Quaternary Geology 

of Boulder Mountain 

Aquarius Plateau, Utah 

By RICHARD F. FLINT and CHARLES S. DENNY 

CONTRIBUTIONS TO GENERAL GEOLOGY '• - -~ _- , -~ ..... ~. 

GEOLOGICAL SURVEY BULLETIN 1061-D 

UNITED sTATEs dov~1l:r·r~EN.i _·PRll'fTING oFF:fCit, wAsHINGTON : t9ss '· ~ . . _, '~ ... ... - ,. ' - . - ~ . . ._ " - . ~~- _,. 
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary 

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director 

For sale by the Superintendent of Documents, U.S. Government Prlntiq Office 

Washington 25, D. C. - Price $1.00 (paper cover) 
CONTENTS 

true 

Abstract------------------------------------------------------~--- 103 

Introooction ___________________ .. .:. _____ :.. _______ --------------------- 104 

Physical geography------------- ________________ ----- __ ------------- 104 

Topography and vegetation------------------------------------- 104 

Bedrock geology ___ - .. _ .. ___ .. ..:.:. __ ..; __ "'~ __ -- __ -_ .. _-- __ - _____ .. ---.. -- 107 

Climate------------------------------------------------------- 108 

1Veathering _____ -'~------------------~------------------~------..;___ 109 

Soils with caliche .. __ ---- _______________________ ..;.-------- __ --·--- 109 

Soils without caliche _____________ --- _____ ----~ _____ ----- ___ ----_ 112 

Exfoliation _________ -- __ --~- _______ ----- __ --_---~--------- .. ..;.--_ 113 

Solution ___ -------- ______________ ----- _____ ---------------"---_ 114 

Patterned ground ____________ ~ __________ .;._ .. ________ .. ______ .... _ .. __ 114 

Glacial features of the plateau tOP----------------------------------- 115 

Glacial drift on the sides of the plateaU---------'--·-'-----'-------------.. 118 Age ___ :...:.. _______________ ---- ______ ~ __ .;. ___________________ --~___ 119 

Weathering .. ______ ..; ____ ..: _____________ ..;;..:..;..: _____________ ---- 120 

Topography-~-- ____ -~- _______ ~_---- _____ ----------------·-- 120 

Relation to bedrock topography----------------------------- 120 

Probable substages of glaciation ...... __ .. ______ .. _ .. _ .. _..; _ _ _ _ _ _ _ _ _ _ _ _ _ _ 121 

I>rntlobes____________________________________________________ 122 

Fish Creek-Grover drnt lobe________________________________ 122 

I>imensions .. ------------------------------------------ 122 Carcass Creek drut ______________ --------- _____ ----- _ ___ 122 

I>onkey Creekdrllt------------------------------------ 125 

Blind Lake drut--------------------------------------- 125 Pleasant Creek drut lobe _______________________________ ----- 12{) 

Boulder Creek drift lobe------------------------------------ 127 Miller Creek drift lobe .. _____________________________________ 128 

Staiaon Creek .drift lobe------------------------------------- 129 

I>onkeyCreekdriftlobe------------------------------------ 130 

I>istribution of drift around the'plateau___________________________ 131 

Rock glaciers ________ ------- ____ ----------------___________________ 13.1 

Talus------------------------------------------------------------- 133 

Bouldery accumulations of undetermined origin________________________ 136 

Landslides-------------------------------------------------------- 136 Independent slumps ________ ------- ____________________________ - 136 

Tonguelike complex landslides ______________________________ ----_ 137 

I>istribution _______ ------- __ __ _ __ _ __ _ _ _ _ _ _ _ _ __ __ _ ___ _ ___ __ _ 137 

TopographY----------------------------------------------- 138 

Composition and thickness __________________ ---------------- 140 

Origin---------------------------------------------------- 141 

Comparison with lobes of glacial drift________________________ 143 

Landslide mantle ___ --------___________________________________ 145 

Time of movement .. ___________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 146 

Itt 
IV CONTENTS 

Alluvial, colluvial, and lacustrine deposits _______ ----------------------

Eolian features----------------------------------------------------

Pediments and terraces _________________ ----------_-----------------

Correlation with Thousand Lake Mountain----------------------------

Quaternary history------ __________ ...:_.:.~ __ --_--------- __ -------------

ftJ::~~~~~~===================~=-:~==~-=~-~=-========================= 

ILLUSTRATIONS 

--- -

Page 

147 

152 

154 

156 

157 

160 

163 

Page 

.PLATE 6. _Map of surfi~ial geology of Boulder Mountain~,_-.,------- In pocket 

:_-._ 7. Block diagr~!llof Boulder Mountain _____ -------:..---.--i-.- In, pocket 

8. Plateau icecap with outlet glaciers1 Ellesmere Island __ ~_Facing 119 

,~IGURE _24. Map showing location of Bol,llder Mountai~.,--c_---~-~-~:---..,- 106 

25. Map of _Boulder Mountain s4owing late Pleistocene drifts, drift _ lobes,_ t:l,nd _tonguelike comple_x landslid~s,..,.. _ ... ______ :.. ___ .. _ _ 117 

26. Sketch ofc_olluvium and river deposits on south. side of Fremont 

River--------- ____________ ---,------~-------------- -,-J< ,..- _ 133 

_ 27. Sketc}b of colluvium and river g~po~i~§ _o_n_ J;lO:t:t_4~;~ide <?(Fremont 

River----- ________________ ..,_-__ ..,...,_--_.., ____ -c-_- ------- _ --- __ --- _ -- _ 

_ 28. Sketc:tt_Qf c9lluvitun and river depositsoverlying till_.__"".,. ___ _ 

~9. Dia_grammatic sketch of complex landslide _______ ~---~..; ..... __ _ 

_ 30 . .AJ!uy~um ~lq_ng 13u1lberry: _C:r:_e_e~ .. -----.,---..:.;.----~-----.-:---·--""' 

134 

135 

139 

149 
) 

CONTRIBUTIONS TO GENERAL GEOLOGY 

QUATERNARY GEOLOGY OF BOULDER MOUNTAIN, 

AQUARIUS PLATEAU, UTAH 

By RicHARD F. FLINT and CHARLES S. DENNY 

ABSTRACT 

Boulder Mountain, the northeastern part of the Aquarius Plateau, exceeds' 

11,000 feet in altitude; it is the highest of the High Plateaus of Utah. The mountain has a nearly flat summit area of about 70 square miles and possesses steep 

side slopes. 

During late Pleistocene time an icecap formed repeatedly on top of the mountain, covering most and possibly all of it. The ice drained off the top through· 

broad canyonlike troughs in the plateau sides. During the most extensive glaciation (Bull Lake? stage), the termini of these outlet glaciers reached down to 

altitudes as low as 6,600 feet. During the later Pinedale(?) stage the outlet 

glaciers followed nearly the same paths but were much less extensive. Glaciation 

of the plateau top is shown mainly by radial grooving, striation, and shaping of 

bedrock features. Glaciation of the plateau sides is recorded by lobes of glacial 

drift having morainic topography. · 

Two sets of conspicuous moraines are identified in Pinedale(?) drift. After 

Pinedale(?) glaciation ended, rock glaciers were built around the base of the cliff' 

that bounds the summit of the plateau. The rock glaciers probably originated 

mainly as local drift deposited by ordinary glaciers of small size, and therefore 

record an episode of cold, wet (Temple Lake? stage of Howard and Hack) climate. 

Talus overlying the rock glaciers is attributed to a later and less rigorous cold 

wet episode. 

The drift bodies are correlated on a basis of degree of weathering of component 

material, modification of the topography by surface agencies, and relative vertical 

positions of drift-lobe termini. 

The kinds of soil developed on the successive sheets of glacial drift are not 

sufficiently well defined to aid in correlating the drift sheets. No undoubted drift 

of pre-Sangamon age was found, and no soil of Sangamon or older date was 

positively identified, although some of the weathered mantle in the district 

probably dates from Sangamon {pre-Bull Lake?) time. 

At the base of the plateau at various altitudes are dissected pediments veneered 

with bouldery deposits. Most of the pediments are believed to have been formed 

in Sangamon or older time; the sediments that cover them are not believed to be; 

glacial outwash. 

In the valley of the Fremont River, which skirts the northern base of the 

plateau, sections of alluvium record two episodes of filling separated by an episode 

of erosion. Eolian(?) sand and flaggy colluvium were deposited in the TorreyTeasdale lowlands during Pinedale and later times. 

103 
104 CONTRmUTIONS TO GENERAL GEOLOGY 

The most noticeable and widespread deposits on the sides of the plateau are 

landslides. These deposits mask the bedrock extensively, and include not only a 

widespread veneer of material that has slumped and flowed down the slopes but 

also large complex tonguelike landslides as much as 4 miles in individual length. 

The slides are of several dates; in places sliding is in progress at present. 

INTRODUCTION 

The Aquarius Plateau, the highest of the High Plateaus of Utah, 

lies about 200 miles south of Salt Lake City and about 150 miles 

north of the Grand Canyon (fig. 24). The northeastern part of the 

plateau, called Boulder Mountain, is a nearly level tableland, most 

of which was covered repeatedly by an icecap during late Pleistocene 

time. Tongues of ice flowed outward from the icecap over the cliffs 

of volcanic rock and down valleys that radiate outward from the 

mountain. 

In 1952, six weeks were devoted to a reconnaissance study of the 

surficial geology of Boulder Mountain, especially its northern and 

eastern slopes for which aerial photographs were available.' Some of 

the geologic boundaries on plate 6 were adjusted on the basis of additional field work by Smith and Huff in 1953 and 1954, and to conform 

with the topography shown on U. S. Geological Survey quadrangle 

maps made subsequent to the field study. 

The reconnaissance was made in conjunction with a detailed study 

of a larger area, Boulder Mountain, Thousand Lake Mountain, 

Rabbit Valley, part of the Awapa Plateau, and a segment of the 

Canyon Lands east of the High Plateaus (fig. 24) by J. Fred Smith, 

Jr., E. N. Hinrichs, L. C. Huff, and R. G. Luedke to whom we are 

in debt for assistance. All too infrequently does the surficial geologist 

have at hand those of his colleagues who are thoroughly acquainted 

with the rocks from which the surficial deposits are derived. We 

are under obligation to G. M. Richmond and C. B. Hunt for showing 

us the surficial geology and soils in Rocky Mountain National Park, 

Colorado, and in the La Sal Mountains, Utah. C. C. Nikiforoff has 

been kind enough to criticize the section on weathering and soils. 

PHYSICAL GEOGRAPHY 

TOPOGRAPHY AND VEGETATION 

The summit of Boulder Mountain is a nearly level upland indented 

by broad, shallow valleys ~ to 1 mile wide and 50 to 200 feet deep. 

