thickness of the
rock layers determine their ability to withstand the forces of fracturing and
erosion and, hence, whether they tend to form cliffs, ledges, fins, or slopes.
Most of the cliff- or ledge-forming rocks are sandstones consisting of sand
deposited by wind or water and later cemented together by silica (SiO₂),
calcium carbonate (CaCO₃), or one of the iron oxides (such as Fe₂O₃), but
some hard, resistant ledges are made of limestone (calcium carbonate). The
rock column (fig. 4) shows in general how these rock formations are
sculptured by erosion and how they protect underlying layers from more
rapid erosion. The nearly vertical cliffs along the lower reaches of Salt and
Courthouse Washes and the Colorado River canyon upstream from Moab
consist of the well-cemented Wingate Sandstone protected above by the even
harder sandstones of the Kayenta Formation. (See figs. 21, 22.) To borrow
from an earlier report of mine (Lohman, 1965, p. 17), “Vertical cliffs and
shafts of the Wingate Sandstone endure only where the top of the formation
is capped by beds of the next younger rock unit—the Kayenta Formation.
The Kayenta is much more resistant than the Wingate, so even a few feet of
the Kayenta * * * protect the rock beneath.” In some places, as shown in
figures 19 and 20, the overlying Navajo Sandstone makes up the topmost
unit of the cliff.

36

JOINTED NORTHEAST FLANK OF SALT VALLEY ANTICLINE, viewed westward from
an airplane. Light-colored wedge in middle background is Salt Valley bordered on
extreme left by Klondike Bluffs. Dark-colored fins and pinnacles on left, of Slick Rock
Member of the Entrada Sandstone, form Devils Garden. Sharp pinnacle above valley is
the Dark Angel. (See fig. 57.) White bands of sandstone extending to foreground are
composed of Moab Member of the Entrada. Note vegetation in the joints. Photograph
by National Park Service. (Fig. 12)

Last but far from least among the factors responsible for the grandeur 37
of Arches National Park and the Plateau in general is the desert
climate, which allows one to see virtually every foot of the vividly colored
naked rocks, and which has made possible the creation and preservation of
such a wide variety of fantastic sculptures. A wetter climate would have
produced a far different, smoother landscape in which most of the rocks and
land forms would have been hidden by vegetation. On the Plateau the
vegetation grows mainly on the high mesas and the narrow flood plains
bordering the rivers, but scanty vegetation also occurs on the gentle slopes or
flats.

The combination of layers of sediments of different composition, hardness
and thickness, the bending and breaking of the rocks, and the desert climate,
has produced steep slopes having many cliffs, ledges, and fins with generally

sharp to angular edges, rather than the subdued rounded forms of more
humid regions.

Origin And Development of The Arches

Among the questions commonly asked by visitors are, “How do arches
form?”, “Why are some openings called windows, others arches?”, “What is
the difference, if any, between arches or windows and natural bridges, such
as those at Natural Bridges National Monument?”, and “How many arches
are there in Arches National Park?” Before taking up the origin and
development of arches, I shall attempt to explain the differences between the
three types of natural rock openings named above and comment upon the
number of arches.

38

INDEX MAP, showing localities where most of the photographs were taken. Arrows
point to distant views. Numbers refer to figure numbers. (Fig. 13)
High-resolution Map

I believe most geologists and geographers are in general agreement 40
with Cleland (1910, p. 314) that “a ‘natural bridge’ is a natural stone
arch that spans a valley of erosion. A ‘natural arch’ is a similar structure
which, however, does not span an erosion valley.” According to this
definition, Natural Bridges National Monument includes three true bridges,
whereas all the larger rock openings in Arches National Park with which I
am familiar are properly termed “arches,” but some are called windows. If
we were to distinguish between arches and windows, we might say that
arches occur at or near the base of a rock wall, as do the doors of a house or
building, whereas windows are found well above ground level. This
distinction was not followed in naming the rock openings in the park,
however; for example, Tunnel Arch (fig. 14) is considerably higher above
the ground than North Window (figs. 37, 38) or South Window (fig. 39).

As to the number of arches in the park, I might begin by saying that there is
no universal agreement as to how large a rock opening must be to qualify as
an arch. The pamphlet formerly handed to visitors entering the park
proclaimed that “Nearly 90 arches have been discovered, and others are
probably hidden away in remote and rugged parts of the area,” but the
average visitor probably sees less than a third of this number.

David May, Assistant Chief of Interpretation and Resource Management,
Moab office of National Park Service (oral commun., Oct. 1973), believes
that if only those in the park having a minimum dimension of 10 feet in any
one direction were considered to be arches, the number would boil down to
about 56 or 57. The most complete count of arches and other openings in all
of southeastern Utah was made by Dale J. Stevens, Professor of Geography
at Brigham Young University, during the period February through April
1973. He considered those with openings of 3 feet or larger and found more
than 300 in southeastern Utah, of which 124 are in Arches National Park,
although he stated that several areas of the park were not intensively
searched because of time limitations (written commun., July and Sept.
1973). The 124 arches and openings are distributed among the several 41
named areas of the park, as follows: Courthouse Towers, 13; Herdina
Park, 11; The Windows section, 25; Delicate Arch area, 3; Fiery Furnace, 19;
Devils Garden, 25; upper Devils Garden (northwest of Devils Garden), 14;
Eagle Park, 2; and Klondike Bluffs, 12.

Professor Stevens generally used a range finder or a steel tape to measure the
width and height of the openings and the width and thickness of the spans,
but estimated a few of the dimensions. In the text descriptions of arches or
captions of figures that follow, I am including all or part of these
measurements, without further acknowledgment.

All the arches in the park were formed in the Entrada Sandstone, mainly in
the Slick Rock Member but partly in the Slick Rock and Dewey Bridge
Members, and a few in the Slick Rock Member occur not far beneath the
base of the overlying Moab Member. The sandstone of the three members is
composed mainly of quartz sand cemented together by calcium carbonate
(CaCO₃), which also forms the mineral calcite and the rock known as
limestone, but the Dewey Bridge Member also contains beds of sandy
mudstone. Limestone and calcite are soluble in acid, even in weak acid such
as carbonic acid, HHCO₃, also written H₂CO₃, formed by the solution of
carbon dioxide (CO₂) in water. Ground water, found everywhere in rock
openings at different depths beneath the land surface, contains dissolved
carbon dioxide derived from decaying organic matter in soil, from the
atmosphere, and from other sources. Even rainwater and snow contain a
little carbon dioxide absorbed from the atmosphere—enough to dissolve
small amounts of limestone or of calcite cement from sandstone. The calcite
cement in the Entrada and in many other sandstones is unevenly distributed,
however, so that all the cement is removed first from places that contain the
least amounts, and, once the cement is dissolved away, the loose sand is
carried away by gravity, wind, or water.

Both nearly flat but slightly irregular beds of sandstone and relatively thin
walls or fins of sandstone are prime targets for this differential erosion. 42
Potholes, as shown in figure 18A, may be formed in relatively flat beds
by the dissolving action of repeated accumulations of rainwater or snowmelt,
even in arid regions like the Plateau.

Relatively thin walls, or fins as they are called in parts of the Plateau
including Arches, are targets for the formation of alcoves and caves by
solution of cement and removal of sand by gravity, wind, and water, aided
by the prying action of frost in joints, bedding planes, or other openings.
Once a breakthrough of a wall or fin occurs, weakened chunks from the
ceiling tend to fall, and natural arches of various shapes and sizes are

produced. Arches form the strongest shapes for supporting overlying rock
loads, as the rock in the arch is compressed toward each abutment by the
heavy loads. Blocks of compressed rock beneath a relatively flat ceiling tend
to be dislodged also by expansion due to release of pent-up pressure, until a
strong self-supporting arch is formed. Release of pent-up pressure in rock
walls may help also in initiating the formation of alcoves or caves in cliff
faces. Man, including the ancient Greeks, Romans, Egyptians, and others,
has long made use of arches in building bridges, aqueducts, temples,
cathedrals, and other enduring edifices.

As vividly shown in figure 12, the Entrada Sandstone on the northeast flank
of the Salt Valley anticline has been broken by Earth forces into thin slabs
mostly 10 to 20 feet thick between nearly parallel joints, but, as will be noted
in the descriptions of individual arches, some rock walls are only 1 or 2 feet
thick, whereas others are 50 feet thick or more. Some weak or thin slabs
have weathered away, leaving the stronger or thicker ones as towering fins,
particularly in the Fiery Furnace and Devils Garden areas. Jointing on a less
spectacular scale also has broken the Entrada in areas south of Salt Valley,
leaving walls or fins of rock.

43

TUNNEL ARCH, reached by short trail north of main trail through Devils Garden.
Opening is 26½ feet wide and 22 feet high; span is about 14 feet thick. (Fig. 14)

Although all the arches in the park were carved from the Entrada 44
Sandstone, slight differences in their mode of origin or placement
within the Entrada allow them to be grouped into three classes: (1) vertical
arches formed in the Slick Rock Member alone or in the Slick Rock and
Moab Members, (2) vertical arches formed mainly in the Slick Rock
Member but partly in, and with the aid of, the incompetent underlying
Dewey Bridge Member, and (3) horizontal arches, or so-called pothole
arches, formed from the union of a vertical pothole and a horizontal cave.
Hereinafter, the three members will be referred to alone, without reference to
the Entrada.

“BABY ARCH,” just southwest of Sheep Rock in Courthouse Towers area. For details,
see text. (Fig. 15)

Before giving examples of arches in each of the three classes, it is
appropriate to remark that the arches and other erosion forms in the park
represent but a fleeting instant in geologic time. Many of the pinnacles or
piles of rock may be the broken remains of former arches, and many of the
arches we see may be gone tomorrow, next year, or a few hundreds of years
and, certainly, before many thousands of years. On the other hand, many
new arches will form by the processes described above as the geologic clock
ticks on.

