Hanscn THE GEOLOGIC STORY OF THE UINTA MOUNTAINS Geological Survey Bulletin 1291

The

Uinta

Mountains

i k *r A geologic review, commemorating

-f John Wesley Powell's historic explorations among the lofty peaks and deep

 '"i canyons of the Uinta Mountains
TURRETED RED CASTLE, altitude 12,825 feet, stands 

above a slacial lake high on the north flank of the 

Uinta Mountains.
"Away to the south, the Uinta Mountains stretch in a long line; high peaks 

thrust into the sky, and snow-fields glittering like lakes of molten silver; and pine 

forests in somber green; and rosy clouds 

playing around the borders of huge, black 

masses; and heights and clouds, and 

mountains and snow-fields, and forests 

and rocklands, are blended into one grand 

view."

Powell's diary, May 24,1869
"Above all it is the rocky region; rocks are strewn along 

the valleys, over the plains and plateaus; the canon walls 

are of naked rock; long escarpments or cliffs of rock stand 

athwart the country, and everywhere are mountains of rock. 

It is the Rocky Mountain region."

Powell, 1876, Keport on the Geology of the 

Eastern Portion of the Uinta Mountains
GEOLOGIC STORY

UINTA MOUNTAINS

By Wallace R. Hansen

GEOLOGICAL SURVEY BULLETIN 1291
UNITED STATES DEPARTMENT OF THE INTERIOR 

JAMES G. WATT, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress catalog-card No. GS 68-327

First printing 1969 

Second printing 1975 

Third printing 1983

U.S. GOVERNMENT PRINTING : 1975

For sale by the Distribution Branch, U.S. Geological Survey, 

604 South Pickett Street, Alexandria, VA 22304
Preface

My earliest recollections of the Uinta Mountains reach 

back almost to the threshold of memory. As a schoolboy I 

made many hikes to the high ridgelines of the Wasatch 

Range, east of Salt Lake City, and on such occasions my 

father often pointed out the snowy peaks of the High Uintas 

shimmering far off to the east. Mount Timpanogos, near 

Provo, was a favorite climb in those days, and from its lofty 

summit all of northern Utah seemed to be spread out at 

one's feet all except the Uinta Mountains, which loomed 

even higher on the horizon. My first actual visit to the 

Uintas was with an uncle who was an ardent fisherman 

and the owner of a 1928 Essex coupe. Mirror Lake, 80 miles 

from Salt Lake City, was at the end of the road and was a 

fair test, even for an Essex. A day's limit at Mirror Lake 

was 30 trout, and catching that many wasn't much of a 

chore. From time to time my uncle and I tried out other 

lakes in that vicinity, dozens of which were visible from the 

summit of Bald Mountain. Scout Lake is one, north of Bald 

Mountain, at Camp Steiner. At an altitude of 10,300 feet 

above sea level, Steiner is the highest Boy Scout camp in 

the United States. It was the ultimate objective of every 

Boy Scout in the Salt Lake Council. No doubt, it still is.

Later, I made the trip to the Uintas many times on my 

own, in my 1932 Chevrolet roadster, arid extended my 

horizons to the Upper Weber, Haydens Fork of the Bear, 

the Duchesne, Rock Creek, and Yellowstone Creek. The 

hike into the lakes was as much fun as the fishing; the cirque 

walls, the polished rock surfaces, and the erratic boulders 

all were rather obvious manifestations of glacial erosion, 

even to an untrained eye.
In 1940 I visited the Uinta Mountains as a student. Under 

the direction of R. E. Marsell and the late Hyrum Schneider, 

the University of Utah had set up a geologic field camp on 

the Duchesne River. Working from there, I gained my first 

real appreciation of the country's impressive geology.

After a dozen years I returned to the Uintas in the early 

1950's, this time in the employ of the U.S. Geological Survey, 

to map a block of quadrangles along the Green River between 

Flaming Gorge and Browns Park. I gained a further appreciation of Uinta Mountain geology, and made lasting friendships with many local people.

Over the years I have become acquainted with most of 

the Uinta Mountains, to some degree, and the following 

report is drawn mostly from my own notes and memory; 

but the observations and conclusions of others have been 

freely utilized. Consciously or unconsciously, I've borrowed 

from the ideas and published works of J. D. Sears, W. H. 

Bradley, D. M. Kinney, and other colleagues of the Geological Survey, and from my friends Ernest and Billie Untermann, Codirectors of the Utah Field House of Natural 

History at Vernal and widely recognized authorities on the 

geology of the Dinosaur National Monument area. Other 

authors have been cited where appropriate, but no attempt 

has been made to exhaust the published literature. Special 

thanks are extended to artist John R. Stacy, who prepared 

the illustrations and artwork in this report.

Many statements on the following pages perhaps seem 

assertive. In a more formal report these statements would 

be carefully documented. But the geologic literature on the 

Uinta Mountains reaches back 100 years and is voluminous. 

Fuller documentation would be distractive in a report of 

this sort. The few reports cited here contain extensive bibliographies of their own, and the reader is referred to them 

for more background literature.

The intended scope of the report is fairly broad, but the 

treatment is not comprehensive. Indeed, in} a report this 

size, only the barest outline can be given on the physical 

traits of an area as geologically encompassing as the Uinta 

Mountains.
Contents

Page

Preface.______-_.__-__-_-__-.-..-._-__-_..-_----_ vii

Introduction ___________________________________ 1

Geographic setting._____________________________ 8

The landscape and its attributes ___________________ 13

The Western Uinta Mountains._______________ 14

Peaks and ridges________________________ 14

Drainage basins,________________________ 16

Sculpture by moving ice__________________ 17

Extent of the ice_ ________________________ 18

Rock-rubble deposits at high altitudes. _____ 26

The Eastern Uinta Mountains.________________ 29

Dutch John-Cold Spring highland. ________ 32

Diamond Mountain highland _____________ 33

Douglas Mountain highland._____________ 35

Blue Mountain highland_________________ 36

The great canyons of the Green and Yampa

Rivers___________________________ 38

Flaming Gorge to Browns Park._______ 40

Browns Park_______________________ 42

Lodore Canyon_____________________ 47

Yampa Canyon_____________________ 48

Whirlpool Canyon and Island Park____ 51

Split Mountain Canyon ______________ 54

How the canyons were formed _________ 55

Other drainage adjustments. __________________ 67

Weber, Provo, and Bear Rivers.___________ 68

Rock Creek and the DuchesneRiver_..______ 73

Glacial diversions on the north flank ________ 73

Time and the rocks______________________________ 77

The old Uinta trough. _______________________ 80

Precambrian time___________________________ 80

Pale.ozoic time: 570-225 million years ago. ______ 83
Page

Time and the rocks Continued

Mesozoic time: 225-65 million years ago________ 87

Cenozoic time: 65 million years ago to the present. 102 

The Tertiary Period and the beginnings of

the modern-day landscape____________^_ 102

Geologic structure.______________________________ 107

Folds_____________________________________ 109

Faults _____________________________________ 115

Crustal warping_ ____________________________ 121

Quaternary crustal movements ________________ 122

What the future holds. ___________________________ 124

Just a few words about the animals. ________________ 125

References _____________________________________ 128

Index _________________________________________ 131
Figures

Page

1. Regional geographic setting of the Uinta Mountains_____________________________________ 9

2. The Uinta Mountains________-_________-____ 11

3. Glacially sharpened Red Castle.______________ 13

4. Ice-sculptured peak at head of Rock Creek

basin _______________________^____________ 15

5. Felsenmeer, valley of Yellowstone Creek. ______ 15

6. Glacial lake near the Duchesne-Bear River

divide.__________________________________ 17

7. Glaciations of the Uinta Mountains.___________ 19

8. Ice Age glaciers of the Uinta Mountains._______ 21

9. Stillwater Fork of the"Bear River_ _____________ 23

10. Brush Creek Gorge__________________________ 24

11. Duchesne-Bear River divide__________________ 25

12. Debris-mantled slopes at the head of Blacks Fork. 26

13. Active rock glacier._________________________ 28

14. Major physiographic subdivisions of the Eastern

Uinta Mountains,________________________ 30

15. Stuntz Ridge, on the south flank of Blue Mountain_____________________________________ 36

16. Graphic profile of the Green River.____________ 38

17. Flaming Gorge, viewed downstream.__________ 39

18. Red Canyon________________.______________ 41

19. Browns Park_______________________________ 42

20. Geologic section across Browns Park___________ 44

21. Lodore Canyon from Douglas Mountain _______ 45

22. West wall of Lodore Canyon_ ________________ 46

23. True-scale profiles of Lodore Canyon__________ 48

24. EchoPark_________________________________ 49

25. Yampa Canyon.___________________________ 50

26. Whirlpool Canyon__________________________ 51

27. View northeast from Harpers Corner__________ 52

28. Island Park________________________________ 53

29. Geologic section through Split Mountain_______ 54

30. Split Mountain_____________________________ 57

31. Present distribution of the Browns Park Formation _____________________________________ 61
32. Development of the Green River drainage system 

in Tertiary time._________________________

33. Drainage adjustment at Dutch John Gap_______

34. Drainage adjustments of the Weber and Provo

Rivers _ _ ___________________^___________ 69

35. Development of Chalk Creek drainage.________ 70

36. Minor stream capture at Windy Peak._________ 71

37. Drainage adjustments of Rock Creek and the

Duchesne River._________________________ 72

38. Stream diversions by glacial obstructions_ ^ _____ 74

39. Rock formations of the Eastern Uinta Mountains_ 76

40. Contorted Red Creek Quartzite_____________ 82

41. Palisades of Sheep Creek.____________________ 85

42. Geographic map of the United States in Middle

Pennsylvanian time_______________________ 86

43. Triassic rocks in Sheep Creek Canyon.________ 88

44. Moenkopi Formation near Flaming Gorge______ 89

45. Glen Canyon Sandstone at Merkley Park_ _____ 91

46. At the dinosaur quarry______________________ 94

47. Fossil ripple marks._________________________ 96

48. Northeastern Utah and adjacent areas in Late

Cretaceous time__________________________ 99

49. Geographic map of the United States in Late

Cretaceous time_ __________________________ 100

50. The Glades, near Flaming Gorge_ ____________ 101

51. A well-preserved Eocene fish_ ________________ 104

52. TheBridgerFormation_____..________________ 105

53. Structural "grain" of the region_______________ 106

54. Geologic cross section through the Western Uinta

Mountains. ______________________________ 109

55. Flat-lying strata at crest of the Uinta Mountains. 110

56. Dipping strata at Sheep Creek Canyon ________ 111

57. Generalized structure map of the Uinta Mountains ____________________________________ 113

58. Geologic cross sections through the Eastern Uinta

Mountains ______________________________ 114

59. Uinta fault_ _______________________________ 117

60. Dragged strata along Mitten Park fault._______ 119

61. Crest fault_________________________________ 120

62. GoslinMountain_________________________.__ 121

63. Quaternary faults cutting glacial outwash_ _ _ _ _ _ 122
Introduction

-Xts

'I

, 7?1 «, #*$:«£ - '", (£** xT****"'- S.VT

 A." . < « .." . r^*Jt 

3^ - .'*'

c

Gates of Lodore

HE OPENING of the West after the Civil War greatly 

stimulated early geologic exploration west of the 100th Meridian. 

One of the areas first studied, the Uinta Mountains region, gained 

wide attention as a result of the explorations of three Territorial 

Surveys, one headed by John Wesley Powell, one by Clarence 

King, and one by Ferdinand V. Hayden. Completion of the 

Union Pacific Railroad across southern Wyoming 100 years ago, 

in 1869, materially assisted geologic exploration, and the railheads at Green River and Rock Springs greatly simplified the 

outfitting of expeditions into the mountains.

The overlap of the Powell, King, and Hayden surveys in the 

Uinta Mountains led to efforts that were less concerted than competitive and not without acrimony. Many parts of the area were 

seen by all three parties at almost the same time. Duplication was 

inevitable, of course, but all three surveys contributed vast quantities of new knowledge to the storehouse of geology, and many 

now-basic concepts arose from their observations.

1
Powell's area of interest extended mainly southward from the 

Uinta Mountains to the Grand Canyon, including the boundless 

plateaus and canyons of southern Utah and northern Arizona. 

King's survey extended eastward from the High Sierra in California to Cheyenne, Wyoming, and encompassed a swath of country more than 100 miles wide. Hayden's explorations covered 

an immense region of mountains and basins from Yellowstone 

Park in Wyoming southeast throughout most of Colorado.

Powell first entered the Uinta Mountains in the fall of 1868, 

having traveled Tiorth around the east end of the range from the 

White River country to Green River, Wyoming, then south over 

a circuitous route to Flaming Gorge and Browns Park, and finally 

back to the White River, where he spent the winter. In 1869, after 

reexamining much of the area visited the previous season, Powell 

embarked on his famous "first boat trip" down the Green and 

Colorado Rivers. This trip was more exploratory than scientific; 

his second, more scientific trip was made 2 years later. Powell revisited the Uinta Mountains in 1874 and 1875 to complete the 

studies begun 6 years earlier. His classic "Report on the Geology 

of the Eastern Portion of the Uinta Mountains and a Region of 

Country Adjacent Thereto" was published in 1876.

King's survey officially "The United States Geological Exploration of the Fortieth Parallel" is better known simply as the "40th 

Parallel Survey." King began working eastward from California 

in 1867. The Uinta Mountains region, however, was mapped by 

S. F. Emmons, under the supervision of King, in the summers of 

1869 and 1871. Emmons' work was monumental, and although 

he emphasized in his letter of transmittal to King the .exploratory 

nature of the work as the formal title of the report indicates 

his maps, descriptions, and conclusions reflect a comprehensive understanding of the country and its rocks. The 40th Parallel report 

contains the best, most complete early descriptions of the Uinta 

Mountains. It, indeed, is a treasurechest of information and a 

landmark contribution to the emerging science of geology.

Hayden visited the Uinta Mountains in 1870, descending the 

valley of Henrys Fork to Flaming Gorge in the fall after having 

earlier examined the higher part of the range to the west. Most of 

Hayden's observations were cursory, and he repeatedly expressed 

regret at having insufficient time for more detailed studies. In reference to the area between Clay Basin and Browns Park, he re-
marked (Hayden, 1871, p. 67) somewhat dryly that "the geology 

of this portion of the Uinta range is very complicated and interesting. To have solved the problem to my entire satisfaction would 

have required a week or two." Eighty-odd years later I spent several months there looking at the same rocks.

Powell was perhaps more creative more intuitive than either 

King or Hayden, and his breadth of interest in the fields of geology, 

physiography, ethnology, and conservation was enormous. King's 

work, however, was distinctly more disciplined and reflected both 

his early professional training at Yale, perhaps, arid the professional acumen of his subordinates. Powell was largely self-taught; 

Hayden was formally trained as a surgeon. PowelPs reports are 

almost lyrical, but King's are more erudite, better organized, and 

more complete as to details than either Powell's or Hayden's. Hayden's reports are chaotic, possibly because he demanded and attained early publication of his findings. His practice was to publish annual reports and, to his lasting credit, most of his results 

appeared in print within a year of his fieldwork. So far as the Uinta 

Mountains are concerned, Hayden's thinking was more modern 

and more sophisticated than that of either of his colleagues.

One example serves to illustrate: The Uinta Mountain Group 

(Precambrian) rests on the Red Creek Quartzite (older Precambrian) with an angular unconformity of considerable local relief. 

A local relief of several tens of feet is evident in many places, and at 

several places it is more than 50 feet. At one place, the relief may

An unconformity. Ancient folded rocks eroded and overlain by tilted younger

rocks
be several hundred feet in a horizontal distance of about a mile. 

The early geologists who visited the area, especially Powell, made 

much of the supposed great magnitude of the unconformity. 

Powell deduced 8,000 feet or more of exposed relief, observing 

correctly the sharp local relief but apparently mistaking a fault 

to be an unconformable contact. Extrapolating further, Powell 

visualized that a lofty headland 20,000 feet high had been buried 

beneath the sediments of an ancient Uinta sea. King concurred. 

But Hayden's view (1871, p. 66) was much more modern: "I am 

inclined to believe that the immense thickness of quartz [Red 

Creek] was thrust up beneath the red quartzites [Uinta Mountain 

Group] carrying the latter so high up that they have been swept 

away by erosion." The Red Creek Quartzite, we now know, was 

indeed uplifted relative to the Uinta Mountain Group by faulting. Although Hayden spent but a month exploring virtually the 

whole north flank of the Uinta Mountains, from the Bear River 

on the west to Browns Park on the east, he had an unmistakable 

grasp of the geology.

Other geologists of note visited the Uinta Mountains in the 

closing decades of the 19th century, about the time of the Territorial Surveys or shortly thereafter. In 1870 O. C. Marsh, a leading paleontologist of his day, began a study of the Tertiary vertebrates of the Green River Basin, particularly the rich faunas of 

the Bridger Forrriation. Marsh's study was made in open competition with E. D. Cope of the Hayden Survey. Marsh, of Yale University, was assured early publication in the American Journal 

of Science published at Yale. Cope therefore resorted to telegraphing fossil descriptions to his publisher to protect his priority of 

discovery (Merrill, 1906, p. 598).

Marsh visited the Uinta Mountains briefly in the fall of 1870 

and published a short description of his travels the following spring 

(Marsh, 1871, p. 191). Marsh Peak, looming above Vernal, bears 

his name. Heading south from Fort Bridger, Wyoming, Marsh followed Henrys Fork to its mouth. He turned east at Flaming Gorge 

to Browns Park, then went south to the Uinta Basin, staying well 

west of Lodore Canyon, via what is now Pot Creek and Diamond 

Mountain Plateau. Returning to Fort Bridger, he recrossed the 

mountains by way of the Uinta River and Sheep Creek Gap, probably skirting North and South Burro Peaks. From some point in his 

descent of the north flank of the Uinta Mountains, Marsh reported
that "While descending the northern slope' of the mountains 

toward the great Tertiary basin of the Green River, which lay in 

the distance, 2,000 feet below us, we passed oyer a high ridge, 

from the summit of which appeared one of the most striking and 

instructive views, of geological structure to be seen in any country. 

Sweeping in gentle curves around the base of the mountains, from 

near where we stood, many miles to the northward, was a descending series of concentric, wave-like ridges, formed of the upturned 

edges of different colored strata, which dipped successively away 

from the Uintahs; those nearest to us, 40° or more, those at a 

distance, seemingly but little altogether a scene never to be forgotten." Marsh could only have been looking north toward 

Lucerne Valley, from Windy Ridge above Sheep Creek, with 

Jessen Butte to his left and Flaming Gorge to his right; this view 

is repeated nowhere else on the north flank of the range. Sheep 

Creek Gap, which, in Marsh's words (1871, p. 197), was "a 

narrow and almost impassable side ravine," now contains paved 

Utah State Highway 44.

Unusually rich vertebrate faunas in the Bridger and Uinta 

Formations attracted other paleontologists, among them Joseph 

Leidy, W. B. Scott, H. F. Osborne, and Earl Douglass. Leidy, 

whose namesake is Leidy Peak, south of Manila, collaborated with 

King. Scott and Osborne represented Princeton University. Later, 

in 1909, Douglass, of the Carnegie Institution, discovered the 

famous dinosaur-bone deposits north of Jensen, Utah, in what 

is now Dinosaur National Monument. These paleontologists were 

interested primarily in the fossil-bearing beds of the basins, particularly those in the badlands where rock exposures are maximal, 

concealment by soil or vegetation is minimal, and the chances of 

finding fossils are optimal. If they visited the forested valleys and 

ridges of the high mountains, they made little note of it, though 

after a hot day of digging in the badlands, they must have glanced 

wistfully at the snow-flecked peaks.

C. A. White reviewed the geology and physiography of the 

Eastern Uinta Mountains in 1889, using, of course, much from the 

works of Powell, King, and Hayden. White described the Eastern 

Uintas in some detail, particularly the folded rocks-at the flanks of 

the range, calling attention to the unusual relations of geologic 

structure to drainage in the remarkable canyon country of the 

Green and Yampa Rivers. How, questioned White, were streams
that were flowing in open valleys on both sides of the range able 

to establish and maintain courses across the mountains? Like 

Powell, with whom White had been associated in the field, White 

attributed the relations to "antecedence" though he did not use 

the term to a belief that the drainage preceded the folding and, 

through vigorous erosion, maintained its course as the mountains 

rose beneath it. In 1877 Emmons had expressed a contrary view. 

He believed that the course of drainage across the Uinta Mountains was superimposed from an earlier, simpler terrain later 

eroded away onto the present complex one. His view, with modifications, is favored here. The details of this bold concept are outlined on a later page. In brief, a stream initiates its course in a particular geologic setting, such as a sloping alluvial plain. Then, as it 

erodes downward it uncovers new, perhaps adverse, rock conditions at depth, but -being now held in by canyon walls of its own 

making it is compelled to remain in its established course. "The 

sihupusness and, irregularity of the course of the Green River 

through the Uinta Range, and its independence of the present 

topographic features of the region," said Emmons, "suggest that 

it must have been determined originally in rocks of an entirely different nature from those, through which it now lies."

C. R. Van Hise visited the Uinta Mountains in 1889 to look 

at the Precambrian core of the range. Van Hise was a leading 

authority on the Precambrian rocks of the United States, and he 

(1892, plate 8) showed insight in assigning the Uinta Mountain 

Group to the Precambrian at a time when most geologists still 

considered it to be Paleozoic. Powell apparently had already 

reached a similar conclusion as early as 1877, according to White 

(1889, p. 687).

The impact of -the Uinta Mountains on early geologic thinking is hinted at by the names that were given to the great peaks. 

Most mountain ranges, by the names of their summits, honor the 

memories of statesmen, politicians, or explorers. The Uintas honor 

geologists. But to be a successful geologist in the third quarter 

of the 19th century, one perhaps had also to be a statesman and 

a politician, and certainly an explorer. Powell was all of these, 

and he excelled as each. Strangely, no Uinta peak bears his name, 

although he himself named many landmarks mountains, 

streams, and canyons throughout the Uinta Mountains and the
Colorado Plateau.1 Pow«lPs names are inclined to be imaginative 

and descriptive, if not downright dramatic Flaming Gorge, 

Kingfisher Canyon, Beehive Point, Swallow Canyon^ Canyon of 

Lodore, Echo Park, Dirty Devil River, Music Temple, and Bright 

Angel Creek, to mention but a few. He also changed the name 

of Browns Hole to Browns Park.

No less than a dozen major Uinta Mountain summits bear the 

names of early-day geologists or topographers Hayden, Agassiz, 

Wilson, Gilbert, Emmons, and King among them. Kings Peak, at 

an altitude of 13,528 feet, is the highest point in the State of Utah. 

Kings Peak, incidentally, is not on the main divide of the Uinta 

Mountains but rises from a subsidiary ridge a mile to the south.

1 After this bulletin was written,. I submitted the name "Mount Powell" 

to the Board of Geographic Names, for a previously unnamed 13,159-foot 

peak at the crest of the Uinta Mountains just east of Red Castle, between 

Henrys Fork and the East Fork of Smith Fork. This name has since been 

approved and will appear on "maps published by the Government in the 

future. Also, the new 7 J/a-minute quadrangle map on which Mount Powell is 

shown is designated the "Mount Powell quadrangle."
Geographic

setting

EOGRAPHERS divide the Rocky Mountain System in the 

Western United States into three parts: the Northern, Middle, 

and Southern Rocky Mountains. The Middle Rocky Mountains, 

of which the Uintas are a part, extend southward from southern 

Montana, through eastern Idaho and western Wyoming, into central Utah and include such ranges as the Teton, Wind River, Salt 

River, and Wasatch. The Uintas are bounded on the north (fig. 1) 

by the Green River Basin, the Rock Springs uplift, and the Washakie and Sand Wash Basins. They are bounded on the south by 

the Uinta and Piceance Basins, which are separated by the 

Douglas Creek arch. Thus, the Uinta Basin is the counterpart 

of the Green River Basin; the Douglas Creek arch is the counterpart of the Rock Springs uplift; and the Piceance basin is the 

counterpart of the Washakie and Sand Wash Basins. The 

Uinta Basin, the Douglas Creek arch, and the Piceance basin 

are components of the Colorado Plateaus province; hence, the 

south margin of the Uinta Mountains also coincides with the north 

margin of the Colorado Plateaus.

The Uinta Mountains have an overall length of about 150 miles 

and a mean width of about 35 miles. At their widest, toward the 

west,, they are more than 45 miles across, and at their narrowest, 

near the center of the range, they are less than 30 miles across. 