It is a roughly triangular area about 12 miles long, 5 to 10 miles wide, 

and 70 square miles in area (pl. 6).1 Its surface is covered partly by 

forests, mainly of Engelmann spruce, and partly by alpine meadows 

with myriads of small ponds or grass and sedge marshes (Dixon, 

1 All p1aces referred to in text are shown on p1ate 6 or figure 24 unless otherwise noted. 
GEOLOGY OF BOULDER M01JNTAIN, UTAH 105 

1935). The maximum relief is about 300 feet; the highest point, 

Bluebell Knoll, reaches an altitude of. 11,328 feet. In many pla~es 

low bedrock knobs rise above the tree- or turf-covered upland, D~tton (1880, p. 284) wrote in glowing terms of the beauty of the Aquarilus 

Plateau; he said that it "should be described.in blank verse and illqstrated on canvas." l 

A cliff that ranges from 100 to nearly 600 feet in height almost 

completely surrounds Boulder Mountain. In many places volcanic 

rocks that. cap the plateau are exposed in the cliff whose base· is 

mantled with sliderock and rock glaciers. Elsewhere great masses :of 

volcanic rock have broken off from the cliff and have slid downward 

and outwa.rd to form ridges parallel with the cliff face. Government 

Point (pls. 6 and 7) is on a block of volcanic rock, nearly a mile. long 

and a quarter of a mile wide, that has slid down about 100 feet, rotating backward toward the cliff from which it was derived. 

A gently sloping bench extends outward from the base of the 

cliff for about a mile in ~many places. Most of the bench is covered by 

forests of Douglas fir p,nd aspen with white fir and Colorado spruce, 

and is dotted with numerous small lakes. The Douglas fir is restricted 

to the steeper and more rocky slopes (Dixon, 1935). The bench is 

dissected by valleys radiating outward from Boulder Mountain, but 

when viewed from a distance the bench is a conspicuous topographic 

feature, particularly on the north, east, and south flanks of the 

mountain. 

Outward from the bench are steep slopes mantled chiefly by landslide debris. The slopes are covered by open forests of yellow pine 

that at lower altitudes are replaced by pinon and juniper. There 

are also grassy openings, oak thickets, and large groves of aspen. 

In places bedrock hills project through the surficial mantle. 

The glaciated valleys of Fish Creek, Pleasant Creek, and Boulder 

Creek cross the bench and descend to the adjacent lowlands. These 

valleys contain moraines left by tonguelike outlet glaciers of late 

Pleistocene age that flowed down from the plateau icecap to altitudes 

as low as 6,600 feet. At their maximum extent the glaciers reached 

the Fremont River north of Grover, and outwash from them extended 

eastward to and probably beyond the Capitol Reef. On the west 

side of Boulder Mountain one moraine extends a short distance out 

over the Awapa Plateau. 

Due north of Boulder Mountain the Fremont River, a tributary 

of the Colorado River, passes through the Red Gate, a narrow rockwalled valley that separates the foothills of Boulder Mountain from 

those of Thousand Lake Mountain to the north. The lowlands 

east of Red Gate, here called the Teasdale-Torrey lowlands, include 

broad plains covered by drift of late Pleistocene age, and bedrock 
106 

40 

39° 

u.1 

l) 

z 

-:::> 

0 

o:::; 

a.. 

CONTRIDUTIONS TO GENERAL GEOLOGY 

Moabo 

NAVAJO SECTION 

111° ao· 

20 80Miles 

LA sAL 

MTNSI 

I 

I 

r 

I 

\\! I 

I 

I 

I 

Cortez 0 

KEY TO NUMBERS 

1. Fish Lake Plateau 

2. Thousand Lake 

Mountain 

3. Rabbit Valley 

4. Awapa Plateau 

5. Grass Valley 

6. Aquarjus Plateau 

109" 

38" 

FIGURE 24.-Map of a portion of the Colorado Plateaus and adjacent provinces showing location of Boulder 

Mountain and area covered by geologic map (pl. 6). 

mesas some of which are capped with sand and gravel. The lowlands 

are partly open grassland and partly covered by sagebrush with 

scattered pinon and juniper. Eastward the Fremont River transects 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 107' 

the north end of Miners Mountain through a canyon and enters the 

Capitol Reef at Fruita. 

The east and south slopes of Boulder Mountain descend into a 

maze of deep valleys, the Canyon Lands of the Colorado Plateaus· 

(fig. 24). Northwest of Boulder Mountain lies Rabbit Valley, a broad 

lowland floored with alluvium and bordered by volcanic rock. To the 

west lies the northward-sloping Awapa Plateau and to the southwest 

the main mass of the Aquarius Plateau. 

Streams radiate out from Boulder Mountain in all directions; 

those on the west side turn northward into Pine Creek which joins 

the Fremont River just west of the Red Gate. The northeast slopes 

drain to the Fremont River west of Miners Mountain. Streams on 

the east slope of Boulder Mountain flow eastward through the Capitol Reef, and those on the southern flanks, such as Boulder Creek,-

flow southward to the Escalante River.· Small streams, especially 

those on the northeast side of Boulder Mountain, follow irregular 

courses around or across slump blocks and other landslide features 

of diverse age and origin. Many streams have not yet excavated 

their channels to bedrock. 

Exposures of both bedrock and surficial deposits are few. A thick~ 

sequence of relatively weak strata overlain by massive volcanic rock 

is favorable for landsliding. Most of the surficial mantle is bouldery 

rubble, either drift or colluvium. 

BEDROCK GEOLOGY 

The bedrock in the northeastern Aquarius Plateau district is 

summarized below. 

Generalized section of bedrock in northeastern Aquarius Plateau district 

[Based on data supplied by J. Fred Smith, Jr., and others]-

System Group, formation, and Thickness Lithology member (feet) 

Alluvium, collu- Clay, silt, sand, and gravel in 

vium, terrace alluvium and colluvium; pedQuaternary. gravel, glacial o-70 iment and terrace gravels 

drift, landslides, include some sand; glacial 

pediment gravel. drift and landslides commonly bouldery or gravelly. 

U nconforroity 

· Volcanic rocks. 500± Chiefly flows with interbedded 

tuffaceous sediments. 

Tertiary. -Unconformity 

Flagstaff(?) lime- Limestone, clay, conglomerate, 

stone. 200+ sandstone, tuff, and tuffaceous sediments. 

461212-58-----2 
CONTRIBUTIONS TO GENERAL GEOLOGY 

Generalized section of bedrock in northeastern Aquarius Plateau district-Continued 

System Group, formation, and Thickness Lithology member (feet) 

Mancos(?) shale. Not exposed. 

Cretaceous. 

Dakota(?) sand- Not exposed. 

stone. 

Unconformity 

Morrison(?) forma- Conglomeratic sandstone, 

350± sandstone, siltstone, clay- tion. stone. 

--Unconformityp. Summerville Siltstone. ::s 

0 formation. 

Jurassic. 14 

0 -Unconformity-

~ Entrada sand- 1800± Earthy sandstone. ~ ...... 

~ stone. ~ 

r:l Carmel forma- Limestone, siltstone, gypsum. ~ 

00 tion. 

---Unconformity 

-?-- p. Navajo sand- 800± Crossbedded sandstone, chiefly ::s 

0 white. stone. 14 

0 

Jurassic(?). r:l Kayenta for- Sandstone, conglomeratic sand- 0 

:>.. 350 stone, shades of red and r:l mation. ~ white. 0 

r:l 

CD Wingate sand- Crossbedded sandstone, red. s stone. 330± 

--Unconformity 

Chinle formation. 450± Siltstone, claystone,_ sandstone; 

variegated. 

Triassic. Shinarump con- 0-90 Sandstone, conglomeratic sand· 

glomerate. stone, claystone. 

-Unconformity 

Moenkopi forma- 900± Siltstone, sandstone, limestone; 

tion. chiefly red. 

Unconformity 

Kaibab limestone. 350± Limestone, sandstone, calcareous siltstone;. white. 

Permian. 

Coconino sandstone. 800± Crossbedded sandstone, white. 

CLIMATE2 

The climate in the northeastern Aquarius Plateau district ranges 

from arid in the lowlands near Fruita, to humid on the top of the 

J Abstracted from Climatic summary of the United States to 1930: U. S. Dept. Agriculture Weather 

Bureau, sec. 21;-nixon(l935); Gregory and Anderson'{l939);-Woolley (1947). 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 109 

plateau. In the lowlands the mean annual rainfall ranges from 5 to 

10 inches; the summers are long and hot, the winters cool; temperatures .of 110° and of -37° have been recorded. There are no climatic records for stations on the plateau top, but the mean annual 

rainfall may be as much as 30 inches per year. High water occurs 

on the larger streams during the spring, as snow melts on the water~ 

sheds. Cloudburst floods occur in the months of July and August 

(Woolley, 1947, p. 83-96). 

WEATHERING 

All profiles of weathering or soils in the Boulder Mountain region 

are developed on surficial deposits. No exposures were seen where 

the bedrock had weathered in place into residual mantle. Most 

profiles of weathering observed are probably of late Pleistocene or 

Recent date, for it is unlikely that a soil developed in Sangamon or 

older time could have survived the later mass movements that have 

affected so large a proportion of the slopes. For this reason special 

attention was paid to profiles of weathering developed in fluvial 

deposits capping isolated mesas, localities favorably situated to escape 

subsequent disturbance by mass movements. These deposits lie 

hundreds of feet above the present drainage, and on topographic 

evidence alone are older than other fluvial deposits that now lie only 

tens of feet above existing streams. No clear evidence was found, 

however, that the weathering on the fluvial deposits changed with 

their height above present drainage. No soils seen by the authors 

resemble those found elsewhere in the Rocky Mountain region (Hunt 

and Sokoloff, 1950; Hunt, Varnes, and Thomas, 1953; Hunt, 1954} 

and known from stratigraphic evidence to date· from pre-Wisconsin 

(Sangamon or older) time. For example, some of the soils developed 

on pre-Wisconsin deposits in the La Sal Mountains (fig. 24) are as 

much as 15 feet thick, contain deeply weathered rock fragments, and 

have caliche horizons as much as 10 feet thick (Richmond, written 

communication). 

· '(he· soils seen on Boulder Mountain show a rough vertical zonation 

(Martfu and Fletcher, 1943; Nikiforoff, 1937; Thorp, 1931). Below 

about 8,400 feet most of the soils examined have a subsoil partly 

cemented with calcium carbonate (caliche); at higher altitudes most~ 

of the soils are free of calcium carbonate. The following brief soilprofile descriptions are the generalized impressions of the geologist, 

and do not include all the types of soil actually present. In the soil 

descriptions all colors are those of dry material. 

SOILS WITH CALICHE 

Below aJtitudes of about 8,400 feet, most of the soils examined· 

consist of 1 or 2 feet of loose, oxidized, and in places leached material 
110 CONTRIBUTIONS TO GENERAL GEOLOGY 

(A horizon?) overlying from 1 to 2 feet of slightly to firmly cemented 

material having a high content of calcium carbonate and (or) gypsum 

(B horizon?). The contact between these horizons is fairly sharp. 

In many places the underlying parent material is also calcareous and 

gypsiferous. In the profiles studied, the texture of the A horizon(?) 

is chiefly sandy; that of the B horizon(?) is a mixture of sand and silt 

with little clay. Colors are primarily dependent on those of the 

parent material. The A horizon(?) is dominantly pinkish or brownish, 

the B horizon(?) white to gray, and the parent material dominantly 

pink to gray. Fragments of rock ranging from a fraction of an inch 

to many feet in diameter are found throughout the profile in widely 

varying proportions. Most fragments are fresh, but may have 

thin weathered rinds. A very few of the small fragments can be 

crumbled between the fingers. A profile of a soil with caliche is 

described below. 

Profile of soil with caliche exposed in bank along Teasdale-Grot1er road near Fish 

Creek 1 (pl. 6, loc. 4) 

Topography: Broad ridge, slope about 5° to northeast. 

Altitude: 6,960 feet. 

Vegetation: Scattered pinon and juniper. 

Parent material: Till of Carcass Creek drift. 