45

BROKEN ARCH, reached by a ½-mile trail leading northward across field that
separates Fiery Furnace from Devils Garden. White thin-bedded unit at top is the Moab
Member, which rests upon the massive salmon-colored Slick Rock Member. Opening
is 59 feet wide and 43 feet high. (Fig. 16)

46

Examples of Arches

Tunnel Arch (fig. 14) is a good example of an arch eroded entirely within the
massive Slick Rock Member. Just southwest of Sheep Rock (fig. 31) is an

unnamed opening in the lower part of the Slick Rock Member which I call
“Baby Arch,” because it is one of the newest ones visible from the park road
(fig. 15). It is only 25½ feet wide and 14 feet high and penetrates a wall 14
feet thick. Note that the breakthrough probably began along the prominent
recessed bedding plane at the base of the arch. Its youthfulness is also
indicated by the sharp, angular breaks in the ceiling and by the pile of
freshly fallen rocks. Some visitors have asked park personnel why they have
not cleared away such debris! Despite its youthfulness, the ceiling has
already taken on the shape of an arch.

Broken Arch (fig. 16) was formed near the top of the Slick Rock Member
and is strengthened and protected by the more resistant overlying Moab
Member, which forms the upper half of the span. The crest is only 6 feet
thick at the thinnest point and is not broken as the name seems to imply.

Double Arch (fig. 17), “one” of the most beautiful in the park, is in The
Windows section near the east end of the road. The southeast arch, which is
160 feet wide and 105 feet high, is the second largest in the park, but the
west arch measures only 60 feet wide and 61 feet high. In common with
most arches in The Windows section, these two arches of the Slick Rock
Member rest upon bases of the weak, easily eroded Dewey Bridge Member.
More rapid erosion of the Dewey Bridge undercut the arches and hastened
their development.

47

DOUBLE ARCH, in The Windows section. (Fig. 17)

48

PROBABLE STEPS IN FORMATION OF POTHOLE ARCH. A, Original pothole probably
formed in relatively level bed of sandstone, such as this one, which is in an older rock
unit—the White Rim Sandstone Member of the Cutler Formation, a unit not present in
Arches. This pothole, which contains 4 feet of water, is in nearby Canyonlands
National Park (Lohman, 1974, fig. 17), just north of the edge of the White Rim, about
4½ miles north of the confluence of the Green and Colorado Rivers. Photograph by E.
N. Hinrichs. B, Pothole is being deepened by solution while cliff is receding toward
pothole by weathering. C, As erosion continues, pothole and cave in cliff face are
growing deeper. D, Pothole Arch formed by union of vertical pothole and horizontal
cave. E, Telephoto view of Pothole Arch from park road near stop 14. Visible span is
90 feet across and 30 feet high. (Fig. 18)

49

The cause of the wavy bedding in the Dewey Bridge Member, as 50
shown in figure 17 but as better shown in the frontispiece, is not
known for sure but generally is regarded to be the result of irregular
slumping during or just after deposition of the sediments in a body of water,
caused by the weight of overlying sediments.

The last example I shall take up is Pothole Arch (fig. 18), which differs from
all the other examples in that this arch is roughly horizontal rather than
vertical. Most park visitors, including me, were not aware of this interesting
feature until after publication of the pamphlet “The Guide to an Auto Tour of
Arches National Park,” which, as previously noted, may be purchased at the
Visitor Center. Pothole Arch caps a ridge high above the road half a mile
northwest of Garden of Eden, so only those who happened to look up at the
right place were aware of its existence.

A different mode of origin than that given in the caption for figure 18 is
depicted on a poster in the Visitor Center, which shows the pothole being
formed by a waterfall having an apparent flow rate of several cubic feet per
second. Potholes can be formed in this manner in places where sufficient
streamflow is available, either continuously or following rainstorms, but I
believe the process depicted in figure 18 is a more likely mode of origin for
Pothole Arch.

How to See the Park

As aptly stated on a poster in the Visitor Center, how to see the park depends
in part upon the question “How long can you stay?” Inasmuch as the park
entrance and Visitor Center are beside a through U.S. Highway (163), many
motorists first become aware of the park’s existence from the entrance 51
sign, and some take time for at least a quick visit, such as a round trip
to The Windows section, which can be made in an hour or so.

For those who have or take more time and are able to walk at least short
distances, a visit of 1 or 2 days is a very rewarding experience. Others,
particularly avid shutterbugs and those with camping gear, profitably spend
from several days to a week or more and hike all or most of the trails.

Regardless of how long you plan to spend, I urge at least a brief stop at the
Visitor Center, where excellent displays and a narrated slide show help
materially in conveying just what the park has to offer. At the counter you
can purchase a copy of “The Guide to an Auto Tour of Arches National
Park,” which explains the views from each of 25 numbered stops along the
park road, as well as other reports describing arches or other parks and
monuments.

The park is open the year round, but, like most high deserts, it gets rather hot
in the summer and cold enough in the winter for occasional snows and is
sometimes closed temporarily because of heavy snowfall. The weather
generally is ideal during the spring and fall. Even though summer daytime
temperatures may exceed 100°F (37.8°C) and slow down hikers, the nights
are cool enough for comfortable sleeping beneath ample covers.

Before beginning our trip through the park proper, let us consider a beautiful
part many people fail to realize actually belongs to the park—the Colorado
River canyon forming the southeastern boundary.

52

A Trip Through The Park

Colorado River Canyon

The southeastern boundary of the park for about 11 miles is the Colorado
River, from the bridge on which U.S. Highway 163 crosses the river to a
point upstream about half a mile below the mouth of Salt Wash. Illuminated
night float trips down part of this reach are run during the summer, as noted
on p. 16. Partly paved State Highway 128 follows the southeast side of the
river for about 30 miles to Dewey Bridge, then goes northward about 15
miles to Cisco, where it connects with Highway I-70.

The rocks of the Glen Canyon Group form the southernmost corner of the
park, as shown in figure 19. About 2 miles northeast of the bridge, we cross
the axis of the Courthouse syncline (fig. 9), which brings the Navajo
Sandstone down nearly to river level, as shown in figure 20. The underlying
Kayenta Formation is largely hidden by vegetation and alluvial deposits in
this view.

53

GLEN CANYON GROUP, forming southernmost point of park, as viewed across the
Colorado River from State Highway 128 half a mile above Moab bridge carrying U.S.
Highway 163. Massive sandstone forming about the lower third of cliff is the Wingate
Sandstone, darker thin-bedded sandstones and mudstones forming middle section of
cliff comprise the Kayenta Formation, upper cliff is the lower part of the Navajo
Sandstone. Note that the saltcedar (tamarisk), which lines both banks of the river, is in
full bloom. (Fig. 19)

54

NAVAJO SANDSTONE CLIFFS, bordering west bank of Colorado River in Courthouse
syncline, from State Highway 128 about 2 miles above the Moab bridge. Note rounded
domes at top of cliff. (Fig. 20)

55

MOUTH OF SALT WASH, viewed across Colorado River from point on State Highway
128, 11 miles above Moab bridge. Dark cliffs on upper right and left are of Wingate
Sandstone capped by thin protective cover of resistant sandstone beds of the Kayenta
Formation. In background Wingate is overlain by entire Kayenta Formation and lower
part of the Navajo Sandstone. Wingate is underlain to river level by weathered slope of
the Chinle Formation. Water in Salt Wash is largely backwater from the bankfull river;
actual flow in wash generally is much less but at times reaches flood proportions.
(Fig. 21)

About 11 miles above the Moab bridge is the mouth of Salt Wash (fig. 1), as
viewed from State Highway 128. (See fig. 21.) Seventeen miles above the
bridge (east of area shown in fig. 1), we get an excellent view of the
southeast end of the highly faulted Cache Valley anticline, as shown in
figure 22. The background shown in the photograph formerly was the 56
easternmost part of the former monument, but when the monument
graduated to a park on November 16, 1971, this part of Cache Valley along
with most of Dry Mesa was withdrawn from the park and put under the
supervision of the Bureau of Land Management, also a part of the
Department of the Interior.

SOUTHEAST END OF FAULTED CACHE VALLEY ANTICLINE, viewed northwestward
across Colorado River from a point on State Highway 128, 17 miles above Moab
bridge. High cliff of Wingate Sandstone on left is capped by thin protective layer of the
Kayenta Formation. About upper third of slope below base of cliff is the Chinle
Formation, below which is the Moenkopi Formation extending to high-water level.
Note bent and broken beds on right. (Fig. 22)

As noted on page 16, part of “Run, Cougar, Run” was filmed just upstream
from the irrigated field in the foreground of figure 22, in a wide part of the
valley called Professor Valley (fig. 7). This valley and the Richardson
Amphitheater on the southeast side of the river were named after a Professor
Richardson who settled in the area in the 1880’s. The long abandoned
townsite of Richardson was 1¼ miles due east from the point from which
figure 22 was taken.

57

Headquarters Area

The junction of the park road with U.S. Highway 163 is shown at the lower
left of figure 23, and the entrance station, Visitor Center, parking lot, and
several buildings are seen at the lower right. Several residences for park
personnel and other buildings are shown in figure 25. As shown in the lower
part of figure 23, the geology at the park entrance is rather complex, as the
park boundary here is partly along the Moab fault and partly along a branch
fault—both in the Seven Mile-Moab Valley anticline (fig. 7). The Moab fault
extends northwestward from Moab for more than 30 miles (McKnight, 1940,
p. 120, 121, pl. 1).

As shown in figure 23, soon after leaving the checking station the park road
begins to ascend the first of several switchbacks, and cuts first into the Slick
Rock Member, then the Dewey Bridge Member, and finally the Navajo
Sandstone the rest of the way to and beyond the top of the hill.