The boundaries are somewhat indefinite, inasmuch as the flanks 

pass into bordering hogback ridges and broad sloping mesas that 

merge gradually with the high arid tablelands of the adjacent 

basins. Figure 2 gives an overall impression of the setting and 

shape of the range.
WIND RIVER 

RANGE

GREEN RIVER 

BASIN GREAT DIVIDE 

BASIN

WASATCH 

PLATEAU

ROCK

SPRINGS

UPLIFT

FOUNTAINS

WASHAKIE 

BASIN

SAND WASH BASIN

UINTA BASIN

COLORADO

I SAN RAFAEL 

SWELL

WHITE 

RIVER 

UPLIFT

UNCOMPAHGRE 

UPLIFT

0

:_

100 MILES

REGIONAL GEOGRAPHIC SETTING of the Uinta Mountains, showing 

distribution of mountainous uplifts and basins. Darkest shading indicates Middle 

Rocky Mountains. (Fig. 1)
w^iP-fc^'/ £** '' ".15 .jaifJaif *J ;~rt-&i'at ;~^-iJ v'/y/v *** *£« & $*" / ~

t ;'Jir-*mal0P*l~£3[ i Jf 3t\-&£, »tf &»&?^

f- ^^ ^^ &>'/&3&fe*??*?? Lt, ¥ / -^^f»^^-^'te^^--- . f '^A'&'A/v fi\***9m?lriK I '> ' HX^X' * ^TIBTOIBS- *

\!^T^f&^^ ^JtAfr'^-''- . - JHss^ ^^%£J^jM ^' "Jl*'f'-L --'-^

10
Rock . Jf .,<'' '" 

ings^^r^-""

WYOMING

yy////.

bW/,

COLORADO

m

BASI.N|

,$1 S' \\

"j f >*<*J,- k *: ~ li ' B^-r-^r ' S 

-'-M* X*T

 ^J "/\7f ' ' ;

^" ' .' '. :,

LOCATION MAP

/- * * -

WYO

2 Dinosaur National

O Monument Headquarte

THE UINTA MOUNTAINS. (Fig. 2)

11
ARETE. Glacially sharpened Red Castle, viewed from the west, dominates 

skyline above Smith Fork just north of the Uintq crestline. Massive flat bedding 

characterizes the Uinta Mountain Group (Precambrian) in this area. (Fig. 3) [>

The Uinta Mountains have been carved from an immense anticlinal uplift, an upward flexing of the earth's crust which nearly 

coincides with the outer limits of the range. This great fold is 

described in some detail on the pages that follow. Down through 

countless centuries, the fold has been attacked and dissected by 

the elements, and in its present eroded form, it is largely responsible 

for the overall character of the range.

For a better understanding of the physical and spatial relations 

of the Uinta Mountains, topographic maps are an invaluable aid. 

Good topographic coverage is available at small scales for ^the 

entire range, and at modern large scales for most of it. Modern 

detailed maps by the U.S. Geological Survey are published at a 

scale of 1:24,000 (2,000 feet per inch). These maps, with a~green 

forest overprint, show roads, trails, buildings, lakes, meadows, and 

springs, and they identify most of the named landmarks. The old 

Coalville (1900), Hayden Peak (1901), Gilbert Peak (1905), and 

Marsh Peak (1906) quadrangle maps, at a scale of 1:125,000

(2 miles per inch), show graphically most of the west half of the 

range, although most of the altitudes have been revised with modern mapping, and the culture is out of date. These fine old maps 

are slowly disappearing from stock and soon will be collector's 

items. Regional relations are very well shown by the 1:250,000

(4 miles per inch) Salt Lake City and Vernal topographic sheets, 

which together portray the entire range. These maps were prepared by the U.S. Army Map Service and are -published in civil 

edition by the U.S. Geological Survey. Plastic raised-relief editions of these maps, available from the U.S. Army Map Service, 

depict the physiography exceedingly well in three dimensions and 

enable the user to see the form of the mountains in a way not 

otherwise possible. Excellent forest maps of the Wasatch and Ashley National Forests are available from the U.S. Forest Service. 

These maps show roads, trails, peaks, streams, and lakes and include a large part of the Uinta Mountains.

12
The landscape 

and its attributes

-.J IMBERLINE in the Uinta Mountains is at an altitude of 

about 11,000 feet. All the high peaks and ridges above that altitude, from Mount Watson on the west to Marsh Peak on the east, 

are in the west half of the range. The range, in fact, can be divided 

topographically as well as structually into west and east counterparts, here referred to as the Western and Eastern Uinta Mountains, respectively, or more simply, as the Western and Eastern 

Uintas. The often-used name "High Uintas" is synonymous with 

the Western Uinta Mountains. A broad low pass north of Vernal, 

drained by Cart Creek on the north and by a tributary of Brush 

Creek on the south, separates the two parts of the range.

13
The Western Uinta Mountains

Peaks and ridges

The main divide, or "backbone," of the Western Uinta Mountains is a narrow sinuous ridge more than 60 miles long and rarely 

as much as a mile across at its base, extending from Hayden Peak 

on the west to Leidy Peak on the east. Until late Tertiary time this 

ridge probably was the Continental Divide. The base of the ridge 

stands near or somewhat above timberline, 11,000-12,000 feet 

above sea level. The crest is 1,000-2,000 feet higher. From the 

head of Stillwater Fork, east of Mount Agassiz, to Island Lake, 

east of the Burro Peaks a distance of about 43 miles the base 

of the ridge is nowhere less than 11,500 feet above sea level; 

most of it is higher than 12,000 feet. North and south from the 

main divide are many subsidiary spurs and ridges, most of them 

equally narrow, equally sinuous, and as high or higher than the 

main divide. The new topographic maps of the Uinta Mountains 

show 26 individual summits, including some subordinate peaks, 

that stand more than 13,000 feet above sea level; however, only 

nine of these are on the main divide.

Particularly near the crest of the range, the summit ridges are 

mostly steep sided forms that alpinists would call aretes. Exposed 

ledges of bedrock, mantled only here and there by talus, are surmounted by little or no flat space at the ridgeline (figs. 3 and 4). 

Subordinate ridges between canyons, on the other hand, commonly broaden away from the crest into lofty plateaus 10,000- 

12,000 feet above sea level. These ridges, and wide places along the 

crest itself, are covered with loose angular rubble a vast felsenmeer or "block field," subjected since Tertiary time to the relentless attack of frost and water (fig. 5). Perhaps most of this rubble

14
JftlitfGLACIAL LANDSCAPE high on the south flank of the Uinta Mountains. 

Unnamed ice-sculptured peak, altitude 12,385 feet, at head of Rock Creek 

basin, looms above morainal ridge in foreground. Photograph by Max D. 

Crittenden, Jr. (Fig. 4)

FELSENMEER. Jumble of frost-riven blocks tops ridges unreached by Ice Age 

glaciers. Valley of Yellowstone Creek, viewed toward the northeast. Compare 

with figures 3 and 4. Photograph by Max D. Crittenden, Jr. (Fig. 5)

15
GLACIAL LAKE near the Duchesne-Bear River divide. Hundreds of such

lakes were left in the Uinta Mountains in the wake of the melted Ice Age \

glaciers. Photograph by Hal Rumel. (Fig. 6) O ]

is a product of the past severe climate of the Pleistocene Epoch, or 

Great Ice Age. At that time, the valleys below were buried repeatedly under great accumulations of moving ice, which swept away 

all loose rock and redeposited it downstream. But the exposed 

ridges, standing high above the ice, were under almost continuous 

attack by frost.

Frost has a ratcheting effect on rocks. Water percolates into an 

opening, freezes and expands, widens the opening, thaws, percolates deeper, refreezes, widens the opening further, and so on. 

Eventually, solid rock is split asunder. The process is effective at 

high altitudes throughout the World and in the polar regions. It is 

particularly effective on brittle jointed quartzite, like that in the 

High Uintas, where moisture has ready access to cracks and 

bedding planes. Even today the process there is very active, inasmuch as freezing temperatures can occur in any month of 

the year. The effect of the process is to soften the sharp outlines 

left by the ice the aretes, headwalls, and cirque basins are all 

being modified by frost, snowmelt, gullying, and wind. If the 

present process continues long enough, the steep-sided ridgelines 

will eventually become mere rubble-covered mounds, buried in 

their own debris.

Drainage basins

The summit ridges of the Western Uintas form the watersheds 

of several major drainage basins. Water falling on the north flank 

drains to the Great Basin via the Weber and Bear Rivers, which 

empty into the Great Salt Lake, and to the Green River Basin 

via Blacks Fork of the Green, Smith Fork, Henrys Fork, Beaver 

Creek, Burnt Fork, Sheep Creek, and Carter Creek. The south 

flank is drained by the Provo, which flows to Utah Lake in the 

Great Basin, by the Duchesne, which flows to the Green River in 

the Uinta Basin, and by such tributaries of the Duchesne as Rock 

Creek, Lake Fork,- Yellowstone Creek, the Uinta River, and the 

Whiterocks River. Ashley Creek and Brush Creek, near Vernal, 

flow independently to the Green River in the Uinta Basin.

16
Sculpture by moving ice

All these streams head near the crest of the range in broad amphitheaterlike basins, or compound cirques, some of extraordinary 

size, scoured out by now-extinct Pleistocene glaciers. Lying near 

timberline, most of these basins are floored by glacially abraded 

bedrock mantled only in part by soil and vegetation. In aggregate, the basins contain hundreds of lakes and ponds some in 

hollows eroded from solid rock, others dammed by glacial moraines 

(fig. 6). Many lakes are arranged in stair-step fashion, one above 

another; the seven Chain Lakes at the foot of Mount Emmons and 

the Red Castle Lakes of Smith Fork are good examples. In a setting 

of deep forests and alpine meadows the silent beauty of these lakes 

enhances the lonely splendor of the mountains. Emmons, in 1877, 

duly impressed by what he had seen, reported that "The scenery of 

this elevated region is singularly wild and picturesque, both in 

form and coloring. In the higher portions of the range, where the 

forest-growth is extremely scanty, the effect is that of desolate 

grandeur; but in the lower basinlike valleys, which support a

17
heavy growth of coniferous trees, the view of one of these mountain lakes, with its deep-green water and fringe of meadowland, 

set in a sombre frame of pine forests, the whole enclosed by high 

walls of reddish-purple rock, whose horizontal bedding gives almost the appearance of a pile of Cyclopean masonry, forms a picture of rare beauty." A few lakes can be reached by automobile, 

especially those in the Mirror Lake-Bald Mountain area on Utah 

State Highway 150. But most of them are accessible only on foot 

or horseback, just as in Emmons' time.

Extent of the ice

The great amphitheaters along the crest of the range extend 

basinward into long steep-sided canyons 2,000-3,000 feet deep. 

During the Great Ice Age these canyons contained large trunk 

glaciers that moved outward from their catchments in the amphitheaters toward their termini near the mountain flanks (fig. 8). 

The form of the amphitheaters and canyons, in fact, is due to the 

scouring action of the ice on their walls and floors. At one time 

some of the glaciers extended well beyond the mountains onto the 

adjacent plains. Several were more than 20 miles long; the longest 

known was the Blacks Fork glacier on the north slope, which, according to Bradley (1936, plate 34), deposited its outermost 

moraine on the plains of the Green River Basin 38 miles north of 

the crest. At an early glacial stage several glaciers on the north 

slope merged into broad piedmont ice sheets. The longest known 

glacier on the south slope was the Uinta River glacier, which 

was about 27 miles long. However, the merged Lake Fork and 

Yellowstone Creek glacier was more massive. Altogether, the ice 

at its maximum extent covered at least 1,000 square miles, according to W. W. Atwood (1909), who first studied in detail 

the effects of the glaciers on the Uinta Mountains. No doubt, the 

ice was much more extensive at one time than Atwood estimated 

because he based his estimate on the extent of relatively late 

Pleistocene glaciers, which were confined largely to the valleys. Atwood was unaware of the farreaching older glaciations, discovered 

later by Bradley, or of extensive piedmont deposits more recently 

mapped by the Geology Department of the University of Utah 

(Stokes and Madsen, 1961). Perhaps the total extent of the 

glaciers was closer to 1,500 square miles.

18
Atwood identified two distinct "epochs" of glaciation and suggested a third. Bradley (1936), although he made no attempt to 

study the glaciations systematically, identified three stages, including one considerably older than Atwood's "earlier glacial epoch." 

This, he called the "Little Dry Stage" for the morainal deposits 

near Little Dry Creek south of Mountainview, Wyoming. Richmond (1965) recognized two additional younger "stades" high 

in the mountains and subdivided Atwood's two "epochs" into 

five "stades" (fig. 7).

Atwood 

(1909)

Later 

glacial 

epoch

Earlier 

glacial 

epoch

Bradley 

(1936)

Smith 

Fork 

Stage

Blacks 

Fork 

Stage

Little

Dry

Stage

Richmond 

(1965)

Neoglaciation

15 'J3 "B-§

kill Lake Tlaciation

Gannett

Peak 

Stade

Temple

Lake

Stade

Late

stade

Middle 

stade

Early

stade

Late 

stade

Early

stade

Years 

ago

800-900

4,000

6,500 

10, 000

'

25, 000- 

32, 000 

45, 000

Pre-Bull Lake

glaciations

Character

Small cirque glaciers. Fresh

young moraines just below the cirque headwalls ; 

protalus ramparts, and 

rock glaciers that support 

no vegetation.

Cirque glaciers. Fresh young

moraines on or near floors

of cirques. Rock glaciers.

Scanty vegetation.

Valley glaciers. Massive 

bouldery fresh-looking 

moraines, both terminal 

and lateral. Striations, 

flutings, and polish on 

bedrock.

Valley glaciers. Massive 

terminal moraines, 

weathered and eroded.

Valley and piedmont

glaciers. Deposits deeply

eroded. Former extent

not fully known.

CORRELATION CHART, showing slaciations of the Uinta Mountains. (Fig. 7)

19
4j . ' ^~*\

* Xx s^ f /

' *r * .!.,* 

20
_i &t if v i,Ji\!\n\^f

Piedmont "*' UTAH

^ I'

ICE AGE GLACIERS of the Uinta Mountains. Maximum known and inferred 

extent of ice. Piedmont glaciers shown on the north flank of the range existed 

only in earlier glacial stages. (Fig. 8)

21
The effects of the glaciers on the Uinta Mountains are still 

clearly visible today, though many streams have since incised themselves into narrow inner gorges. U-shaped canyon profiles, truncated ridge spurs, hanging tributary canyons, falls and cataracts, 

and polished rock surfaces all testify to the abrasive action of moving ice. (fig. 9).

Although the glaciers swept the upper reaches of many canyons 

nearly clean of loose rock, they deposited, hummocky moraines in 

most of the downstream reaches. Some of these moraines are well 

shown on the new topographic maps, particularly those of the Taylor Mountain, Whiterocks Lake, Leidy Peak, Hole-In-The-Roek, 

and Gilbert Peak Northeast quadrangles. The Taylor Mountain 

quadrangle map shows massive looped moraines crowded with 

hundreds of little kettle ponds along the South Fork .of Ashley 

Creek. The Whiterocks Lake and Leidy Peak quadrangle maps 

show several sequences of downstream moraines on the forks of 

Sheep and Carter Creeks, as well as younger moraines high in the 

cirques and many cirque lakes. The Hole-In-The-Rock quadrangle 

map shows massive moraines of Bull Lake and Pinedale age and 

broad outwash plains along the West and Middle Forks of Beaver 

Creek. The Gilbert Peak Northeast quadrangle map shows a complex of large pitted moraines along Henrys Fork and an unusual 

constriction of the valley where the glacier flowed between resistant 

ramparts of Mississippian limestone.

Many canyons are choked with morainal debris for several miles 

above their mouths. Conspicuous terracelike lateral moraines extend along the valley sides. Especially on the north flank of the 

range in such canyons as Smith Fork, Henrys Fork, and the West 

Fork of Beaver Creek, the drainage through the morainal belts 

is interrupted by ponds, marshes, and meadows an ideal habitat 

for America's (and no doubt the World's) southernmost moose 

herd.

In the eastern part of the High Uintas, some valleys, such as 

Sheep Creek, Carter Creek, and Ashley Creek, were glaciated only 

in their upper reaches. Downstream from the heads of these valleys, 

broad U-shaped canyons carved by glaciers give way to extremely 

narrow precipitous gorges cut entirely by running water. Such 

gorges are greatly influenced in form and character by the particular rock formation into which they are cut. For example, canyons eroded into the Weber Sandstone one of the prime cliff22
STILLWATER FORK of the Bear River, a slaciated valley in the High Uintas. 

Pyramidal peaks, hanging tributaries, and flat valley bottoms are scenic products 

of the Ice Age. Ostler Peak is just left of center. Photograph by Hal Rumel. 

(Fig. 9)

forming units in the Uinta Mountains are wild and picturesque. 

Sheep Creek, Brush Creek (fig. 10), and Dry Fork of Ashley Creek, 

as well as the wonderful canyon of the Yampa in the Eastern 

Uinta Mountains, owe most of their grandeur to the Weber Sandstone. (See also fig. 25.)

A glance at a topographic map shows plainly that the crestline of the Western Uinta Mountains is closer to the north flank 

of the range than to the south flank. Streams draining the south 

flank are therefore longer than those draining the north flank. On 

the average, they are about twice as long. Their canyons are correspondingly long, and the amphitheaters at their heads are both 

longer and wider. Because the area available for the catchment 

of snow was larger on the south flank than on the north, the 

glaciers there were generally larger, too, except in an early pied23
BRUSH CREEK GORGE. A precipitous nonglacial gorge carved by running 

water. Walls of Weber Sandstone are capped by the Park City Formation. 

Flat-topped Taylor Mountain in distance is a remnant of the Gilbert Peak 

erosion surface, an ancient high-level plain. (Fig. 10)

mont (Little Dry Glaciation) stage of the north flank, when 

coalesced sheets of ice spread out beyond the mountain front.

At their maximum the glaciers on the south flank of the Uintas 

were able to eliminate many of the intervening divides of their 

headward tributaries and, in so doing, to carve out the great compound cirques, or amphitheaters, which now make the scenery so 

striking. In the southwestern part of the range, centered near Bald 

Mountain, the ice succeeded in removing all but a few isolated 

peaks. These peaks rose as nunataks, or islands of rock, above a 

massive icecap from which long tongues of ice extended radially 

down the canyons of the Bear, the Weber, the Provo, the Duchesne, and Rock Creek (fig. 11). Even Bald Mountain and other 

nearby peaks may have been covered by ice at an early stage 

of glaciation. Bald Mountain,appears to have been reshaped by 

ice moving across it from the northwest. If the ice ever was thick 

enough to cover Bald Mountain, the whole western part of the 

range at one time must have been locked in an immense, unbroken expanse of ice.

The glaciers of the south flank carved much larger amphitheaters than their northerly counterparts did and, thus, were 

evidently more effective in attacking their headwalls and broadening their cirques perhaps because they generally were larger and

24
had larger catchment areas. Why, then, should the northerly landscape be more rugged and alpine? The Uinta Mountains are at 

their scenic best north of the crestline between the Bear River on 

the west and Henrys Fork on the east; Red Castle at the head of 

Smith Fork is the crown jewel of the range.

Undoubtedly, the great amphitheaters date from an early glacial episode, perhaps the Little Dry Glaciation, which may really 

be a composite of several early glacial advances and a time or 

times when great thicknesses of ice nearly buried the range. The 

Little Dry ice may thus have opened the cirques, sapped away the 

tributary divides, and excavated the amphitheaters. Then, after a 

long warm interglacial period, when weathering had softened the 

contours of the land and the rivers had cut new canyons into the 

valley bottoms, the younger Bull Lake and Pinedale glaciers reoccupied the area. Although large, these glaciers were thinner and 

less massive than their predecessors. They reexcavated the valleys, 

eroded new U-shaped inner gorges, and attacked north-facing 

slopes and hillsides with great vigor, but they had minimal effects 

on the south-facing slopes of the divides themselves. Almost without 

exception, the younger glaciers were more effective against northfacing exposures than against south-facing ones.

DUCHESNE-BEAR RIVER DIVIDE, Western Uinta Mountains. All the dark 

forested area was covered by a Pleistocene icecap which flowed radially outward from the mountains. Low round summits in middle distance were overridden 

by the ice, as, perhaps, was Bald Mountain (lower left) at an early glacial 

stage. Photograph by Hal Rumel. (Fig. 11)

KETTLING PEAK

BALD MOUNTAIN
Rock-rubble deposits at high altitudes

DEBRIS-MANTLED SLOPES at the head of Blacks Fork of the Green River 

Rocky peaks and ridges are slowly being engulfed in their own talus. Note 

protalus ramparts, outlined by snowbanks (lower right). Photograph by Max D. 

Girfenden, Jr. (Fig. 12)

The felsenmeers of the Western Uinta Mountains (p. 14) are 

residual deposits that accumulated in place through long periods 

of sustained severe climate. Other deposits of loose rock, also riven 

by frost but transported some distance largely by gravity, have accumulated near the bottoms of slopes at many places in the higher 

parts of the range. Three distinct kinds of loose-rock accumulations grade into one another: talus, protalus, and rock glaciers. 

Although they are relatively minor features of the alpine landscape, 

in bulk and in topographic relief, they contribute greatly to the 

overall scenery. All three require a brittle blocky bedrock source.

Talus (fig. 12) is a sheetlike or conelike deposit familiar to all 

hikers in the high country. It blankets the feet of steep slopes or

26
cliffs in large accumulations of loose angular rubble often only 

marginally stable and containing poorly balanced blocks of rock 

weighing many tons a fine place for the unwary hiker to turn an 

ankle. Talus, however, is not confined to high altitudes in the Uinta 

Mountains; it is abundant below cliffs everywhere, as in Lodore 

and Red Canyons along the Green River in the Eastern Uinta 

Mountains.

Protalus and rock glaciers, on the other hand, are restricted to 

alpine settings in the Western Uintas, largely to areas above 

timberline. They are abundant, for example, in the Kings Peak, 

Wilson Peak, and Red Castle areas, in the highest part of the 

range.

Protalus accumulates in rampartlike deposits at the foot of 

semipermanent snowbanks or ice banks. Rocks are dislodged from 

above. They roll down the snowbank to its base where, when the 

snow finally melts,, they remain behind as low ridges. And inasmuch as thick accumulations of snow or ice obviously are essential to the process, protalus ramparts formed chiefly in the recent 

geologic past, the "neoglaciation" of the last few thousand years, 

when such accumulations of snow and ice were prevalent. Some 

ice accumulations at that time grew into small true glaciers and, 

thus, provided a link between protalus ramparts and small glacial moraines. No clear-cut distinction exists, in fact, - between 

moraines and protalus ramparts.. They share the same climatic 

and topographic setting, and they grade transitionally into each 

other. At the foot of Kings Peak, modern talus cones are forming 

across inactive neoglacial protalus ramparts.

Rock glaciers are abundant in the Kings Peak, Wilson Peak, 

and Red Castle areas also. Rock glaciers were first identified by 

S. R. Capps (1910) in the mountains of Alaska, but they have 

since been widely recognized in high mountains elsewhere. They 

have been described in a definitive paper by Wahrhaftig and Cox 

(1959).

Although rock glaciers consist largely of coarse angular rock 

fragments, they also commonly have cores of ice mixed with 

boulders, gravel, sand, and silt. Indeed, fed from above by avalanches and streams of talus, they are thought to move by intergranular flowage between ice and rock. Interstitial ice and a 

climate in which the ice can form are therefore essential for the 

nourishment and growth of rock glaciers.

27
Like true glaciers, active rock glaciers in the Uinta Mountains 

produce rock flour, a milky suspension of pulverized rock that 

causes turbidity in nearby lakes and streams. Rock flour is formed 

by the grinding action of rock particles rubbing against one another during glacier flowagc.

Rock glaciers resemble small true glaciers in shape, size, and 

mode of flowage (fig. 13). They form lobate mounds a few hundred feet high, a few hundred to a few thousand feet across, and 

generally less than a mile long. They have steep snoutlike fronts, 

sinuous longitudinal ridges analogous to medial moraines, and 

transverse ridges and furrows analogous to crevasses. They are, in 

brief, among the more intriguing details of the alpine scene.
The Eastern Uinta Mountains

Although the main divide is very well defined in the Western 

Uinta Mountains it is very poorly defined in the Eastern Uintas. 

Because the Eastern Uinta Mountains are more complex structurally than the Western Uintas, and because they have had a 

more complex Tertiary history, their physiography is more complex, and they lack the grand simplicity of the west half of the 

range. The main divide has shifted with time from a position 

that once must have coincided with the crest of the anticline to 

its present position on the south flank. The crest of the anticline, 

moreover, passes beneath the valley of Browns Park, which extends deep into the heart of the range and separates the northeast 

flank from the rest of the range.

The physiography of the Eastern Uinta Mountains is further 

complicated by the great canyon systems of the Green and Yampa Rivers. These canyons sources of awe and wonder since the 

days of the mountain men stimulated early-day thinking on many 

geologic problems, most particularly on folding and faulting, which 

are grandly portrayed, and on the relations of drainage development to the formation and growth of mountains. Speculation as 

to how the Green River established its course across the Uinta 

Mountains led Powell to introduce such terms as "superposition" 

and "antecedence" to identify processes by which streams are able 

to establish and maintain courses across mountain barriers. Although Powell coined the terms, he alone did not devise the 

concepts.

ACTIVE ROCK GLACIER causes turbidity in adjacent glacial lake, east side 

of Red Castle. Rock glacier is nourished by talus and avalanching. Lake is 

dammed by a moraine. (Fig. 1 3)

29
* 'Horseshoe. 

Canyon ~ 

fistftr

mF f^y-- ^P s*twarn

*^*' ~ ^F "53k. SwallowlLT^Mtn 

Ir^ '"it .T "'*K*: '-. Canyon TOfet .

^ff-J'S ^^-Sl^. ^W-**«n jT> '%: point ^^

f^ - « jt*?^ '"^ ":^

/. * « ^J^Z-^%, ~f-^ ^TJy^r 'fe. % ;

lop

igai" .DUTCH JOHNC*,COLD SPRING HIGHLAIN

- s -^.£2%k U.I-

% -sA *S*,'% '%:. 1*. J-.f ^?::.;,-vo ' r 'j£/^^% ^: :M$C "H\-;/J. ^^|L°"ore ' /^*"

 |?---;p-;;%: |s|and %^^Hok|ir o^ t ,f

:|:, Dinosaur ^v;;:,,. , pa^ -gm

^°'r^^*^ 

 :%,. ,""^^'0 ^ Harpers Corne 

, /%:. C^*°0 ', '^ii^

4 .*; ^t. T'O'

DIAMOND , , 

HIGHLAND

:l:; /" :

: ?:, Dinosau 

%. Quarry s y 

Jif'BROWNS

I, DOUGLAS MTN 

%^ HIGH LAND

( ^\\ion Blu/

Mtn

Lilly Park '

'7%.