Depth 

(inches) 

G-3 

3-10 

lQ-22 

22-28 

28-60+ 

Description 

Loamy fine sand, pinkish-gray to brown (7 .5 YR 6/2-5/2) ; non calcareous; contains small fragments of volcanic rock and a little organic 

matter; abundant boulders of volcanic rock on the surface. 

Contact gradational. 

Loamy sand, brown (7.5 YR 5/4); loose; noncalcareous; contains 

numerous small fragments of volcanic rock. 

Contact sharp. 

Loamy fine sand, pinkish-white (7.5 YR 8/2); moderately cemented, 

friable; highly calcareous; contains numerous fragments of volcanic 

and sedimentary rock. 

Contact gradational through 3 inches. 

Sandy loam, pinkish-white to pink (7.5 YR 8/2-7/4); slightly cemented, 

friable; calcareous; contains numerous fragments of volcanic and 

sedimentary rock. 

Contact gradational through 3 inches. 

Sandy loam, pinkish-gray (7.5 YR 7/2); moderately firm, friable; 

calcareous; contains numerous fragments of volcanic and sedimentary 

rock; interpreted as till. 

Remarks: Boulders of volcanic rock 1-6 feet in diameter are found throughout 

the profile. 

t The descriptions of color use the._ numerical symbols of the Munsell system and were determined with 

the color chart used by soil scientists (Soil Survey Staff, 1951, p. 194-203) rather than with the Rock-Color 

@hart-of the National Research Council {Goddard and others, 1948). The former contains a wider variety 

of color chips that correspond to colors in surficial deposits than does the latter. Both charts use the numerl· 

cal symbols of the Munsell system. 
G_EOLOGY QF BOULDER MOUNTAIN, UTAH 

The soils with caliche . are· developed on Carcass Creek drift, on 

pediment and terrace gravel and sand deposited in Carcass Creek and 

in earlier (Sangamon? and older) times, on bouldery accumulations of 

undetermined origin, and on landslides. In places the soils with 

caliche are overlain by several feet of loose sand believed to be eolian~ 

The vegetation is dominantly pinon, juniper, and sagebrush. On. 

Lion Mountain soils with caliche occ~ under yellow pine (PinuS: 

ponderosa). . 

A soil with a thick, massive horizon of caliche is developed in the 

gravel and sand that caps the high pediment on the north side of Lion 

Mountain. This pediment remnant is about 700 feet above the 

adjacent lowlands, suggesting that the gravel and sand may be 

considerably older than the Carcass Creek drift, the oldest drift 

recognized in the lowlands. However, rock fragments in the soil are 

not more weathered than those found elsewhere and the profile differs 

but little from that on the Carcass Creek drift except in thickness 

and cementation of the caliche horizon. The soil on Lion Mountain 

is described below. 

Son1e of the pediment remnants in the Teasdale-Torrey lowlands 

rise more than 300 feet above adjacent valley floors that are mantled 

by Carcass Creek drift; hence, such remnants may also be older 

than the Carcass Creek drift and may date from Sangamon or earlier 

times. However, the soil developed in the veneer on one of these 

pediments is similar to that on the adjacent Carcass Creek drift 

except that the caliche horizon is thicker (about 18 to 24 inches) in 

the pediment cover than in the drift. 

Profile of soil with caliche exposed in pit on top of mesa on north side of Lion Mountain 

(pl. 6, loc. 11) 

Topography: Undulating plain sloping n01 theastward at angle of about 4°. 

Altitude: 8,400 feet. 

Vegetation: Open forest of yellow pine. 

Parent ma.ierfal: Pediment sand and gravel, perhaps deposited in Sangamon or earlier times. 

Depth 

(inches) 

Q-1 

Description 

Loamy fine sand, dark grayish-brown (10 YR 4/2) loose; calcareous; contains organic matter. 

Contact sharp. 

1-4 Loamy sand, reddish-brown to yellowish-red (5 YR 4/4-4/6); 

loose to slightly firm, very friable; calcareous; contains 

numerous fragments of volcanic and sedimentary rocks; 

roots. 

Contact grades through 1 inch. 

4-10 Loamy coarse sand, grayish-brown (10 YR 5/2); loose, calcareous; contains numerous fragments of volcanic and sedimentary rocks; roots. 

Contact gradational through 5 inches. 

Range in thickness 

(inches) 

o-2 
112 CONTRIBUTIONS TO GENERAL GEOLOGY 

Profile of soil with caliche exposed in pit on top of mesa on north side of Lion Mountain 

(pl. 6, loc. 11)-Continued 

Depth 

(inchea) 

lG-15 

Deacription · Ra:nge in 

thickneaa 

(inchea) 

Loamy coarse sand, grayish-brown (10 YR 5/2), contains a few 

fragments of lime about one-half inch in diameter; loose; calcareous; contains numerous fragments of volcanic and sedimentary rocks; roots. 

Contact sharp. 

3-8 

15-36 Loamy sand, pink (7.5 YR 7/4); firmly cemented, difficult to 2Q-25 

excavate with shovel, unstratified; highly calcareous; contains numerous angular fragments of volcanic rock 1-3 inches 

in diameter, a few as much as 1 foot in diameter, fragments 

covered with %-1 inch layer of lime; scattered roots. 

Contact gradational. 

36-48 Silt, pink (7.5 YR 8/4); slightly cemented, unstratified; calcareous and gypsiferous; contains numerous fragments of 

volcanic and sedimentary rocks; roots; probably is slightly 

weathered veneer on pediment. 

Remarks: A sample of 62 rock fragments from the upper 2 feet of profile contained the following rock types: 

Percent Volcanic rock__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 60 

Chert and quartzite-------------------------------------------- 21 

Conglomerate and sandstone------------------------------------ 16 Calcareous sandstone__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 3 

Of the 37 fragments of volcanic rock, one was weathered throughout, 5 were 

slightly weathered, and 31 were fresh. All rock fragments were more or less 

covered by a rind of caliche ~ 1 inch thick, especially on the under side. 

SOILS WITHOUT CALICHE 

Most of the caliche-free soils were found above an altitude of about 

8,400 feet. The soil consists of a surface layer high in organi~ matter 

(A horizon), ranging from a few inches to 1 foot in thickness, overlying from 1 to. 3 feet of pale yellowish-brown material (B horizon) 

that grades downward into the grayish-brown parent material (C 

horizon). The contact between the A and B horizons is sharp, that 

between the B. and C horizons may grade through a distance of about 

1 foot. In a few places a thin (about 1 inch) grayish-brown horizon 

(A2 ?) separates the surface layer of organic material from the B 

horizon below. No marked textural development or increase in day 

content was noted in the B horizon. The soil material is loose, and 

boulders, cobbles, and pebbles are found throughout the profile. 

Most of the fragments are of volcanic rock, and are fresh or have 

thin weathered rinds; a few of the small fragments can be crumbled 

between the fingers. Most parent material is non calcareous; its 

matrix is dominantly sandy or silty, and ranges from pale yellowish-
GEOLOGY OF BOULDER MOUNTAIN, UTAH '11.3 

brown to gray or "1-ed, depending on the character of local surficial 

deposits. A profile of a soil without a caliche is described below. 

Profile of soil without caliche exposed in a morainic ridge (Blind Lake drift) on 

northeast side of Blind Lake (pl. 6, loc. 1 0). Exposure in artificial outlet channel 

Topography: Ridge about 100 feet wide and 15 feet high. Profile taken near center of ridge, slope about ~ 

I to the southwest. 

Altitude: 10,250 feet. 

Vegetation: Open spruce woods with scattered aspen. 

Parent material: Till. 

Depth 

(inches) 

o-6 

Range in 

thickness 

Description (inches) 

Organic matter, very dark gray (10 YR 3/1); occurs as a filling 

around pebbles, cobbles, and boulders of volcanic rock; roots. o-6 

Contact sharp, wavy. 

6-13 Silt loam, mixture of mineral and organic matter, grayish-brown 

to dark grayish-brown (10 YR 5/2-4/2); loose; noncalcareous; 

contains numerous pebbles of volcanic rock; roots. 

Contact sharp, wavy._ 

13-18 Loamy fine sand, light-gray (10 YR 7/2); massive; noncalcareous; contains a few pebbles of volcanic rock; roots, 0-6 

Contact sharp, wavy. 

18-40 Loamy sand, pale-brown (10 YR 6/3); moderately firm, friable• 

structureless; noncalcareous; contains numerous pebbles, cobbles, and boulders of volcanic rock; roots. 20-26 

Contact gradational through 6 inches. 

4o-72+ Loamy sand, light-gray (10 YR 7/2); moderately firm, friable, 

structureless; noncalcareous; contains numerous pebbles, cobbles, and boulders of volcanic rock; a 3-foot boulder striated; 

no roots. 

The vegetation is dominantly spruce, but caliche-free soils are 

present also under yellow pine (Pinus ponderosa). 

Soils without caliche are developed on all three of the late Pleistocene drifts recognized in the area .and on landslides, and occur in both 

glaciated and nonglaciated areas of the plateau top. They were not 

observed buried beneath lat~r deposits. 

EXFOLIATION 

Most of the ubiquitous boulders of volcanic rock that mantle much 

of the surface (drift, pediment veneers, bouldery accumulations of 

undetermined origin, and landslides) are surrounded by shells or 

spalls that range from 1 to 20 inches in thickness and from a few 

inches to 2 feet in length; The boulders have· rough, pitted, and 

lichen-covered surfaces, except those that are being or recently have 

been polished by wind-driven sand or form part of the modern sliderock. The exfoliated boulders have weathered toxidized?) ·rinds 

generally not more than 1 inch thick. Most boulders on Carcass 

Creek drift are more exfoliated than those on Donkey Creek and 
114 CONTRIBUTIONS TO GENERAL GEOLOGY 

Blind Lake drifts, but the difference is slight. Boulders at the surfaces of the rock glaciers are only slightly exfoliated. Weathered 

rinds are usually absent, but many of the boulders have a partial 

covering of crustose lichens on their exposed surfaces. 

SOLUTION 

Solution pits a few inches in diameter and ranging from a fraction 

of an inch to 2 inches in depth occur on many boulders of volcanic 

rock. However, some exceptionally large solution pits are in boulders 

of volcanic rock found on a nonglaciated(?) part of the summit of 

Boulder Mountain, about 2 miles west of Chokecherry Point along 

Willow Draw (pl. 7). The boulders lie ~ a grassy meadow on slopes 

that range from about 1° to 5°. The pits range from 2 inches to 

3 feet in diameter, and from a few inches to 2 feet in depth. The 

rims of some pits are overhanging. The pits contain a mixture of 

water, mineral grains, organisms, and excrement, and are believed 

to have originated initially from a small depression on the upper 

surface of a boulder. This initiaJ depression could originate in various 

ways: through frost breakup, through solution around a patch of 

lichens, as a vesicle, or as an initial irregularity on a joint face. The 

initial depression was enlarged by various processes such as frost 

·breakup and solution alded by.lichens, organisms, and excrement. 

FinesL and solutes were decanted or washed out of the pit. 

M3ny bare surfaces of ·limestone or calcareous sandstone are 

groo~ed or pitted by solution. Such solution-faceted surfaces have 

a microrelief as great as 3 inches but are not as pronounced as in 

, other areas m Southwestern United States (Smith and Albritton, 

1941). 