From points a mile or so up the hill may be seen interesting features in
[5]
several directions. The view to the southwest is shown in figure 23, to the
west are the Three Penguins (fig. 24). A good view of the Moab Valley is had
by looking southeastward (fig. 25). A well in the Navajo Sandstone at the
base of the hill supplies water to all the residences and to the Visitor Center,
where a drinking fountain and modern restrooms are available to the public.
Storage is provided by a steel tank hidden in a ravine above the buildings
shown in figure 25.

To the north the wall of Entrada Sandstone is cut by a normal fault (fig. 6),
as shown in figure 26.

58

FAULTED SEVEN MILE-MOAB VALLEY ANTICLINE. Top, View toward the southwest
from park road about 1 mile above entrance station. Bottom, Geologic interpretation of
photograph in part after McKnight (1940, pl. 1). Moab fault and branch fault (both
normal faults, fig. 6) unite just beyond ridge of Slick Rock Member. Total vertical
displacement along both faults is about 2,500 feet. H.F., unnamed upper member of
Hermosa Formation; M.F., Moenkopi Formation; D, downthrown side of faults; U,
upthrown side. Valley fill and slope wash of recent (Holocene) age obscure faults and
underlying rocks. The original sequence of the rocks may be visualized by placing the
Navajo Sandstone, the upper part of which is exposed at the lower right, on top of the
Kayenta Formation, the lower few feet of which cap and protect the cliffs of Wingate
Sandstone in the background. The Pacific Northwest (gas) Pipeline mentioned on
page 15 is buried beneath the slice of the Moenkopi Formation between the two faults,
which accounts for the disturbed appearance of the rock. (Fig. 23)

59

THREE PENGUINS, viewed westward from park road about 1 mile above entrance
station. Penguins are carved in massive Slick Rock Member seen resting upon thin-
bedded Dewey Bridge Member. (Fig. 24)

60

MOAB VALLEY, viewed southeastward from park road about 1 mile above entrance
station. Moab fault in about middle of valley, hidden beneath recent (Holocene) valley
fill and slope wash, separates unnamed upper member of Hermosa Formation just
above U.S. Highway 163 on right from Navajo Sandstone forming hills on left and
ledges in foreground. Park Service residences at base of hill. White patch bordering
Colorado River on northwest is tailings pile of Atlas Corporation’s uranium mill. Moab
and Spanish Valley are beyond river, and south end of La Sal Mountains forms distant
skyline. (Fig. 25)

61

FAULTED WALL OF ENTRADA SANDSTONE, north of park road about 1 mile above
entrance station. Fault is nearly vertical and normal (fig. 6), but fault trace slopes
steeply downward to right, separating upthrown Slick Rock and Dewey Bridge
Members on left from downthrown Slick Rock Member on right. Light-colored rock in
foreground is Navajo Sandstone. Displacement probably does not exceed 50 feet. (Fig.
26)

62

PARK AVENUE, viewed to the north along trail. (Fig. 27)

63

Courthouse Towers Area

About 2.3 miles from the entrance station is a turnoff and parking area at the
south end of the Park Avenue trail (stop 2), which is about 1 mile long and
ends at another parking area 1.7 miles farther north. An interesting hike is
best made from south to north in a downhill direction, and hikers generally
meet the cars of relatives or friends awaiting them at the northern parking
area. The trail begins in a canyon cut in the soft Dewey Bridge Member and
walled by high fins of the Slick Rock Member (fig. 27), but farther north the
canyon is floored by the bare Navajo Sandstone. The avenue was named
from the resemblance of the east wall to a row of tall buildings. Atop the
west wall, just to the left of the view in figure 27, are two balanced rocks
(fig. 28). The one on the left, which resembles somewhat the head of an
Egyptian queen, is offset to the right along a bedding plane, and this offset
may have been caused by an earthquake.

As we progress toward Courthouse Towers proper, lofty fins and monoliths
lie mostly on our left, and to the right are fine distant views of the La Sal
Mountains (stop 4). A general view of the Courthouse Towers is shown in
figure 29, and closeups of two of the named rock sculptures—the Three
Gossips and Sheep Rock—are shown in figures 30 and 31. Just beyond
Sheep Rock, which some think resembles the Sphinx, we see “Baby Arch,”
shown in figure 15.

Five miles from the entrance station, the road crosses Courthouse Wash on a
modern bridge (stop 6)—a distinct improvement over the two tracks in the
sand we used in 1946. The Courthouse syncline, named after the wash,
extends northwestward through here. (See figs. 8, 9, 20.) About a mile west
of the bridge, Professor Stevens found another pothole arch. A mile and a
half north of the bridge is stop 7, where attention is called in the booklet to
the vast area of “petrified dunes” east of the road, which are simply dunelike
exposures of the crossbedded Navajo Sandstone formed originally by the
cementation of a vast area of sand dunes. My view of these was taken about
1 mile beyond the stop (fig. 32).

64

BALANCED ROCKS ON SOUTH WALL OF PARK AVENUE, at south end of trail. (Fig.
28)

65

COURTHOUSE TOWERS, viewed to the northwest from point on park road about
three-fourths of a mile northeast of the south end of Park Avenue trail. Sandstone
towers are Slick Rock Member resting on Dewey Bridge Member, which also forms

foreground. Three Gossips at upper left, Sheep Rock just beyond. The Organ and
Tower of Babel are on right. (Fig. 29)

66

THE THREE GOSSIPS, shown at upper left of figure 29. (Fig. 30)

SHEEP ROCK, shown on center-left skyline in figure 29. (Fig. 31)

West of the road between the petrified dunes and The Windows section, the
Entrada Sandstone, particularly the Dewey Bridge Member, has been
weathered into grotesque spires and pinnacles resembling the so-called
“hoodoos and goblins” in Goblin Valley State Park, just north of Hanksville,
Utah. Typical examples of “hoodoos and goblins” are shown in figure 33
(near stop 8). It seems reasonable to assume that some of these spires are the
skeletal remains of former arch abutments. From here may be seen North
and South Windows and Turret Arch on the skyline to the northeast (figs. 37-
40).

67

PETRIFIED SAND DUNES, looking northeast from park road 2.7 miles north of
Courthouse Wash. The Navajo Sandstone was once a huge sandpile of dunes laid
down by winds during an arid interval, so it is interesting to note that the irregularly
weathered sandstone once again resembles a pile of crossbedded dunes. See also
figure 35. (Fig. 32)

68

“HOODOOS AND GOBLINS,” weathered from Dewey Bridge Member, viewed
northwest from park road about 2½ miles north of Courthouse Wash. (Fig. 33)

The Windows Section

The Windows section, one of the most beautiful parts of the park, once was
the only readily accessible part of the former monument and is still the only
collection of arches seen by many visitors who either do not have or do not
take time to travel farther north. All the arches and erosion forms are on or
near a high crest called Elephant Butte (Dane, 1935, p. 126, 127), which
separates Salt Valley from the Courthouse syncline. The ridge also marks the
south edge of several minor anticlines and synclines termed by Dane the
“Elephant Butte folds.”

69

EYE OF THE WHALE, one of several arches in Herdina Park, just south of jeep trail
about 2 miles northwest of Balanced Rock. Cut in Slick Rock Member. Front opening
is 60 feet wide and 27 feet high, but back opening is only 35 feet wide and 11 feet high.
Photograph by Professor Dale J. Stevens, Brigham Young University. (Fig. 34)

Guarding the approach to The Windows section is Balanced Rock (stop 9).
As shown in the frontispiece, it is accompanied on the right by another
balanced rock and a third one may be seen in the distance. The original route
to The Windows section, pioneered by Goulding, passed just north of
Balanced Rock. Traces of the old road between here and the Garden of Eden
parking area are still visible but no longer used. To the west, however, a part
of the old road is the starting point of a jeep trail leading northwestward
through Herdina Park to a point near Klondike Bluffs, where it joins the dirt
road in Salt Valley (fig. 1). Visitors having four-wheel-drive vehicles may
wish to drive at least as far as Eye of The Whale (fig. 34), which is 70
about 2 miles northwest of Balanced Rock. There are several picnic
tables at the beginning of this jeep trail, but no water.

INTRICATE CROSSBEDS IN NAVAJO SANDSTONE, on north side of road between
Garden of Eden and Cove of Caves. Red crest is basal part of Dewey Bridge Member.
(Fig. 35)

Just beyond Balanced Rock, a branch paved road turns eastward 2½ miles to
the main parking lots in The Windows section. Between the Garden of Eden
(stop 13) and Cove of Caves are spectacular exposures of the Navajo
Sandstone showing the crossbedding typical of the original dunes (fig. 35).
Just east of the crossbedded Navajo Sandstone, shown in figure 35, we pass
Cove Arch and Cove of Caves (stop 10) on the north side of the road (fig.
36).

Just around the curve east of Cove of Caves is the first of two parking lots
(stop 11) forming a one-way loop at the end of this branch of the road. From
the loop may be seen the greatest concentration of readily accessible arches

in the park, all of which are roofed by the Slick Rock Member and 71
floored by the Dewey Bridge Member. Let us take the short paved trail
from the upper lot to the southeast, where we come first to North Window
(fig. 37). If we walk through this arch and climb the rock beyond (fig. 37
caption), we see one of the best views in the park (fig. 38). A short walk
south of North Window brings us to South Window (fig. 39). The other side
of this arch may be reached either by walking around the nearby southeast
end of the fin or by walking through North Window. A short walk to the
southwest brings us to Turret Arch—the one seen through North Window in
figure 38. Figure 40 was taken from the southwest side of Turret Arch,
viewed northeastward toward South Window, one corner of which appears at
the left. Both North and South Windows may be seen in one photograph
taken from points near Turret Arch.