BLUE MTN "=%

x HIGHLAND /.

MAJOR PHYSIOGRAPHIC SUBDIVISIONS, Eastern Uinra Mountains. (Fi g . 1 4)

30
Limb

An anticline, breached at its crest, or axis, by erosion

The canyons of the Green and Yampa are the most impressive 

features of the Eastern Uinta Mountains, but even without them, 

the mountains would possess much to fire the interest of the 

traveler and the imagination of the geologist. Physiographically, 

the Eastern Uinta Mountains are almost totally unlike their 

western counterpart. The lofty summits are lacking; no part has 

been glaciated; and there is no climatic timberline, although many 

of the summits are bare of trees. The highest point, Diamond 

Peak altitude 9,710 feet, and site of the infamous diamond hoax 

of 1872 is an outlier completely separated from the rest of the 

range. Mount Lena, south of Flaming Gorge Dam, at an altitude 

of 9,600± feet, is the highest point on the main divide. Most of 

the country lies below 8,000 feet.

Lacking high peaks to intercept moisture-laden air masses and 

standing in the rain shadow of the higher mountains to the west, 

the Eastern Uintas are relatively arid. Whereas parts of the Western Uintas probably receive 50 inches or more of moisture per 

year, only the Mount Lena area in the Eastern Uintas is likely to 

get half that much, and such places as Lucerne and Ashley Valleys get only 8-10 inches. Consequently, the pine, fir, and spruce 

forests of the Western Uintas give way largely to pigmy forests 

of juniper and pinyon, although stands of lodgepole pine are dense 

in the Mount Lena area, and, locally, elsewhere there are groves of 

ponderosa pine or stands of Douglas-fir. The lush high-altitude 

meadows of the Western Uintas have no eastern counterpart. If

31
any one characteristic thus identifies the Eastern Uinta Mountains, thanks to the aridity of the climate, it is well-exposed bedrock. Bedrock is everywhere in the bottoms and sides of gullies, 

along the ridges, in tremendous cliffs along the canyon walls, and 

on the faces and barren tops of the mesas. The plant cover is 

light, and the soil is thin.

Topographically, the Eastern Uinta Mountains are divisible 

into four large highland blocks separated by the canyons of the 

Green, the valley of Browns Park, and the canyon of the Yampa. 

These blocks, for convenience, can be referred to as (1) the Dutch 

John-Cold Spring highland, (2) the Diamond Mountain highland, (3) the Douglas Mountain highland, and (4) the Blue 

Mountain highland (fig. 14)..The intervening canyons are formidable barriers that make vehicular access from one highland 

block to another difficult, if not impossible. Thus, Diamond Mountain, Douglas Mountain, and Blue Mountain are mutually exclusive; none can be reached directly from either of the others. The 

Dutch John-Cold Spring highland can be reached from the south 

by a scenic mountain highway (Utah State Highway 44) that connects Dutch John to Vernal, by way of Flaming Gorge Dam. But 

before the dam was built, access from the south involved many 

circuitous miles of difficult driving.

Dutch John-Cold Spring highland

The Dutch John-Cold Spring highland is not really a topographic entity; rather, it is a heterogeneous belt of bare-topped 

hills, hogbacks, and mesas bounded vaguely by the Green River 

Basin on the north and the Flaming Gorge-Red Canyon-Browns 

Park valley complex on the south. On the east it terminates 

at Vermilion Creek, in a narrow slot 600 feet deep. This highland contains some of the most diverse topography, some of the 

most complex geology, and the oldest rocks in the entire Uinta 

Mountains; it also contains Utah's oldest commercial gas field, 

Clay Basin.

Large flat-topped mesas, such as Bare Top (Bear Mountain), 

Goslin, and Cold Spring Mountain, are remnants of a broad 

erosional plain that once extended along the flank of the moutains

32
for the length of the range, between the high peaks on the south 

and the basin on the north. Named the Gilbert Peak erosion surface and described by W. H. Bradley (1936), this plain has been 

faulted and tilted and has been dissected by deep canyons since 

it was formed.

Most of the Dutch John-Cold Spring highland is on the northeast limb of the Uinta anticline, where a great thickness of upturned strata is beveled by erosion and exposed to view. More 

than 20,000 feet of strata is exposed in one continuous section 

on Cold Spring Mountain, even though much of the total section 

is omitted from surface exposure by faulting. Altogether, the area 

contains more than 40,000 feet of strata, not counting the ancient 

metamorphosed Red Creek Quartzite, which forms the crystalline core of the range and which itself is probably 20,000 feet 

thick. Thanks to large-scale faulting and deep erosion, the Red 

Creek Quartzite is well exposed along the north side of Browns 

Park. The age of the Red Creek, as determined by radiometric 

dating, is 2.3 billion years."

Diamond Mountain highland

The Diamond Mountain highland, south of Red Canyon and 

Browns Park, is a dissected upland along the main divide of the 

Uinta Mountains. As seen from the south near Vernal, it presents 

an even skyline that belies a more rugged interior. It is surmounted 

by many craggy peaks and ledges of somber red quartzite and is 

flanked on the south by a thick sequence of colorful, well-exposed 

rock formations made up mostly of sandstone and limestone. It is 

almost completely enclosed by deep canyons and steep escarpments. On the west it is separated from the Western Uinta Mountains by a low pass which also provides the route for Utah State 

Highway 44. The pass drains north into Cart Creek, which 

meanders through a verdant meadow and plunges into a gorge 

a thousand feet deep before joining the Green River near Flaming 

Gorge Dam. The south side of the pass drains into Little Brush 

Creek through another gorge nearly as deep and even more 

precipitous.

2 A brief discussion of rock formations begins on p. 77.

33
On the north the Diamond Mountain highland is bounded 

by rugged terrain along Red Canyon and Browns Park. Several 

small spring-fed streams flow north in open valleys with floors 

of the soft Browns Park Formation. None of these streams has a 

mean flow of more than a few cubic feet per second. They then 

descend into narrow quartzite canyons, some of which rival Red 

Canyon itself, before joining the Green River. Grouse Creek is 

typical: its canyon affords access into Browns Park by way of a 

rough but generally passable truck road. The creek bottom is 

chocked with brush and trees cottonwood, boxelder, alder, choke 

cherry, red-osier dogwood, willow, wild rose, and poison ivy a 

good habitat for beaver, bobcat, and cougar.

The relation of these north-flowing streams to Pot Creek the 

"Summit Valley" of Powell's day is very strange. Pot Creek 

flows southeast the full length of the highland to Lodore Canyon. 

Yet the several divides between Pot Creek and the north-flowing 

drainages are low saddles only a few feet high. The whole drainage 

system of the Diamond Mountain highland is on the Browns 

Park Formation, which, in turn, fills an older pre-Browns Park 

valley system cut into the hard quartzite of the Uinta Mountain 

Group. In many places the present drainage is directly opposite 

the original drainage, and in some places, creeks flowing in opposite directions share the same pre-Browns Park valley. Many minor 

tributaries are "barbed"; they flow south into creeks that flow 

north. The distribution of the Browns Park Formation is very 

significant because the discordant relation of the Green and 

Yampa Rivers to the Uinta Mountains is tied to the deposition 

and removal of the Browns Park Formation.

On the east the Diamond Mountain highland is bounded by 

the deep chasms of Lodore and Whirlpool Canyons. From the rim 

of Wild Mountain at the southeast corner of the highland to the 

river below is a drop of more than 3,000 feet. Though a delight to 

white-water boatmen, these canyons are insurmountable barriers 

to cross-country travel; west of the canyons, a corner of Colorado 

is completely cut off from the rest of the State and can be reached 

only through Utah.

On the south the highland is bounded by the rim of the Diamond Mountain Plateau, a broad nearly flat upland and a likely 

correlative of the Gilbert Peak erosion surface of the north flank 

of the range. Diamond Mountain is capped by gravel and volcanic

34
ash of the Browns Park Formation. Diamond Gulch drains southeastward across this area in a course nearly parallel to that of Pot 

Creek. It joins the Green River in Whirlpool Canyon via Jones 

Hole, a hidden spring-fed valley of rare beauty.

Douglas Mountain highland

East of the Diamond Mountain highland, across Lodore Canyon, is Douglas Mountain. This dissected highland, nearly triangular in outline, is a jumble of cliffs, ledges, ravines, and parklike clearings. It is bounded on the north by an arid extension of 

Browns Park, on the east by the Little Snake River, and on the 

south by the twisty canyon of the Yampa. Access is only from the 

north over rough mountain roads and trails. Zenobia Peak, at an 

altitude of 9,006 feet, the highest summit, commands impressive 

views in all directions. It also is the highest point in Dinosaur 

National Monument.

Douglas Mountain is an area of brightly colored rocks. The 

brilliant white exposures of the Browns Park Formation, dazzling 

in the sun, contrast with the deep-red hues of the adjacent Uinta 

Mountain Group. Blue, gray, and pale-pink limestones cap Zenobia Peak and reach south in long sloping ridges toward the 

Yampa River. The canyons themselves are variegated in reds, gray, 

and buff, depending partly on the particular rock formation exposed in the walls and partly on the time of day. Douglas Mountain has a few small springs but no perennial drainage.

A monocline, faulted at deplh

35
Blue Mountain highland

South of Douglas Mountain, across Yampa Canyon, is Blue 

Mountain, the southeasternmost highland block of the Uinta 

Mountains. Steep, even precipitous, escarpments on the west, 

south, and east of this highland block are surmounted by an open, 

rolling interior, which rises gradually northward to the bald summits of Round Mountain, Marthas Peak, and Tanks Peak. Rewarding views are had from these peaks, also. To the north, the 

ground drops away more than 2,000 feet in a giant step down 

to the flats that rim Yampa Canyon. The river itself is another 

1,000 feet below.

Abrupt monoclinal folds characterize the flanks of the Blue 

Mountain block, and they are grandly displayed. Monoclines are 

steplike bends in otherwise flat or gently dipping strata. The monoclines were formed by the warping of strata across concealed faults, 

or by the sharp flexing of strata on the flanks of flat-topped anticlines. On Blue Mountain these structures owe their dramatic appearance to the erosive resistance of the Park City Formation, to 

the massive character of the underlying Weber Sandstone, and 

to the easy erosion of the overlying Moenkopi Formation. As the 

soft Moenkopi is stripped away, the Park City and Weber are left 

standing in enormous dip slopes and "flatirons."

STUNTZ RIDGE, a sharp monoclinal bend on the south flank of Blue Mountain. 

Eroded "flatirons" in front of ridge were once continuous with strata on top.

(Fi 3 .15)
One of the more spectacular folds of this type is just north 

of U.S. Highway 40, where Stuntz Ridge, a westward extension 

of Blue Mountain, forms a jutting promontory nearly 3,000 feet 

high (fig. 15). This remarkable flexure passes downward and 

laterally into a large fault.

Other flexures nearly as dramatic form the north face of the 

Blue Mountain, where the strata have been folded into sharp 

monoclinal bends along the Yampa fault and subordinate fractures in the stairstep noted before. These structures are seen to advantage from observation points along the high road to Harpers 

Corner, from Harpers Corner itself, or from the access road to 

Echo Park far below (fig. 60). Harpers Corner, incidentally, is the 

best canyon overlook in Dinosaur National Monument. It projects 

north as a sharp ridge from the main mass of Blue Mountain, 

where it looks down on Whirlpool, Lodore, and Yampa Canyons, 

and on Steamboat Rock at the confluence of the Green and Yampa 

Rivers.

To the west, on the same structural trend as the Yampa fault, 

is Split Mountain, a nearly symmetrical anticline breached to its 

core by the Green River (fig. 30). The outer shell of Split Mountain consists mostly of Weber Sandstone, which is deeply eroded 

into parapets, buttresses, and other fanciful architectural forms; 

even so, the outer shell reflects the overall shape of the fold. 

Younger rocks at the flanks form encircling hogback ridges and 

racetrack valleys; hard layers are etched into relief. The famous 

dinosaur quarry is on the sputh limb of the fold, where the dinosaur-bearing Morrison Formation is laid bare by erosion.

Split Mountain has been a source of wonderment since the days 

of Powell, particularly because a seemingly easier course for the 

Green River is available in the soft beds of the racetracks that encircle the anticline, as opposed to the hard rocks in the core. The 

river, however, had no other options at the time that downcutting began. Split Mountain did not exist as a topographic feature, 

and once entrenched, the river had no alternative but to pursue its 

established course. The "easy" course in the racetrack was eroded 

out later by tributaries. Meanwhile, the shape of the fold was 

brought into relief as soft beds were removed and hard beds were 

uncovered.

37
The great canyons

of the

Green and Yampa Rivers

The Green and Yampa Rivers arise in distant watersheds, fed 

by snowmelt from the Wind River and Park Ranges, as well as 

from the Uintas. Both streams flow in broad valleys, but they 

enter the Uinta Mountains in narrow gorges and flow across the 

mountains with a startling disregard for the geologic implications 

of their crossing. The sequence, altitudes, and gradients of canyons 

through the range ar^ shown graphically in figure 16.

G^V*" 

«&***

GRAPHIC PROFILE of the Green River across the Uinta Mountains from mouth 

of Blacks Fork to mouth of the White River. Data from Woolley, 1930, pi. 30. 

(fig. 16)

38
FLAMING GORGE, viewed downstream, as photographed by E. C. LaRue 

in 1914. Flaming Gorge Reservoir now fills the lower third of the canyon. Glen 

Canyon Sandstone, topping the cliff, overlies Chinle and Moenkopi Formations. 

(Fi 9 . 17)

One hundred years ago Powell and his aides floated leisurely 

through the twisty canyons of southern Wyoming on the first leg 

of their historic boat trip down the Green and Colorado Rivers. 

In PowelPs time the Green was regarded as the source of the Colorado. Just below the 41st parallel now the Utah State line the 

current quickened, and PowelPs party abruptly entered the Uinta 

Mountains. "The Green River enters the Uinta Mountains by 

a flaring, brilliant, vermilion gorge, a conspicuous and well-known 

locality, to which, several years ago, I gave the name Flaming 

Gorge." (Powell, 1876, p. 146). The same scene, viewed by E. C. 

LaRue in 1914, is shown in figure 17.

39
Flaming Gorge to Browns Park

Flaming Gorge Dam, completed in 1964, has greatly changed 

the appearance of the country upstream. Today, a manmade lake 

extends 90-odd miles to Green River, Wyoming; it forms a broad 

embayment above Flaming Gorge but constricts tightly at the 

gorge entry. The rapids are quiet, replaced by a f jordlike body of 

still, blue water, hardly more than twice the width of the former 

river in some places but elsewhere widened into bays and inlets. 

Whole mountains are now islands.

Flaming Gorge is cut into Jurassic and Triassic rocks. Its sweep 

and grandeur are due largely to its high cap of Glen Canyon Sandstone (the Nugget or Navajo Sandstone of earlier reports), but it 

takes its name from the riot of reds, ochers, and oranges in the shaly 

Triassic beds below. It is more a water gap than a gorge in the 

usual sense. At the portal the rocks are standing on edge, but, arching over, they flatten rapidly a short distance downstream. Just 

below Flaming Gorge, the shoreline of the reservoir swings left 

into the Weber Sandstone, which forms the smooth walls of Horseshoe Canyon. Curving right, through Horseshoe Canyon, the reservoir then turns back into Triassic rocks in a broad curve to the 

left, then right again into the Weber in Kingfisher Canyon. Powell 

met his first real rapid at the mouth of Kingfisher Canyon, where 

he crossed the great Uinta fault and entered Red Canyon (fig. 18). 

Red Canyon, about 30 miles long, is cut entirely in Precambrian 

rocks, except at Little Hole, a parklike opening underlain by the 

Browns Park Formation and a pleasant contrast to the rugged 

canyons upstream and down.

The roar of the river overprints the scenery of Red Canyon. 

Red Creek Rapid below Little Hole is particularly unrestrained. 

Just about all the rapids in Red Canyon are at the mouths of tributaries, where from time to time, coarse rock debris is flushed into 

the main channel by flash floods. Most rapids in Lodore, Yampa, 

and Split Mountain Canyons were formed in the same way.

At the mouth of Red Canyon the river emerges into Browns 

Ifark, the legendary hideout of Butch Cassidy and his notorious 

"Wild Bunch," who terrorized southern Wyoming, eastern Utah, 

and western Colorado near the turn of the century.

RED CANYON, about IVi miles below Flaming Gorge Dam. Red Canyon is 

cut in flat-lying Precambrian quartzite (Uinta Mountain Group). (Fig. 18.) |>

40

Browns Park

Browns Park is a picturesque intermontane valley, which, in 

Powell's words, is "really an expansion of the canon." It is broad, 

averaging about 4 miles across, but it is much longer than wide. 

Its actual length is arguable, but most people believe that it extends from Red Creek on the west to Vermilion Creek on the east, 

a length of about 25 miles.

Steep mountain fronts bound the valley on both sides, the mountaintops rising 3,000 feet or more above the valley floor. The 

north front is more abrupt than the south, partly because it is 

bounded for most of its length by faults, which drop the valley 

side relative to the mountains. Small creeks, after descending from 

the heights, enter the valley from both sides through deep brushy 

canyons.

Browns Park gains most of its distinctive appearance from its 

thick fill of Tertiary gravel, sand, clay, and volcanic ash the 

Browns Park Formation. This fill forms the broad flat bottom of 

the valley, and its brilliant white exposure contrasts with the somber 

appearance of the nearby mountains (fig. 19). Flat-topped Quaternary terraces arc characteristic, also.

42
BROWNS PARK, viewed north toward O-Wi-Yu-Kuts Mountain. Steep mountain front is bounded by faults. The white Browns Park Formation contrasts 

sharply with the somber Uinta Mountain Group. Flat top of O-Wi-Yu-Kuts 

Mountain is a remnant of the Gilbert Peak erosion surface, a broad Tertiary 

plain which once flanked the Uinta Mountains. (Fig. 19)

Browns Park is doubly curious because of its structure. The 

Browns Park Formation accumulated on the floor of a preexisting canyonlike valley. The valley was formed partly by ordinary 

erosion and partly by downfaulting along the crest of the great 

Uinta anticline. Faulting probably helped to establish drainage 

there in the first place. As the fill accumulated, the contour of the 

old valley gradually softened, until it took the shape of a shallow 

elongate syncline (something like an extra-long celery dish). Thus, 

we have a syncline of deposition, modified by later faulting, superimposed on the crest of a folded anticline. The axis of the syncline 

is well north of the present valley bottom, which crowds the south 

margin of. the valley. Clearly, the deepest, thickest part of the old 

fill is well to the north of the present river (fig. 20).

As the old fill spread over the floor of Browns Park, it slowly 

rose up the valley sides until it eventually buried tributary canyons and intervening ridges alike. Ultimately, it probably filled 

the valley to the rims. Then, when downcutting was resumed, the 

soft fill was removed preferentially, so that buried promontories, 

such as Kings Point, were exhumed an ancient Tertiary landscape faithfully, if incompletely, restored.

Tertiary drainage through Browns Park was obstructed from 

time to time by one thing or another: alluvial fans of sand and 

gravel spread across the valley from its margins, chiefly its north 

margin, and formed lakes. Earth movements along faults may 

also have caused impoundments. Tiny organisms, such as ostracodes and diatoms, thrived in standing water, and their remains 

were preserved iri the lake-bottom muds. The environment may 

have been too hostile for more complex forms of life, for no other 

remains have been found.

Frequent falls of volcanic ash blanketed the whole countryside. 

Ash that fell in the valley is preserved just as it accumulated; it 

gives the Browns Park Formation its white brilliance. Much ash 

that fell on the adjacent hills was washed into the valley by rains 

and freshets. Thus, the resulting Browns Park Formation is a 

varied accumulation of stream-laid sand and gravel, lacustrine 

clay, and volcanic ash. Its known thickness is more than 1,500 feet.

43
N

10,000'-,

5000'

GEOLOGIC SECTION across Browns Park, showing troughlike form of Browns 

Park synclinc superimposed on Uinta anticline and showing normal faulting 

along north,valley margin. Browns Park is not notably faulted on the south, 

although some investigators have suggested that it is. p-Cr, Red Creek Quartzite;, 

p u, Uinta Mountain Group,- Tbp, Browns Park Formation. (Fig. 20)

After entering Browns Park, the Green River flows swiftly but 

quietly for several miles across the Browns Park Formation. Just 

after crossing the axis of the Uinta anticline on the south side of 

the valley, the Green enters Swallow Canyon (a short but steepwalled gorge) cut into the Uinta Mountain Group in a classic 

example of drainage superposition. The course of the river through 

Swallow Canyon was fixed at a higher altitude than now in soft 

Browns Park beds that have since been removed. As the river 

eroded downward, it reached a buried spur of hard red quartzite 

through which it was constrained to cut its gorge. The spur, since 

exhumed, 4s now King's Point, high above/-the canyon walls. 

Although Swallow Canyon is perhaps the most obvious example 

of superimposed drainage in the entire Uinta Mountains, many 

other canyons in the region and elsewhere in the Rockies for that 

matter were carved in the same way. Below Swallow Canyon the 

river swings back again onto the Browns Park Formation, and as 

its grade flattens and its current slackens, it meanders lazily the 

20 miles or so to the Gates of Lodore.

44
UINTA 

ANTICLINE

pCu

LODORE CANYON, viewed north, toward the Gates of Lodore and Browns 

Park, from Douglas Mountain. The west wall is 2,280 feet high. (Fig. 21)
. \» l» * ! ^tr"' :^i

.^S'

Wr
Lodore Canyon

As noted before, the river crosses the axis of the Uinta anticline 

in Browns Park above Swallow Canyon. Lodore Canyon, therefore, is on the south limb of the fold. The river enters Lodore 

Canyon deep in the red Precambrian quartzite of the Uinta 

Mountain Group. And, inasmuch as the dip of the strata, though 

gentle, is steeper than the gradient of the river, the river crosses 

successively younger rocks en route. About half way through 

the canyon, above Triplet Falls, the Lodore Formation (Cambrian Period), the Lodgepole Limestone, and the Deseret Limestone (both Mississippian) first come into view. The Mississippian 

limestones form a sheer gray cliff 400 feet high that surmounts 

the somber red beds below. At each bend of the river the cliff 

.descends lower, finally reaching river level 2 miles above the 

mouth of the canyon. At the mouth of Lodore Canyon, at Echo 

Park, the river flows on Weber Sandstone, having crossed strata, 

about 1 1/2. miles thick, of Precambrian, Cambrian, Mississippian, 

and Pennsylvanian age. Then, around the next bend, a sharp fault 

(Mitten Park fault) has raised the Precambrian back again above 

river level.

Lodore is the deepest and most precipitous of the great river 

canyons in the Uinta Mountains (fig. 21), and the Gates of 

Lodore could hardly be more imposing. Looking into the gates, 

one senses some of the mixed emotions exhiliration, wonder, and 

apprehension that must have bestirred Powell and his boatmen.

The river, after meandering parallel to the mountain front 

through Browns Park, swings to the right in a broad arc and drives 

headlong into the canyon. The current quickens, but the river flows 

smoothly and in a nearly straight line for about 3 l/2 miles. Then, 

a thundering roar ahead signals approaching turbulence, and 

after a sharp bend to the right, the river plunges into its first rapid. 

It drops from one rapid into another for the next 8 miles, with short 

respites of quiet water in between. PowelPs names for some of these 

rapids Upper and Lower Disaster Falls, Hells Half Mile give 

some idea of the fury of the river.

<] WEST WALL OF LODORE CANYON, as photographed by James Gilluly 

in 1921. Buttresslike forms halfway up canyon wall suggest two stages of canyon 

cutting an inner gorge incised into an outer one. (Fig. 22)

47
At the Gates of Lodore the canyon walls rise abruptly from the 

water's edge. A mile downstream the canyon rim is more than 

2,000 feet above the river. The walls are most precipitous near the 

head of the canyon, although they are higher downstream at Wild 

Mountain, where the drop from rim to river is more than 3,000 

feet. Lodore Canyon may have been cut in two stages. As shown 

in figure 22, a steep inner gorge rises 600-800 feet above the river, 

then a series of buttresslike forms slope up several hundred feet 

to the base of precipitous outer walls a thousand feet higher. Canyon profiles (fig. 23) suggest that the postulated outer canyon was 

about 1,500 feet deep when the inner gorge was cut, probably in 

Quaternary time.

East

TRUE-SCALE PROFILES OF LODORE CANYON, just below Gates of 

Lodore, susgesting two stages of canyon cutting. Canyon was about 1,500 feet 

deep when postulated reentrenchment began. Compare with figure 22. (Fig. 23)

Yampa Canyon

At Echo Park, or Pats Hole, as it is also known, the Yampa 

River flows into the Green. Echo Park (fig. 24) is a longtime favorite of canyon visitors and is accessible to automobiles by way of 

a rough but scenic dirt road. Yampa Canyon extends upstream 

about 45 river miles from Echo Park to a point near the east end 

of the Uinta Mountains called Lily Park. Just below Lily Park * 

the Yampa River cuts abruptly across Cretaceous, Jurassic, Triassic, and Permian strata, then across the Weber Sandstone, and 

into older Pennsylvanian rocks generally called the Morgan For- < 

mation. The river flows across the Morgan at about the same ' 

stratigraphic level for 18 miles. It then cuts back into the Weber 

Sandstone and stays mainly in the Weber to its confluence with the 

Green. 'i
ECHO PARK (lower right) and Yampa Canyon, carved from massive Weber 

Sandstone, which dips gently to the south (right). Viewed east from Harpers 

Corner. Steamboat Rock in foreground. National Park Service photograph. 