PATTERNED GROUND 

A few areas of patterned ground (Washburn, 1950) were noted on 

·the summit of Boulder Mountain, but the areas are small and the 

patterns are not clearly expr~ssed. Something like half the summit 

area is forest covered; the remainder is turf interspersed with numerous 

exposures of bedrock. In a few places are clumps of boulders and 

imperfect boulder rings surrounded by turf and suggestive of ancient 

frost action. One small ancient boulder field was observed near the 

north end of Willow Draw in the nonglaciated portion of the summit. 

However, this boulder field is very small in comparison with the 

ancient boulder fields in areas of landsiiding and slumping on the 

northeast slope of Boulder Mountain. 

. No terracettes that might be the result of mass-wasting were 

observed on the glaciated portions of. the summit. There is little. or 

no evidence of the disturbance of turf by frost action during the last 

· few years. On the sides of Willow Draw, boulders as much as 6 feet 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 115 

in diameter have moved a few inches down 3°-5° slopes during the 

last year or two. Each boulder has a 6-inch ridge of turf on its 

downhill side and a narrow break in the surrounding turf on its 

uphill side. 

Considerable areas near Bluebell Knoll, within the glaciated 

portion of the plateau top, have patterned ground. Subcircular 

patches of turf ranging from 2 to 6 inches across are separated by 

shallow troughs 3 inches to 3 feet in diameter, about 1 inch deep, and 

floored by small rock fragments. The troughs form roughly polygonal 

patterns on gentle turf-covered slopes. These patterns are analogous 

to some on tropical mountains described by Troll (1944, figs. 38-40, 

"Kuchenboden") and attributed to daily temperature changes across 

the freezing point. Such a hypothesis is reasonable, although rainwash is also a factor at least after a trough is once formed. 

The scarcity of present-day patterned ground indicates that 

modern frost disturbance of the mantle is largely inhibited by the 

vegetative cover despite an altitude of more than 11,000 feet. 

GLACIAL FEATURES OF THE PLATEAU TOP 

A small ice cap covered the nearly level top of Boulder Mountain 

as indicated by both erosional and depositional features. The 

general character of the area has been described by Gould (1939). 

The most conspicuous erosional feature consists of streamlined 

lineation of the surface of the volcanic rocks. Lineation is expressed 

in subparallel flutings a few feet in height and of variable length, 

minor grooves, and coarse striations, all oriented radially to the 

central part of the plateau top. Such erosional features are best 

developed near the heads of the reentrants of Pleasant, Fish, and 

Donkey Creeks (pl. 7), and also near the head of the Miller Creek 

canyon on the western edge of the plateau. They are essentially 

absent from the central area. All the striated surfaces seen are rough 

rather than polished. No evidence of more than one generation of 

striations was seen. 

The flutings undoubtedly mark the areas of most effective glacial 

erosion, in which the chief factor probably was a high rate of How. 

Maximum How is to be expected at the reentrants, through which 

the ice cap drained off the plateau top (pl. 8). In places the flutings 

exhibit stoss-and-lee topography that indicates movement radially 

outward from the center of the plateau. 

Many basins, mostly shallow, dot the plateau top; some are rock 

basins, but others are rimmed partly by grass-covered or forested 

ridges that may consist wholly or partly of drift. Because of the 

general cover of vegetation and almost total lack of exposures, it was 

not possible to determine the thickness or extent of the drift. The 

461212-58-8 
116 CONTRIBUTIONS TO GENERAL GEOLOGY 

large areas of exposed bedrock and the general absence of a characteristic drift topography implies that the drift is patchy and thin. In 

a few places fresh boulders of volcanic rock were seen lying on volcanic bedrock of a different kind. Evidently the boulders are glacial 

erratics. 

The aggregate of small areas with interior drainage is considerable. 

Probably such areas are the result of glaciation. Evidently they are 

drained by percolation downward through the jointed lava flows, with 

emergence on the plateau slopes where underlying less permeable 

rocks are exposed, because the volume of water flowing down the 

middle slopes far exceeds that which flows over the summit cliff. 

Indeed, only Pleasant Creek flows over the summit cliff throughout 

the summer season. 

The only end moraine observed on the plateau top is a faint irregular ridge, a few feet high, a few tens of feet wide, and about 2 miles 

long. Its northern end is about 2 miles east of the head of Miller 

Creek canyon. This faint moraine does not represent the outer limit 

of the icecap margin because flutings occur between it and the cliff. 

Evidently the moraine was built by a thin glacier of relatively late 

date. Although the age of the moraine is unknown, its position suggests correlation with the Donkey Creek or Blind Lake drifts on the 

sides of the plateau. 

The limit of conspicuous glaciation on the plateau top is only approximately located (pl. 6 and fig. 25). The evidence is chiefly topographic. Inside the limit are basins, flutings, striations and other 

features attributed to glacial action. Outside the line the topography 

is gently rolling, with lesser relief, gentler slopes and fewer exposures 

of bare rock than in the glaciated area. The surficial material is an 

unsorted mantle. In places boulder-strewn steplike forms suggest 

the eroded edges of lava flows. Most of the exposed boulders are 

exfoliated and roughened in detail by weathering, and are covered 

with lichens. 

The line separating these groups of features is only the approximation of an indistinct zone. The indistinctness may result in part 

from variations in the area of the icecap during late Pleistocene time. 

However, the inferred approximate line is reasonable, for it delimits 

the broad main area of the plateau top from the principal cusplike 

points. Bown's Point and Chokecherry Point, each with an area of 

several square miles, as well as the much smaller tips of Trail Point 

and Government Point, apparently were not glaciated since Carcass 

Creek time. The evidence of glaciation on the top agrees in areal 

distribution with the evidence of Donkey Creek, Blind Lake, and 

later glaciations on the sides of the plateau, as described in the next 

section of this paper. 
GEOLOGY OF BOULD'ER MOUNTAIN, UTAH 117 

EXPLANATION 

I 

u s Shown only near mouth of Donkey 

CtHkr along Pleasant Creek, and 

nHr Fruit ... Eluwhere outwash Included with illdjacenl dri(l 

Bedrock and undifferentiated Includes volcanic rods: : bouldery deposits origin 1 

~luvium, colluvium, rock glaciers, 51/de~kl 

and grarel and sand on pediments, forming terraces 

[Btihlili] Ton11uelike complex land· shdes. Arrow indicates 

direction'of movem!lnt 

>-

a: 

< 

z 

a: 

~ Inferred bciiiridarybeiWeen glaciated :::J part of top of Boulder Mountain · 

C1 and drift lobes 

---contaa .._ 

General~:1.~/1::! !; P"fit":"t."rll"• .. • T""""""'T'""I-r-.,- ~~ 

Summit cliff 

Dashed whete outs~~ of., .. of el·t~ ' .. ~ 

FIGURE 25.-Generalized map of Boulder Mountain region, Utah, showing drift lobes, three drifts of 

late Pleistocene age, and tonguelike complex landslides. Compiled from plate 6. Southwest part 

based on map of Powell National Forest, U. S. Forest Service. 
118 CONTRIBUTIONS TO GENERAL GEOLOGY 

GLACIAL DRIFT ON THE SIDES OF THE PLATEAU 

Most of the 'drift is till, although small bodies of outwash are 

present also. The till is composed of fragments of volcanic rock with 

:small amounts of sandstone, siltstone, shale, conglomerate, limestone, 

and gypsum, the proportion varying from place to place with differences in the local bedrock. Most fragments are of fresh, unweathered rock. A few fragments are soft and crumble between the 

fingers; nevertheless individual grains seem to be little altered. The 

matrix is generally calcareous and is composed largely of sand and 

silt. The fragments of rock range from ~ inch to as much as 30 feet 

in diameter; boulders from 1 to 6 feet in diameter are common. Almost without exception large boulders are of volcanic rock. The 

fragments are dominantly angular to subangular; water-worn fragments are scarce. Many large fragments have smooth abraded edges 

and corners between joint faces. Striated or soled fragments are 

rare. The percentage of fragments to matrix ranges roughly from 20 

to 30 percent by volume. Most unweathered till is light gray, varying toward white or pink according to the nature of the local bedrock. 

No stratified material was observed enclosed within the till. No fissility, cleavage, or evidences of fabric were noted. The maximum 

exposed thickness of till is 10 feet, but the maximum inferred thickn·ess, based on heights of morainic ridges and on scattered exposures 

near the Fremont River, is about 40 feet. It is difficult to distinguish 

till from debris transported by mass movement (p. 143). On plate 6 

drift is shown only in those areas where it has morainic topography 

recognizable on the ground or on aerial photographs. 

The outwash has lithologic characteristics similar to the till, and 

ranges in grain size from silt to boulders which, near the mouth of 

Carcass Creek and along the Fremont River near Fruita, reach _a 

maximum of more than 12 feet in diameter. The boulders and cobbles are angular to slightly rounded, the pebbles subangular to well 

rounded. Some layers of bouldery outwash are as much as 10 feet 

thick. Pebbly and col;>bly outwash forms irregular beds from 1 to 

several feet thick. Most outwash has a calcareous sandy matrix. 

The maximum observed thickness of outwash is 10 feet, but a thickness of about 50 feet is inferred from scattered outcrops n~ar the 

mouth of Carcass Creek and along the Fremont River near Fruita. 

Outwash has been observed to overlie bedrock and also till (near the 

mouth of Fish Creek along the Grover-Torrey road). Outwash 

underlies narrow valley floors and terraces and has been mapped 

principally along Fish Creek, Carcass Creek, Fremont River, and 

Pleasant Creek. In this region outwash, terrace gravel, and pediment veneers are indistinguishable on the basis of internal character. 
GEOLOGICAL SURVEY BULLETIN 1061 PLATE 8 

PLATEAU ICECAP WITH OUTLET GLACIERS, CONGER RANGE, ELLESMERE ISLAND. 

The icecap on Boulder Mountain and the outlet glaciers flowing down the steep plateau slopes probably resembled those shown in this view. 

Photograph by Royal Canadian Air Force. 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 119 

On plate 6 outwash is shown only where it occurs downstream from 

areas covered by drift. 

Drift on the sides of the plateau forms lobes of varied shape extending radially outward from the plateau top (fig. 25). Most drift 

lobes include deposits of all three late Pleistocene glaciations recognized on Boulder Mountain. The ice tongues that formed these 

lobes apparently originated in the plateau icecap and spilled downward over the summit cliff (pl. 8). Some lobes are confined to the 

shelf at the base of the summit cliff; other lobes extend down the steep 

slopes beyond the shelf to more gently sloping terrain. The lobes 

are broader and more irregular than most tongues of drift deposited by 

valley glaciers in the Cordilleran region (table below). The difference 

results from extensive landsliding during the Quaternary period that 

widened valley sides and aggraded valley floors, thus tending to 

inhibit the excavation of deep valleys. Quite evidently glacier ice 

that spilled down over the summit cliff followed diverse paths created 

by various combinations of stream cutting and landslide modification; 

accordingly, some ice lobes were narrow tongues, and others were 

broad sheets. 