COVE ARCH AND COVE OF CAVES, on north side of road just west of Double Arch
and Parade of Elephants. Arch at left and three of the caves on right are roofed by
Slick Rock Member and floored by Dewey Bridge Member. Arch is 48½ feet wide and
34 feet high. In time the caves will eat through the 30-foot-thick fin and become

arches. Note sharp contact between Dewey Bridge Member and Navajo Sandstone.
(Fig. 36)

72

NORTH WINDOW, viewed to the northeast. Large rock seemingly partly blocking left
end of arch actually is the southeast end of a fin some 50 feet or more beyond the
arch, from which figure 38 was taken. Arch is 93 feet wide and 51 feet high. (Fig. 37)

From the lower parking lot (stop 12), a short walk by paved trail takes us to
spectacular Double Arch, shown in figure 17. This arch is visible from the
parking lot but is best seen and photographed from at or near the end of the
trail. Looking westward from near the trail’s end, we see the Parade of
Elephants, shown in figure 41. This feature is described on pages 16 and 17
of “The Guide to an Auto Tour of Arches National Park” as “whimsical stone

statuary resembling a circus pachyderm parade. With tail in trunk, the
elephants rumble toward you along a sandstone roadway.”

Ribbon Arch, on the north side of Elephant Butte, is one of the most delicate
ones in the park (fig. 1). Although it is 50 feet wide and 55 feet high, the
rock span is only 1½ feet wide and 1 foot thick.

On the way back to the intersection with the main park road, we pass 73
stop 14, from which may be seen Pothole Arch (fig. 18). One and one-
half miles north of the intersection with the main road is the Panorama Point
parking area (stop 15), which affords fine distant views of Salt and Cache
Valleys and points beyond. A roadside exhibit portrays the gradual
development of the Salt Valley anticline, which supplements my description
on pages 27-32. A parking space a short distance farther down the hill (stop
16) provides good distant views of the Fiery Furnace. I tried several
telephoto shots from this viewpoint, but preferred my closeup views, such as
the one shown in figure 44.

LOOKING SOUTHWESTWARD THROUGH NORTH WINDOW, from fin shown beyond
left side of North Window in figure 37. Turret Arch (fig. 40) is seen at right middle
ground, south rim of Moab Valley to left of arch, Colorado River canyon forms left
skyline. (Fig. 38)

74

SOUTH WINDOW, viewed toward northeast. Arch is 105 feet wide and 66 feet high. See
text. (Fig. 39)

Delicate Arch Area

Two and a half miles northeast of the road intersection near Balanced Rock,
a gravelled side road leads northeastward to several points of considerable
interest. The photograph in figure 11 was taken from this side road about
half a mile northeast of the intersection. About 2 miles to the northeast, just
beyond Salt Valley Wash, is a parking area (stop 17) at the beginning of the

trail past Wolfe’s Bar-DX Ranch (fig. 3) to famed Delicate Arch, which is
featured on the front cover. Although the trail to the arch is only 1½ miles
long, it crosses several hills at the outset, then climbs 500 feet, mostly on
bare Entrada Sandstone, so is considered quite strenuous, particularly 75
in hot weather. The Park Service advises hikers to carry water. The
Walt Disney crew, cameras, gear, cougars, and all climbed this trail in the
hottest part of the summer of 1971 (see p. 16), while my wife and I were
working in the vicinity. Visitors who do not wish to make the hike may get a
distant view of Delicate Arch by driving to a parking area (stop 18) 1.3 miles
farther east.

TURRET ARCH, viewed northeast toward South Window, part of which is visible on
left. Small opening on right is visible also in figure 38. Largest arch is 39 feet wide and
64 feet high; smaller one is 12 feet wide and 13 feet high. A still smaller one, not
visible in the photograph, is 8 feet wide and only 4½ feet high. (Fig. 40)

76

PARADE OF ELEPHANTS, viewed west from end of trail to Double Arch. Two
elephants are on right, one on left. (Fig. 41)

After leaving Wolfe’s Ranch, the trail to Delicate Arch crosses Salt 77
Wash on a suspension foot bridge (fig. 42). Just beyond the bridge, a
short walk to the left (north) leads to the Ute petroglyphs shown in the lower
photograph of figure 2. The most difficult part of the trail, on bare sandstone,
is marked by cairns of stones placed at sufficient intervals to keep hikers
from losing the barely visible trail. When the summit finally is reached and
the last corner rounded, one suddenly sees perhaps the most sublime view in
the park—famed Delicate Arch, framing part of the La Sal Mountains
beyond (fig. 43). This graceful arch and mighty Landscape Arch (fig. 53)
were considered to be in serious jeopardy during the era of sonic booms, but
hopefully this danger now is past. (See p. 16-17.)

It may be of interest to shutterbugs that professional photographer Hal
Rumel lugged an 8- × 10-inch camera plus a heavy tripod and accessories up
the steep trail to get the excellent photograph of Delicate Arch shown in
figure 43. The late afternoon sun intensified the red somewhat, but my shots
made earlier in the day using both 4- × 5-inch and 35-mm equipment

resulted in unwanted shadows, even though the salmon color of the Slick
Rock Member was more nearly normal.

After leaving the junction with the side road, the main park road traverses
slices of vertical strata squeezed between faults along the north side of Salt
Valley, then gradually climbs out of the valley for about 2 miles to a parking
area (stop 19), from which good views are had of the southeast end of Salt
Valley and of the grabens in the west end of Cache Valley. (See fig. 11.)

78

SUSPENSION FOOT BRIDGE ACROSS SALT WASH, in front of Wolfe’s cabin at
beginning of Delicate Arch trail. (Fig. 42)

DELICATE ARCH, from end of trail 1½ miles above Wolfe’s Ranch. The opening is 33
feet wide and 45 feet high. The left abutment is only 5 feet wide at the narrowest point.
The arch is carved near the top of the Slick Rock Member, and the top of the span, 19
feet thick, is capped by a few feet of the more resistant Moab Member, as is Broken
Arch (fig. 16). Photograph by Hal Rumel, Salt Lake City. (Fig. 43)

79

Fiery Furnace

About half a mile farther uphill is a parking area for viewing the
southeastern part of the Fiery Furnace (stop 20), a vast array of towering fins
and pinnacles of the reddish Slick Rock Member separated by narrow slots,

vaguely resembling flames shooting skyward. The view of the Fiery Furnace
in figure 44 was taken about 1 mile farther up the hill. It is not difficult to get
lost among this myriad of fins and narrow slots, so ranger-guided tours are
conducted during the summer.

About 1 mile farther northwest is a parking area (stop 23) from which a short
walk to the north end of Fiery Furnace leads to a narrow slot between high
fins (fig. 45), along which a short sandy trail leads to a recess along the
southwest wall containing Sand Dune Arch (fig. 46). This hidden arch
receives sunshine only near the middle of the day and is a delightful, shady
place to rest.

From the entrance to the slot leading to Sand Dune Arch, a trail goes half a
mile north across an open field to Broken Arch, shown in figure 16. This
field, which separates the Fiery Furnace and Devils Garden areas, is seen
from the air in figure 12.

80

FIERY FURNACE, viewed northwest along park road about 1 mile northwest from stop
20. Fins and spires are of the jointed Slick Rock Member (fig. 12), but the top of the
Dewey Bridge Member is seen to the right of the curve in the road. (Fig. 44)

81

TRAIL TO SAND DUNE ARCH, looking northwest away from arch, between towering
fins of Slick Rock Member, at northwest end of Fiery Furnace. Southeast end of Devils
Garden in distance. (Fig. 45)

82

SAND DUNE ARCH, in recess along southwest wall of narrow slot shown in figure 45.
Slick Rock Member. (Fig. 46)

Salt Valley and Klondike Bluffs

Before proceeding to the end of the paved road, let us take an unimproved
side road, which turns south about a third of a mile beyond the last stop, in
order to see more of Salt Valley and to visit Klondike Bluffs in the
northwestern part of the park. After descending 2.3 miles of winding road we

reach the normally dry bed of Salt Valley Wash, and turn abruptly to the
northwest. For the next three-fourths of a mile the “road” is simply two
tracks in the loose, sandy bed of the wash, which obviously should not be
travelled when flooded or when there is even a hint of rain. In dry weather,
however, this road may be travelled by ordinary passenger car. This stretch
of the wash cuts through an intruded block of the Paradox Member of the
Hermosa Formation consisting mainly of gray and brown gypsum, the
common salt having been dissolved out by ground water. Such an 83
intrusive block of salt-bearing rock is known to geologists as a diapir
—not to be confused with the garment (diaper) worn by infants.

From here on the road traverses a rather uninteresting stretch of valley north
of Salt Valley Wash. Eleven miles from the starting point, the road reaches
an intersection from which a side road leads southwestward three-fourths of
a mile to a parking area at the foot of Klondike Bluffs, which form the south
side of Salt Valley. From here, one may make a strenuous hike over a
primitive trail about 1½ miles long to beautiful Tower Arch (fig. 47).

The valley road continues northwestward from the intersection to and
beyond the northwest end of the park and connects with roads to Crescent
Junction, Thompson, and the Yellow Cat mining district, north of the park
(p. 14).

Let us return to the paved road and continue our tour of the park.

Devils Garden

Turning left (northwest) at the intersection with the paved park road, we
enter Devils Garden—another large maze of towering red fins separated by
narrow slots, which resembles the Fiery Furnace. After a third of a mile, we
reach stop 24 and walk 100 feet or more to the north for a good view of
Skyline Arch (fig. 48). This arch is very appropriately named, as it forms the
skyline viewed either from the road on the south or from the campground on
the north, from points south of the amphitheater. Less well known is the fact
that Skyline Arch is clearly visible to the naked eye or through binoculars
from stretches of Highway I-70 (or old U.S. Highways 6 and 50) about 11

miles to the north. Most arches and other erosion forms do not change
appearance much from day to day or year to year, but some, like “Baby
Arch” (fig. 15), show evidence of relatively recent origin. In November 1940
(Abbey, 1971, p. 42) Skyline Arch suddenly doubled in size by the fall of a
large rock that occupied what is now the northwest half of the arch.
Photographs taken before and after this event appear on pages 24 and 25 of
the road guide and also in the museum at the Visitor Center.