(Fig. 24)

Because of marked differences in color, bedding habit, and lithology between the Morgan and the Weber, the appearance of 

Yampa Canyon changes drastically across the formation boundary. 

Through the Morgan, the canyon is mostly wide and asymmetrical; it is steep, or precipitous, on the south side, and ledgy and 

sloping on the north. Layers of pink sandstone and siltstone 

alternate with gray, tan, and pink limestone. The course of the 

river is curvy but not tortuous. Through the Weber Sandstone the 

canyon is narrow, precipitous, and spectacular. Smooth canyon 

walls overhang the river in places, rising sheer for hundreds of 

feet above the water, particularly on the outside bends of meanders. The course of the river is extremely twisty in less than 10 

miles, straight line, the river meanders 22 miles, and each turn 

opens a new vista (fig. 25).

49
YAMPA CANYON. Weber Sandstone (cliff in background) overlying the 

Morgan Formation. National Park Service photograph. (Fig. 25)

50
Whirlpool Canyon and Island Park

Just below Echo Park the Green River makes a long hairpin 

bend around Steamboat Rock, crosses the Mitten Park fault, and 

enters Whirlpool Canyon, a spacious gorge about 2,500 feet deep 

and Ij/a miles across. Shown in profile in figure 26, the walls of 

Whirlpool Canyon are less precipitous than those of Lodore Canyon and are less picturesque than those of Yampa. but they are 

very impressive, nevertheless. The dip of the strata, again, is downstream, so that the river flows across successively younger rocks 

the same formations exposed in Lodore Canyon. The Uinta Mountain Group forms a vertically walled inner gorge 300 feet deep 

in the headward part of the canyon, and the river fills the bottom, 

wall to wall. Then at the first bend, the Uinta Mountain Group 

passes below drainage. Although the heights of the canyon are

WHIRLPOOL CANYON, viewed downstream from Harpers Corner. Stairsteps 

of cliffs and ledges are caused by resistant and nonresistant strata. (Fig. 26)
eroded mainly from Mississippian and Pennsylvania!! strata, Cambrian rocks (Lodore Formation) are well exposed in the canyon 

bottom from the Mitten Park fault downstream to about midcanyon. In the upper canyon walls, massive limestone beds of Mississippian and Pennsylvanian age form giant stairsteps of sheer 

cliffs and sloping ledges, capping off the rims at Wild Mountain 

and Harpers Corner.

Halfway through Whirlpool Canyon, entering from the right 

(north) is spring-fed Jones Hole Creek, a sparkly stream that 

issues at full volume from openings in the Pennsylvanian Round 

Valley Limestone. Jones Hole is dominated by towering cliffs 

of Weber Sandstone in a picturesque and dramatic setting. It is 

one of the foremost attractions of Dinosaur National Monument 

and a remembered highlight of any float trip down the Green. 

It can also be reached overland, on foot.

VIEW NORTHEAST FROM HARPERS CORNER, looking down on Mitten 

Park fault. National Park Service photograph. (Fig. 27)

Zenobia 

Peak A S MOUNTAIN

'
WILD MOUNTAIN

 <**«»«

WHIRLPOOL CANYON

ISLAND PARK, viewed northeast. Island Park fault separates uplifted block 

(right) from downfaulted block (left). Photograph by Hal Rumel. (Fig. 28)

Large faults bound Whirlpool Canyon upstream and down 

the Mitten Park and Island Park faults, respectively. Between 

these faults, the canyon area has been raised about 3,000 feet 

relative to the areas upstream and down. One must realize, however, that the faulting took place long before the canyon was 

eroded. The Mitten Park fault can be seen very well from the 

river and from Harpers Corner high above (fig. 27). The Island 

Park fault can be seen well from the mouth of Whirlpool Canyon 

(fig. 28) and from Jones Hole.

Whirlpool Canyon opens downstream through a flaring gateway into Island Park, which together with Rainbow Park is an 

attractive alluviated valley of a few square miles between Whirlpool and Split Mountain Canyons. Island Park is on the axis 

of a faulted asymmetrical syncline, first cited by Powell; it trends 

west between the main Uinta anticline to the north and the Split 

Mountain anticline to the south (fig. 29). The syncline axis is 

crowded against the flank of Split Mountain. Cretaceous rocks 

are preserved in the trough of the syncline, their first occurrence 

downstream from Flaming Gorge.

53
SSE

Stuntz Ridge

GEOLOGIC SECTION through Split Mountain, showing inferred relation of 

faults to folds. Vertical scale is exaggerated X 2. p u, Uinta Mountain Group,- 

 1, Lodore Formation; Mu, Mississippian rocks; PPwm, Weber and Morgan 

Formations; Pp, Park City Formation; "Eu, Triassic rocks,- J~Eg, Glen Canyon 

Sandstone; Jce, Curtis, Entrada, and Carmel Formations,- Jm, Morrison Formation,- Kd, Dakota Sandstone,- Kmy, Mowry Shale,- Kf, Frontier Formation,- Km, 

Mancos Shale; Kmv, Mesaverde Group,- Tu, Tertiary rocks. (Fig. 29)

Split Mountain Canyon

After meandering placidly through Island and Rainbow Parks, 

the Green River heads into Split Mountain Canyon, an eroded anticline (fig. 30). Flowing swiftly across upturned beds, the river 

passes from Jurassic rocks at Rainbow Park onto rocks of Mississippian age in the core of the Split Mountain anticline. After crossing the fold axis, the river then recrosses the same beds, but in 

reverse order, on the south limb of the fold. Varicolored Mississippian, Pennsylvanian, and Permian rocks form the sloping inner 

canyon walls. Weber Sandstone forms the heights, eroded into a 

craggy terrain of fanciful turrents, domes, and ramparts. On the 

south flank of the Split Mountain anticline, the Weber is eroded 

into an array of buttresslike forms great monoliths separated 

from one another by deep, extremely narrow tributary ravines, 

some of which expand upstream into wide but nearly hidden' 

alcoves.

The Green River runs fast through Split Mountain Canyon, 

having there its greatest average rate of fall 20.7 feet per mile 

in the Eastern Uinta Mountains. At the mouth of the canyon, 

the gradient flattens, the current slackens, and the river emerges 

at last from the Uinta Mountains into the Uinta Basin, 118 miles 

below its point of entry at Flaming Gorge.

54
How the canyons were formed

Catastrophism as a rationale to explain the origin of canyons 

has gone out of style. In the past, many people viewing the 

great river gorges of the west would have guessed that the earth 

just split open, sundered by some frightful cataclysm, the waters 

then simply plunging headlong into the void. Cataclysmic events 

have indeed been recorded in geology. The overflow of extinct 

Lake Bonneville was such an event; so was the Alaska earthquake 

of 1964. But these events are rare and, anyway, are not on the 

order of magnitude needed to cut canyons across mountain ranges. 

The energy requirements of canyon cutting are infinitely greater, 

although the energy is expended much more slowly. So, the concept that the great canyons were carved slowly and inexorably 

by their own drainage is a truism that most people now accept 

without further explanation.

In fact, the events leading up to the cutting of a canyon by a 

river can be quite complex and can involve the interaction of 

many separate processes. To be sure, the river is the chief agent 

of erosion and the prime mover of eroded rock, but it alone could 

not do the job. Atmospheric weathering chemical decomposition, 

as well as mechanical disintegration of rock frost action, gullying, rill action during showers, and downslope movement of rock 

debris under the influence of gravity all help prepare the ground, 

widen the canyon walls, and transport material to the canyon bottom. Only then does the river take over, wearing away and carrying off its suspended load and, at the same time, attacking and 

eroding its bed.

The river is most effective during high water, in early summer 

when runoff is swollen by snowmelt from the high mountains or 

by thunderstorms over the watershed. As the volume of water increases, so does the velocity. Increase the velocity, and the carrying power increases geometrically. If the velocity is doubled, the 

capacity is tripled a principle spelled out many years ago by 

G. K. Gilbert, whose namesake Gilbert Peak dominates the Western Uinta Mountains on the north. The roily water of flood stage

55

SPLIT MOUNTAIN, viewed upstream, showing the nearly symmetrical form 

of the anticline, breached by the Green River. Photograph by Hal Rumel. 

(Fig. 30)

57
is an obvious expression of the erosive power of the river, And

no one who has seen a large river in flood can doubt its ability j

to do its work. ,

But the most intriguing question related to the origin of the j 

great canyons of the Uinta Mountains is not so much the mechanics of erosion as it is how the rivers were able to cross 

the mountains in the first place. How could rivers establish and 

maintain their courses across a great mountain range in utter | 

disregard for the structural complexities within the range? Such ' 

canyons as Swallow and Split Mountain provide clues, but not j 

answers, and the evidence for the whole canyon system is even 

less obvious. Differences of opinion through the years have marked 

the development of thought. J

Three concepts, at one time or another, have gained some ac- ' 

ceptance: antecedence, superposition, and stream capture. Antecedence, the concept favored by Powell, assumes that the drainage 

pattern predates uplift and that, as uplift begins and folding 

progresses, vigorous rivers are able to lower their beds as fast as 

the land is elevated. Antecedence has been authenticated in some 

drainage basins, but cogent evidence rules it out for the Eastern 

Uinta Mountains. For example, early in the history of the range, 

drainage clearly was away from the rising mountain mass, just as 

one would expect, rather than toward or across it, as it is now. > 

Rock materials eroded from the heights were redeposited at the j 

flanks, where they now comprise several rock formations younger 

than the mountains but older than the canyons. As the mountains 

rose, closed basins formed on both flanks. These basins, the Uinta 

and Green River, contained great lakes whose deposits now make 

up the Green River Formation, famous for its fossil fishes, oil shale, 1 

and enormously large deposits of sodium salts. Finally, broad ero- \ 

sion surfaces or pediments (for example, the Gilbert Peak erosion ; 

surface) were formed on both flanks of the range, sloping outward 

to the basins. As long as these surfaces were intact, drainage across 

the range was impossible.

Emmons in 1877 propounded the concept of superposition. He 

believed, and I think correctly, that the Green River established 

its course on an old fill of Tertiary sediments (the Browns Park 

Formation) that spread across the eastern part of the range after ' 

the range had been uplifted and deeply eroded. Much of this old 1 

fill is still preserved. The Green River, then, according to Emmons'

58
concept, cut down through the fill and incised itself into the buried, 

older rocks in the core of the range. The Green was thus able to 

cut across anticlines, synclines, and broad fault zones without undue deflections in its course. It was, in fact, compelled to do so because it was held in by its own banks, and the deeper it cut, the 

more firmly committed it was to its course. The present discordance between drainage and topography is therefore due more to 

selective erosion of hard and soft rocks after the drainage pattern 

was fixed than to differential uplift.

W. H. Bradley (1936) studied the north flank of the Uinta 

Mountains in the 1920's-30's. Bradley surmised that the ancestral 

drainage of the Green River Basin was east, toward the North 

Platte River, and possibly into the Gulf of Mexico. He also found 

evidence that the ancestral drainage in the Browns Park area was 

eastward, possibly into the ancestral Yampa River, or possibly 

across the present Continental Divide and into the Mississippi 

drainage system as well.

As a topographic eminence, the present Continental Divide is 

indeed very subdued all the way from the southern Wind River 

Range to the northern Sierra Madre in southern Wyoming. In that 

area, broad closed depressions actually exist along the divide, and 

the true position of the divide is very obscure. The Sweetwater 

River arises on the west side of the Wind River Range in what 

structurally is part of the Green River Basin; it turns south, then 

east, and flows to the North Platte. Thus, even now, part of the 

drainage from the Green River Basin flows to the Gulf of Mexico.

Bradley's suggestion of eastward drainage is also supported by 

remnants of an old valley filled with the Browns Park Formation. 

The old valley trended east from Browns Park toward Craig, Colorado. Beyond Craig, the valley may have extended north into 

Wyoming toward Baggs, but the evidence is obscure. Northeast of 

Baggs, remnants of the Browns Park Formation or its equivalent 

extend well into the present North Platte drainage, though there 

is no real assurance that any of those deposits originated in the 

Uinta Mountains region.

Bradley agreed that the course of the Green was superimposed 

upstream and down from Lodore Canyon, but he argued that if 

the course were superimposed through Lodore, an inordinate 

amount of fill had to have been removed from Browns Park. Bradley also called attention to the relatively straight course of Lodore

59
Canyon, which he contrasted with the sweeping meanders farther 

upstream and down. Following a suggestion by J. D. Sears (1924), 

Bradley postulated that an east-flowing stream in Browns Park 

(the ancestral Green) was diverted south by a small but vigorous 

stream eroding headward in what is now Lodore Canyon. This 

stream, nibbling away at the intervening divide, undercut the 

channel of the ancestral Green River and turned it southward. 

Bradley thus introduced the concept of stream capture to explain
Lodore Canyon and the southward flow of a river that very clearly 

once flowed east.

PRESENT DISTRIBUTION OF THE BROWNS PARK FORMATION in the 

Eastern Uinta Mountains. Small unmapped renmants rest on Blue and Douglas 

Mountains, also. Hypothetical course of the ancestral Green River is shown by 

the heavy line. (Fig. 31)

Dinosaur National 

Monument Headquarters
In more recent years, widespread Tertiary fills have been found 

in the highlands south of Browns Park (fig. 31). These fills are 

identical with the Browns Park Formation and no doubt correlative with it. Along Pot Creek, Grouse Creek, Cart Creek, and 

other streams on Diamond Mountain are deposits of white volcanic ash and standstone at altitudes comparable to the rims of 

Lodore Canyon. In fact, most of the valleys are blanketed by 

such deposits; only the ridges and peaks protrude through them. 

At widely scattered localities on Douglas Mountain, Harpers Corner, and Blue Mountain, deposits of conglomerate and volcanic 

ash probably are eroded remnants of the Browns Park Formation 

also. Most of Harpers Corner is capped with gravel or conglomerate. The extent and distribution of all these deposits demand that 

the old Tertiary fill was very thick indeed and that a tremendous 

volume was surely removed by erosion. These deposits, therefore, 

seem to confirm Emmons' view that the course of the Green River 

across the Uinta Mountains is superimposed.

The establishment of the Green River across the Uintas, as 

I see it, is thus postulated as follows: An ancient river flowed 

eastward from Browns Park, as Bradley suggested, hypothetically 

toward the north end of the Sierra Madre and into the North 

Platte. If so, the crestline of the Uinta Mountains at that time 

was the Continental Divide. Steps in the drainage history are 

shown in figure 32. Meanwhile, crustal movements preceded, perhaps accompanied, and certainly followed deposition of the 

Browns Park Formation. In brief, the whole eastern part of the 

Uinta Mountains between the Uinta fault on the north and the 

Yampa fault on the south was involved in a complicated "graben" 

movement, or collapse. First noted by Powell, the collapse of the 

Eastern Uintas has since been affirmed by many geologists, particularly by Sears and by Bradley. The present Continental Divide 

across central Wyoming is viewed as having begun to rise at about 

the same time. All these crustal movements, combined with immense outfallings of volcanic ash from some distant source, led 

to the stagnation and ultimate ponding of all the drainage in the 

Eastern Uinta Moutains. The old valley of Browns Park finally 

became filled to overflowing with a great thickness of gravel, sand, 

clay, and volcanic ash. The fill spread onto and across the main 

highland mass of the mountains to the south, leaving only the peaks 

and ridges exposed. Sears expressed much the same view in 1924.

62
The fill also extended east to west at least from Craig to Flaming 

Gorge and north to south across the Uinta Mountains from 

Browns Park at least to Diamond Mountain. It enveloped Cold 

Spring Mountain on the north and possibly even overtopped it. 

Its southward limit in the Uinta Basin is unknown, for it has been 

erased by erosion.

Conditions were then ripe for superposition. With drainage obstructed to the east by the rising Continental Divide and with 

Browns Park filling with sediment, the stagnating, meandering 

Green River spilled across the Uinta crest, along what is now 

Lodore Canyon, to the Uinta Basin, whereat became tributary to 

the Colorado. Below the spillover point, the course of the river 

probably was nearly straight, just as it is today.

Drainage presumably had already been established out of the 

Uinta Basin to the south, across the high Tavaputs Plateau. The 

Green there has since cut a canyon 4,800 feet deep, with a rim 

9,200 feet above sea level. Either this rim was breached before the 

Eastern Uinta Mountains collapsed or it rose after it was breached, 

possibly both; otherwise, the basin would have drained north 

across the Uintas to the Gulf of Mexico. Even now, the Continental Divide in southern Wyoming is little more than 6,800 feet 

above sea level much lower than the rims of the Tavaputs Plateau (and scarcely as high as the rims of the Lodore).

In any event, the Green River, rejuvenated in its new course, 

must have quickly incised through the soft Browns Park Formation atop the Uintas down into the harder rocks underneath.

At about this time, as thus visualized, the main drainage of the 

Green River Basin was still flowing eastward at a hydraulic disadvantage across the rising Continental Divide. But the invigorated 

Green River, with a new, lower base level, now began to entrench 

its meanders upstream from Browns Park, carving out the spectacular loops in Red Canyon, Horseshoe Canyon, and Flaming 

Gorge. Near Flaming Gorge the river captured drainage that once 

flowed north into the Green River Basin and possibly even reversed 

the flow direction of the present reach of river between Flaming 

Gorge and Green River, Wyoming. Presumably, it then captured 

the main drainage of the Green River Basin. Bradley (1936) noted 

that the main Uinta Mountain tributaries of the Green flow well 

north into the basin before turning east and south into the Green, 

as if in response to a diverted master stream.

63
1. Drainage pattern after disappearance of the Green River lakes and shortly 

after cutting of the Gilbert Peak erosion surface. Drainage is away from 

mountainous uplifts shown by dark-gray tint. Upper Green River drains 

east into North Platte. Former Continental Divide is shown by heavy 

dashed line. Time, possibly earliest Miocene.

3. Eastward drainage in Uinta Mountains, now flowing on a thick Browns 

Park fill (not shown), spills across Uinta crest at site of Lodore Canyon 

(arrow) and begins to incise itself. Eastward flow of Upper Green River is 

being ponded by rising incipient Continental Divide. Pliocene time.

POSTULATED DEVELOPMENT OF THE GREEN RIVER 

64
\

2. Eastward drainage has been initiated in Eastern Uinta Mountains by collapse 

of Uinta anticline. Collapse continues as Browns Park Formation begins 

to accumulate (not shown) and as incipient Continental Divide begins 

to rise. Time, possibly late Miocene.

4. Modern drainage. Continental Divide shifts eastward as Upper Green 

River is captured and turned south by rejuvenated drainage across Uinta 

Mountains. Canyon cutting continues.

DRAINAGE SYSTEM IN TERTIARY TIME. (Fig. 32)

65
Meanwhile, the course of the Yampa River was being established on the south flank of the range. The ancestral history of the 

Yampa is still in some doubt, even though it has received considerable attention. The pattern of drainage suggests that the Yampa 

may once have even flowed east from the Uinta Mountains, along 

with the Green. The Yampa may have joined the ancestral Green 

somewhere near Cross Mountain. At any rate, the remarkably entrenched meanders of the Yampa in Yampa Canyon point clearly 

toward superposition of that reach of river. J. D. Sears (1962) discussed in detail the character and origin of these features. Once 

again, the distribution of the Browns Park Formation leads to the 

inference that the Yampa entrenched itself down through a Browns 

Park fill onto the underlying, harder formations. There, down 

through hundreds of feet of hard rock, it faithfully reproduced the 

intricate meander pattern that it had originally developed on an 

old valley fill long since removed.

Flaming Gorge

7" Dam

_l_______i_______l 1_

5 MILES

66
Other drainage 

adjustments

Many other streams in the Uinta Mountains have had their 

courses drastically altered during the past few million years. Particularly at the flanks of the range, drainage became channeled into 

courses controlled by alternately hard and soft strata. In such 

areas, as downcutting progressed in belts of tilted rock, streams 

eroding across resistant ledges tended to yield to streams that 

flowed along softer strata. Much like a board left to weather in 

the elements, the harder layers were etched into relief, the softer 

ones were hollowed out.

Drainage of this sort, said to be structurally adjusted, is clearly 

visible in the Flaming Gorge area, where several ancestral drainage lines are indicated by abandoned wind gaps. Dutch John Gap 

is an excellent example (fig. 33); Irish Canyon, at the east end of 

Cold Spring Mountain, is another (Sears, 1924). Dutch John Gap 

once channeled the drainage that now flows down Spring Creek; 

Irish Canyon may once have contained Vermilion Creek.

On the south slope of the range, the hogbacks and racetrack 

valleys that encircle Split Mountain and that flank Blue Mountain 

are fine examples of structurally adjusted drainage lines. Although 

the master streams of these areas, the Green and Yampa Rivers, 

were able to ignore geologic structure, many of their less competent tributaries were forced into courses adjusted to rock hardness. Many of these tributaries, in fact, are so well adjusted to 

the structure of the underlying bedrock that the trained eye can 

discern the structural form from the drainage pattern alone.

<] DRAINAGE ADJUSTMENT AT DUTCH JOHN GAP. Dutch John Gap 

was abandoned when ancestral Jarvies Creek, which flowed across the structural 

"grain," was beheaded by Spring Creek, which eroded headword (east) in the 

Milliard Shale. A future capture north of The Glades could cause abandonment 

of Minnies Gap. Note also imminent drainage diversion i"st south of Boars 

Tusk. (Fig. 33)

67
Weber, Provo,

and Bear Rivers

Notable stream adjustments at the west end of the Uinta 

Mountains are clearly shown on the old (1900) Coalville quadrangle map and are reproduced in figure 34. At one time the 

Weber River, which flows to Great Salt Lake, quite apparently 

drained all the western part of the range, including areas now 

drained by the Provo, which flows to Utah Lake. The Provo 

River has greatly expanded its drainage basin and, hence, its 

discharge, at the expense of the Weber. The Upper Provo once 

flowed north through Rhodes Valley into the Weber. It was diverted into the present Provo River, however, when it was captured at a point about 2 miles south of the town of Kamas.

There, the present river leaves a wide, flat-bottomed valley 

and enters a narrow canyon en route to Heber Valley and, 

ultimately, Utah Lake. Its diversion was aided, perhaps, by the 

clogging of Rhodes Valley with late glacial outwash. Hence, the 

diversion probably was a geologically recent event.

Other adjustments on the Provo have occurred farther 

upstream. The headwaters of the present river once flowed into 

Beaver Creek, a tributary of the Weber, but they were beheaded 

by a tributary of the ancestral Provo that eroded northeastward 

through Pine Valley. A broad low saddle marks the site, and many 

motorists today pass this point on Utah State Highway 150 without realizing that they have crossed from one drainage basin 

to another and that waters on opposite sides of the saddle flow to 

outlets 65 miles apart.

Although the Weber River has thus lost nearly half its flow 

to the Provo, it has gained flow from the Bear in drainage adjustments that are not really momentous, perhaps, but that are important to the drainage budgets of the streams involved. Chalk

DRAINAGE ADJUSTMENTS OF THE WEBER AND PROVO RIVERS. > 

The headwaters of the Provo formerly drained northwest into the Weber via 

Beaver Creek and Rhodes Valley but were diverted west and south into the 

Provo by stream captures at points A and B. Heavy dashed lines indicate 

former drainage courses. (Fig. 34)

68
69
Creek, a major tributary of the Weber, arises in the northwestern 

Uinta Mountains (fig. 35). The headwaters of Chalk Creek flow 

north and northwest, enter Wyoming, and then turn abruptly 

south and southwest, back into Utah toward the Weber. Chalk 

Creek's north-flowing reach is separated from the Bear River by a 

low divide, but its southwest reach passes through deep canyons 

en route to the Weber. In all probability the headwaters of Chalk 

Creek formerly drained into the Bear, either directly or via Yellow 

Creek, but they were diverted southwestward by headward erosion 

of lower Chalk Creek, and the point of diversion was the "elbow" 

in its course at the Wyoming State line. Between that point and 

Pine Cliff, the direction of flow has probably been reversed. 

Nptice (fig. 35) how the tributaries upstream from Pine Cliff 

are "barbed" they flow in the opposite direction from Chalk 

Creek itself.

DEVELOPMENT OF CHALK CREEK DRAINAGE: North-flowin 9 tributaries 

of Yellow Creek, which drains into the Bear River, were captured and turned 

westward by Chalk Creek, which drains into the Weber River. (Fig. 35)

The Weber has also captured drainage from the West Fork of 

the Bear (fig. 36). A relatively minor but illustrative stream diversion north of Holiday Park characterizes a type of capture that 

has happened time and again elsewhere in the Uinta Mountains. 

Near Holiday Park, the Weber Valley is 1,200-1,500 feet lower

70
Ill"00'

Y 

I

Windy Peak/ pR£SENL_ i -J~"~~ V

\ Holiday Park

40°JO'

\

3 MILES

MINOR STREAM CAPTURE at Windy Peak. Drainage down the east slope 

of Windy Peak, formerly to the Bear River, has been turned southward into the 

Weber River by Larrabee Creek. (Fig. 36)

than the West Fork of the Bear just across the divide. With much 

steeper gradients, the headwaters of the Weber, therefore, have 

a distinct hydraulic advantage over the headwaters of the West 

Fork. Larrabee Creek, a small steep tributary of the Weber, has 

eroded headward to the north, has thus intercepted the eastflowing drainage of Windy Peak, and has diverted it south from 

the Bear to the Weber drainage. This drainage capture was a 

minor physiographic event, but in a small way it typifies the everchanging, ever-evolving sequence of events begun eons ago that 

culminated, from man's point of view, in the dramatic landscape 

of the present Uinta Mountains.