Dimensions and altitudes of drift lobes 

Altitude (in feet) Restored Maximum Total Avera~e Name of drift lobe length (in width (in descent of slope in miles) miles) At ter- At base of lobe (in feet per minus summit feet) mile) 

ciifi 

Fish Creek-Grover ____ 9 2% 6,600 10,200 3,600 400 

Pleasant Creek__ _ ___ 9 1~ 7,200 10,200 3,000 333 

Boulder Creek ________ 9 2 1 7, 000 10,200 3,200 1 355 

Miller Creek _________ 3 2 8,500 10,500 2,000 666 

Station Creek___ _ ___ 1~ % 9,800 10,600 800 640 

I>onkey Creek ________ 3 1~ 9,000 10,400 1,400 466 

1 Estimated. 

AGE 

All the drift is probably of late Pleistocene age. This belief is 

based on three kinds of evidence: weathering of the drift, topography 

of the drift, and position of the drift with respect to topography of 

the bedrock. However, Smith and Huff (written communication) 

believe that some of the drift near the mouths of Fish and Carcass 

Creeks and along parts of Pleasant Creek is older than the Carcass 

Creek drift and is perhaps of pre-Sangamon age. 
120 CONTRIBUTIONS TO GENERAL GEOLOGY 

WEATHERING 

Weathering of the drift is slight to moderate. Pebbles and cobbles 

within 2 feet of the surface show no more than superficial decomposi~ 

tion. Although boulders lying on the ground are considerably ex~ 

foliated, the accompanying chemical alteration is apparently slight. 

Soils developed in the drift record the movement of carbonates and 

sulfates, some development of secondary oxides, but apparently 

little or no production of secondary clay minerals. 

Such weathering and soils are similar to those found in drift at~ 

tributed to the Wisconsin stage in the Ruby-East Humboldt Range, 

Nev. (Sharp, 1938, p. 302), Wasatch Plateau, Utah (Spieker and 

Billings, 1940, p. 1193), La Sal Mountains, Utah (Richmond, written 

communication), San Francisco Mountains, Ariz. (Sharp, 1942), 

Rocky Mountains in Colorado (Bryan and Ray, 1940, p. 1856), 

Grand Mesa, Colo. (Retzer, 1954), and Fish Lake Plateau, Utah 

(Hardy and Muessig, 1952). 

Along Pleasant Creek, L. C. Huff (written communication) found 

what he believes is the remnant of a soil formed in pre-Wisconsin 

(pre-Carcass Creek) time on what the authors have mapped as 

Carcass Creek drift. 

TOPOGRAPHY 

All known drift in the district is little dissected and has distinct 

morainal topography. The younger drift appears to have been 

modified very little since deposition. The older drift, although 

clearly modified by soil creep and other processes of mass-wasting, has 

lost neither its ridges nor all its basins. Owing to the lack of modi~ 

fication, the drift is tentatively assigned to late Pleistocene (post~ 

Sangamon) time. 

RELATION TO BEDROCK TOPOGRAPHY 

The drift occurs principally within the present canyonlike valleys 

that drain the plateau, and hence postdates most of the erosion of 

these valleys. Near the mouths of Carcass and Fish creeks, where its 

base is exposed, the drift overlies a bedrock surface with a relief of 

about 150 feet. The Fremont River has incised that surface to a 

depth of about 250 feet near the mouth of Carcass Creek, and to a 

smaller depth near the mouth of Fish Creek. These depths of erosion 

are less than those generally reported (Richmond, written communica~ 

tion; Sharp, 1942, p. 486) to have followed the deposition of pre-Bull 

Lake (pre-Wisconsin?) drift in other Cordilleran mountain areas; 

such depths are more nearly commensurate with the erosion that 

postdates Bull Lake (lower Wisconsin?) drift in the mountains. 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 121 

PROBABLE SUBSTAGES OF GLACIATION 

The drift (pl. 6) is subdivided into drift of the Carcass Creek 

glacial advance, probably of Bull Lake age, drifts of the Donkey 

Creek and Blind Lake glacial advances, probably of Pinedale age, 

and rock glaciers probably of Recent age. Direct and conclusive 

evidence of the age and correlation of drift sheets, i. e., stratigraphic 

superposition exposed in section, is lacking in the Aquarius Plateau 

district because there are virtually no deep exposures. Evidence 

derived from soils, although useful in other regions, is unsatisfactory 

here because the known differences in soils could be entirely the 

result of differences of climate (altitude) and vegetation rather than 

of age of parent materials. Therefore drift-sheet correlation is based 

primarily on relative areal extent and altitude, degree of weathering, 

and amount of postdrift erosion. 

Lobes of Carcass Creek drift (fig. 25) are longer than lobes of 

Donkey Creek drift by a ratio ranging from 2:1 to 2%: 1. The 

morainic topography is subdued: Slopes are relatively gentle, as 

much as 25° but averaging nearer 15°, and are comparatively smooth 

and free from minor irregularities. Basins are few and shallow; 

many are partly filled with colluvium. Boulders on the ground are 

somewhat pitted by solution, and are deeply exfoliated; they retain 

little or none of the surface they possessed at the time of deposition 

and have shells as much as 20 inches thick in process of detachment. 

The ground between the boulders is littered with angular spalls 

and oxidized fine-grained disintegration products nearly to the 

exclusion of other material. 

Lobes of Donkey Creek drift are longer than lobes of Blind Lake 

drift in a ratio from 3: 1 to 4: 1. Morainic topography is bold 

and only moderately smooth, with local relief as much as 200 feet 

and with slopes as steep as 30° but averaging nearer 20°. Basins 

are plentiful and show little evidence of filling with colluvium. 

Boulders are little affected by solution and only moderately exfoliated. 

Lobes of Blind Lake drift are small, extending only % to 1% miles 

outward from the summit cliff. Morainic topography is bold but is 

on a small scale, consisting of sharp ridges commonly 8 to 15 feet 

high, and numerous subrounded basins some of which contain lakes. 

The basins show little evidence of filling. Surface boulders are very 

numerous and show little effect of either solution or exfoliation; 

glacially abraded surfaces and even crude striations are visible on a 

few of them. Topographic expression of the Blind Lake and Donkey 

Creek drifts are similar, and differ from that of Carcass Creek drift. 

Post-Blind Lake drift consists entirely of rock glaciers whose component boulders are virtually unaltered by weathering. In summary, 
122 CONTRIBUTIONS TO GENERAL GEOLOGY 

the evidence suggests that the Donkey Creek and Blind Lake drift 

sheets are more closely related in time to each other than to the 

Carcass Creek drift. 

DRIFT LOBES 

FISH CREEK-GROVER DRIFT LOBE 

DIMENSIONS 

The lobe (fig. 25, table p. 119) which extends from the reentrant in 

the plateau top at the head of Fish and Spring Creeks northeastward 

to the Fremont River is about 2J~ miles wide at its upper end;lit 

narrows to less than ~mile near Hickman Pasture and widens to about 

2~ miles near the tiny community of Grover. The distal segment of 

this Fish Creek-Grover drift lobe, 1~ to 2 miles long, is split into two 

sublobes separated by bedrock hills. The eastern sublobe occupies 

the valley of Carcass Creek; the western, that of Fish Creek. 

The thickness of the drift is unknown. A.t the mouths of the two 

creeks mentioned above about 40 feet of till is exposed or can be 

confidently inferred. However, the maximum thickness of the lobe 

is probably larger than its greatest exposed thickness. 

The Fish Creek-Grover drift lobe includes drift of three glaciationsCarcass Creek, Donkey Creek, and Blind Lake. 

CARCASS CREEK DRIFT 

Internal character and topographic expression.-The distd half of 

the Fish Creek-Grover drift lobe consists of Carcass Creek drift. It 

is composed chiefly of till with morainal topography. Many exposures 

of till are seen in cuts along the roads that traverse the lobe; elsewhere 

the presence of till is inferred from the ubiquitous end-moraine 

topography and from great numbers of surficial boulders of all sizes. 

Carcass Creek drift commonly has a subparallel series of looped, 

boulder-covered end moraines consisting of long laterals curving into 

incomplete, nested terminals. The laterals approximate 50 feet in 

height in their upstream segments and gradually become lower in the 

downstream direction, curving into terminal ridges no more than 

10 or 15 feet high. Successive moraine ridges are separated by narrow 

swales floored with sandy alluvium and colluvium. 

The end moraines are interrupted only in places, mainly by buttes 

of Navajo sandstone. This fact suggests that the bedrock surface 

beneath the drift is of moderate relief with small steep-sided hills. One 

conspicuous interruption to the pattern is caused by a hill (presumably 

bedrock, but covered by bouldery accumulations, pl. 6) 2~ miles 

southwest of Grover. End-moraine ridges are wrapped around this 

hill which probably parted the flowing glacier into two streams. 

Drainage.-In the Fish Creek-Grover lobe, Carcass Creek drift has 

marginal drainage. In general, Carcass Creek follows the eastern 
G.EOLOGY OF BOULDER MOUNTAIN, UTAH 123 

margin of the drift, Fish Creek, the western; however, where the drift 

splits into two sublobes, each stream follows the axis, rather than the 

margin, of a sublobe. Evidently the creeks originated as melt-water 

streams following the lateral margins of the glacier. 

The tonguelike form of the Carcass Creek drift in the Fish CreekGrover lobe implies a former glacier of similar outline, filling a preexisting valley whose axis was probably parallel with and about a mile 

east of Fish Creek. Presumably this inferred valley, now largely 

obliterated by drift, carried the pre-Carcass Creek drainage of this sector 

of the plateau. 

Outwash.-Drift of the Carcass Creek glacial advance contains little 

outwash. Narrow tongues of outwash occur along the downstream 

parts of Fish and Carcass Creeks, largely between the TeasdaleGrover road and the Fremont River. Fanlike bodies and small-scale 

fills with flat surfaces are present at several places within the drift 

lobe, commonly between adjacent end-moraine ridges. Probably 

these are outwash; they are included with drift on the map (pl. 6). 

The scarcity of outwash and the fact that exposures of till show little 

sorted material convey the impression that melt water may have been 

scanty. However, large boulders of volcanic rock are found on the 

walls of the Fremont River canyon through Miners Mountain (J. F. 

Smith and R. G. Luedke, oral communication), and Johnson Mesa 

near Fruita is capped by gravel. These boulders and this gravel are 

believed to be outwash from the Carcass Creek glacier and suggest 

large volumes of fast-moving melt water at least for short periods. 

Near the mouth of Fish Creek, bouldery outwash underlies a fanshaped surface graded to a level about 100 feet above Fremont River. 

Some of the surfaces of the outwash are original; others appear to have 

been cut below the original outwash profiles. In places outwash is 

overlain by eolian(?) sand and by colluvium. 

Johnson Mesa (Gregory and Anderson, 1939, p. 1848) has a cap of 

pebble and cobble gravel, composed chiefly of fragments of volcanic 

rock, that ranges in thickness from 10 to perhaps 50 feet. The gravel 

contains a few angular to subangular boulders, most of which range in 

size from 1 to 3 feet; a few are more than 12 feet in diameter. Lenses 

of white to gray silty sand are present. The surface of the mesa is 

littered with exfoliated boulders of volcanic rock. No ventifacts were 

seen. The surface is faintly channelled, has a local relief of about 10 

feet, slopes gently northeastward, and stands 250 to 300 feet above 

the Fremont River. 

Weathering, soils, and erosion.-Drift of the Carcass Creek glaciation 

constitutes parent material of soils with caliche. This fact is compat ... 

ible with but does not support the hypothesis that this glaciation is the 

probable correlative of the Bull Lake stage in the Rocky Mountains 

461212-58-4 
124 CONTRIBUTIONS TO GENERAL GEOLOGY 

(table, p. 158). However, one possible remnant of a pre-Carcass 

Creek (Sangamon or older) soil is exposed near the mouth of Carcass 

Creek (table below). Perhaps the 5 feet of silty material (caliche) is 

the B horizon or part of the B horizon of a soil profile whose upper 

part was removed by erosion prior to deposition of the overlying 

outwash. This horizon of caliche is thicker than that in soils with 

caliche described in this paper and suggests the caliche typical of the 

pre-Wisconsin paleosol of Hunt and Sokoloff {1950}. Perhaps the 

till was deposited and weathered in pre-Carcass Creek (Sangamon and 

older) time. Erosion was followed by outwash deposition in Carcass 

Creek time. Thus the drift near the mouths of Fish Creek and Carcass 

Creek may possibly be pre-Carcass Creek in age. 