84

TOWER ARCH, on Klondike Bluffs, viewed eastward. Arch is in Slick Rock Member but
tower on left, after which arch was named, is capped by a protective layer of the
resistant Moab Member. Opening is 88 feet wide and 43 feet high. Photograph by
Robert D. Miller. (Fig. 47)

85

SKYLINE ARCH, viewed north from point about 100 feet north of stop 24, in Slick Rock
Member. Although fins are vertical, note that the strata seem to dip about 15° to the
right, although the actual dip is to the northeast. (See fig. 50.) (Fig. 48)

Another half mile brings us to a one-way (to right) loop at the end of 86
the park road. Just beyond the beginning of the loop is a parking lot
and very attractive picnic area containing several picnic tables shaded by
piñon pines at the foot of a towering red fin of the Slick Rock Member. Just
north of this picnic ground, a paved side road leads eastward into a truly
beautiful, well-equipped campground comprising both back-in and drive-
through campsites for trailers, campers, or tents; three pairs of modern
restrooms, hydrants, and drinking fountains; and an amphitheater, where
illustrated campfire talks are given nightly during the summer. The east end
of the campground is shown in figure 49.

CAMPGROUND IN DEVILS GARDEN, viewed northwestward across turn-around at
southeastern end. (Fig. 49)

Devils Garden in general and the campground in particular are on the crest
of a ridge separating Salt Valley to the southwest from the Sagers Wash
syncline to the northeast, which lies north of Yellow Cat Flat and north of the
area shown in figure 1. From the higher parts of the campground 87
striking views are to be had toward the north and northeast, particularly
late in the afternoon, as shown in figure 50.

VIEW NORTH FROM CAMPGROUND, in late afternoon. Reddish Slick Rock Member
capped by light-colored Moab Member are seen dipping northeastward toward Sagers
Wash syncline. Book Cliffs, north of Thompson, are 16 miles north on left skyline.
(Fig. 50)

In about the middle of the one-way loop at the end of the park road is a well
that supplies water to the campground from early in the spring until the
return of freezing weather late in the fall. The well, which was drilled in
1962 to a depth of 900 feet, obtains a small amount of water from the
Wingate Sandstone. No water was found in the overlying Navajo and
Entrada Sandstones because of the pronounced dip of the rocks toward the
northeast, which allows any water in these rocks to drain northeastward (Ted
Arnow, written commun., 1963). Water from this well is pumped to a steel
tank in a high part of the campground, whence it flows by gravity to 88
the three sets of restrooms.

SOUTHEASTERN PART OF DEVILS GARDEN TRAIL, viewed northwestward. Narrow
slot between fins of Slick Rock Member indicates local spacing of joints. (Fig. 51)

At the northwest end of the one-way loop is a large parking area for use by
people hiking the Devils Garden trail. This trail leads to seven of the most

interesting arches in the park, all of which are in the Slick Rock Member,
and there are many more farther to the northwest. The approximate distances
to the seven arches are given in the paragraphs that follow. The trail is paved
for about 1 mile as far as Landscape Arch (fig. 53), but from there to Double
O Arch (fig. 56) the trail is primitive, and the Park Service recommends
rubber soles as part of the trail is on bare sandstone. For these reasons, many
visitors hike only as far as Landscape Arch.

89

PINE TREE ARCH, viewed northeastward. Opening is 46 feet wide and 48 feet high. Fin
is 30 feet thick. (Fig. 52)

Much of the trail, particularly the first part, lies in a narrow slot 90
between fins of the Slick Rock Member, as shown in figure 51. After
about half a mile, a side trail to the north leads to a Y, the right-hand fork of
which goes to Tunnel Arch (fig. 14). The left-hand fork leads to Pine Tree
Arch, obviously named for the piñon pine framed by this arch (fig. 52).

At the end of the improved part of the trail, we reach Landscape Arch (fig.
53), claimed by the Park Service to be the longest known natural arch in the
world. According to Ouellette (1958) it is 291 feet long and 118 feet high,
but Professor Stevens’ measurements indicate it to be 287 feet long and 106
feet high. At its thinnest point on the right, the span is only 11 feet wide and
11 feet thick. In 1958 three young men made what was claimed to be the
second known ascent of Landscape Arch, using ropes and other climbing
gear, after which they walked across (Ouellette, 1958). This crossing was
made with the permission of a park ranger, but such permission is no longer
given, for the safety of both the arch and of would-be climbers.

Wall Arch is about a quarter of a mile beyond the end of the improved part
of the trail, and another three-fourths mile brings us to Navajo Arch (fig. 54)
and Partition Arch (fig. 55). A distant view of Partition Arch may be had just
before reaching Landscape Arch. Part of the remaining trail to Double O
Arch (fig. 56) is on the top of a low sandstone fin, in part between somewhat
higher fins and in part above lower slots.

91

LANDSCAPE ARCH, viewed southwestward from near end of improved part of Devils
Garden trail. Note that ground beneath arch is covered by slope wash and near the
middle with what appears to be a small landslide. Slick Rock Member here is more
nearly buff than salmon colored, because of a smaller content of iron oxide. Fresh
breaks and angular blocks of stone at right abutment indicate relatively recent rock
falls. See text for size. (Fig. 53)

92

NAVAJO ARCH, viewed northeastward from a branch of Devils Garden trail. One of few
arches having a flat soil-covered floor. Opening is 40½ feet wide. Photograph by
National Park Service. (Fig. 54)

Beautiful Double O Arch (fig. 56) is at the end of the Devils Garden trail
about 2½ miles northwest of the trailhead. About half a mile northwest of the
trail’s end is a prominent landmark called Dark Angel (fig. 57), which is
visible in figure 12 and from the unimproved road in Salt Valley.

93

PARTITION ARCH, viewed southwestward from near Devils Garden trail. Arch frames
part of south wall of Salt Valley and, on skyline, mesas south of Moab Valley. Opening
is 27½ feet wide and 26 feet high. A smaller opening to the right measures 8½ feet
wide and 8 feet high. Photograph by Dawn E. Reed. (Fig. 55)

DOUBLE O ARCH, viewed about north from northwest end of Devils Garden trail.
Large opening is 71 feet wide and 45 feet high; small one at lower left is 21 feet wide
and 11 feet high. Span of large opening is 11 feet wide and 6 feet thick. Arch frames a
part of the Book Cliffs about 14 miles to the north. Photograph by Hildegard Hamilton,
Flagstaff, Ariz. (Fig. 56)

94

DARK ANGEL, a shaft of the Slick Rock Member that is an erosional remnant of a once
high, narrow fin. About one-half mile northwest of Double O Arch. Photograph by
National Park Service. (Fig. 57)

95

“INDIAN-HEAD ARCH,” in upper Devils Garden. Arch and most of head are in Slick
Rock Member, top of head is basal part of Moab Member. Opening is 4 feet wide and
4½ feet high. Photograph by Professor Dale J. Stevens, Brigham Young University.
(Fig. 58)

96

GEOLOGIC TIME SPIRAL, showing the sequence, names, and ages of the geologic
eras, periods, and epochs, and the evolution of plant and animal life on land and in the
sea. The primitive animals that evolved in the sea during the vast Precambrian Era left
few traces in the rocks because they had not developed hard parts, such as shells, but
hard shell or skeletal parts became abundant during and after the Paleozoic Era. (Fig.
59)

GEOLOGIC TIME
The Age of the Earth

The Earth is very old—4.5 billion years or more according to recent estimates.
Most of the evidence for an ancient Earth is contained in the rocks that form the
Earth’s crust. The rock layers themselves—like pages in a long and
complicated history—record the surface-shaping events of the past, and buried
within them are traces of life—the plants and animals that evolved from organic
structures that existed perhaps 3 billion years ago.

Also contained in rocks once molten are radioactive elements whose isotopes
provide Earth scientists with an atomic clock. Within these rocks, “parent”

isotopes decay at a predictable rate to form “daughter” isotopes. By
determining the relative amounts of parent and daughter isotopes, the age of
these rocks can be calculated.

Thus, the results of studies of rock layers (stratigraphy), and of fossils
(paleontology), coupled with the ages of certain rocks as measured by atomic
clocks (geochronology), attest to a very old Earth!

Professor Stevens found 14 arches in what he called upper Devils 98
Garden, northwest of Double O Arch, and two arches in the
northwesternmost extension of the park known as Eagle Park (fig. 1). One of
the unnamed arches in upper Devils Garden is shown in figure 58. I am
tentatively calling it “Indian-Head Arch,” because of the rather obvious
resemblance.

This ends our journey through Arches National Park, but there remains for
consideration a summary of the principal geologic events leading to the
formation of this beautiful part of the Colorado Plateau and a brief
comparison with the geology of other national parks and monuments on the
Plateau.

Summary of Geologic History

Having finished our geologic trip through Arches National Park, let us see
how the arches and other features fit into the bigger scheme of things—the
geologic age and events of the Earth as a whole, as depicted in figure 59. As
shown in figure 4, the rock strata still preserved in the park range in age
from Pennsylvanian to Cretaceous, or from about 300 million to 100 million
years old—a span of about 200 million years. This seems an incredibly long
time, until one notes that the earth is some 4.5 billion years old, and that our
rock pile is but 1/23 or 4½ percent of the age of the Earth as a whole. Thus,
in figure 59, the rocks exposed in the park occupy only about the left half of
the top whorl of the spiral.