71
MILES 

I

a .^.^...^wl

72
i Rock Creek and 

i the Duchesne River

Old drainage adjustments are probable between the headwaters 

of the Duchesne River and Rock Creek. The Duchesne River 

drains a well-watered area, south of the crest of the range, centered 

between Bald Mountain and Mount Agassiz. Drainage from this 

area probably flowed at one time into Rock Creek by way of the 

West Fork of Rock Creek (fig. 37). The evidence of capture by 

the Duchesne still looks convincing on topographic maps, especially on the raised relief edition of the Salt Lake City map (4 

miles per inch) and on the old Hayden Peak quadrangle map (2 

miles per inch), despite intensive glacial scouring since the postulated diversion. Early glaciation may even have contributed to 

capture by abrasively reducing the height of the intervening 

divide. At present, the upper Duchesne is deeply entrenched in 

a youthful canyon, whereas the West Fork of Rock Creek heads 

in a broad wind gap perched above the Duchesne and open in 

that direction. The difference in altitude between the wind gap 

and the Duchesne River below is nearly 800 feet.

Glacial diversions 

on the north flank

Glaciers commonly obstruct and divert preglacial drainage lines, 

either by blocking them directly with ice or, on melting, by obstructing them with morainal debris. Good examples of such diversions can be seen on the north flank of the Uinta Mountains in 

tributaries of Beaver Creek and Burnt Fork. Diversions by glaciers of the last major advance (Pinedale) are particularly evident. The Middle Fork of Beaver Creek, for example, probably 

once flowed directly north into the West Fork, as shown in figure 

38, but it has since been diverted eastward into its present course

<] DRAINAGE ADJUSTMENTS OF ROCK CREEK AND THE DUCHESNE 

RIVER. The Duchesne River has captured the headwaters of the West Fork of 

Rock Creek, probably in late Tertiary or early Pleistocene time. (Fig. 37)

73
no°20'

OUTCRO? , .;;^\

74
by massive lateral moraines left across its course by the last glacier 

to occupy its valley. Note also how Fellow Creek was shouldered 

aside by Pinedale moraines and how a tributary of Henrys Fork 

was diverted into Fellow Creek (fig. 38).

Hoop Lake and Lost Creek are other examples shown in figure 

38. Preglacial drainage of the Hoop Lake basin was east into 

Burnt Fork, but it was obstructed by moraines of the former 

Burnt Fork glacier. The resulting depression was filled with 

water thus forming Hoop Lake and drainage from Hoop Lake 

spilled over into the East Fork of Beaver Creek. (Hoop Lake is a 

natural water body, although its level has been raised by a dam.)

Lost Creek no doubt once flowed unhindered into Burnt Fork, 

but its course, too, was blocked by a large moraine of the Burnt 

Fork glacier. Lost Creek then found an outlet in a solution cavern 

in the Mississippian limestone. Where the water goes from there 

has long been a matter of cracker-barrel speculation among oldtime residents. Some guess that it emerges 15 miles to the east in 

Sheep Creek Canyon, where large springs issue from the Mississippian at Palisade Park. Perhaps they are right. Reportedly, roily 

discharge from the springs sometimes follows shower activity over 

the Lost Creek watershed.

<J STREAM DIVERSIONS caused by glacial obstructions on the north Flank of 

the Uinta Mountains. Upper diagram shows Former drainage and points oF 

diversion (arrows). Lower diagram shows present drainage and obstructing moraines. Other moraines are omitted. (Fig. 38)

75
WHERE BEST TO SEE FORMATION OR GROUP

BROWNS PARK

BISHOP MOUNTAIN

FORT BR1DGER, WYOMING

UINTA BASIN

GREEN RIVER, WYOMING

FLAMING GORGE RESERVOIR

MANILA, UTAH

ASPHALT RIDGE

CLAY BASIN 

ANTELOPE FLAT

ASHLEY VALLEY

SOUTH OF MANILA

DINOSAUR QUARRY

PLUG HAT ROCK 

MERKLEY PARK 

FLAMING GORGE

AGE, IN

MILLIONS PERIOD ERA 

OF YEARS

SHEEP CREEK 

SPUT MOUNTAIN - 

YAMPA CANYON 

HORSESHOE CANYON 

BRUSH CREEK GORGE 

WILD MOUNTAIN 

WHIRLPOOL CANYON

PALISADES OF 

SHEEP CREEK

GATES OF LODORE 

RED CANYON

COLD SPRING 

MOUNTAIN

RED CREEK 

CANYON

BROWNS PARK FORMATION AND

BISHOP CONGLOMERATE 

DUCHESNE RIVER. UINTA, Attjtai 

BRIOGER FORMATIONS .|HJ

GREEN RIVER FORMATION 

WASATCH FORMATION 

FORT UNION FORMATION

MESAVERDE GROUP

HILLIARD, BAXTER, AND 

MANCOS SHALES

FRONTIER FORMATION

MOWRY SHALE

DAKOTA SANDSTONE

CEDAR MOUNTAIN FORMATION

__JORRISON FORMATION 

SHE

RTIS FORMATION 

ENTRADA SANDSTONE 

iRMEL FORMATION 

GLEN CANYON SANDSTONE |B! 

CHINLE FORMATION flj 

MOENKOPI FORMATION B 

DINWO'ODY FORMATION 

PARK CITY FORMATION

WEBER SANDSTONE

MORGAN FORMATION

ROUND VALLEY LIMESTON-i

DOUGHNUT SHALE

HUMBUG FORMATION

DESERET LIMESTONE

iODGEPOLE LIMESTONE

ORE FORMATION 

UINTA MOUNTAIN GROUP 

RED CREEK QUARTZITE

'

in*

o

l*xj

o

60

75

95

100

120

135

o

LU 

 CJ> <t

PERMIAN

340

500

2,320

CAMBRIAN

PRECAMBR1AN
Time 

and the rocks

O:NE CAN say little about the Uinta Mountains without 

talking about rock formations, and, one cannot really understand 

the structure, history, or development of the range without some 

knowledge of the rocks. It follows that the better one understands 

the rocks and how they form, the better one can appreciate the 

grandeur and beauty of the mountains. The mountains rising 

from arid basins north and south and' standing starkly bare above 

timberline in the high interior are clothed in dense forest only at 

middle altitudes. Above and below these altitudes, the mountainsides are mostly bare rock.

To many people, the term "rock formation" is ambiguous. Contrary to much popular misunderstanding, a rock formation is 

neither an unusual outcrop, nor a strange erosional form, nor a 

particular proturberance on a given piece of real estate. Rather, 

a rock formation is a large body of rock that has specific identifying characteristics, such as composition, color, and thickness. It 

may be of sedimentary, igneous, or metamorphic origin. Two or 

more formations of similar age or origin are sometimes lumped 

together as a "group," such as the Uinta Mountain Group and 

the Mesaverde Group.

GENERALIZED COMPOSITE SECTION of rock formations of the Eastern 

Uinta Mountains. Total thickness, excluding the Red Creek Quartzite, is more 

than 50,000 feet. The Western Uinta section is similar, but even thicker. Age 

estimates are based on data by J. L. Kulp (1961), except that .the Red Creek 

Quartzite was dated radiometrically by C. E. Hedge of the U.S. Geological 

Survey. (Fig. 39)

77
A rock formation need not even be exposed at ground surface, 

but it can and generally does have lateral continuity at depth. 

Many formations, in fact, extend long distances under cover 

that is, they pass beneath hills or basins and reappear only where 

brought to the surface by uplift or erosion. Some formations that 

are known almost entirely from drill-hole data are studied intently 

by specialists looking for clues to the occurrence of petroleum or 

other mineral resources. Thus, a limestone bed that forms a line 

of cliffs high in the Uinta Mountains may be penetrated by a drill 

many miles away an'd thousands of feet underground in one of the 

adjoining basins. A geologist might visit the mountains to learn 

about formations that are deeply buried many miles away. Many 

rock formations that crop out in the Uinta Mountains are recognized throughout much of the Western Interior of the United 

States.

Rock formations of the Uinta Mountains range widely in age, 

composition, and appearance. The oldest are more than 2 billion 

years old; the youngest are just now being deposited in lakes and 

streams. Figure 39 shows diagrammatically the sequence of rock 

formations in the middle and eastern parts of the range. Many 

particulars are omitted from this chart, and the reader should 

turn to more technical publications for the details. Moreover, rocks 

vary appreciably from place to place. Some formations in one part 

of the range are lacking in other parts. Most of the formations of 

the Uinta Mountains are sedimentary and were deposited on flat 

beds as broad blankets of sand, gravel, clay, or limy mud. Solidified, such deposits became sandstone, quartzite, conglomerate, 

shale, and limestone, with many gradations between. Though they 

may be only a few hundred or a few thousand feet thick, these 

formations may extend laterally for hundreds or thousands of 

square miles.

Travelers crossing the range on Utah State Highway 44 between Vernal and Manila have an excellent opportunity to acquaint themselves with the formations that make up most of the 

range. From the flanks inward, progressively older rocks are exposed, somewhat like the rings of a tree. Recognizing the unique 

value of this section, the U.S. Forest Service and the Utah Field 

House of Natural History have erected markers along the road, 

identifying each formation in turn.

78
The same formations, but without labels, are widely exposed 

elsewhere in the range, at such places as Dinosaur National Monument, Vermilion Greek, and Flaming Gorge, and with much variation along the Weber and Duchesne Rivers. With some training, 

anyone can quickly identify the major rock units exposed throughout the range. In particular, such units as the Uinta Mountain 

Group, the Deseret Limestone, the Weber Sandstone, the Glen 

Canyon Sandstone, the Morrison Formation, and the Dakota 

Sandstone lend special character and distinction to the Uinta 

Mountain scene. These units, however, are but half a dozen of 

more than 30 recognized formations in the Uinta Mountains.

CENOZOIC

MESOZOIC

PALEOZOIC

PRECAMBRIAN 

QUATERNARY and TERTIARY 

CRETACEOUS

JURASSIC 

TRIASSIC

PENNSYLVANIAN 

MISSISSIPPIAN

DEVONIAN 

SILURIAN

ORDOVICIAN 

CAMBRIAN

300 400 500 1000

MILLIONS OF YEARS AGO

Major divisions of geologic time

Rocks of the Uinta Mountains are of many ages, ranging from 

Precambrian to Quaternary. Two distinctive Precambrian formations are present: the older Red Creek Quartzite and the younger 

Uinta Mountain Group. The Red Creek is confined to a few 

square miles in the northeastern part of the range, but the Uinta 

Mountain Group is exposed over many hundreds of square miles, 

from one end of the range to the other and across the crest from 

flank to flank. All the high peaks consist of this rock. In brief, its 

name is well chosen.

79
Cambrian rocks crop out along the south flank of the range, but 

they were eroded from the north and northeast flanks before Mississippian time. Ordovician, Silurian, and Devonian rocks are 

lacking, although rocks doubtfully regarded as Devonian are exposed in a' few places. Each subsequent geologic period is represented by one or more rock formations.

The old Uinta trough

Throughout most of recorded geologic time, long before the 

mountains themselves appeared, the Uinta Mountains region was 

occupied by a slowly subsiding basin a broad elongate trough 

flooded much of the time by shallow-marine waters. This trough 

was an arm, or embayment, of a great seaway that intermittently 

covered western North America from Arctic Canada to Mexico. 

At times the seaway connected the Arctic Ocean to the Gulf of 

Mexico. Gentle flexing of the earth's crust caused repeated incursions and withdrawls of marine waters. Weight from accumulating sediments that were washed in from the sides of the trough 

helped cause the sea floor to subside.

The Uinta trough generally subsided more toward the west 

than toward the east. Marine conditions were therefore more prevalent toward the west, and deposits accumulated more rapidly. 

As a result, most formations thicken toward the west but thin 

to the east, north, and south. The present Uinta Mountains, uplifted by mountain-forming movements in the crust 70^: million 

years ago, are relative latecomers to the scene.

Precambrian time

The earliest, most complex sequence of events recorded in the 

Uinta Mountains took place more than 2 billion years ago, at a 

time so remote that it boggles the mind. The details of what happened, even though they are incompletely known, are too involved 

to be reiterated here, but they are described elsewhere (Hansen, 

1965, p." 22). In summary, the Red Creek Quartzite was deposited

80
on a well-washed shore. Made up mostly of clean sand, but including some mud and limy mud, it was then compacted, uplifted, folded, metamorphosed, and faulted. Sandstone, shale, and 

limestone were transformed by heat and pressure deep within the 

earth into quartzite, mica schist, and marble. Molten igneous rock 

was then injected into fractures and bedding planes, where it 

cooled and solidified and, finally, was transformed by renewed heat 

and pressure into hornblende schist, or amphibolite (fig. 40). 

New minerals were recrystallized from old, including such showy 

varieties as actinolite, garnet, kyanite, and staurolite.

Thus was formed the Red Creek mountain range, long since 

disappeared. The mountains trended east to west, much like the 

present Uintas, but, no doubt, they were larger and higher. The 

age of the mountains, 2.3 billion years, has been determined by 

radiometric dating that is, by measuring the decay products of 

radioactive minerals whose decay rates are known physical constants. Erosion then reduced the Red Creek mountains to their 

roots a nearly flat plain on which the Uinta Mountain Group 

began to accumulate. The base of the Uinta Mountain Group 

and the roots of the old mountains are well exposed north of 

Browns Park in a great unconformity visible from the floor of the 

valley.

When the Uinta Mountain Group began to accumulate, possibly a billion years ago, mountains of Red Creek Quartzite still 

stood to the northeast not far away. Bouldery alluvial fans spread 

out into the Uinta trough and formed coarse conglomerates that 

now are preserved in the Uinta Mountain Group north of Browns 

Park. The trough subsided slowly, and its rate of subsidence was 

counterbalanced almost exactly by the accumulation of sediment. 

No doubt the weight of the sediment was a factor in causing the 

subsidence. Ripple marks, fossil mud cracks, and even rain prints 

suggest shallow tidal pools and desiccating mudflats. True marine 

conditions existed in the western part of the range, where C.A. 

Wallace has identified an ancient shoreline. At the top of the 

Uinta Mountain Group, in the western part of the range, a thick 

shale formation called the Red Pine may have accumulated well 

offshore. Altogether about 24,000 feet of sandstone, shale, and 

conglomerate accumulated in the old Uinta trough before gentle 

uplift ended Precambrian deposition and ushered in the Paleozoic 

Era.

81

Paleozoic time: 

570-225 million years ago

The Uinta Mountain area once again was an expanse of hills, 

this time composed of red sandstone, quartzite, and shale. It was 

exposed to erosion until Middle to Late Cambrian time, when the 

sea moved in again. The sea encroached from west to east, depositing first the Tintic Quartzite and Ophir Shale at the west end 

of the range and then, as it spread eastward, depositing the Lodore 

Formation toward the east. The Lodore, well exposed in Dinosaur National Monument, is a succession of red, gray, and green 

sandstone and shale containing brachiopods and rare trilobites, 

primitive little cousins of our modern horseshoe crab. These fossils 

are the oldest clear evidence of life in the Uinta Mountains.

Cambrian time was followed again by emergence of the land. 

Just when this happened is uncertain because there is a stratigraphic gap of about 150 million years; Ordovician, Silurian, and 

probably Devonian rocks are lacking. At any rate, marine Mississippian rocks (Lodgepole Limestone) overlap the eroded edges 

of the Cambrian in many parts of the range. Along most of the 

present north flank, Cambrian rocks were completely eroded away 

before Mississippian time.

Trilobite, about natural size

CONTORTED RED CREEK QUARTZITE, more than 2 billion years old 

intruded by dark igneous dike. Exposure is about 100 feet high. (Fig..40)

83
The Mississippian Period brought in a reexpansion of the seaway and, with it, widespread deposition of the Madison Limestone and its equivalents. These rocks crop out from Alberta to 

Arizona, even to Sonora. The famous Redwall of Grand Canyon 

is the southern correlative. In the Uintas these rocks comprise 

four formations: the Lodgepole, Deseret, Humbug, and Doughnut. The Mississippian limestones form bold outcrops wherever 

they are exposed. They form the imposing "gateways" in Blacks 

Fork, Henrys Fork, Beaver Creek, and Burnt Fork, the "Palisades" of Sheep Creek (fig. 41), the east wall of Irish Canyon, 

and the giant stairsteps of Whirlpool and Lodore Canyons. Though 

resistant to erosion, these limestones are highly susceptible to solution by carbonatic waters, and many caverns have formed along 

their outcrops. Large springs issue from some of them, as at Sheep 

Creek. At other places whole streams disappear into the ground. 

Lost Creek, on the north flank near Burnt Fork, is such a stream; 

it empties into a sinkhole at the base of the Lodgepole Limestone. 

Dry Fork of Ashley Creek, Pole Creek (.a tributary of the Uinta), 

Brush Creek, and Little Brush Creek all lose drainage into the Mississippian limestone.

In addition to limestone, rocks of Mississippian age in the Uinta 

Mountains include sandstone and shale. Marine organisms flourished, and their fossilized remains are abundant, especially corals, 

brachiopods, crinoids, and snails.

Spirifer, a common late Paleozoic brachiopod, 

about natural size

PALISADES OF SHEEP CREEK. Eroded edge of. upturned Mississippian 

limestone in contact with the Uinta Mountain Group, left. (Fig. 41)

84
*r

"n- 
Throughout the remainder of Paleozoic time, the restless sea 

ebbed and flowed. The formations succeeding the Mississippian 

rocks the Round Valley, Morgan, Weber, and Park City all 

contain marine fossils. Yet, deposition was interrupted from time 

to time as the sea floor emerged. High mountainous islands stood 

to the southeast in Colorado and far to the west in Nevada in late 

Paleozoic time (fig. 42). The Round Valley Limestone was deposited well offshore, and the Morgan Formation was deposited near 

shore in shallow water of variable depth. The Weber Sandstone 

is mainly a beach deposit, and some of it may have accumulated 

as onshore sand dunes. But it also contains fossiliferous marine 

limestone. Much more could be said about the Weber; it is one of 

the most impressive and picturesque formations in the entire Uinta 

Mountains.

GENERALIZED GEOGRAPHIC MAP of the United States in Middle Pennsylvanian time. (Fig. 42)

86
The Park City Formation, on top of the Weber, is varied most 

of all. It contains a host of rock types laid down under diverse conditions. Deep water lay west of the Uintas; a shoreline lay east. 

Limestone predominates in most places and makes long resistant 

hill slopes (fig. 56), but phosphate rock is the most distinctive. 

It formed by the upwelling of organic-rich marine waters on the 

margin of a long-vanished continental shelf. These deposits are 

now being mined in big open pits near Vernal for use in the production of phosphatic fertilizer. The Park City Formation also contains gypsum, sandstone, conglomerate, and mudstone, cherty 

nodules and geodes, and, locally, many fossils.

Mesozoic time: 

225-65 million years ago

The Paleozoic Era drew to a close with clear marine waters still 

spread across the Uinta Mountains region. Following in Triassic 

time, environmental conditions continued to change. At first, 

shallow-marine muds of various shades of gray, red, and green 

were spread across the region, perhaps in a broad tidal delta, 

shoaling toward the east (the Woodside, Dinwoody, and Moenkopi Formations). As time passed, the sea floor subsided toward 

the west, and marine limestones (Thaynes Limestone) again began to accumulate. A few clams and their cousins lived in the 

Western Uinta region at that time, and countless ammonites 

teemed in the waters farther west. But in the Eastern Uinta region, 

gypsum was forming from concentrated sulfate brines in shallow 

arms of the sea, and few organisms survived. These gypsum beds 

are in the lower and middle parts of the Moenkopi Formation, 

laterally equivalent in the eastern part of the range to the Thaynes 

Limestone in the west. The gypsum is interbedded with ripplemarked red mudstone; together they form a conspicuous pinkish 

band several hundred feet thick in the Moenkopi north of Vernal 

and south of Manila (fig. 43).

87
Regional uplift followed deposition of the Moenkopi Formation. Thousands of square miles of eastern and southern Utah, 

northern Arizona, western Colorado, and southern Wyoming were 

gently elevated, draining off the sea. No mountains were formed, 

but much of the Moenkopi was carried away by erosion (fig. 44). 

The succeeding Chinle and Ankareh Formations (lateral equivalents, in part) began to form first as gravelly river-channel deposits, filling hollows and swales in the eroded top of the Moenkopi, then as a complex assemblage of red, purple, ocher, and 

green silts, muds, sands, and gravels, augmented by occasional 

falls of ash from distant volcanoes. Conditions clearly were nonmarine; fossil wood and remains of reptiles, amphibians, and mollusks, though uncommon, all suggest a terrestrial, perhaps marshy 

environment. Utter desiccation then ensued, and the whole Western Interior of the country became a vast desert.

TRIASSIC ROCKS exposed in Sheep Creek Canyon near Flaming Gorge. Gray 

Dinwoody Formation (foreground) overlain by Moenkopi, Chinle, and Glen 

Canyon, forming canyon wall and skyline. (Fig. 43)
The Chinie and Ankareh Formations extend upward into the 

Glen Canyon Sandstone, 3 a thick deposit of pink and gray to 

orange fossil sand dunes, which advanced across the old ChinleAnkareh landscape.

MOENKOPI FORMATION (lower right) beveled by erosion and overlain 

unconformably by Chinie Formation (upper left). One mile southwest of Flaming 

Gorge. (Fig. 44)

3 The name "Glen Canyon" has been applied recently in the Uinta Mountains to rocks formerly called Nugget or Navajo, a new usage which obviates 

certain correlation problems with other regions.

89
The Glen Canyon is one of the prominent cliff-forming units in 

the Uinta Mountains, and it enhances the local scenery wherever 

it crops out. Northwest of Vernal it forms the walls of Merkley 

Park (fig. 45) and the "beehives," arches, and alcoves of Neal 

Dome. Near Manila the Glen Canyon forms the heights of Jessen 

Butte, the north wall of Sheep Creek Canyon, the caprocks of 

Flaming Gorge, and the spine of Dutch John Mountain. Equivalent rocks are widespread in the canyon lands of southern Utah, 

where, for example, they form the towering walls of Zion 

and Glen Canyons. Altogether, an immense expanse of dunes 

covered much of the Western Interior of the country. Though 

centered in Utah, the dunes extended into Nevada, Arizona, New 

Mexico, Colorado, Wyoming, and Idaho. The crossbedded internal structure of the Glen Canyon Sandstone, ,a clear indication of 

its origin, is well preserved in the solid rock and gives the formation much of its scenic character.

Deposition of the Glen Canyon Sandstone ended when the Interior seaway readvanced across the region, again from the west. 

The sea bottom deepened to the west, like the earlier pattern of 

encroachment, and it shoaled to the east. Desert conditions persisted along the shore as the water lapped eastward. Accordingly, 

thick gray limestones interbedded with gray and red shales west 

of the Uinta Mountains diminish in thickness and pass gradually 

eastward into a much thinner section of red, green, and gray mudstone, shale, gypsum, and subordinate limestone. The thick section is called the Twin Creek Limestone. Its thin eastward counterpart is called the Carmel Formation. The Carmel disappears at 

about Skull Creek near the east end of the Uinta Mountains.

The Twin Creek sea was well populated with shellfish, and their 

remains are easy to find. Some limestone beds contain abundant 

fossilized clams, oysters, ammonites, sea urchins, and crinoids. Near 

Flaming Gorge, shell beds, or "coquinas," consist almost entirely 

of tightly packed shells and shell fragments. North of Vernal, 

beautifully preserved fossil clam shells have been replaced 

through the process of petrifaction by reddish-orange jasper. 

Conditions for the survival of life were unfavorable, however, when 

or where gypsum and red mud were accumulating in the Carmel 

Formation; these deposits, of course, contain no fossils.

90
CLIFF-FORMING GLEN CANYON SANDSTONE, overlying the Chinle 

Formation, at Merkley Park, Vernal, Utah. Photograph by Hal Rumel. (Fig. 45)

After the Twin Creek and the Carmel were deposited, the sea 

withdrew again. Its withdrawal this time was recorded by the 

Entrada Sandstone. The Entrada consists of clean white to pink 

cliff-forming sandstone interbedded with red or brown mudstone. 

The red or brown beds, locally called the Preuss Sandstone, mayhave accumulated in shallow stagnant water, but the white to 

pink sandstones were dunes. As the sea withdrew the dunes

91
crowded close against the shore, and as the sea readvanced the 

dunes pulled back. Mudstone thus predominates toward the west 

along the mountains, and sandstone, toward the east. In the more 

easterly sections, the Entrada consists entirely of windblown sand. 

East of the pinchout of the underlying Carmel Formation, the Entrada and the Glen Canyon combine to form a single thick body 

of cliff-forming sandstone.

The withdrawal was short lived, for the sea returned again, 

readvancing far beyond its previous shoreline to central Colorado. 

Its deposits this time were gray to greenish-gray marine sandstone, 

shale, and limestone, called the Curtis Formation. (In the Weber 

River drainage, it is generally called the Stump Sandstone.) The 

Curtis sea had a diverse fauna. Among the more typical inhabitants 

was the belemnite, a soft-bodied relative of the squid and cuttlefish, 

having an internal shell of '"cuttlebone," commonly preserved 

as a fossil. Several kinds of clams, snails, and, locally, ammonites 

were also abundant. Near Manila, countless little brachiopods left 

their shells in the uppermost beds of the formation.