Outwash of Carcass Creek age, derived from the Fish Creek-Grover 

lobe is considerably dissected. Along the downstream parts of Fish 

and Carcass Creeks the dissection ranges from 30 to 60 feet; along the 

Fremont River it is about 100 feet near Fish Creek and more than 

250 feet near Fruita. 

Section of surficial deposits exposed near mouth of Carcass Creek (NW*N~ sec. 26, 

T. 29 S., R. 5 E.) (pl. 6, loc. 9) 

Feet 

Top. 

Slumped---------------------------------------------------------- 8 

Gravel, pebbly, and sand, calcareous and moderately cemented; probably 

outwash of Carcass Creek glacier __________ ------__________________ 4 

Silty material, heterogeneous, loose, fluffy, white; apparently contains 

abundant caliche; includes numerous essentially unweathered fragments 

of volcanic rock; perhaps the material is a horizon or part of a horizon 

caliche developed in upper part of underlying till(?)__________________ 5 

Silty sand, unsorted, compact, pink, highly calcareous; contains many 

angular fragments of volcanic rock; possibly till of pre-Carcass Creek 

(pre-Sangamon?) age _____________ ---------- __ ------- _______ ------ 3 

Total ___ -------------------------------------------------- 20 

Base. 

Possible stratigraphic subdivisions.--The Carcass Creek drift in the 

Carcass Creek and Fish Creek sublobes of the Fish Creek-Grover lobe 

is perhaps slightly older than Carcass Creek drift of the main Fish 

Creek-Grover lobe to the south. The evidence for this possibility is: 

{1) End-moraine ridges in the sublobes are fainter and less numerous 

than those in the main lobe. (2) A faint drift border, consisting of 

both end moraine and the proximal end of outwash bodies, separates 

the sublobes from the main lobe. {3) Outwash is more abundant in 

the sublobes than in the main lobe. These facts indicate that a glacier 

margin may have stood at the heads of the sublobes for a relatively 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 125 

long time. Ilowever, the only indication that this position might be 

the culmination of a significant readvance is the comparative faintness 

of the moraines north of this position. 

DONKEY CREEK DRIFT 

The southern part of the Fish Creek-Grover drift lobe is composed 

of drift assigned to the Donkey Creek and Blind Lake glaciations. 

Near the base of the summit cliff, Donkey Creek drift covers an area 

about 3 miles wide. Conspicuous end moraines outline a lobe of drift 

reaching down to an altitude of about 8,400 feet in the valley of Fish 

Creek and a shorter lobe in the headwater area of Spring Creek. The 

lateral moraines along Fish Creek are 150 feet high in places; where 

they merge into terminal moraines their pattern is discordant with 

that of the older moraines of the Carcass Creek drift. The end moraine 

in the valley of Spring Creek is less massive but clearly a continuation 

of the western lateral moraine along Fish Creek, from which it is separated abruptly by a gap half a mile long. Postmoraine slumping 

probably is responsible for the discontinuity, because slumping is evident in and near the gap. Extensive slumping has also destroyed the 

proximal end of the eastern lateral along Fish Creek. 

Near Hickman Pasture, Donkey Creek drift narrows to a width of 

less than 1,200 feet, probably because of massive slumping on the 

eastern side of the valley. The slumping antedates the moraines of 

the Donkey Creek drift and may have narrowed the valley from a 

former width of more than a mile to its present width, forcing the 

Donkey Creek glacier to accommodate itself to the slump blocks. In 

addition, near Hickman Pasture the eastern lateral moraine of Donkey 

Creek drift is cut by an earthflow; hence landslide movements occurred 

here both before and after the Donkey Creek glacial maximum. 

Outwash probably derived from the Donkey Creek glacier occurs 

along Fish Creek downstream from Donkey Creek drift. A surface 

apparently cut by melt water during Donkey Creek deglaciation occurs 

at and upstream from Hickman Pasture. 

BLIND LAKE DRIFT 

Drift of the Blind Lake glaciation, the type locality of which is in 

the Fish Creek-Grover drift lobe, consists of 3 small deposits marked 

at their peripheries by end moraines varying from a few feet to 60 

feet in height. The largest mass extends only 1 mile beyond the toe 

of the cliff, down to an altitude of 9,900 to 10,200 feet and includes the 

basins of Blind and Pear Lakes. The lakes are dan1med by end 

moraines; other indistinct moraines are present close to the summit 

cliff. 

The second deposit is marked by a moraine that forms the basin of 

Fish Creek Lake; the third and smallest, includes the small basin of 
126 CONTRIBUTIONS TO GENERAL GEOLOGY 

Clark Lake (not shown on pl. 6). These small deposits seem to conform to topography created by slumping; it is inferred, therefore, that 

they postdate the landslides that have locally affected the Donkey 

Creek drift in the vicinity. 

PLEASANT CREEK DRIFT LOBE 

The Pleasant Creek drift lobe includes Carcass Creek and Donkey 

Creek drifts (fig. 25, table, p. 119) and occupies the capacious valley 

drained by Pleasant Creek on the east flank of the plateau. Its 

headward segment is particularly narrow, apparently because the 

valley had been narrowed by slumping before the drift was deposited. 

The drift is believed to consist mainly of till rich in large boulders 

of volcanic rock. However. natural exposures are few and superficial, 

and the boulder-covered slopes defy excavation with ordinary field 

tools. 

In the distal4-mile segment of the lobe the drift is characterized by 

subparallel lateral moraines, some of which curve around to form 

incomplete terminals. The moraines are low with smooth, gentle 

sideslopes and few closed depressions. All are mantled with boulders. 

Between the moraines are swales in which stream channels expose 

several feet of sandy alluvium. 

The surface drift in this 4-mile sector is believed to be the Carcass 

Creek drift. L. C. Huff (written communication) found an exposure 

in this sector showing alluvium overlying a caliche zone more than 5 

feet thick in a bouldery mass that may be till. As the caliche may be 

a remnant of a pre-Carcass Creek (Sangamon or older) soil (Hunt and 

Sokoloff, 1950), it is possible that pre-Carcass Creek drift is present 

at this place. However, the surface drift in this sector is probably of 

Carcass Creek age, because degree of weathering, topography, and 

altitude of terminus are comparable with those of drift of the Carcass 

Creek glaciation in the Fish Creek-Grover lobe. 

The Pleasant Creek drift lobe is flanked, at distances of less than a 

mile, by remnants of a pediment that stand high above present 

drainage and that appear to antedate the drift lobe. The altitudes of 

the remnants suggest that the drift lobe was deposited in a shallow 

valley cut into the pediment. However, the pediment is so nearly 

destroyed by dissection that this relationship could not be established. 

The outer part of the Pleasant Creek drift lobe is drained by Pleasant 

Creek on the north, and, throughout all but the last 2~~ miles, by Oak 

Creek on the south. These streams must have assumed their courses 

while the drift lobe was accumulating. The lobe is also drained 

medially by a short stream now impounded to form Bown's Reservoir. 

Drift of the Donkey Creek glaciation forms the Pleasant Creek 

drift lobe from near the base of the summit cliff down the valley 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 127 

drained by Pleasant Creek to the vicinity of the Wildcat Ranger 

Station, where the drift reaches a minimum altitude of about 8,400 

feet. This drift is characterized by discontinuous lateral moraines 

generally 50 to 7 5 feet high, with steep sideslopes. In places there 

are two laterals about 500 feet apart. Close to its terminus the lobe 

is marked by outwash accumulations at its two lateral marginsL 

Through a distance of more than a mile outward from the summit 

cliff moraines are absent, and there is much evidence of slumping that 

probably destroyed most Donkey Creek drift in this segment. 

Although destroyed by slumping or covered by younger drift in its 

headward part, drift of the Carcass Creek glaciation in the Pleasant 

Creek lobe evidently is the product of glacier ice that originated on the 

plateau top and that flowed down over the summit cliff, probably 

between Meeks Lake and a point one mile east of Pleasant Creek 

Meadows. No evidence has been found that the plateau top outside 

the area between these two points was ever covered by glacier ice. 

A small mass of drift ascribed to the Blind Lake glaciation forms 

the head of the Pleasant Creek drift lobe near the junction of Meeks 

Draw with Pleasant Creek. The mass is bordered by a miniature end 

moraine at an altitude of about 9,500 feet. Its areal position suggests a 

small lobe of glacier ice flowing down Meeks Draw from the plateau top. 

There is no evidence of a contemporaneous glacier in the headwaters 

of Pleasant Creek. 

BOULDER CREEK DRIFT LOBE 

The Boulder Creek drift lobe lies in the valley of Boulder Creek, 

the principal stream draining the south side of the plateau (fig. 25) 

and is much like the lobes described previously (table, p. 119). 

In the distal 3 miles of the lobe, drift tentatively correlated with the 

Carcass Creek glaciation is at the surface. The drift forms faint 

subparallel moraines and is apparently buried in part by its outwash 

so that it is difficult to fix closely the outer limit of the former glacier. 

The lobe had its source in glacier ice which poured over the summit 

cliff into the deep valleys of East Boulder Creek and West Boulder 

Creek, leaving the intervening projection, Trail Point, unglaciated. 

Drift in the form of massive moraines occupies both branches of 

the Boulder Creek valley to the vicinity of their junction, 5 miles 

southward from the summit cliff. Because the extent, morphology, 

and terminal altitude of this drift are similar to Donkey Creek drift 

in the other major lobes, this drift is tentatively assigned to the 

Donkey Creek glaciation. 

In both branches of the valley, 1~ to 2 miles downstream from the 

summit cliff, fresh miniature end-moraines reach altitudes of 9,200 to 
128 CONTRIBUTIONS TO GENERAL GEOLOGY 

9,600 feet. These are assigned by analogy to the Blind Lake drift. 

The moraine in the valley of West Boulder Creek forms the basin 

of Baker Lake. 

MILLER CREEK DRIFT LOBE 

The Miller Creek lobe occupies the short, very deep canyon that 

drains the west-facing scarp of Boulder Mountain 1 mile south of 

Lookout Peak, and extendsoutovertheadjacentlowland (table, p.119). 

This lobe is believed to be drift, but a landslide origin has not been 

entirely excluded. The problem is discussed in the section on 

''Tonguelike Complex Landslides (p. 137)." 

The canyon portion of the lobe is barely 2 miles long, but the lobe 

abruptly widens on the flat floor of Dark Valley into a terminal bulb 

more than 2 miles in diameter. With a maximum height of about 

100 feet above the floor, the bulb is a remarkably symmetrical mass 

with discontinuous concentric ridges having a local relief of about 

50 feet. The ridges are more irregular and more closely spaced than 

those in the other lobes; individual knolls and basins are more distinct, 

and although slopes are generally gentle, some, including the distal 

slope itself, have angles as much as 30°. The ridges are underlain 

by material that is probably a bouldery till. 