But this is not the whole story. As indicated earlier, younger Mesozoic and
Tertiary rocks more than 1 mile thick that once covered the area have been
carried away by erosion, and if we include these the span is increased 99
to about 250 million years, or nearly a full whorl of the spiral.

Deep tests for oil and gas tell us that much older rocks underlie the area, and
we have seen that some of these played a part in shaping the park we see
today. In addition to the Precambrian igneous and metamorphic rocks, there

is about 2,000 feet of Paleozoic sedimentary rocks older than the
Pennsylvanian Paradox Member of the Hermosa Formation, most of which
was laid down in ancient seas. This includes strata of Cambrian, Ordovician,
Devonian, Mississippian, and Pennsylvanian ages (fig. 59). There are some
gaps in the rock record caused by temporary emergence of the land above
sea level and erosion of the land surface before the land again subsided
below sea level so that deposition could resume. Silurian rocks are absent,
presumably because, here, the Silurian Period was dominated by erosion
rather than deposition.

While Pennsylvanian and Permian rocks were being laid down in and
southwest of the park, a large area to the northeast, called by geologists the
Uncompahgre Highland (because it occupied the same general area as part
of the present Uncompahgre Plateau), rose slowly above sea level. Whatever
Paleozoic rocks were on this rising land plus part of the underlying
Precambrian rocks were eroded and carried by streams into deep basins to
the northeast and southwest. Thus, while some marine or near-shore deposits
were being laid down in and south of the park, thousands of feet of red beds
were being laid down by streams between the park and what is now the
Uncompahgre Plateau. During part of Middle Pennsylvanian time, a large
area, including the park, known as the Paradox basin, was alternately
connected to or cut off from the sea, so that the water was evaporated during
cutoff periods and replenished during periods when connection with the sea
resumed. In these huge evaporation basins were deposited the salt and
gypsum plus some potash salts and shale that now make up the Paradox
Member of the Hermosa Formation.

Arches National Park contains four northwesterly trending major 100
folds—the Salt Valley and Cache Valley salt anticlines, the
Courthouse syncline, and the faulted Moab-Seven Mile anticline, which
forms the southwestern border. How these folds were formed was explained
on pages 27-32. The history of their growth, however, was a long one that
began about 300 million years ago in the Pennsylvanian and ended about 50
million years ago in the early Tertiary. The growth of these folds occurred in
two stages. The first stage, which involved the development of the salt cores
of the anticlines, ended in the Jurassic with the beginning of Morrison time;
the second stage, which involved additional folding that intensified the
magnitude and shape of existing folds, occurred in the early Tertiary and was

followed later by collapse of the salt anticlines. The formation and collapse
of the Salt Valley and Cache Valley anticlines was accompanied by
pronounced jointing (fig. 12), which allowed differential erosion to produce
the tall fins in which the arches were formed.

The old Uncompahgre Highland continued to shed debris into the bordering
basins until Triassic time, when it began to be covered by a veneer of red
sandstone and siltstone of the Chinle Formation (Lohman, 1965). The area
remained above sea level during the Triassic Period and most, if not all, of
the Jurassic Period, although the Jurassic Carmel Formation was laid down
in a sea that lay just to the west.

Late in the Cretaceous Period a large part of Central and Southeastern
United States, including the eastern half of Utah, sank beneath the sea and
received thousands of feet of mud, silt, and some sand that later compacted
into the Mancos Shale. This formation, as well as all younger and some
older strata, has long since been eroded from most of the park area, but a
little of the Mancos is preserved in the Cache Valley graben (fig. 11), and the
entire Mancos Shale and younger rocks are present in adjacent areas, such as
the Book Cliffs north of Green River, Crescent Junction, and Cisco (figs. 7,
50, 56).

The land rose above the sea at about the close of the Cretaceous and has
remained above ever since, although inland basins and lakes received
sediment during parts of the Tertiary Period. Compressive forces in 101
the Earth’s crust produced some gentle folding of the strata at the
close of the Cretaceous, but more pronounced folding and some faulting
occurred during the Eocene Epoch, when most of the Rocky Mountains took
form. During the Miocene Epoch igneous rock welled up into older rocks to
form the cores of the nearby La Sal, Abajo, and Henry Mountains.
Additional uplift and some folding occurred in the Pliocene and Pleistocene
Epochs.

Much of the course of the Colorado River was established during the
Miocene Epoch, with some additional adjustments in the late Pliocene and
early Pleistocene Epochs (Hunt, C. B., 1969, p. 67). Erosion during much of
the Tertiary Period and all of the Quaternary Period plus some sagging and
breaking of the crest of the anticlines, brought on by solution and lateral

squeezing of salt beds beneath the Moab-Seven Mile, Salt Valley, and Cache
Valley anticlines, combined to produce the landscape as we now see it.

The Precambrian rocks beneath the area are about 1.5 billion years old; so an
enormous span of time is represented by the rocks and events in and beneath
Canyonlands National Park.

If we consider the geologic formations that make up the national parks
(N.P.), national monuments (N.M.) (excluding small historical or
archaeological ones), Monument Valley, San Rafael Swell, and Glen Canyon
National Recreation Area, all in the Colorado Plateau, it becomes apparent
that certain formations or groups of formations play starring roles in some
parks or monuments, some play supporting roles, and in a few places the
entire cast of rocks gets about equal billing. Let us compare them and see
how and where they fit into the “Geologic Time Spiral” (fig. 59).

Dinosaur N.M., with exposed rocks ranging in age from Precambrian to
Cretaceous, covers the greatest time span (nearly 2 billion years), but has
one unit—the Jurassic Morrison Formation—in the starring role, for this unit
contains the many dinosaur fossils that give the monument its name and
fame, although there are several older units in supporting roles. Grand 102
Canyon N.P. and N.M. are next, with rocks ranging in age from
Precambrian through Permian (excluding the Quaternary lava flows in the
N.M.), but here there is truly a team effort, for the entire cast gets about
equal billing. Canyonlands N.P. stands third in this category, with rocks
ranging from Pennsylvanian to Jurassic, but we would have to give top
billing to the Permian Cedar Mesa Sandstone Member of the Cutler
Formation, from which The Needles, The Grabens, and most of the arches
were sculptured; the Triassic Wingate Sandstone and the Triassic(?) Kayenta
Formation get second billing for their roles in forming and preserving Island
in the Sky and other high mesas.

Now let us consider other areas with only one or few players in the cast,
beginning at the bottom of the time spiral. Black Canyon of the Gunnison
N.M., cut entirely in rocks of early Precambrian age with only a veneer of
much younger rocks, obviously has but one star in its cast. Colorado N.M.
contains rocks ranging from Precambrian to Cretaceous—equal to Dinosaur
in this respect, but Colorado is unique in that all the rocks of the long

Paleozoic Era and some others are missing from the cast; of those that
remain, the Triassic Wingate and the Triassic(?) Kayenta are the stars, with
strong support from the Jurassic Entrada Sandstone.

All the bridges in Natural Bridges N.M. were carved from the Permian
Cedar Mesa Sandstone Member of the Cutler Formation, also one of the
stars in Canyonlands N.P. In Canyon de Chelly (pronounced dee shay) N.M.
and Monument Valley (neither a national park nor a national monument, as it
is owned and administered by the Navajo Tribe), the De Chelly Sandstone
Member of the Cutler Formation—a Permian member younger than the
Cedar Mesa—plays the starring role.

Wupatki N.M. near Flagstaff, Ariz., stars the Triassic Moenkopi Formation.
Petrified Forest N.P. (which now includes part of the Painted Desert) has but
one star—the Triassic Chinle Formation, in which are found many petrified
logs and stumps of ancient trees. The Triassic-Jurassic Glen Canyon Group
(fig. 19), which includes the Triassic Wingate Sandstone, the 103
Triassic(?) Kayenta Formation, and the Triassic(?)-Jurassic Navajo
Sandstone, receives top billing in recently enlarged Capitol Reef N.P., but
the Triassic Moenkopi and Chinle Formations enjoy supporting roles.

The Triassic(?)-Jurassic Navajo Sandstone, which has a supporting role in
Arches N.P., is the undisputed star of Zion N.P., Rainbow Bridge N.M., and
Glen Canyon National Recreation Area, despite the fact that the latter is the
type locality of the entire Glen Canyon Group. The Navajo also forms the
impressive reef at the east edge of the beautiful San Rafael Swell, a dome, or
closed anticline, now crossed by Highway I-70 between Green River and
Fremont Junction, Utah.

As we journey upward in the time spiral (fig. 59), we come to the Jurassic
Entrada Sandstone, which stars in Arches N.P., with help from the
underlying Navajo Sandstone, and a supporting cast of both older and
younger rocks. The Entrada also forms the grotesque erosion forms called
“hoodoos and goblins” in Goblin Valley State Park, north of Hanksville,
Utah.

Moving ever upward in the spiral, we come to the Cretaceous—the age of
the starring Mesaverde Group, in which the caves of Mesaverde N.P. were

formed, and which now house beautifully preserved ruins once occupied by
the Anasazi, the same ancient people who once dwelt in Arches N.P. and
nearby areas.

This brings us up to the Tertiary Period, during the early part of which the
pink limestones and shales of the Paleocene and Eocene Wasatch Formation
were laid down in inland basins. Beautifully sculptured cliffs, pinnacles, and
caves of the Wasatch star in Bryce Canyon N.P. and in nearby Cedar Breaks
N.M. This concludes our climb up the time spiral, except for Quaternary
volcanoes and some older volcanic features at Sunset Crater N.M., near
Flagstaff, Ariz.