Squidlike belemnite, about one-fourth natural size

As the Curtis sea pulled back, nonmarine mud, sand, and gravel 

from distant sources to the west or south built up a thick alluvial 

plain, now the Morrison Formation. Frequent falls of volcanic

92
ash must have dimmed the hot Jurassic sun. The Morrison Formation is famed especially for its dinosaurs, nowhere better exemplified than in Dinosaur National Monument.- But it also is one of 

the West's leading uranium producers, though not in the Uinta 

Mountains. Chief production from the Morrison is in southwestern Colorado and southeastern Utah.

The Morrison Formation is very widespread, and its variegated 

red, gray, green, and lavender clays are everywhere characteristic. 

It crops out around mountainous uplifts throughout most of the 

Rocky Mountain region and passes deep underground in between.

Dinosaur bones from the Uinta Mountains have been known 

for many years. Powell noted "reptilian remains" during his explorations, and O. A. Peterson of the American Museum of 

Natural History identified dinosaur bones in 1893. The worldfamous deposit north of Jensen was discovered in 1909 by Earl 

Douglass of the Carnegie Museum. Carnegie Museum operated 

the quarry from that time to 1922. The United States National 

Museum, the American Museum of Natural History, and the University of Utah operated it in 1923-24. After that time, collecting 

was discontinued. Assembled specimens are on display in museums 

at Denver, Lincoln, New York, Pittsburgh, Salt Lake City, Toronto, and Washington. In all, 26 nearly complete skeletons and 

parts of about 300, representing 10 different species, were recovered before the quarry was shut down (Good and others, 

1958). Meateaters as well as vegetarian dinosaurs, large and small, 

were taken from the quarry. Among the more noteworthy were 

Diplodocus, about 76 feet long; Apatosaurus, about 70 feet long; 

and Stegosaurus, about 20 feet long all vegetarians and Antrodemus, a bipedal carnivore, about 30 feet long.

Small dinosaurs were collected also, some only the size of chickens. A nearly complete lizardlike adult crocodile found by the 

Carnegie Museum was only about 7/2 inches long. In addition, 

the quarry has yielded the remains of large crocodiles and of tortoises, fresh-water clams, and plants surely one of the most 

extraordinary fossil deposits in the world.

The miracle of fossilization is thus reaffirmed by the dinosaur 

quarry. The odds against such a deposit being preserved are almost 

astronomical. The likelihood that the' remains of a particular creature will be preserved, especially a land-dwelling animal, is extremely remote. At best, only the hard parts, such as the bones,

93
AT THE DINOSAUR QUARRY. A paleontologist carefully chips rock matrix 

From a column of dinosaur vertebrae. These bones will be left in place for the 

visitor to see them just as they were deposited. National Park Service photograph. (Fig. 46)

are apt to be preserved. When, for example, one contemplates the 

millions of bison that roamed the Great Plains only 100 years ago 

and the present scarcity of their remains, one can appreciate the 

odds against fossilization. Of the trillions of organisms that have 

lived and died on the earth, only the smallest fraction has been 

left behind as fossils.

Quick burial is essential, to remove the remains from the weather. Bones left to the sun and elements soon disintegrate; wood left

94
lying in the forest soon returns to the soil. Petrifaction then must 

replace or reinforce the organic tissues with stone generally silica, 

molecule by molecule to forestall destruction during subsequent 

earth movements or rapid deterioration on reexposure to the elements. Finally, reexposure must be at the right place and at the 

right time for man to discover the fossils before they are destroyed 

by weathering and erosion.

Today, the National Park Service is developing the dinosaur 

quarry as an in-place exhibit. Bones are being carefully uncovered 

from their stony matrix, but left in place, so that the visitor can 

see them just as they were deposited (fig. 46). As pointed out by 

John Good of the National Park Service, the dinosaurs did not all 

live together in one habitat group, nor did they all die together 

in some great catastrophe. Their remains probably accumulated 

one by one on a bar of an ancient, river as their dead bodies 

floated downstream from time to time. Sediment rapidly covered 

the deposit, protecting the bones from decay. Lithification followed, encasing the bones in solid rock. Mountain-forming uplift 

and erosion finally exposed the deposit as'Douglass found it 130 

million years later.

95
As the Morrison episode was drawing to a close, events far to 

the west of the Uinta Mountains were shaping the depositional 

pattern of the future. High mountains were rising in California, 

and were soon to rise in Nevada and western Utah, shedding their 

sediments eastward. The seas, which through much of Paleozoic 

and Mesozoic time had invaded the region from the west, were 

pushed to the east; the newly formed lands to the west were never 

again flooded. Nonmarine Lower Cretaceous rocks accumulated 

on the Morrison Formation without any clear-cut interruption in 

deposition. These rocks are called the Cedar Mountain Formation. They have a varied content and variegated color, like the 

Morrison, but they are characterized especially by soft mudstones 

in pale-lavender tints. In many places they contain "gastroliths," 

the so-called gizzard stones of dinosaurs. (Whether or not these 

were ever actually ingested by dinosaurs is open to question. Authorities do not agree.) The base of the Cedar Mountain is indicated in some places by a pebbly ledge-forming unit called
the Buckhorn Conglomerate Member. The Buckhorn is well exposed, for example, just south of Escalante Overlook, along the 

road from Dinosaur National Monument Headquarters to Harpers Corner, but, where the Buckhorn is lacking, even experts are 

hard put to find the precise top of the Morrison or the bottom of 

the Cedar Mountain.

On top of the Cedar Mountain is the Dakota Sandstone. This 

formation is also very widespread. It extends from Montana to 

New Mexico and from central Utah to the Great Plains. The 

Dakota was deposited on the shore of a reexpanding seaway, 

which encroached this, time from the east as part of an inland 

sea connected to the Gulf of Mexico. As the sea again spread across 

the shore, sands and gravels accumulated on the beach. The 

Dakota thus contains marine as well as nonmarine sandstone, 

conglomerate, and coal-bearing shale that must have accumulated 

in coastal swamps. Here and there are bits of petrified wood. 

Many fossil ripple marks and mud cracks indicate intermittent 

wetting and drying (fig. 47).

FOSSIL RIPPLE MARKS in the Dakota Sandstone. Together with mud cracks, 

these features indicate deposition in intermittent shallow water. Photograph by 

John R. Stacy. (Fig. 47)

Because it is resistant to erosion, the Dakota Sandstone forms 

bold outcrops on the flanks of the mountains. Where its dip is 

gentle, it forms sloping bedrock plains (cuestas) bounded by cliffs 

facing toward the mountains. Where its dip is steep, it forms 

narrow rocky ridges (hogbacks) that may extend for miles without 

a break.

Subsidence of the crust and a flood of ocean water brought 

Dakota time to a close and introduced the overlying Mowry 

Shale. This distinctive dark-gray sea-bottom deposit weathers 

silvery gray. Most of it was derived from airborne volcanic ash 

that settled into the water. The ash had a high silica content that 

gave the shale a hard porcelainlike quality, one of its distinctive 

attributes. Inasmuch as the shale thickens greatly to the northwest of the Uinta Mountains, its volcanic source may have been

97
in that direction. Another attribute of the Mowry Shale a really 

diagnostic one, and an unmistakable clue to the identity of the 

formation is the presence of countless well-preserved fish scales 

found with very little effort on nearly every outcrop. Powell called 

the formation the "teleost shale" in allusion to the ill-fated donors 

of the scales. Perhaps the fish were killed by ash falls. The Mowry 

sea contained, as well as fish, a few oysters, and at times, some very 

large ammonites. The largest of these were more than 2 feet across. 

At the close of Mowry time, the sea pulled back again, and the 

bottom temporarily emerged. Then, with a few pulsations back 

and forth, the sea returned decisively for a long time. During the 

pulsating phase, the Frontier Formation was deposited. This formation, like the Dakota, consists of beach-laid sandstone, nearshore marine sandstones, and coastal-swamp deposits. Throughout 

most of the Uinta Mountains the Frontier Formation is twofold: 

a slope-forming shaly unit below, and.a cliff-forming, sandstone 

above. Oysters and other oysterlike shellfish are very characteristic, 

but the faunal list includes many other mollusks, also, particularly 

in the shaly lower part of the formation. A coal zone near the top 

of the shale yielded a few tons of coal in pioneer days, when nearness of supply was more important than the tonnage available. 

(In other parts of the West, such as Kemmerer, Wyoming, and 

Coalville, Utah, the Frontier contains large reserves of coal.) The 

upper sandstone unit of the Frontier, where it is not faulted out 

or concealed by overlapping rocks, forms a hogback on both flanks 

of the Uinta Mountains. Travelers on U.S. Highway 40 drive beside it for many miles along the south side of Blue Mountain; at 

Dinosaur National Monument it crops out just behind Monument 

Headquarters. The road across Blue Mountain, from Monument 

Headquarters into Harpers Corner and Echo Park, incidentally, 

provides excellent views of the whole geologic section of the Eastern 

Uinta Mountains, from the Frontier Formation down to the Uinta 

Mountain Group.

Scaphites, a Cretaceous ammonite, 

about one-third natural size

98
As the Frontier Formation accumulated in the Uinta Mountains area, high, newly formed mountains stood not far to the 

west, perhaps just west of the present Wasatch Range. Inasmuch as 

these mountains were the source of the sediments, the Frontier 

Formation thickens enormously in that direction. In the Eastern 

Uinta Mountains, it is only 100-200 feet thick, but at Coalville, 

just west of the Uintas, the Frontier is more than 4,400 feet thick 

and contains coarse conglomerate, as well as sandstone, shale, and 

coal. A few miles farther west, near Salt Lake City, it is more 

than 8,700 feet thick.

The Late Cretaceous geography of northeastern Utah can thus 

be visualized as follows: A broad shallow sea extended eastward 

from the foot of high north-trending coastal mountains that 

stood some distance west of the present Uintas (fig. 48). Gravelly 

alluvial fans reached east from the mountains to the shore. Waves 

and shore currents constructed sandy beaches and offshore bars. 

Dense junglelike forests grew down to lagoons behind barrier 

beaches. The waters teemed with shellfish.

NORTHEASTERN UTAH AND ADJACENT AREAS in Late Cretaceous 

time. High, newly formed mountains in western Utah shed debris eastward. 

Coastal-plain deposits accumulated between the mountains and the old Cretaceous 

seaway, and the crust subsided in the piedmont belt. (Fig. 48)

99
The buildup of high mountains to the west perhaps depressed 

the crust in front of them, for the crust is not rigid, and it responded to the added weight. The sea deepened, and the Frontier 

Formation thinned eastward, giving way to deep-water clays 

and muds that later became the Mancos Shale and its equivalents.

The Mancos Shale and its equivalents are very thick deposits 

of soft, dark-gray shale. They weather into shades of light gray 

or tan and form dreary badlands on both flanks of the eastern 

part of the range. On the north flank the names Hilliard and, 

locally Baxter Shale are used. Though the tops and bottoms are 

not exactly equivalent, all three units Mancos, Hilliard, and 

Baxter were deposited in the same sea and were once continuous bodies of the same clay.

Where not eroded, the Hilliard, Baxter, and Mancos have a 

thickness of several thousand feet, a maximum of more than a 

mile. This is not to say that the water was ever a mile deep. The 

sea bottom subsided slowly as the mud accumulated, and the 

crust was depressed beneath it. The shale thins to the west, intertonguing in that direction with sandstones and conglomerates of 

the thickening Frontier Formation.

fj i

n/

GENERALIZED GEOGRAPHIC MAP of the United States in Late Cretaceous 

time. (Fig. 49)

100
Geologic events at this time became very complex throughout 

western Utah but remained fairly simple in the area that was to 

become the Uinta Mountains. The Mancos seaway gradually withdrew to the southeast not however, without many short-lived readvances (fig. 49). Long tongues of beach sand interlayered 

with coal-bearing coastal swamp deposits marked its retreat and 

introduced the Mesaverde Group, which overlies and intertongues 

with the Mancos (fig. 50). Sandstone, shale, and coal comprise the 

Mesaverde Group, and geologists recognize many distinctive subdivisions. Different names, therefore, have been applied to the 

Mesaverde in various parts of the West, but for our purposes, 

the name Mesaverde Group will suffice.

THE GLADES. Hogbacks formed from resistant sandstone of the Mesaverde 

Group, northeast of Flaming Gorge. Antelope Flat (left) is underlain by soft 

Hilliard Shale. (Fig. 50)

By Mesaverde time, the old seaway that had dominated the 

geography of the Uinta Mountains area since Precambrian time 

was yielding, finally and irrevocably, to mountain-building forces 

stirring again to the west. The Mesaverde is the youngest group 

of rocks that predates uplift of the Uinta Mountains. If anything 

younger was deposited, it was stripped away by erosion as the 

mountains began to rise,

101
The whole Rocky Mountain System was taking shape at about 

this time. Mountain ranges were forming in response to forces in 

the earth's crust that were directed horizontally, obliquely, and 

vertically. Some ranges began to rise before others. At the same 

time, large basins were forming between the mountain ranges, 

where the crust buckled down instead of up. Many of these began 

to fill with water and sediment. Some parts of the crust were 

stressed to the point of rupture, and they failed by fracturing, or 

faulting, as great blocks of rock moved past one another, particularly at the flanks of the mountains. Compression dominated 

in some places, and when it finally slackened, uplifted masses began to subside, in response to gravity. By Cenozoic time, most of 

the Rocky Mountain ranges and basins as we know them today 

not all, but most of them were well delineated.

Cenozoic time: 

65 million years ago 

to the present

The Tertiary Period and the beginnings 

of the modern-day landscape

The rise of the Uinta Mountains in Late Cretaceous time was 

guided by the east-trending old Uinta trough and the thick prism 

of sediments that had accumulated through the ages. Near the west 

end of the range, the Evanston Formation, of Late Cretaceous and 

Paleocene age, contains conglomerate that seems to have been 

shed from the Uinta Mountains as erosion attacked the newly 

formed heights. This conglomerate thins toward the west away 

from the Uinta Mountains, and coarsens toward the east (T. E. 

Mullens, oral communication, 1968). It contains quartzitic 

cobbles, moreover, that probably came from the Uintas. Similar 

conglomerate accumulated in the Currant Creek area near the 

Duchesne River.

102
Deposits of latest Cretaceous age are lacking in the Eastern 

Uinta Mountains and may never have been deposited, but strong 

uplift and deep erosion plainly had taken place by earliest Tertiary 

(Paleocene) time. Large-scale faulting had thrust the mountainous 

core of the range thousands of feet up over the flanks, especially 

near Flaming Gorge. The Fort Union Formation near Flaming 

Gorge was deposited across the eroded edges of the older pre-Tertiary formations. Besides carrying the impressions of Paleocene 

leaves (oak, hickory, sycamore, and others) the Fort Union contains pebbles derived from the new Uinta Mountains to the south, 

including shale chips that contain fish scales from the Mowry 

Shale. By this time erosion must have penetrated at least 8,500 feet 

into the cover of the Uinta arch. By Wasatch time (Eocene) the 

Eastern Uinta Mountains were breached to their quartzitic core, 

and a flood of quartzite pebbles, cobbles, and boulders eroded 

from the Uinta Mountain Group was deposited in alluvial fans at 

the foot of the mountains. These fans became the Wasatch Formation, a widespread accumulation of sandstone, conglomerate, shale, 

and limestone in variegated shades of red and gray. North of 

Manila, the Wasatch contains enormous boulders of Paleozoic 

limestone some 8 feet or more across that were carried off the 

mountains by Tertiary flash floods or mudflows.

Meanwhile, as the mountains rose and faulting continued, the 

adjacent basins subsided. Large fresh-water lakes formed to the 

north and south, filling the basins and lapping against the mountains. The complex history of these lakes a story in itself cannot be told here. It has been studied intensively by many geologists, 

most particularly by W. H. Bradley (1948, 1964). In aggregate, 

the lake deposits are called the Green River Formation, famous for 

its vast reserves of oil shale, its enormously large deposits of sodium salts (trona beds), and its remarkably well-preserved fossils. 

The accumulations of limy muds on the lake bottoms proved to 

be an ideal medium for the preservation of fossils. Fish remains 

from the Green River Formation have become world famous, not 

only for their excellent preservation (fig. 51), but also for their 

abundance. They are displayed in museums throughout the world. 

In addition, wonderful impressions of leaves, flowers, fruits, and 

insects, a feather, and even the remains of a bat, have all been 

collected from the Green River Formation.

103
Most lakes are relatively short-lived geologic features. They are 

filled to overflowing with sediment; they are drained dry by erosion at their outlets; or their basins are destroyed by crustal warping. The Green River lakes were no exception. They varied greatly 

in extent and depth from time to time. Saline phases occurred when 

lake levels dropped below their outlets. At high stages, overflow 

around the east end of the mountains, according to Bradley, may 

have joined the Green River Basin to the Uinta. Inevitably, as 

deltal and alluvial deposits encroached upon the basins, the lakes

A WELL-PRESERVED EOCENE FISH, Diplomystus dentatus, collected from 

the Green River Formation. About one-third natural size. Photograph by W. T. 

Lee. (Fig. 51)

finally disappeared. They were succeeded by the Bridger and Uinta 

Formations, north and south. These formations soft mudstone 

and sandstone mixed with volcanic ash (fig. 52) attracted the 

attention of early-day collectors for their rich faunas of Eocene 

mammals and reptiles, including the bizarre many-horned Uintatherium. Another formation in the Western Uinta Basin, the 

Duchesne River Formation, also contains remains of early Tertiary reptiles and primitive mammals.

By Oligocene time the Uinta Mountain scene was beginning to 

have a fairly modern appearance. The present divide probably had 

taken shape. Broad sloping plains (pediments) were forming on 

the flanks. An apron of coarse gravel, the Bishop Conglomerate 

(of uncertain age but either Oligocene or Miocene), was accumulating at the outer margin of the plains. Thick remnants of this 

conglomerate still cap high mesas along the edge of the mountains. 

Large-scale faulting, propelled by gravity, was beginning in the 

eastern part of the range, dropping the eastern crest relative to the 

flanks. The Browns Park Formation was beginning to accumulate; 

this, perhaps, in Miocene time.

104
THE BRIDGER FORMATION, typically exposed in badlands southeast of 

Fort Bridger, Wyoming (Fig. 52)

The stage was now set for the sequence of events that shaped 

the present scene the development of modern drainage across 

the mountains, the cutting of the great river canyons, and the glacial sculpture of the high peaks events already discussed in the 

section on landscapes. All these events helped mold the Uinta 

Mountains as we know them today. All past geologic events, in 

fact, helped shape the present landscape, even the deposition of the 

Red Creek Quartzite more than 2 billion years ago. Clearly, the 

landscape, the rocks, and the processes that formed them both are 

not entities unto themselves. They are interdependent parts of an 

integrated whole, a continuum of matter, space, and time.

^"'/^ *,'. X fff />' 

tor

#,,.'//>', %

. < r^r^-

Uintatherium, about 5 feet tall

105
STRUCTURAL "GRAIN" of the region surrounding the Uinta Mountains, 

much generalized. The Uinta trend intersects the Wasatch trend (left) at a 90° 

angle but merges concordantly with the northwesterly trends to the east. Axes 

of anticlines and uplifts, spindle-shaped patterns,- axes of syncline; and 

basins, dashed lines,- faults, solid lines. (Fig. 53)

106
Geologic structure

s TRUCTURAL geology deals with the relations of rock 

masses to one another, particularly insofar as the rocks have been 

deformed by forces within the earth. Studying the geologic structure helps the geologist unravel the history of the earth.

Most of the early-day geologists who visited the Uinta Mountains commented on the unusual structural relation of the range 

to its neighbors. Trending due east 150 miles from the little town 

of Kamas, the range is directly athwart the northerly trend of the 

neighboring ranges and uplifts of the Rocky Mountains. The 

crestline of the Uinta Mountains actually is broadly arcuate, trending about N. 10° E. from Kamas to about the center of the range 

near the Burro Peaks, then swinging gradually east-southeastward to its eastern terminus near the Little Snake River. Structurally and topographically, the Uinta Mountains intersect the northtrending Wasatch Range on. the west at an abrupt 90° angle.

On the east, however, the trend of the Uinta Mountains veers 

to the southeast and merges with the northwest-trending folds 

of the White River Plateau and the Park Range. All the major 

structural trends in that part of the Rocky Mountains and the adjacent Colorado Plateau, for that matter, are northwest, including 

most major faults. So, the only really major discordance of the 

Uinta Mountains is along the west margin of the Rocky Mountains, particularly at the Wasatch juncture (fig. 53).

107
In trying to visualize the crustal movements that produced the 

Rocky Mountains 60-70 million years ago, one is bemused by 

the magnitude of the uplifting forces that raised thousands of 

cubic miles of rock in the Uinta Mountains alone from a position 

near or even below sea level to present altitudes, thousands of feet 

higher. If the strata that have been eroded from the Uinta Mountains were restored in our imagination, the upper layers would be 

30,000-40,000 feet above sea level. This is not to say that the 

mountains ever stood that high, even though some early-day geologists surmized that they did. For as the mountains rose, erosion 

attacked and carried away the heights, and the higher the mountains rose, the more vigorous the attack. It is doubtful that the 

mountains were ever really much higher than now possibly a few 

thousand feet higher, but never Himalayan, certainly, in size.

The upbuckling that produced the mountains was accompanied 

by comparable downbuckling under the basins. As the mountains 

rose, the basins subsided, so that deposits once near sea level 

throughout the region are now 12,000-13,000 feet high in the 

mountains but are as much as 30,000 feet below sea level beneath 

the Green River and Uinta Basins. Moreover, debris shed from 

the mountains accumulated in the adjacent basins, and its added 

weight further depressed the basin floors. Obviously, the crust 

is not unyielding; it responds to pressures directed horizontally, 

vertically, or obliquely. Such pressures building up at the end 

of the Cretaceous Period caused the crustal movements that produced the Uinta Mountains.

An eroded syncline

108
Folds

In the High Uintas, the Crestline is much closer to the north 

flank than to the south. The marked asymmetry of the range is 

related to the structure of the underlying bedrock. In brief, the 

Uinta Mountains are carved from an immense anticlinal fold 

whose outline closely coincides with the outer limits of the mountains. The uplifted strata of the range, therefore, slope outward 

from the crest of the fold toward the flanks, so that successively 

younger rocks are crossed as one travels outward from the interior 

of the range toward the flanks (fig. 54). The Uinta anticline is

Kinqs Peak 

Red Castle

North Burro Peak 

.Mount Emmons

-^ Uinta River Canyon

GEOLOGIC CROSS SECTION through the Western Uinta Mountains, p 

Precambrian rocks,- C, Cambrian; M, Mississippian,- PP, Permian and Pennsylvanian,- J"fi, Jurassic and Triassic; K, Cretaceous; T, Tertiary. Compare "ith 

figure 58. Vertical scaleX2. (Fig. 54)

compound in that its crest has two main apexes or culminations 

one in the Western Uinta Mountains and one in the Eastern 

Uintas something like two peanuts in one shell. In a general 

way, however, the crest of the fold is nearly flat, so that the bedding or stratification along the crest is almost horizontal, from 

Mount Watson on the Provo-Weber divide all the way to Douglas Mountain near the east end of the range. Away from the fold 

axis the dip of the strata steepens, first gradually, then abruptly 

toward the flanks (figs. 55 and 56).

109
FLAT-LYING STRATA in the Uinta Mountain Group (Precambrian) at crest 

of Uinta Mountains, accentuated by an early August snowfall. Wilson Peak, 

altitude 13,053 feet. (Fig. 55)

Like the mountains themselves, the Uinta anticline is asymmetrical. Its crest is much closer to the north flank than to the 

south; therefore, the strata on the north flank dip more steeply 

than the strata on the south. Severe bending along the flanks, 

moreover, has led to rupture and large-scale faulting, particularly 

along the north flank.

In the west half of the range, the crest of the anticline very nearly 

coincides with the crest of the range in some places it is slightly 

north, in others, slightly south. Thus, despite the removal of many 

thousands of feet of rock by erosion, the position of the main divide 

apparently has remained almost unchanged since the fold came 

into being 70-odd million years ago.

Figure 57 is a generalized map of the Uinta anticline; in detail 

the anticline is more complex. Elongate east and west domes share 

a common axis, or Crestline, which curves gently to the north in 

a broad arc. The east and west domes are almost mirror images of 

each other comparable in size and shape although the east

110
dome is appreciably more complex than the west. Each dome 

is 70 75 miles long and 30 35 miles across. Both are faulted internally, and both are partly bounded by faults.

Associated with the east dome, but not the west, are several 

large subsidiary folds, known since the time of Powell; they 

include the Blue Mountain, Split Mountain, and Section Ridge 

anticlines and their synclinal counterparts. These are shown in 

figure 58. In addition, there are many smaller folds, a few miles 

long, on the flanks of the larger ones. Most of these have been 

actively prospected for petroleum, and among them are several 

economically important oil fields, the most significant recent discovery being that of the Bridger Lake field, just west of Henrys 

Fork, high on the north flank. Bedrock at Bridger Lake is concealed by thick glacial deposits, and the oil field was discovered by 

purely geophysical means. Its discovery in 1965 set off a flurry of 

exploration and leasing activity that is still in progress.

.«-r

"SJfc

DIPPING STRATA, north flank of Uinta Mountains at Sheep Creek Canyon. 

Dipslopes and cliffs in foreground are eroded from the Park City Formation. 