The distal slope of the bulb is cut by two reentrants that contain 

partly dissected fanshaped deposits, probably outwash (not shown 

on pl. 6). The deposits merge with a thin, broad apron of alluvium 

that originates along the distal slopes of the bulb and sweeps clockwise 

around its perimeter, draining northward along Dark Valley Draw. 

Most of the drift of the Miller Creek lobe probably is of Carcass 

Creek age despite the fact that its terminus is more than 2,000 feet 

above that of the other lobes of that age (table, p. 119). The boulders 

on the surface of Miller Creek lobe are similar in degree of weathering 

to those on Carcass Creek drift on the northeastern side of Boulder 

Mountain. Basins in the Miller Creek lobe, despite locally steep 

slopes, are partly filled with colluvium; some contain small alluvial fans. 

The broad terminus of the Miller Creek drift lobe differs from that of 

the other drift lobes in width and in altitude. The difference in form 

is attributed to the spreading-out of ice on a flat floor. Because the 

glacier was shorter than the others, its terminus occupied each position 

during a relatively long time; hence, the lobe has somewhat steeper 

slopes and more distinct morainic expression than the other lobes. 

Most of the canyon portion of the drift lobe has been removed by 

landsliding, but near the canyon mouth are truncated stumps of lateral 

moraines. 

Younger drift in this lobe is represented only by a small patch of 

end moraine, with a local relief of about 15 feet, that forms the basin 

of Miller Lake at an altitude of about 10,500 feet (pl. 6). Slopes are 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 129 

steeper than those in the piedmont bulb, and the degree of exfoliation 

is less. These facts, coupled with the high altitude of the mass, 

suggest that this drift probably belongs to the Donkey Creek glaciation. The rest of the drift deposited at this substage has been 

obscured or removed by landsliding. 

STATION CREEK DRIFT LOBE 

The Station Creek drift lobe 3 is a crudely semicircular mass of 

drift that covers part of the nearly flat surface of a fault or slump 

block 2~ miles north of Miller Creek and 1~ miles southeast of the 

Aquarius Ranger Station (table,p.119). Itsheadwardparthas been destroyed or obscured by landsliding. The lobe does not, and apparently 

never did, occupy a canyon or other obvious depression; it simply 

covers an area of irregular topography resulting from slumping and 

possibly also faulting. 

A few exposures suggest that the lobe is built of till consisting of 

pebbles, cobbles, and boulders in a matrix of sandy grit. The larger 

fragments are abraded, but their shapes are not diagnostic of abrasion 

by glacier ice. 

The outer part of the lobe consists of low and very bouldery concentric ridges, low knolls, and basins; these features together have a 

local relief of about 25 feet. The apronlike distal slope of the lobe is 

steep and is strewn with boulders. The inner part of the lobe has 

very low relief and gentle slopes and probably is ground moraine. 

Drift of the Station Creek lobe is tentatively correlated with the 

Carcass Creek glaciation because the extent of exfoliation of its 

boulders is comparable with that of the Carcass Creek drift of the 

Fish Creek-Grover drift lobe. The high altitude of the Station Creek 

drift lobe terminus, which is 700 to 800 feet above the Miller Creeks 

bulb (table, p.119), does not preclude such correlation, because the paths 

of the corresponding glaciers were different. Both glaciers are believed to have originated on the plateau top because neither had an 

adequate catchment area beneath the summit cliff. The flow of Miller 

Creek glacier was facilitated, however, by the presence of a deep 

canyon, whereas the Station Creek ice lobe had no canyon, and furthermore flowed from a narrow part of the plateau top where the ice supply 

would have been relatively small. Accordingly a smaller volume of ice 

had to make its way over an irregular topography consisting of dislocated blocks, without benefit of any channel. This seems an adequate explanation of the relatively high altitude of the terminus of 

the Station Creek lobe. 

a The name is not entirely appropriate because Station Creek does not actually drain any part of the lobe. 

However, the headward part of the creek lies close to the north flank of the lobe, and is the nearest feature 

bearing a name on existing maps. 
130 CONTRIBUTIONS TO GENERAL GEOLOGY 

A small body of end moraine on the northwest side of a small unnamed lake half a mile north of Cook Lake is much like that at Miller 

Lake, although it appears to be slightly less weathered and masswasted. On the basis of weathering and degree of slope modification 

it is tentatively correlated with the Donkey Creek drift. 

The fine-textured topography of the Station Creek drift lobe implies an origin in a small, thin glacier. The position of the drift body is 

unusual in that it is unrelated to a recess in the summit cliff. Apparently it represents a small and short-lived stream of ice that spilled 

over the cliff from the plateau icecap. 

DONKEY CREEK DRIFT LOBE 

The Donkey Creek drift lobe (fig. 25) occupies the headwater area 

of Donkey Creek in a broad reentrant in the summit cliff between 

Government Point and Donkey Point (pl. 7). Like the Station Creek 

drift lobe it lies on a mass of slump blocks rather than in a definite 

valley. 

The periphery of the lobe is marked by a nearly continuous endmoraine 15 to 35 feet high that is hummocky and covered with boulders. At Donkey Creek the moraine attains an extreme distance of 3 

miles from the summit cliff (table, p.119). Two local and discontinuous 

inner moraines in the vicinity of Round Lake probably record later 

readvances of the Donkey Creek glacier. 

A pronounced though somewhat less continuous end moraine, 5 to 

20 feet high, lies much closer to the cliff. It retains Donkey Lake 

(now artificially heightened by a dam), Green Lake, and smaller lakes 

between them. 

On a basis of position, altitude, topography, and extent of weathering the outer moraine is tentatively correlated with the Donkey 

Creek drift, and the inner moraine, near the cliff, with the Blind 

Lake drift. 

The Donkey Creek lobe apparently includes no drift of Carcass 

Creek age. Two possible explanations suggest themselves. One is 

that a Carcass Creek glacier tongue occupied approximately this area, 

probably extended northward beyond the present Donkey Creek drift 

border, and left deposits that were completely disrupted by landsliding 

in Donkey Creek time. Favoring this explanation is the presence of 

continuous landslide topography outside of, and controlling the detailed trend of, the moraine of the Donkey Creek glaciation. The 

other explanation notes that the Donkey Creek drift lobe is northeast 

of the narrow northern end of the plateau summit. The plateau ice 

on this narrow projection may have drained chiefly eastward into the 

Fish Creek-Grover lobe, leaving little ice to flow northward into the 

Donkey Creek area. As a result, in the latter area the Carcass Creek 
GEOLOGY OF BOULD-ER MOUNTAIN, UTAH 131 

ice may have been no more extensive than the Donkey Creek ice. 

Of the two explanations the first seems the more probable, but no 

firm basis has been found for eliminating either one. 

DISTRIBUTION OF DRIFT AROUND THE PLATEAU 

The extent of the drift is almost equal on the south, east, and north 

sides of the plateau (table, p. 119, and fig. 25). On the west side the 

drift is much less extensive. This distribution of drift is unlike that 

on many mountain ranges in the Cordilleran region where glaciation 

is dominant on the north and east flanks. 

The explanation is probably as follows: The regimen of glaciers 

heading in cirques below the narrow crest of a mountain range depends 

in part on wind-drifting of snow on the lee (usually east) side of the 

range, and on conservation of snow and ice owing to more shade offered 

by the range crest from southern and western exposure to the sun. 

In contrast, the element of topographic protection is less important 

in the regimen of the icecap outlet glacier (pl. 8), because the source 

ice-body stands above the bedrock surface. Furthermore, the thickness and activity of an icecap from place to place is affected by the 

distribution of snowfall on it. On a high plateau this depends on the 

direction from which air masses bring orographic precipitation to the 

highland. Today, on the Aquarius Plateau, this direction is west 

and southwest. There is no reason to believe that during the glacial 

ages the direction was significantly different. Hence the icecap may 

have been somewhat thicker over the western and southwestern parts 

than over other parts of the plateau. 

These considerations possibly explain why the Boulder Creek drift 

lobe, on the south side of the plateau is as long and bulky as the Pleasant Creek and Fish Creek-Grover drift lobes, and why drift is fairly 

extensive on the west side of the highland. 

ROCK GLACIERS 

Rock glaciers (Capps, 1910; Sharpe, 1938, p. 42) occur on all sides 

of the plateau near the base of the summit cliff, at altitudes approximating 10,500 to 10,700 feet. They are apparently largest and most 

abundant on the north side, in the Fish Creek and Donkey Creek 

reentrants. The rock glaciers are uni- or multi-lobate, with widths 

(parallel with the cliff) of 200 to 2,500 feet, and with lengths (normal 

to the cliff toe) up to 1,200 feet. They have steep terminal slopes, 

commonly 38° to 42°, and terminal heights of 30 to 110 feet. 

The sm·face material of the rock glaciers consists of large angular 

boulders of volcanic rock derived from the adjacent cliffs. No fragments smaller than boulder size are visible. Some boulders exceed 

12 feet in diameter; many of them are inequidimensional, and no 

461212-58-5 
132 CONTRIBUTIONS. TO GENERAL GEOLOGY 

preferred orientation was observed. No exposure of the interior of a 

rock glacier was found. 

Most of the rock glaciers have concentric ridges, as much as 15 feet 

high, around their lateral and terminal margins. Some of the larger 

glaciers have low, irregular knolls and shallow basins near the center 

of their upper surfaces. All surfaces are bare and free of vegetation 

except for lichens. The boulders are superficially oxidized and some 

are slightly exfoliated. 

The rock glaciers are overlapped commonly by talus composed of 

smaller fragments of volcanic rock that are generally less weathered 

than those of the rock glaciers, although the differences are small. 

Some rock glaciers overlie Blind Lake drift with marked topographic 

discordance. 

The rock glaciers originated below the rim of the summit cliff and 

in general are largest and most numerous beneath high cliffs that 

face northeast. They are absent below some conspicuous notches in 

the cliff which are ideal avenues for the movement of ice downward 

from the plateau top. 

Two principal hypotheses of origin of rock glaciers have been put 

forward. One is that these features are the surface moraines of 

vanished true glaciers (Capps, 1910; Kesseli, 1941). The other is 

that they are mass-wasting phenomena. There is evidence that some 

rock glaciers are moving at present in the absence of underlying 

glacier ice. Such rock glaciers are bodies of slide-rock that flow with 

the aid of an interstitial lubricant such as ice other than glacier ice 

(Roots, 1954, p. 24-29). 

The distribution of the rock glaciers around the Aquarius Plateau 

favors the view that they are mainly frost-weathered cliff debris incorporated in and transported downslope by small glaciers which were 

nourished by snow that collected at the base of the escarpment. 

The Pleistocene drift lobes, on the other hand, were built by ice that 

flowed down over the summit cliff from a plateau icecap. Some additional movement of rock glaciers, caused by interstitial ice of nonglacial origin, may have preceded and may also have followed glacial 

movement. For example, in a climate becoming colder, ice might 

form in the voids within an existing body of boulders, and some 

movement might occur through melting and refreezing of such ice. 

At least some of the rock glaciers postdate the Blind Lake drift. 

These probably represent the inception, expansion, and decay of 

nun1erous very small glaciers in Recent time and possibly are correlatives of ice bodies in the Sierra Nevada that may date from less 

than 4,000 years ago (Matthes, 1939, p. 519). 

In places on the west slope of Boulder Mountain, small rock glaciers 

consist of two members, one overlying the proximal part of the other 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 133 

(Kesseli, 1941, p. 222 and fig. 13). This relationship suggests two 

very minor pulses of glaciation. No basis for dating the two members 

was found but perhaps in this west-facing, little-protected position 

the lower member is of Blind Lake age, whereas the upper member is 

of the post-Blind Lake generation which is present more conspicuously 

on the north side of the plateau. 