Thus, one way or another, many rock units formed during the last couple of
billion years have performed on the stage of the Colorado Plateau and,
hamlike, still lurk in the wings eagerly awaiting your applause to recall them
to the footlights. Don’t let them down—visit and enjoy the national 104
parks and monuments of the Plateau, for they probably are the
greatest collection of scenic wonderlands in the world.

Additional Reading

Many reports covering various aspects of the area have been cited in the text
by author and year, and these plus a few additional ones are listed in
“Selected References.” A few works of general or special interest should be
mentioned, however.

Between 1926 and 1929 the entire area now included in the park was
mapped geologically in classic reports by Dane (1935) and by McKnight
(1940). These men and their field assistants mapped the area by use of the
plane-table and telescopic alidade without benefit of modern topographic
maps or aerial photographs, except for topographic maps of the narrow
stretch along the Colorado River mapped under the direction of Herron
(1917). Only small sections could be reached by automobile, so nearly all
the area was traversed using horses and mules or by hiking. This work plus
mapping done in nearby areas to the south and to the north (Stokes, 1952)
during the uranium boom of the mid-fifties was used by Williams (1964) in
compiling a geologic map of the Moab quadrangle at a scale of 1:250,000.

Several early reports on the Colorado River and its potential utilization
contain a wealth of information and many fine photographs, including two
by La Rue (1916, 1925) and one by Follansbee (1929).

You may be interested in brief accounts of the geology of other national
parks and monuments, or other areas of special interest, such as the reports
on the Uinta Mountains by Hansen (1969), Mount Rainier by Crandell 105
(1969), Yellowstone National Park by Keefer (1971), and ones by me
on Colorado National Monument (Lohman, 1965) and Canyonlands
National Park (1974).

For those who wish to learn more about the science of geology, I suggest the
textbook by Gilluly, Waters, and Woodford (1968).

Acknowledgments
I am greatly indebted to Bates Wilson, former Superintendent, and to former
Assistant Superintendent Joe Carithers, for their splendid cooperation in
supplying data and information; to Chuck Budge, former Chief Ranger;
Dave May, Assistant Chief of Interpretation and Resource Management; Joe
Miller, former Maintenance Engineer; Bob Kerr, new Superintendent;
Maxine Newell, Park Historian and member of the staff at Arches National
Park; Jerry Banta, former Park Ranger at Arches; and Carl Mikesell, Park
Ranger at Arches, for their many favors.

I am grateful to several colleagues and friends for the loan of photographs,
for geologic help and data, and for reviewing this report. I am also deeply
grateful to my wife, Ruth, for accompanying me on all the fieldwork and for
her help and encouragement.

Selected References
Abbey, Edward, 1971, Desert solitaire, a season in the wilderness: New
York, Ballantine Books, 303 p.
Baker, A. A., 1933, Geology and oil possibilities of the Moab district, Grand
and San Juan Counties, Utah: U.S. Geol. Survey Bull. 841, 95 p.
Baker, Pearl, 1971, The Wild Bunch at Robbers Roost: New York, Aberlard-
Schuman, 224 p.
Beckwith, Frank, 1934, A group of petroglyphs near Moab, Utah: Santa Fe,
N. Mex., El Palacio, v. 36, p. 177-178.
Breed, Jack, 1947, Utah’s arches of stone: Natl. Geog. Mag., p. 173-192,
August.
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Footnotes

[1]
Mrs. Tanner, of Phoenix, Ariz., is the author of an earlier history of Moab
(her hometown). She has completed a revision entitled, “The Far
Country—A Regional History of Moab and La Sal, Utah,” which will be
serialized in the Moab Times-Independent, after which it will be
published.

[2]
For the benefit of visitors from countries in which the metric system is
used, the following conversion factors may be helpful: 1 inch = 2.54
centimeters, 1 foot = 0.305 meter, 1 mile = 1.609 kilometers, 1 U.S.
gallon = 0.00379 cubic meter.

[3]
Barrier Creek flows through Horseshoe Canyon in the detached unit of
Canyonlands National Park. The canyon walls are adorned by striking
pictographs (Lohman, 1974, fig. 2). “Barrier Canyon style” is named
after the pictographs found in Horseshoe Canyon.

[4]
Plastic-relief maps are no longer available from the U.S. Army Map
Service but may be obtained from the T. N. Hubbard Scientific Co., Box
105, Northbrook, Ill. 60062. A topographic map at a scale of 1:250,000
of the Moab quadrangle and similar maps at a scale of 1:62,500 for the
Thompson, Cisco, Moab, and Castle Valley quadrangles are available
from the U.S. Geological Survey, Denver Distribution Section, Federal
Center, Denver, Colo. 80225, from the Canyonlands Natural History
Association at Moab, and from privately owned shops where maps are
sold. Most of the park is covered by the Thompson and Moab
quadrangles. The southern part of the park is shown also on the Moab 4

NW, Moab 4 NE, and Mt. Waas 3 NW quadrangles at a scale of
1:24,000. A special topographic map of Arches National Park at a scale
of 1:50,000 is in preparation by the U.S. Geological Survey. These maps
also may be obtained from the above-listed sources.

[5]
This is numbered stop 1 in the booklet referred to earlier “The Guide to an
Auto Tour of Arches National Park,” and corresponds to the numeral one
on a small sign at the roadside parking place. Some of the other numbers
are given in the pages that follow.
109

Index

A B C D E F G H I J K L M N O P Q R S T U V W
X Y Z
[Italic page numbers indicate major references]

A
Page
Abajo Mountains 101
artifacts 9
Abbey, Edward 3
Aborigines, occupation of area 9
Acknowledgments 105
Anasazi people, petroglyphs 10
Anasazi ruins 9, 103
Ancestral Colorado River 33
Anomalies, gravity, Salt Valley 32
Anticlines, salt 31
Arches, broken remains 44
examples 46
former abutments 68
horizontal 44
how they are formed 42
natural, defined 40
number in the park 40, 41
origin and development 37
pothole 44
vertical 42, 44
Artifacts, La Sal and Abajo Mountains 9
Aspinall, Wayne, Representative 8

B
“Baby Arch” 46, 63, 83
Balanced Rock 69, 70, 74
Banta, Jerry 105
Bar-DX Ranch 12, 13, 14
“Barrier Canyon style” 10
Bedding, wavy, Dewey Bridge Member 46
Beeson, Stib 13
Beginning of a monument 1
Bending of rocks 24
Bennett, Wallace F., Senator 8
Beroni, Pete 14, 15
Black Canyon of the Gunnison National Monument 102
Book Cliffs 100
Breaking of rocks 24
Bridge, natural, defined 40
Broken Arch 46, 79
Brown-Stanton expedition, exploration 15
Bryce Canyon National Park 103
Budge, Chuck 105

C
Cache Valley 56, 73, 77
Cache Valley anticline 25, 32, 34, 55, 100, 101
Cache Valley graben 34, 100
Campground 86
water supply 87
Cane Creek anticline 24
Canyon de Chelly National Monument 102
Canyon King 8
Canyon Lands Section, Colorado Plateau 9, 22
Canyonlands National Park 3, 9, 15, 102
Canyonlands Natural History Association 8
Capitol Reef National Park 103
Carithers, Joe 105
Carmel Formation 100
Cassidy, Butch 12
Caves, Entrada Sandstone 9

Cedar Breaks National Monument 103
Cedar Mesa Sandstone Member, Cutler Formation 22, 102
Chinle Formation 32, 100, 102, 103
“Cisco Cutoff” 16
Civilian Conservation Corps 2
Cliff dwellers 9
Climate, desert 35, 51
wetter, different landscape produced 37
Collapse, salt anticlines 33, 34
Color photographs, equipment used 8
Colorado National Monument 102
Colorado Plateau, geologic formations included 101
rock formations 103, 104
subdivisions 18
uranium-vanadium mining 14
Colorado Plateaus Province 18
Colorado River, course established 101
nighttime illuminated float trip 16, 52
Colorado River canyon 35, 51, 52
Cores, salt 100
Corral mine 15
Courthouse syncline 25, 30, 31, 32, 52, 63, 68, 100
Courthouse Towers area 25, 63
number of arches 41
Courthouse Wash 2, 3, 18, 35, 63
Cove Arch 70
Cove of Caves 70
Crossbedding, Navajo Sandstone 63, 66, 70
Cutler Formation 32, 102
Cedar Mesa Sandstone Member 22
White Rim Sandstone Member 22

110

D
Dark Angel 92
De Chelly Sandstone Member, Cutler Formation 102
Dead Horse Point 33

Dedication of the park 8
Delicate Arch 16, 25, 74, 75, 77
Delicate Arch area, number of arches 41
Density, average, Paradox Member 32
Deposition of rock materials, environments 20
Desert varnish 10
Development of the arches 37
Devils Garden 2, 5, 25, 79, 83, 86
fins 42
number of arches 41
trail 88, 92
Dewey Bridge 52
Dewey Bridge Member 46, 63
Entrada Sandstone, composition 41
“hoodoos and goblins” 66
park road cutting 57
The Windows section 71
vertical arches 44
“Dewey Road” 16
Diapir 83
Differential erosion 42
Dinosaur National Monument 101, 102
Dissimilarity of Arches vs. Canyonlands 23, 24
Double Arch 2, 46, 72
Double O Arch 90, 92, 98
Drainage, Arches National Park 18
Dry Mesa 5, 56

E
Eagle Park 25, 98
number of arches 41
Early dwellers 9
Earthquake, rock offset along bedding plane 63
Egyptian queen, arch resembling 63
Eisenhower, Dwight D., Mission 66 4
Elephant Butte 72
Elephant Butte folds 68
Elizondo, Emmett 13

Entrada Sandstone 23, 74, 102, 103
arches, modes of origin 42
caves 9
cut by normal fault 57
Moab Member 24
no water found 87
Environments of deposition 20
Erosion 99
Colorado Plateau 33
Evaporation basins 99
Evaporites 30
Eye of The Whale 69