(Fig. 56)

111
Duchesne

- , . -r; , '>'IS

112
EXPLANATION

/ , Anticline Syncline Fault 

* Showing plunge Dashed 

where 

approximate

GENERALIZED STRUCTURE MAP of the Uinta Mountains. Darker tint indicates Precambrian core of the range. (Fig. 57)

113
- North 

Sand Wajh"

^ Monument 

'^Headquarters

GEOLOGIC CROSS SECTIONS through the Eastern Uinta Mountains. p , 

Precambrian rocks; C, Cambrian,- M, Mississippian; PP, Permian and Pennsylvanian,- J~S, Jurassic and Triassic,- K, Cretaceous; T, Tertiary. Note that Cambrian 

rocks are missing from the north flank. Vertical scaleX2. (Fig. 58)

114
Faults

Mention has been made of the asymmetry of the Uinta anticline. 

The crest of the fold is much nearer the north flank than the 

south; consequently, the strata slope, or dip, more steeply down 

the north limb of the fold than down the south (figs. 54 and 58). 

To a large extent, bending on the north limb proceeded to the 

point of rupture. Even solid rock will yield to long-sustained stress. 

As the folding progressed, the strata were first tilted, then overturned, and, finally, broken. Deep crustal movements pushed the 

Uinta anticline northward over the margin of the Green River 

Basin, causing the development of three large faults: the North 

Flank fault to the west, the Henrys Fork fault at the center, and 

the Uinta fault to the east. These are reverse, or "thrust," faults, 

the fault surfaces dip steeply under the mountains, and the upthrust, mountainward block overrides the basinward block. Of 

the three faults, the Uinta appears to be the largest, having a displacement of about 34,000 feet, or the distance one block moved 

past the other. The North Flank fault may have a displacement of 

as much as 25,000 feet; the Henrys Fork fault, perhaps more 

than 12,000 feet.

Large faults also broke the south limb of the anticline, although 

none of these appears to have displaced the strata as much as those 

on the north limb. From west to east, they include the South 

Flank fault, extending 80 miles east from the Duchesne River 

area to Ashley Creek, the Deep Creek fault zone northwest of 

Vernal, and the Willow Creek, Island Park, Mitten Park, Wolf 

Creek, and Yampa faults of Dinosaur National Monument. These 

faults have generally been regarded as "normal faults," faults in 

which the surface of rupture slopes under the downdropped block. 

Recent studies by several investigators, however, suggest that some 

of them are "reverse" faults, at least at depth. In other words, the 

mountainward, upthrown side moved up and over the basinward, 

downthrown side. In the cross sections (figs. 54 and 58) the 

Yampa, Island Park, Wolf Creek, and Willow Creek faults are 

shown as reverse faults; the South Flank fault is shown as a normal 

fault.
A normal fault, showing repetition of strata

A reverse fault, showing "drag

116
Most of the large faults of the Uinta Mountains are fairly 

broad zones of disturbance rather than simple fractures. There is 

much ground-up and shattered rock, much distortion, and many 

subsidiary fractures. The Uinta fault, largest in the range, serves 

to illustrate.

The Uinta fault was named and first described by Powell 

(1876, p. 177). A more detailed description can be found in 

U.S. Geological Survey Professional Paper 490 (Hansen, 1965). 

The fault is well exposed and readily accessible; the best places 

to see it are just north of the town of Dutch John and just south 

of Clay Basin. Figure 59 shows the fault at Hideout Canyon, before 

Flaming Gorge Dam was built. From its terminus southwest of 

Manila, the Uinta fault trends sinuouly east-northeast for about 

45 miles as a continuous fracture. It increases in displacement 

and width to about the 109th Meridian, where it passes beneath 

the Browns Park Formation. About 10 miles to the east, it emerges 

as the Sparks fault and is virtually continuous for another 20 miles. 

Discontinuous fractures extend at least another 30 miles.

UINTA FAULT from rim of Hideout Canyon. Weber Sandstone (left and 

center), is upturned against Uinta Mountain Group. (Fig. 59)
The Uinta fault has many subsidiary branches. It also contains 

large slices of rock torn from the walls and dragged into the fault 

zone. One such slice north of Dutch John is more than 2 miles 

long possibly 3 miles and as much as 400 feet across. Well 

back from the fault surface the strata have been tilted up on edge 

and even overturned, but where Tertiary rocks are involved, they 

are little deformed despite the severe deformation in the immediately underlying Cretaceous rocks. Apparently, the fault had more 

than one period of movement: the first and strongest movement 

in Late Cretaceous or earliest Tertiary time severely dislocated the 

involved rocks; a second movement, after the Tertiary rocks had 

been deposited across the fault, simply sheared off the Tertiary 

strata with little other effect. Still later, gravitative movements 

accompanied the collapse of the Eastern Uinta Mountains (p. 

62 and 104).

Some further mention must be made of the faults of Dinosaur 

National Monument. These faults are especially significant for 

their dramatic physical expression and for the part they had, 

therefore, in shaping the impressive local scene. Few faults anywhere are better displayed. All of them happen to be eroded to 

levels in the earth's crust where contrasting strata help disclose 

their geometric form. Thus, between Round Top Mountain and 

Echo Park in the heart of the monument, the Weber Sandstone is 

repeated topographically in four huge escarpments, or stairsteps, 

bounded from rim to river by the Yampa, Red Rock, and Mitten 

Park faults and the canyon of the Yampa River itself. The fault 

relations are unmistakably clear.

Strata repeated by stair-step faulting

The faults of the Dinosaur National Monument area further 

disclose sharp flexing of the strata in their walls, again dramatically exposed (fig. 60). Like an expression of frozen movement, or

118
SHARPLY DRAGGED STRATA along the Mitten Park fault below Harpers 

Corner. Red Moenkopi Formation in foreground is downdropped against folded 

Weber Sandstone in background. (Fig. 60)

of time standing still, these faults accent the grandeur of the scene 

and stir wonder in the heart of the viewer. Even the most languid 

boater, lazing in the hot summer sun, is duly awed as he floats past 

the Mitten Park and Island Park faults, upstream and down, respectively, from Whirlpool Canyon.

Internally, the Uinta Mountains are also extensively faulted, 

and few large expanses of rock can be seen that do not have some 

faulting. Two major zones are especially noteworthy. One zone 

named the Crest fault by J. D. Forrester (1937, p. 645), extends 

west to east for many miles along the west dome of the anticline 

just north of the crest (fig. 61). Recent mapping by Crittenden, 

Wallace, and Sheridan (1967, plate 1) showed that the Crest 

fault is a complex zone of many interrelated fractures with various 

trends and offsets. Neither the total displacement nor the direction of movement is known with certainty, although the north side 

of the zone, according to Crittenden, Wallace, and Sheridan probably has dropped about 2,000 feet.

119
The other zone extends along the east dome of the anticline, 

also north of the crest, from the vicinity of Red Canyon to Browns 

Park, and to the east end of Cold Spring Mountain. This fault 

zone was instrumental in the collapse of the east end of the Uinta 

Mountains in Tertiary time. Augmented by gravitative movements on the Uinta fault to the north, and in concert with movement on the Yampa fault to the south, it led to the collapse of the 

Uinta Mountain "graben," noted on page 62. In summary, the 

crestal part of the east dome collapsed under gravity relative to 

the flanks of the dome some time after compressive mountain 

building had ended. When the compressional forces that arched 

up the dome relaxed, gravity began to pull the dome back down. 

Total collapse along the crestline amounted to about 4,500 feet 

and, thus, accounts for most of the difference in altitude between 

the east and west halves of the range (Hansen, 1965, p. 172).

CREST FAULT, a zone of fractures, viewed from the head of Backs Fork of the 

Green River. Note flat strata (left of fault zone) and dipping strata (right). Photograph by Max D. Crittenden, Jr. (Fig. 61)

120
GOSLIN MOUNTAIN. A tilted remnant of the Gilbert Peak erosion surface 

on the north flank of the range. Now sloping southward (left), it formerly sloped 

northward. (Fig. 62)

warping

Gravitative movements of the earth's crust began in the Uinta 

Mountains before the Browns Park Formation was deposited, 

even before the Gilbert Peak erosion surface was cut. These movements continued until after deposition of the Browns Park Formation was completed. Along the north side of Browns Park the strata 

were fractured, tilted, and dragged into near-vertical attitudes. 

Locally, they were even overturned, as in Jesse Ewing Canyon, 

near the west end of Browns Park. Elsewhere, collapse was accompanied by large-scale regional tilting of the ground surface, clearly 

shown by deformation of the Gilbert Peak erosion surface on the 

north flank of the range (fig. 62), by tilting of correlative surfaces 

on the south flank, and by tilting, of strata, such as the Browns 

Park Formation. Partly bounded by faults, different areas were 

tilted in different directions. But the tilting on the north flank 

was predominantly inward toward the south, and on the south 

flank, predominantly inward toward the north, just as one would 

expect of a foundering mountain range.

121
Quaternary

crustal movements

How long warping and faulting continued in the Uinta Mountains after the Browns Park Formation was deposited is unknown, 

although both processes clearly extended into the Quaternary 

Period and may still be in progress. Little direct evidence of 

Quaternary deformation has been observed, but careful search 

perhaps would disclose more.

Some evidence is available in Lodore Canyon. After the Green 

River had entrenched itself 1,500 feet or so into Lodore Canyon, 

it apparently stopped cutting downward and began to widen its 

valley. But the river was then rejuvenated, and it resumed cutting 

downward an additional 600-800 feet to its present depth. Thus

R. 5 W. R. 4 W.

Qbm Qpo

Qbo

Tdr

R. 5 W. R. 4 W. 

2 MILES

QUATERNARY FAULTS (heavy lines) cutting glacial outwash, south of Uinta 

Mountains. Prominent scarps, heavy hachured lines; subdued fault traces, heavy 

dashed lines,- terrace margins, light hachured lines. Tdr, Duchesne River Formation,- Qbm, moraine of Bull Lake age,- Qbo, outwash of Bull Lake age,- Qpo/ 

outwash of Pinedale age,- Ql landslide. (Fig. 63)

122
was formed the two-tiered valley, shown in profile (p. 48). 

Although the cause of rejuvenation is unclear, renewed uplift is 

suspect, and it might have happened in Quaternary time. Canyon 

profiles suggest similar rejuvenation upstream in Red Canyon, 

but the evidence is not compelling.

In the Uinta Basin at Towanta Flat, just south of the mountain 

front and just west of Lake Fork (fig. 63), local but clear-cut deformation occurred in late Pleistocene time. A graben and several 

subordinate fault scarps more than 3 miles long displace what 

probably are Bull Lake age (late Pleistocene) glacial-outwash terraces, but the faults do not cut across younger terraces or moraines 

of Pinedale age. One of the fault scarps is about 40 feet high.

A simple sraben formed by tension

On the north flank of the range just north of Phil Pico Mountain 

a probable faulted alluvial fan was noticed by Max Crittenden, 

Jr. (oral communication, 1968), on aerial photographs. The age 

of this feature is uncertain, but it probably is no younger than the 

Bull Lake Glaciation.

On the Middle Fork of Blacks Fork just south of the North 

Flank fault are the remains of a spectacular rock-fall avalanche. 

Thousands of tons of rock, now spread over an area of perhaps 

100 acres, broke free from the tilted outcrop of the Mississippian 

limestone and plummeted 1,000 feet to the canyon floor. There, 

part of the rock avalanche crossed the Middle Fork and traveled 

200 feet up the opposite canyon wall. Just when this event happened is unknown, but the evidence is very fresh, and it must have 

happened in the not-too-distant past a few hundred years ago, 

at most. Although the avalanche might have been released by 

gravity alone, it is the sort of feature that commonly is associated 

with earthquakes, such as the 1959 Madison River slide in Montana. Because of nearness of the avalanche to the North Flank 

fault, its release could easily be ascribed to geologically recent 

activity on the North Flank fault.

123
Historically, however, the Uinta Mountains have been seismically quiet, even though many earthquakes are recorded annually 

in the Wasatch Range to the west. But the historic period has been 

too short geologically to permit valid projections of events in the 

Uinta Mountains, either into the past or into the future.

What the future holds

l/l/E CAN affirm, however, that changes will indeed continue. Slowly, perhaps, but inexorably. The deep canyons, the 

mountain peaks, and the "everlasting" hills though firm they 

stand are only bit players acting out their roles on the endless 

stage of time. John Wesley Powell would agree.

Each summer, hikers will hear the reports of loosened rocks, 

crashing shotlike from the ridge lines into the valleys far below. 

Each winter, unseen avalanches will sweep more rocks down from 

the heights. Each spring, freshets will scour the beds of creeks and 

rivers. And each fall, when new ice coats the ponds and fresh snow 

powders the summits, fingers of frost will again reach deep into the 

rocks, searching out each crack and crevice.

Each year, landslides and mudflows will carry more debris to 

the bottom lands, leaving new scars on the hillsides. In time these 

will heal and leave no trace. Through sthe years, lakes and ponds 

will slowly gather silt. First, pond lilies, then rushes, grasses, herbs, 

and finally, willows will encroach upon the shores, converting some 

lakes to ponds, some ponds to marshes, and some marshes to 

meadowlands. Some meadowlands, gullied and dissected by erosion, will become badlands. Some of these, perhaps, will grow into 

canyons.

Drainage adjustments will follow the patterns of the past; some 

streams will capture the headwaters of others. Aided by the hand 

of man, some changes will outpace all those gone before. And with 

wisdom, man's way will be the right way. If man's way prevails, 

snowmelt from the High Uintas will moisten the parched fields of 

central Utah. Powell would approve.

Much of the high country -unchanged wilderness since the 

time of Powell and now protected by law will remain inviolate 

for the enjoyment of generations yet unborn. Powell would 

applaud.

124
Just a few words 

about the 

animals

NIMALS furred and feathered are so much a part of the 

Uinta M.ountain scene that I would be remiss not 'to mention 

them. The casual visitor one who crosses the mountains in a 

high-powered automobile or who stops briefly at Dinosaur National Monument may see a few rodents, a few birds, or possibly 

even a badger or a mule deer, but probably not much else. But 

anyone who spends a few hours or a few days away from the highway will be abundantly rewarded.

More than a quarter of a million acres.of the High Uintas 

in the Wasatch and Ashley National Forests has been protected 

for many years as a primitive area and, under the Wilderness Act 

of 1964, has been reserved for study as a possible future part of 

the National Wilderness System. Aside from the primitive area, 

many additional thousands of acres are in fact wilderness. Game 

in these areas roams free, unmolested by the encroachments of 

civilization.

125
The largest wild animal in the Uinta Mountains is the moose, 

which ranges mostly on the north slope but occasionally strays over 

the top into the Duchesne and Provo drainages. His smaller but 

still-large cousin, the American elk or wapiti, is more widespread, 

ranging the mountains from end to end and slope to slope. A sizable herd, for example, summers on Cold Spring Mountain. Another ungulate, the mule deer, is very abundant the big-game 

animal most likely to be seen. Mule deer prefer open brushy country along the mountain flanks. I have even seen them along the 

high road to Harpers Corner in Dinosaur National Monument.

Bighorn sheep once were plentiful in the high country and in 

the canyons as well (hence the name Sheep Creek Canyon). Powell 

mentioned seeing them in Echo Park. A small herd is sometimes 

seen by boaters in Lodore Canyon. Elsewhere, they are rare.

The pronghorn antelope, shy but inquisitive, favors the arid 

flats and benches at the flanks of the range. Pronghorns were common in the Flaming Gorge area 15 years ago, when I first was 

there. Perhaps they still are. They even flourished on Cold Spring. 

Mountain at altitudes above 8,000 feet, where I once saw an 

angry doe chasing a coyote.

Mustangs, or wild horses, used to haunt the Flaming Gorge area 

also, particularly the wide-open country north of Clay Basin. I 

saw them often at Dutch John Flat before the dam was built. Domestic horses turned loose on the range, of course, are easily 

mistaken for mustangs, unless they wear bells.

Of the predators, cougars were fairly common in the Eastern 

Uintas when I was working there, although they were seldom 

seen. And the experienced camper took precautions to protect his 

gear from marauding black bears. Coyotes seem to be holding 

their own, despite the determined onslaughts of well-intentioned 

exterminators. Many local stockmen recognize their value in helping stem the rodent population, which competes with livestock 

for food. A "save the coyotes" campaign was mounted a few years 

ago by alert ranchers. ;

Smaller animals are on the scene everywhere, and a sharp eye 

isn't needed to see them, although it helps. Bobcats, badgers, 

skunks, porcupines, beavers, muskrats, marmots, jack rabbits, cottontails, pikas, golden-mantled ground squirrels, tree squirrels, 

and chipmunks all are ubiquitous. I used to see an occasional 

fox, fisher, and weasel.

126
Whiptail lizards are abundant at lower altitudes, where they 

often are seen sunning themselves on the warm rocks. Snakes are 

uncommon. Gopher snakes formidable of mien, but harmless 

are sometimes seen in the dry foothills. Garter snakes and graceful 

little green snakes thrive in the montane zone. In 6 or 8 years I 

saw only three rattlesnakes two near Flaming Gorge and one 

in Browns Park all little fellows 12-14 inches long, but each a 

mature adult fully arrayed with rattles. Small rattlesnakes of this 

type belong to a dwarf subspecies of the Western rattlesnake, 

Crotalus viridis. Not being adapted to the rigors of .the alpine 

climate, they favor the lower country in the basins and along the 

mountain flanks.

Birds, of course, are plentiful, and a good watcher could compile a long list. The more notable kinds include the golden and the 

bald eagle, the turkey vulture, several species of hawks and falcons, 

the great horned owl, other smaller owls, the nighthawk, many 

water birds and waders (including the Canada goose and the great 

blue heron), the pine grouse and sage hen, the crow, raven, and 

magpie, the black bird, cliff swallow, junco, bluebird, pinyon jay, 

and canyon wren, and the favorite of campers, Clarks nutcracker.

127
References

The following short list of references refers mostly to authors 

cited directly in the text. The geologic literature on the Uinta 

Mountains is very extensive, and no attempt has been made here 

at completeness. A few papers of general interest or wide scope not 

directly cited in the text, however, have been included. All of these 

papers are technical or semitechnical in content. Most of them can 

be seen in any big city library. Some of the Government publications are available from the Superintendent of Documents, although most of them are out of print.

Atwood, W. W., 1909, Glaciation of the Uinta -and Wasatch 

Mountains: U.S. Geological Survey Professional Paper 61, 

96 pages.

Bradley, W. H., 1936, Geomorphology of the north flank of the 

Uinta Mountains [Utah]: U.S. Geological Survey Professional Paper 185-1, pages 163-199.

Bradley, W. H., 1948, Limnology and the Eocene lakes of the 

Rocky Mountain region: Geological Society of America 

Bulletin, volume 59, number 7, pages 635-648.

Bradley, W. H., 1964, Geology of the Green River Formation 

and associated Eocene rocks in southwestern Wyoming and 

adjacent parts of Colorado and Utah: U.S. Geological Survey Professional Paper 496-A, 86 pages [1965].

Capps, S. R., 1910, Rock glaciers in Alaska: Journal of Geology, 

volume 18, pages 359-375.

Crittenden, M. D., Jr., Wallace, C. A., and Sheridan, M. J., 

1967, Mineral resources of the High Uintas Primitive area, 

Utah: U.S. Geological Survey Bulletin 1230-1, 27 pages.

Emmons, S. F., 1877, Descriptive geology: U.S. Geological Exploration 40th Parallel (King), volume 2, 890 pages.

Forrester, J. D., 1937, Structure of the Uinta Mountains: Geological Society of America Bulletin, volume 48, number 5, 

pages 631-666.

128
Good, J. M., White, T. E., and Stucker/, G. F., 1958, The Dinosaur Quarry, Dinosaur National Monument, ColoradoUtah: Washington, D.C., [U.S.] National Park Service, 47 

pages.

Hansen, W. R., 1965, Geology of the Flaming Gorge area, UtahColorado-Wyoming: U.S. Geological Survey Professional 

Paper 490,196 pages.

Hayden, F. V., 1871, Preliminary report [fourth annual] of the 

United States Geological Survey of Wyoming and portions 

of contiguous Territories (being a second annual report of 

progress): U.S. Geological Survey Territories, 4th Annual 

Report, 511 pages.

Kinney, D. M., 1955, Geology of the Uinta River-Brush Creek 

area, Duchesne and Uintah Counties, Utah: U.S. Geological 

Survey Bulletin 1007, 185 pages.

Kulp, J. L., 1961, Geologic time scale: Science, volume 133, number 3459, p. 1105-1114.

Marsh, O. C., 1871, On the geology of the eastern Uinta Mountains: American Journal of Science, 3d series, volume 1, 

pages 191-198.

Merrill, G. P., 1906, Contributions to the history of American 

geology: Washington, D.C., U.S. National Museum, Annual 

report of the Smithsonian Institution, 1904, pages 189-733.

Powell, J. W., 1876, Report on the geology of the eastern portion 

of the Uinta Mountains and a region of country adjacent 

thereto: U.S. Geological and Geographical Survey Territories (Powell), 218 p.

Richmond, G. M., 1965, Glaciation of the Rocky Mountains in 

Wright, H. E., Jr., and Frey, D. G., eds., The Quaternary of 

the United States: Princeton, New Jersey, Princeton University Press, pages 217-230.

Ritzma, H. R., 1959, Geologic atlas of Utah, Dagget County: 

Salt Lake City, Utah, Utah Geological and Mineralogical 

Survey Bulletin 66, 111 pages.

Sears, J. D., 1924, Relations of the Browns Park formation and 

the Bishop conglomerate and their role in the origin of the 

Green and Yampa Rivers: Geological Society of America 

Bulletin, volume 35, pages 279-304.

129
Sears, J. D., 1962, Yampa Canyon in the Uinta Mountains,

Colorado: U.S. Geological Survey Professional Paper 374-1,

33 pages. 

Stokes, W. L., and Madsen, J. H., Jr., compilers, 1961, Geologic

map of Utah northeast quarter: Salt Lake City, Utah,

Utah Geological and Mineralogical Survey, scale 1: 250,000. 

Untermann, G. E., and Untermann, B. R., 1954, Geology of

Dinosaur National Monument and vicinity, Utah-Colorado:

Salt Lake City, Utah, Utah Geological and Mineralogical

Survey Bulletin 42, 228 pages. 

Van Hise, C. R., 1892, Correlation Papers; Archean and Algonkian: U.S. Geological Survey Bulletin 86, 549 pages. 

Wahrhaftig, Clyde, and Cox, Allan, 1959, Rock glaciers in the

Alaska Range: Geological Society of America Bulletin,

volume 70, pages 383-436. 

Walton, P. T., 1944, Geology of the Cretaceous of the Uinta Basin,

Utah: Geological Society of America Bulletin, volume 55,

number 1, pages 91-130. 

White, C. A., 1889, On the geology and physiography of a portion

of northwestern Colorado and adjacent parts of Utah and

Wyoming: U.S. Geological Survey 9th Annual Report,

pages 677-712. 

Woolley, R. R., 1930, The Green River and its utilization: U.S.

Geological Survey Water-Supply Paper 618, 45,6 pages.

130
Index

[Italic page numbers indicate major references]

A

Accessibility, highland blocks..................................... 32

Agassiz Peak, named............................................ 7

Age of rock formations........................................... 78

Alaska earthquake, cataclysmic event.............................. 55

Alluvial fans, effect on Late Cretaceous geography................... 99

faulted, north of Phil Pico Mountain.......................... 123

Wasatch Formation......................................... 103

Alpine rock glaciers............ '. ................................ 28

Altitude, Continental Divide, southern Wyoming.................... 63

range crest................................................. 14

Amphitheaters, scoured by glaciers................................ 18

south flank of Western Uintas................................ 24

Ancestral drainage, Green River Basin............................. 59

Animals....................................................... 125

Ankareh Formation, terrestrial environment........................ 88

Antecedence, drainage concept......................:............ 58

Antrodemus..................................:................. 93

Apatosaurus.................................................... 93

Ar£tes, along crest of range...................................... 14

Ash falls, preservation of fish scales, Mowry Shale................... 98

Ashley Valley, precipitation...................................... 31

Atwood, W. W., study of glacial effects in the Uinta Mountains. ...... 18

Avalanche, rock-fall, south of North Flank fault.................... 123, 124

B

Badlands, fossil-bearing beds..................................... 5

Mancos Shale, Eastern Uinta Mountains....................... 100

Bald Mountain, drainage........................................ 73

reshaped by glaciation....................................... 24

Baxter Shale, north flank of Eastern Uintas......................... 100

Bears, black................................................... 126

Bedrock, characteristically exposed, Eastern Uinta Mountains......... 32

glacially abraded............................................ 17

structure, relation to asymmetry of range.......;............... 109

Beehive Point, named by Powell.................................. 7

Belemnite.................................................... : . 92

Birds.......................................................... 127

Bishop Conglomerate............................................ 104

Blacks Fork glacier, extent....................................... 18

	131
Block field..................................................... 14, 26

Blue Mountain................................................. 37, 62

Blue Mountain anticline......................................... Ill

Blue Mountain highland......................................... 36

Boundaries of range............................................. 8

Brachiopods, Lodore Formation................................... 83

Bradley, W. H. stream capture, Lodore Canyon..................... 60

study, north flank........................................... 59

fresh-water lakes........................................ 103

Bridger Formation, vertebrate faunas.............................. 5

volcanic ash................................................ 104

Bridger Lake field, petroleum..................................... Ill

Bright Angel Creek, named by Powell............................. 7

Browns Park, fill................................................ 43

fracture^'and tilted strata.................................... 121

intermontane valley......................................... 42

Red Creek Quartzite exposures........................... .^.. . 33

relief of area............................................... 42

renamed by Powell.......................................... 7

Browns Park Formation, age..................................... 104

Blue Mountain............................................. 62

composition and known thickness............................. 43

Diamond Mountain highland................................. 34

Buckhorn Conglomerate Member, outcrops......................... 97

Bull Lake glacier............................................... 25

Burnt Fork glacial moraine, blocking of Lost Creek.................. 75

G

Cambrian time, Middle to Late, sea encroachment.................. 83

Canyon of Lodore. See Lodore Canyon.

Canyons, barriers between highlands.............................. 32

cutting, energy requirements............................,.;.. 55

Tavaputs Plateau, height of walls............................. 63

U-shaped, carved by glaciers................................. 22

Capps, R. S., rock glaciers identified.............................. 27

Carmel Formation, lithology..................................... 90

Cassidy, Butch, legendary hideout................................. 40

Catastrophism, origin of canyons.................................. 55

Cedar Mountain Formation, gastroliths............................ 96

Cenozoic time, Rocky Mountain System. .......................... 102

Chinle Formation, terrestrial environment.......................... 88

Clay Basin, commercial gas field.................................. 32

Cliffs, Entrada Sandstone........................................ 91

Glen Canyon Sandstone..................................... 90

Jones Hole. ............................................... 52

Coal, Frontier Formation......................................... 98

Coalville quadrangle map, physical and spatial relations.............. 12

Cold Spring Mountain, continuous section exposed.................. 33

enveloped by fill............................................ 63

summer homp for American elk herd.......................... 126

Collapse, Eastern Uintas......................................... 62

Colorado Plateau, structural trends................................ 107

132
Colorado Plateaus province, components........................... 8

Compression, crustal stresses...................................... 102

Uinta Mountain graben.................................... 120

Cones, talus, Kings Peak......................................... 27

Conglomerate, accumulations from the Uintas...................... 102

Continental Divide, altitude in southern Wyoming................... 63

drainage................................................... 59

Cope, E. D., Tertiary vertebrate study............................. 4

Coquinas, near Flaming Gorge................................... 90

Corals......................................................... 84

Cougars....................................................... 126

Coyotes........................................................ 126

Crest, Uinta anticline, relation to range crest....................... 110

Crest fault, named by J. D. Forrester.............................. i 19

Crestline, High Uintas........................................... 109

Cretaceous geography, Late, northeastern Utah..................... 99

Crinoids....................................................... 84

Crustal movements.............................................. 108

Eastern Uinta Mountains.................................... 62

60-70 million years ago...................................... 108

stresses.................................................... 102

Cuestas........................................................ 97

Curtis Formation, fossils......................................... 92

D

Dakota Sandstone, extent........................................ 97

Decay products, radioactive minerals............................... 81

Deep Creek fault zone........................................... 115

Deer, mule.................................................... 126

Deseret Formation.............................................. 84

Diamond Montain highland...................................... 32, 34

Diamond Mountain Plateau...................................... 34

Diamond Peak, altitude.......................................... 31

Diatoms, Browns Park Formation................................. 43

Dinosaur National Monument, animals............................ 126

bone deposits............................................... 5, 93

canyon overlook, Harpers Corner............................. 37

fault relations.............................................. 118

faults.............. r ....................................... 115

Jones Hole................................................. 52

Morrison Formation......................................... 93

Weber Sandstone........................................... 52

Zenobia Peak.............................................. 35

Dinosaurs, in-place quarry exhibit................................. 95

Morrison Formation......................................... 37, 93

Dinwoody Formation, depositional environment..................... 87

Diplodocus..................................................... 93

Dirty Devil River, nanied by Powell.............................. 7

Disaster Falls, Upper and Lower, named by Powell.................. 47

Discordance between the Uinta and the Rocky Mountains............ 107

Displacement, along major thrust faults............................. 115

Crest fault zone............................................. 119

Divide, main, Western Uinta Mountains........................... 29

	133
Doughnut Formation............................................ 84

Douglas Creek arch, counterpart of the Rock Springs uplift. ........... 8

Douglas Mountain, Browns Park Formation........................ 62

Douglas Mountain highland...................................... 35

Douglass, Earl, dinosaur-bone deposits discovered................... 5, 93

Downbuckling, Green River and Uinta Basins...................... 108

Drainage, adjustments. .......................................... 124

ancestral, Green River Basin................................. 59

Browns Park Formation...................................... 59

captured................................................... 68, 70

concepts................................................... 58

controlled by strata......................................... 67

Douglas Mountain.......................................... 35

from Browns Park........................................... 43

Green River, discordance with topography..................... 59

modern, development....................................... 105

obstructed, Continental Divide................................ 63

old adjustments:........................... v . ................ 73

present Continental Divide.................................... 59

related to stream capture.................................... 70

structurally .adjusted......................................... 67

superposition, Green River in Swallow Canyon.................. 44

Tertiary, Browns Park ........................................ 43

Drill-hole data, study of subsurface formations. ..................... 78

Duchesne River, drainage adjustments............................. 73

Duchesne River Formation, Tertiary reptiles and primitive mammals.. 104

Dunes.......................................................... 89-91

Dutch John-Cold Spring highland........................:....... 32

Dutch John Mountain, Glen Canyon Sandstone..................... 90

Eastern Uinta Mountains, breached to quartzitic core................ 103

characteristically exposed bedrock............................. 32

climate.................................................... 31

drainage concepts........................................... 58

erosion.................................................... 103

extent of fill............................................... 63

geologic section............................................. 98

graben movement ........................................... 62

Green and Yampa Canyons.................................. 31

main divide................................................ 29

.physiography............................................... 29, 31

ponded drainage............................................ 62

talus...................................................... 27

Weber Sandstone........................................... 54

Echo Park, access............................................... 48

named by Powell........................................... 7

Elk, American.................................................. 126

Emmons, S. F., drainage-development theory....................... 6

drainage superposition.......................................

quoted. ...................................................

description of lakes ......................................

summit named ...............................................

134
Entrada Sandstone, withdrawal of sea............................. 91

Environmental conditions, Triassic time............................ 87

Eocene mammals and reptiles.................................... 104

Erosion, Eastern Uinta Mountains................................ 103

effect on mountain building.................................... 108

preferential, Browns Park.................................... 43

Green River........................................... 59

Erosional plain, remnants........................................ 32

Evanston Formation, lithology.................................... 102

Extent of Uinta Mountains...................................... 8

F

Faults, Blue Mountain highland.................................. 36

discussion.................................................. 117

large-scale, eastern part of range.............................. 104

near Flaming Gorge..................................... 103

Red Creek Quartzite exposures............................... 33

relations, Dinosaur National Monument........................ 118

thrust, major............................................... 115

Uinta anticline..................:.......................... 110

Whirlpool Canyon.......................................... 53

Felsenmeers.............................................. .^. .... 14, 26

 Fertilizer, phosphatic............................................ 87

Fish remains, Green River Formation.............................. 103

Mowry Shale.............................................. 98, 103

Flaming Gorge, Glen Canyon Sandstone........................... 90

Green River meanders....................................... 63

Jurassic and Triassic rocks................................... 40

mustangs in the area........................................ 126

named by Powell........................................... 7

Flaming Gorge-Red Canyon-Browns Park valley complex............ 32

Flatirons, Stuntz Ridge. ......................................... 36, 37

Floods, flash, Tertiary........................................... 103

Folds, Blue Mountain highland................................... 36

crest of Uinta anticline...................................... 109

monoclinal, Blue Mountain block............................. 36

Uinta anticline........................................... 110, 111

Fort Union Formation, Paleocene fossils............................ 103

40th Parallel Survey, by King.................................... 2

Fossil-bearing beds, Uinta and Bridget Formations.................. 5

Fossils, in Carmel Formation..................................... 90

brachiopods................................................ 83

Browns Park Formation..................................... 43

corals ....................................................... 84

Curtis Formation ............................................ 92

crinoids ................................................... 84

Dakota Sandstone. .......................................... 97

diatoms.................................................... 43

Dinosaur National Monument................................ 93

dinosaurs. See Dinosaurs.

135
Diplodocus..................................................... 93

fish-scale, Mowry Shale...................................... 98

fishes, Green River Formation............................... 58/103

Fort Union Formation...................................... 103

Green River Formation.................................... 103, 104

Lodore Formation.......................................... 83

Mississippian limestones....................................... 84

Morgan Formation........................................... 86

odds against preservation.................................... 93, 94

ostracodes................................................. 43

Paleocene.................................................. 103

Park City Formation........................................ 86

trilobites................................................... 83

vertebrate................................................. 4, 5

Weber Sandstone, marine.................................... 86

Fractures, crustal stresses.......................................... 102

stair-step faulting................................ .... .......... 37

Frontier Formation............................................. 98

Frost, effect on rocks............................................ 14, 16

G

Gas field, commercial, Clay Basin. ................................ 32

Gastroliths, Cedar Mountain Formation............................ 96

Gates of Lodore, Green River.................................... 44

height of canyon walls....................................... 48

Geography, northeastern Utah, Late Cretaceous..................;.. 99

Geologic events, past, effect on present landscape.................... 105

Geologic periods, rock formations represented in the Uintas........... 80

Geologic section, Eastern Uinta Mountains......................... 98

Geologic structure, studied to unravel history of the earth............. 107

Gilbert, G. K., principle of velocity................................. 55

summit named for................................'.......... 7

Gilbert Peak................................................... 55

quadrangle map, physical and spatial relations.................. 12

Gilbert Peak erosion surface ....................................... 34, 121

Glacial action, nunataks......................................... 24

Glacial epochs, defined by Atwopd................................ 19

Glacial moraines, lakes and ponds.............................. 17, 22, 27

Glacial-outwash terraces, Pleistocene deformation..................... 123

Glaciations, contribution to stream capture. ........................ 73

correlation chart............................................. 19

Glaciers, former extent.......................................... 18, 23

Glen Canyon Sandstone......................................... 89, 90

Gorges, cut by running water..................................... 22

Graben movement, Eastern Uinta Mountains. ...................... 62

Gravitative movements, collapse of the Eastern Uintas............... 118

relative to age of formations.................................. 121

Uinta Mountain garben ....................... ^ ............. 120

Great Ice Age products.......................................... 16

Green River, Emmons' concept of superposition..................... 58

Gates of Lodore............................................ 44

Lodore Canyon............................................. 63

136
postulated establishment..................................... 62

Split Mountain Canyon...................................... 54

Green River Basin, boundary to Uintas ............................ 8

Green River Formation, fossils. ................................. 103, 104

sodium salts and oil shales................................... 58

Green River lakes............................................... 104

Gypsum beds, Moenkopi Formation............................... 87

H

Hansen, W. R., theory on establishment of the Green River. ......... 62

Harpers Corner, Browns Park Formation........................... 62

Hayden, Ferdinand V., exploration route.......................... 2

quoted. ......... ...... ........................ ..... .............. . 2, 4

summit named1 . ............................................ 7

Territorial Survey study..................................... 1

unconformity observed...................................... 4

Hayden Peak quadrangle map, physical and spatial relations. ......... 12

Heber Valley, Upper Provo River................................. 68

Hells Half Mile, named by Powell................................. 47

Henrys Fork fault............................................... 115

High Uintas, denned............................................ 13

See also Western Uinta Mountains.

Highland blocks ................................................ 32

Hilliard Shale, north flank of Eastern Uintas........................ 100

Hogbacks...................................................... 97

Hoop Lake basin, preglacial drainage.............................. 75

Horseshoe Canyon, Green River meanders......................... 63

Humbug Formation............................................. 84

I

Island Park fault.............................................. 115, 119

Whirlpool Canyon ................... i ...................... 53

J

Jesse Ewing Canyon, overturned strata............................. 121

Jessen Butte, Glen Canyon Sandstone.............................. 90

Jones Hole, Whirlpool Canyon................................... 52

Jurassic rocks, Flaming Gorge.................................... 40

Rainbow Park.............................................. 54

K

King, Clarence, exploration route. ................................ 2

Territorial Survey study ..................................... 1

summit named............................................. 7

Kingfisher Canyon, named by Powell.............................. 7

rapids...................................................... 40

Kings Peak.................................................... 7, 27

Kings Point, exhumed red quartzite spur........................... 44

137
Lake Bonneville, overflow, cataclysmic event........................ 55

Lake deposits, Green River Formation. ............................. 103

Lake Fork glacier, broad piedmont ice sheet. ....................... 18

Lakes, fresh-water, formation. .................................... 103

glacial..................................................... 17

Mirror Lake-Bald Mountain area. ............................ 18

Landslides..................................................... 124

Late Cretaceous geography, northeastern Utah...................... 99

Lily Park, strata just below....................................... 48

Limestone beds, Wild Mountain and Harpers Corner................ 52

Lithification................................................... 95

Little Dry Glaciation............................................ 23, 25

Little Dry Stade, morainal deposits................................ 19

Lizards, whiptail................................................ 127

Lodgepole Limestone, age........................................ 83

Lodore Canyon, age of strata..................................... 52

barrier to cross-country travel................................ 34

bighorn sheep....................................... ... .... 126

Green River............................................... 63

named by Powell........................................... 7

Pot Creek.................................................. 34

stages of cutting....................... ; .................... 48

stairsteps.................................................. 84

stream erosion.............................................. 60

theory of origin.:........................................... 59

Uinta" Mountain Group...................................... 47

Lodore Formation.............................................. 122

Whirlpool Canyon........................................... 52

Loose-rock accumulations, types................................... 26

Lost Creek watershed, related to spring discharge.................... 75

Lucerne Valley, precipitation..................................... 31

M

Madison Limestone, deposition................................... 84

Mancos Shale, eastern part of range......;......................... 100

Marine conditions, Uinta Mountains region........................ 80

Marsh, O. C., quoted........................................... 4

Tertiary vertebrate.study .................................... 4

travel route described....................................... 4

Marsh Peak quadrangle map, physical and spatial relations........... 12

Meadows, high-altitude, Western Uintas ........................... 31

Meanders, Green River.......................................... 63

Yampa Canyon............................................ 49, 66

Mesaverde time, mountain building............................... 101

Middle Rocky Mountains........................................ 8

Miocene time, Browns Park Formation............................. 104

Mississippian Period, reexpansion of seaway......................... 84

Mississippian rocks, Split Mountain............................... 54

Mitten Park.................................................... 53

Mitten Park fault. ......................................... 51, 115, 119

Whirlpool Canyon.......................................... 52, 53

138
Moenkopi Formation, depositional environment..................... 87

erosion.................................................... 36

Moose............................ ; ............................ 22, 126

Moraines, glacial..............................................'. 22

Morgan Formation, marine fossils................................. 86

Morrison episode, events toward the end........................... 96

Morrison Formation, dinosaur quarry ............................. 37, 93

nonmarine deposition....................................... 92

uranium................................................... 93

Mount Agassiz, drainage......................................... 73

Mount Lena................................................... 31

Mount Powell.................................................. 7

Mowry Shale, depositional environment............................ 97

Mudflows...................................................... 124

Muds, shallow-marine, Triassic time............................... :-87

Music Temple, named by Powell.................................. 7

Mustangs...................................................... 126

N

Navajo Formation .............................................. 89, 90

Neal Dome, Glen Canyon Sandstone.............................. 90

Neoglaciation.................................................. 27

Nonmarine conditions, Chinle and Ankareh Formations.............. 88

North Flank fault. .............................................. 115

possible relation to rock-fall avalanche. ........................ 123

Nugget Formation. See Glen Canyon Sandstone.

Nunataks...................................................... 24

O

Oil shale, Green River Formation................................. 58

Oligocene time, geography........................................ 104

Ophir Shale.................................................... 83

Ostracodes, Browns Park Formation................................ 43

P

Paleozoic time, emergence of sea floor............................. 86 

limestone boulders.......................................... 103

strong uplift................................................ 103

Palisade Park, large springs...................................... 75

Palisades of Sheep Creek.......................................... 84

Park City Formation, depositional conditions. ....................... 87

erosive resistance............................................ 36

lithology................................................... 87

marine fossils............................................... 86

Park Range, structural relation to the Uintas....................... 107

Pats Hole, Yampa River. ......................................... 48

Petrifaction.................................................... 90, 95

Petroleum..................................................... Ill

Phil Pico -Mountain............................................. 123

Phosphate rock................................................. 87

Physiography, Eastern and Western Uintas compared................ 31

Piceance basin, counterpart of the Washakie and Sand Wash Basins.... 8

	139
Piedmont ice sheets, merged glaciers............................... 18

Pine Cliff, tributaries upstream................................... 70

Pinedale glacier................................................ 25

Pleistocene Epoch, felsenmeer..................................... 16

Pleistocene glaciers, late, confined to valleys........................ 18

Pleistocene time, late, evidence of deformation...................... 123

Ponds, glacial.................................................. 17

Pot Creek, drainage to Lodore Canyon............................ 34

Powell, J. W., boat trip on Green and Colorado Rivers.............. 2, 37

concept of drainage antecedence.............................. 58

describing Green River....................................... 39

exploration route........................................... 2

landmark names given....................................... 6

quoted from diary ........................................... Ill

quoted from 1876 report. .................................... IV

Territorial Survey study..................................... 1

unconformity observed....................................... 4

Precambrian formation, Red Creek Quartzite....................... 79

Precambrian quartzite, Red Canyon............................... 40

Precambrian rocks, study by C. R. Van Hise....................... 6

Precipitation, Eastern Uinta Mountains............................ 31

Mount Lena area........................................... 31

Predators. See specific animals.

Preuss Sandstone, depositional environment......................... 91

Protalus....................................................... 26, 27

Q

Quartzite, effects of freezing and thawing.......................... 16

Quaternary terraces, Browns Park................................. 42

Quaternary time, stream rejuvenation............................. 123

R

Rainbow Park, alluviated valley.................................. 53

Rapids, Kingfisher Canyon....................................... 40

named by Powell........................................... 47

Rattlesnakes. .................................................. 127

Red Canyon, Green River meanders............................... 63

Red Creek mountain range (ancient).............................. 81

Red Creek Quartzite, age........................................ 79, 81

deposition................................................. 80.

Dutch John-Cold Spring highland ............................ 33

effect on modern landscape................................... 105

radiometric dating.......................................... 33

unconformity............................... ............... 4

uplifted by faulting........................................... 4

Red Creek Rapid............................................... 40

Red Pine Formation, Western Uinta Moutains...................... 81

Regional relations, shown by topographic maps..................... 12

Regional tilting, deformation of Gilbert Peak erosion surface........... 121

Remnants, erosional plain....................................... 32

Rhodes Valley, glacial outwash................................... 68

Rock Creek, drainage adjustments................................. 73

140
Rock-fall avalanches ............................................ 1 24

south of North Flank fault .................................... 123

Rock flour. .................................................... 28

Rock formations, defined ........................................ 77

major, exposed in Uintas ..................................... 79

range in age ............................................... 78

river courses adjusted to hardness ............................. 67

Rock glaciers ................................................ 26, 27, 28

Rock islands. See Nunataks.

Rocky Mountain System, development. ............................. 102

major divisions ............................................. 8

Rocky Mountains, strucural trends ................................ 107

Round Valley Limestone, marine fossils. ........................... 86

Whirlpool Canyon .......................................... 52

Rubble, Pleistocene Epoch ....................................... 16

Rupture, response to crustal stress. .............................. 102, 1 15

Salt Lake City topographic sheet, regional relations. ................. 12

Salt River Range, Middle Rocky Mountains ........................ 8

Sand dunes, Entrada Sandstone. .................................. 91

Glen Canyon Sandstone ...................................... 89

Western Interior ............................................ 90

Seaway, Mancos ...........................................;.... 101

Section Ridge anticline .......................................... Ill

Seismic activity ................................................. 124

Sheep, bighorn ................................................. 126

Sheep Creek, Palisades .......................................... 84

Sheep Creek Canyon, Glen Canyon Sandstone ...................... 90

Shell beds ..................................................... 90

Snails ......................................................... 84

Snakes. ....................................................... 127

Snowmelt, Wind River and Park Ranges. .......................... 38

Sodium salt deposits. ............................................. 58

Split Mountain, erosion. ......................................... 37

Split Mountain anticline. .................................... 53, 54, 1 1 1

Split Mountain Canyon, Green River, gradient ..................... 54

Spring discharge, related to shower activity, ........................ 75

Stades, glacial. .................................................. 19

Stages, glaciation, identified by Bradley. ........................... 19

Stair-step cliffs, Whirlpool Canyon ................................ 52

Stair-step lakes, formed by Pleistocene glaciers ...................... 17

Stairsteps, Lodore and Whirlpool Canyons ......................... 84

Steamboat Rock ................................................ 51

Stegosaurus .................................................... 93

Stream adjustment, west end of mountains ......................... 68

Stream capture, drainage concept ................................. 58

Duchesne River ............................................ 73

Lodore Canyon ............................................. 60

near Flaming Gorge ......................................... 63

141
Streams, adjusted to structure.................................... 67

rejuvenation.............................................:. 123

velocity, geometric increase in carrying power................... 55

Structure, boundaries of the Uintas................................ 8

Browns, Park............................................... 43

drainage adjustments...........'............................. 67

Eastern Uinta Mountains.................................... 29

geologic................................................... 107

Stuntz Ridge, spectacular folds................................... 37

Subsidence, old Uinta trough..................................... 81

response to gravity.......................................... 102

Sulfate brines, gypsum beds ...................................... 87

Summit ridges, aretes............................................ 14

Summit Valley................................................. 34

Superposition, conditions for...................................... 63

drainage concept............................................. 58

Green River established by................................... 62

Swallow Canyon, named by Powell............................... 7

Swamp deposits, coastal, coal-bearing............................. 97, 101

Sweetwater River, Wind River Range............................. 59

Syncline, asymmetrical, at Island Park............................. 53

T

Talus, Eastern Uinta Mountains.................................. 26,27

Tavaputs Plateau............................................... 63

Teleost shale.................................................. 98, 103

Terraces, glacial-outwash} displaced by faults ....................... 123

Quaternary, Browns Park.................................... 42

Terrestrial environment, Chinle Formation......................... 88

Territorial Surveys.............................................. 1, 3

Tertiary drainage, Browns Park................................... 43

Tertiary fill, Browns Park. ....................................... 42, 62

Teton Range, Middle Rocky Mountains........................... 8

Thrust faults, major............................................. 115

Tintic Quartzite................................................ 83

Topographic barriers, canyons between highlands................... 32

Topographic division of the Uinta Mountains....................... 13

Topographic maps, glacial moraines............................... 22

Topographic relations of the range to its neighbors.................. 107

Towanta Flat, late Pleistocene deformation. ........................ 123

Triassic rocks, Flaming Gorge..................................... 40

Trilobites, Lodore Formation..................................... 83

Trona beds. See Sodium salt deposits.

Twin Creek Limestone, lithology ................................. 90

U

Uinta anticline................................................ 53, 109

Browns Park............................................... 43

severe bending and faulting.................................. 110

Uinta Basin, counterpart of the Green River Basin................... 8

Uinta fault................................................... 115, 117

Uinta Formation, vertebrate faunas............................... 5

volcanic ash................................................ 104

142
Uinta Mountain graben........................................ 62, 120

Uinta Mountain Group, age.;.................................... 79

bouldery alluvial fans........................................ 81

Lodore Canyon............................................. 47

Whirlpool Canyon........:................................. 51

Uinta Mountains, maps showing physical and spatial relations. ....... 12

structural relation to the Wasatch Range. ...................... 107

Uinta River glacier, extent. ...................................... 18

Uinta sea, ancient, buried headland............................... 4

Uinta trough, marine conditions.................................. 80

rise of the mountain range................................... 102

Uintatherium.................................................. 104

Uplift, end of Precambrian deposition............................. 81

Uranium, Morrison Formation................................... 93

V

Valley fill, Eastern Uinta Mountains.............................. 62, 63

Van Hise, C. R., study of Precambrian rocks....................... 6

Vernal topographic sheet, regional relations ........................ 12

Volcanic ash, Bridger and Uinta Formations........................ 104

Browns Park Formation...................................... 43

Diamond Mountain......................................... 34

south of Browns Park........................................ 62

W

Wallace, C. A., ancient shoreline identified. ........................ 81

Wapiti. ...:.................................................... 126

Wasatch Formation............................................. 103

Wasatch Range, Middle Rocky Mountains......................... 8

seismic activity.............................................. 124

topographic relation to Uinta Mountains....................... 107

Watersheds, major drainage basins................................ 16

Weathering, hard and soft strata.................................. 67

Weber Sandstone, cliff-forming unit............................... 22, 52

Horseshoe Canyon.......................................... 40

marine fossils............................................... 86

outer shell of Split Mountain................................. 37

Split Mountain Canyon...................................... 54

stair-step escarpments....................................... 118

Whirlpool Canyon.......................................... 52

Yampa Canyon............................................. 49

Western Interior, desert.......................................... 88

sand dunes................................................. 90

Western Uinta Mountains........................................ 14

felsenmeers................................................. 26

frost. ..................................................... 16

high peaks................................................. 13

meadows.................................................. 31

separated from Diamond Mountain highland ................... 33

watersheds................................................. 16

	143
Whirlpool Canyon, barrier to cross-country travel................... 34, 52

depth of gorge.............................................. 51

faults...................................................... 53

stairsteps.................................................. 84

White, C. A., geologic review of the Eastern Uinta Mountains........ 5

White River Plateau............................................ 107

Wild Mountain................................................ 48

Willow Creek fault.............................................. 115

Wind River Range, Middle Rocky Mountains...................... 8

Wolf Creek fault................................................ 115

Woodside Formation, depositional environment...................... 87

Y

Yampa Canyon, bedding differences.......................... 49

Yampa fault.................................................. 37, 115

Yampa River, confluence with Green River......................... 48.

course established........................................... 63, 66

Yellowstone Creek glacier, piedmont ice sheet....................... 18

Z

Zenobia Peak, altitude........................................... 35

144