F
Facies changes 22
“Father of the monument,” J. W. Williams 1, 4
Faults, Cache Valley anticline 34
Salt Valley anticline 34
Fiery Furnace 25, 42, 73, 79, 83
number of arches 41
Fins 63, 79
Float trip, nighttime illuminated, down Colorado River 52
Folds 24, 30, 100
Four-wheel-drive vehicles 69
Fractures 24
Fremont people, occupation of area 9
pictographs 10
Frost, prying action 42

G
Garden of Eden 50, 69, 70
Gas exploration, deep tests 15, 99
Geographic setting 18
Geologic age of rocks in park 98
Geologic events forming the Colorado Plateau 98
Geologic history, summary 98
Geologic Time Spiral 101, 103
Geology, at the park entrance 57

Glen Canyon Group 52, 102, 103
Glen Canyon National Recreation Area 101, 103
Goblin Valley State Park 66, 103
Gould, Lawrence M. 1
Goulding, Harry, first person to drive into The Windows section 2, 69
Grabens 34
Grand Canyon National Park and National Monument 102
Gravity anomalies, Salt Valley 32
Green River 103
Ground water 41
“Guide to an Auto Tour of Arches National Park,” (The) 5, 50, 51, 72
Gulf of California 33

H
Hastier, (Mrs.) Hazel Wolfe 13
Headquarters area 57
Henry Mountains 101
Herdina Park 25, 69
number of arches 41
Hermosa Formation, Paradox Member 23, 25, 29, 30, 32
History, early 9
geologic, summary 98
“Hoodoos and goblins” 66, 103
Hoover, Herbert, proclamation 1
Horizontal arches 44
Horseshoe Canyon, pictographs 10
Horseshoe Canyon Detached Unit of Canyonlands 23
Humid regions, subdued rounded landforms 37

I
Igneous rocks 22, 99
“Indian-Head Arch” 98
Iron in the rocks 23
Island in the Sky 102

111

J

Jeep trail 69, 70
Johnson, Lyndon B., proclamation 2
Joints 24, 34, 100

K
Kayenta Formation 35, 52, 102, 103
Kerr, Bob 105
Klondike Bluffs 25, 69, 82, 83
number of arches 41

L
La Sal Mountains 22, 63, 77, 101
artifacts 9
Lake Mead 33
Lake Powell 33
Land forms, formation in the park 33
Landscape Arch 16, 77, 88
second known ascent 90
Larson, Tommy 13
Lloyd, Sherman P., Representative 8
Lohman, (Mrs.) Ruth 105

M
Mahan, Russel L. 2
Mancos Shale 32, 100
Maxwell, Ross A., investigation of caves 9, 10
May, David 40, 105
Melich, Mitchell, Solicitor General 8
Mesaverde Group 32, 103
Mesaverde National Park 103
Metamorphic rocks 22, 99
Metric unit conversion factors 2
Mikesell, Carl 105
Miller, Joe 105
Mission 66, presidential and congressional support 4
Mississippi River sternwheeler replica 8
Moab, uranium-vanadium mill 14
Moab bridge 52

Moab Canyon 15, 18
Moab fault 26, 57
Moab Lions Club 1, 8
“Moab Mail Road” 16
Moab Member, Entrada Sandstone 24, 35
Entrada Sandstone, Broken Arch 46
composition 41
“Moab panel” 10
Moab-Spanish Valley anticline 26
Moab Valley 57
Moab Valley-Seven Mile anticline 100, 101
Moenkopi Formation 32, 102, 103
Monoliths 63
Monument, beginning 1
Monument Valley 101, 102
Morrison Formation 32, 101
Morton, Rogers C. B., Secretary of the Interior 8
Moss, Frank E., Senator 8
Moss Back Member, Chinle Formation 15

N
National Park Service 8, 12, 40, 75, 90
Natural Bridges National Monument 3, 37, 40, 102
Navajo Arch 90
Navajo Sandstone 24, 35, 52, 103
canyon floor 63
crossbedding 63, 66, 70
park road cutting 57
water supply 57, 87
Navajo Tribe 102
Needles section, The, Canyonlands National Park 16, 102
Newell, (Mrs.) Maxine 12, 105
Nixon, Richard M., Congressional Bill 5
North Window 40, 68, 71

O
Oil exploration 15
Cane Creek anticline 24

deep tests 99
Origin of the arches 37

P
Pacific Northwest Pipeline 15
Painted Desert 102
Panorama Point 73
Parade of Elephants 72
Paradox basin 23
Paradox Member, Hermosa Formation 23, 25, 29, 30, 82, 99
Hermosa Formation, average density 32
upward intrusion 34
Park, a trip through 52
dedication 8
how to see 50
improvements 4
Park Avenue, trail 63
Park Service. See National Park Service.
Partition Arch 90
Petrified dunes 63, 66
Petrified Forest National Park 102
Petroglyphs, Ute 10, 75
Pictographs, Fremont people 10
Pine Tree Arch 90
Piñon pines 86
Pipeline scars, Pacific Northwest Pipeline 15
Plateau, uplift and erosion 33
Potash occurrence 15
Pothole Arch 50, 73
Pothole arches 44
Powell, John Wesley, Canyonlands National Park 15
Professor Valley 56

R
Rainbow Bridge National Monument 103
Rainwater 41, 42
Rampton, Calvin L., Utah Governor 8
Reading, additional 104

References, selected 105
112

Relief map, shaded, Arches National Park, described 18, 19
Ribbon Arch 72
Richardson Amphitheater 56
Richardson, Professor 56
Rico Formation 23
Rison, (Mrs.) Esther Stanley 13
Rock formations, sculptured by erosion 35
Rock openings, natural, types 37
Rock types in the park 35
Roosevelt, Franklin D., proclamation 2
Rumel, Hal, photographer 77
“Run, Cougar, Run” 16, 56, 75

S
Sagers Wash syncline 86
Salt, occurrence 15
properties critical to formation of salt anticlines 30
Salt anticlines 30, 31, 100
collapse 33, 34
Salt-bearing rock 83
Salt rolls 31
Salt Valley 2, 68, 73, 77, 82, 83, 92
gravity anomalies 32
Salt Valley anticline 25, 30, 31, 32, 73, 100, 101
collapse 34
fins 42
Salt Valley Wash 3, 74, 82, 83
Salt Wash 35, 55
Anasazi ruins 9
drainage 18
grabens 34
sandstone caves near 10
Salt Wash Sandstone Member, Morrison Formation 14
San Juan Basin, natural gas 15
San Rafael Swell 101, 103

Sand Dune Arch 79
Sandstone fins 41, 42
Schaafsma, Polly, quoted 10, 12
Scenic drive, Moab to Cisco 16
“Scenic Inch,” Pacific Northwest Pipeline 15
Sedimentary rocks 20
modes of deposition 99
Seven Mile-Moab Valley anticline 26, 32, 57
Sevenmile Canyon 15
Sheep Rock 63
Skyline Arch 83
Slick Rock Member, Entrada Sandstone 34
Entrada Sandstone, composition 41
high fins and pinnacles 63, 79, 86
hiking trail between fins 90
park road cutting 57
salmon 77
The Windows section 71
Tunnel Arch 46
vertical arches 42, 44
Slumping of sediments, irregular 50
Snow 41, 51
Sonic booms, dangers posed to arches 16, 17
South Window 40, 68, 71
Spanish explorers 12
introduction of horses to this country 10
Squaw Flat Campground 16
Stanley, Esther 13
(Mrs.) Flora 13
Volna 13
Stevens, Dale J. 40, 41, 63, 90, 98
Strata, lateral changes across the park 22
Sundance Kid 12
Sunset Crater National Monument 103
Supersonic flights banned, Moab-Times Independent 17
Suspension bridge, Colorado River 16

T

Tanner, (Mrs.) Faun McConkie 1
Taylor, L. L. (Bish) 1
Temperatures 51
“The Guide to an Auto Tour of Arches National Park” 5, 50, 51, 72
The Needles section, Canyonlands National Park 16, 102
The Windows section 25, 41, 46, 51, 66, 68, 69, 70
Three Gossips 63
Three Penguins 57
Tower Arch 83
Tunnel Arch 40, 46, 90
Turnbow, Mary 1
Turnbow cabin 13
Turret Arch 68, 71

U
Uncompahgre Highland 23, 99, 100
Uncompahgre Plateau 23, 99
Uplift, Colorado Plateau 33
Upper Devils Garden 98
number of arches 41
Uranium mines 14
Ute petroglyphs 10, 75

V
Vanadium mines 14
Vegetation 37
Vertical arches 42, 44
Visitor Center 50, 51, 57, 86
Volz, J. Leonard 8

W
Walker, Lester 13
Wall Arch 90
Walt Disney crew, “Run, Cougar, Run” 75
Wasatch Formation 32
Water supply, Navajo Sandstone 57
to the campground 87

113

White Rim Sandstone Member, Cutler Formation 22
Wild Bunch, The 12
Williams, J. W. 1, 4
Wilson, Bates 1, 3, 105
Wilson, (Mrs.) Bates 3
Windows, distinguished from arches 40
Windows section, The 25, 46, 51, 66, 68, 69, 70
number of arches 41
Wingate Sandstone 35, 87, 102, 103
Wirth, Conrad L. 4
Wolfe cabin 1, 3, 12, 13, 14
Wolfe, Fred 12, 13
Wolfe, John Wesley 12, 13
Wolfe’s Bar-DX Ranch 9, 10, 14, 74, 75
Wupatki National Monument 102

Y
Yellow Cat area (Thompson’s area) 14
Yellow Cat Flat 86
Yellow Cat mining district 83

Z
Zion National Park 103

★U.S. GOVERNMENT PRINTING OFFICE: 1975—679-138

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