TALUS 

Slide-rock in the form of apronlike talus occurs at the bases of rock 

cliffs along the Fremont River and elsewhere in the Teasdale-Torrey 

lowlands, but the deposits are too smaJl to be shown on plate 6. The 

fragments are dominantly of sedimentary rock. Much of the sliderock overlies a red flaggy colluvium (figs. 26, 27, and 28) believed to 

have accumulated duringlate Pleistocene (Donkey Creek and Blind 

Lake) time; the talus is now being dissected. Possibly it accumulated 

in part during an episode of cool climate that followed the Thermal 

Maximum (Flint and Deevey, 1951, p. 275). 

N. 

0~-------------------------------------------------~ 

50 100 Feet 

FIGURE 26.-Colluvium and river deposits exposed in gulches on south side of Fremont River 

just northwest of the Torrey-Grover road (pl. 6, Ioc. ll). 

150' 

100' 

50' 

Talus aprons partly cloak the summit cliff and seem to consist of 

two groups. The older talus is the more extensive; it commonly 

masks more than the lower half, and in some places almost all, of the 

cliff. Most of this talus is stable and supports a sparse vegetation. 

It is confined to those parts of the cliff where the adjacent plateau top 

shows no evidence of glaciation, such as the Chokecherry Point and 
NW. 2501 

200' 

·j 

100~ 

Red flaggy colluvium 

r:· 0 

1501 6 

Q: 

100' 

~ 0 ·~ 50' 

~1 I I I 9 400Feet 

FIGURE 27.-Colluvium and liver deposits exposed in tributary valley on north side of Fremont River along T01rey-Grover road (pl. 6, loc. 6). Vertical 

exaggeration 2 times. 

~ '"""" 

~ 

c 

~ 1-1 

txl 

I 

8 

0 

0 

! 

~ t"l 

0 

t;l 

0 

t'f 

0 

~ 
150' 

100' 

50' 

S. 

Gray and brown Sllt/''J::":·;;· ... ·,-:\:·.\:. 

..... IJ. .... ~ 

., ., "'"~ ~ ., -4 

N. 150" 

100' 

50' 

... ., .,4.,-4,.,. ..... '"~ Y' -4 ~ .. A y A r' 

0 

/Level of Fremont River 

~----~--~-------------~0 100 0 200 Feet 

FIGURE 28.-Colluvium and river deposits overlying till. Exposure in gulch on south side of Fremont River between 

Fish and Carcass Creeks (pl. 6, loc. 8). Vertical exaggeration 2 times. 

0 

i::':l 

0 

s 

~ 

0 

lo%j 

t:d 

0 

..... 

~ 

~ !;:tl 

~ 0 

~ lZ 

~ 

1--l 

~ 

01 
136 CONTRIBUTIONS TO GENERAL GEOLOGY 

Bowns Point "peninsulas", Trail Point, and the southwest margin of 

Boulder Mountain. Such a distribution implies that this group of 

taluses antedates the Blind Lake glaciation. 

The younger talus forms rather narrow sheets along the lower parts 

of the cliff and is less extensive than the older group. It is unstable 

and is virtually free of vegetation. It occurs along the foot of cliffs 

that fringe the distinctly glaciated parts of the plateau top, and where 

in contact with rock glaciers it overlies and hence postdates those 

features. 

The younger talus in itself affords no evidence that it is not the 

product of continuous accumulation during the whole time since the 

rock glaciers were formed. 

BOULDERY ACCUMULATIONS OF 

UNDETERMINED ORIGIN 

Bouldery accumulations of undetermined origin (pl. 6) are masses 

of boulders with some finer material that cover large areas principally 

on the slopes of Boulder Mountain. Many of these accumulations 

mantle areas of conspicuous landsliding and slumping and are described 

in the following section. These accumulations are doubtless of both 

Pleistocene and Recent age, but their ultimate origin, whether drift, 

pediment gravel, or landslide debris, is largely unknown. 

LANDSLIDES 

The most extensive type of superficial deposit that mantles the sides 

of the plateau, far exceeding the total areal extent of drift or of exposed 

bedrock, is landslide debris. For the purpose of this paper a landslide 

is defined as any downward and outward movement of bedrock or 

mantle on slopes, at rates greater than that of creep.4 In accordance 

with general usage the term is applied also to lobate bodies of debris 

resulting from distinct individual slides. 

Three types of landslide deposits are present on the sides of the 

plateau. The simplest type is slump blocks, mostly at the base of the 

summit cliff; the second consists of lobate or tongue-like complex landslides; the third is a widespread mantle of landslide debris. The three 

types differ in character and in time of origin. 

INDEPENDENT SLUMPS 

Slump blocks that are not obviously integral parts of tonguelike 

complex landslides are here grouped under the term "independent 

4 Modified from Highway Research Board Landslide Committee (unpublished classification sheet). 

Landslide terms used in this paper are drawn from the same source. 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 137 

slumps." They range from 100 feet to thousands of feet in length and 

generally are as much as 100 feet (in extreme examples 200 feet) in 

height. They occur at all altitudes on the plateau sides, in sedimentary 

bedrock, in lateral moraines and, most abundantly, in volcanic rocks 

at and below the summit cliff. 

Some slumps have been rotated backward; less commonly, others 

have been rotated forward and have been displaced vertically by as 

much as 200 feet. Some have broken up into boulder rubble since 

their displacement but still preserve the general continuity of their 

layered rock. In the Fish Creek reentrant successive slumps, traced 

outward and downward from the summit cliff, show progressive 

differences in weathering that imply progressive increase in age. Some 

large eroded slumps, half a mile or more beyond the parent cliff and 

close to the altitude of the cliff toe, could hardly have moved to their 

position from the present locus of the cliff. The movement of such 

blocks may have occurred when the cliffs were adjacent to them. The 

cliffs have since retreated, probably because of glacial erosion and 

repeated slumping. 

Some large slumps are covered with Donkey Creek drift and clearly 

have determined the local directions of flow of the Blind Lake glaciers. 

Others cut lateral moraines of the Donkey Creek drift. Still others 

are obviously very recent. Independent slumps have formed at various 

times, and it is quite possible that sh·mping has substantially reduced 

the area of the plateau top in post-Sangamon time (cf. Retzer, 1954). 

TONGUELIKE COMPLEX LANDSLIDES 

Six known lobate or tonguelike complex landslides on the slopes of 

Boulder Mountain are the Aquarius Ranger Station, Coleman, Bullberry, Hickman, Singletree, and Lion Mountain slides. Their locations 

are shown on figure 25 and their areal and vertical extent summarized 

below. These landslides are a combination of slumps, earthflows, and 

perhaps of debris-slides. 

DISTRIBUTION 

Four of the slides, Aquarius Ranger Station, Coleman, Hickman, 

and Singletree, originate at or near the summit cliff where they form 

peninsulas adjacent to segments of the plateau top that were not 

glaciated, at least during Donkey Creek and later times. The remaining two slides head in the lower slopes of Boulder Mountain and are 

relatively long and narrow. 
138 CONTRIBUTIONS TO GENERAL GEOLOGY 

Principal dimensions of tonguelike complex landslides around Boulder Mountain 

Difference In 

Name of slide Minimum length Maximum width altitude between 

(feet) (feet) head and toe (feet) 

Aquarius Ranger Station ____________ 6,000 5,000 Unknown Coleman __________________________ 17,000 8,600 2,800 

Bullberry ___ --------- _____________ 11,800 1,000 840 

Hickman __________________________ 4,600 1,950 950 

Singletree _________________________ 16,100 6, 700 2,400 Lion ~tn _________________________ 1,800 450 280 

TOPOGRA.l•HY 

Each of the tonguelike complex landslides consists of an upstream 

portion marked by transverse steplike slump blocks separated by 

scarps and a longer downstream portion consisting of a lobate earthflow (fig. 29). The slump blocks resemble the independent slumps 

previously described. Individual blocks become progessively smaller 

and more broken up downstream. The landslides occuped preexisting 

valleys and forced the streams to assume positions along their lateral 

margins. 

Simple and complex slumps have been observed elsewhere to possess 

undersurfaces of rupture and displacement on which the slump blocks 

have moved over the underlying material. In the downslope direction 

the surface of rupture is the continuation of the surface of the main 

or highest slump scarp. Ordinarily the surface is concave, both 

transversely and longitudinally. At some point downslope, at the 

foot (fig. 29), the surface of rupture intersects the ground surface, and 

may be visible there. In the complex landslides on Boulder Mountain, however, the foot is concealed beneath earthflow debris. 

The transverse cracks, well developed in the downstream half. of 

the Hickman slide, very likely represent tension in the surface of the 

earthflow as it passed over the foot of the surface of rupture (fig. 29). 

If so, they are analogous to the crevasses in a valley glacier developed 

where the ice flows over an abruptly steepened slope. 

The Coleman slide is described in detail as typical of the tonguelike 

complex landslides on the slopes of Bounder Mountain: In this slide 

the slumped portion is confined to the head. Downslope there is an 

intermediate zone of boulders and finer debris arranged in discontinuous irregular ridges parallel with the margin of the slide. This has 

some characteristcs of a debris-slide. The terminal, lobate earthflow 

occupies a depression in the lower part of the plateau sideslope and 

has well defined lateral margins. The slump blocks evidently broke 

up within a short distance of travel. The stream along the west 
FIGURE 29.-Diagrammatic sketch of a complex landslide such as the Coleman slide and Singletree slide, showing component parts. (In part after Highway 

Research Board Landslide Committee, unpublished). 

0 

1?:1 

8 

~ 

0 

1-:zj 

t:xj 

8 

~ P::l 

a= 

I 

d 

~ 

......... 

CJ,j 

c:o 
140 CONTRIBUTIONS TO GENERAL GEOLOGY 

margin of the slide has incised itself slightly into the underlying 

bedrock. 

In the downstream portion of the Coleman slide the features imply 

flowing movement rather than slumping and sliding. The toe of the 

slide, where not greatly altered by erosion, is convex downstream and 

has a frontal slope of about 40°. Upstream from and parallel with 

the toe are two or more arcuate ridges as muchas40feethigh. Farther 

upstream are irregular knolls, hummocks, and basins without apparent 

pattern and with a relief of about 30 to 40 feet. Relief is twice as 

great where there are long deep furrows transverse to the long axis 

of the slide. Some of these furrows contain lakelets. 

The zone of transition from slumping to flowing is widest and most 

clearly defined in the Coleman slide, where the local topography 

suggests flowing movement around the sides of large stranded slump 

blocks. One of the stranded blocks, consisting largely of sedimentary 

rock, appears to have been cut at both ends by thin, slicelike slumps, 

parallel with the direction of flow. Some of these slumps were broken 

up and carried downstream. The main block is like a short. loaf of 

bread cut by slices at both ends, with the outer slices merging into 

the surrounding earthflow. Basins between the slicelike slump 

blocks contain two long narrow lakelets. · 

COMPOSITION AND THICKNESS 

In slump blocks at the heads of tonguelike complex landslides only 

volcanic rocks are exposed; in earthflow portions superficial exposures 

show volcanic fragments well mixed with material derived from sedimentary rocks such as silt, clay, and mashed and deformed masses 

of shale and siltstone. The landslides are usually mantled by rubble 

that consists of joint blocks and other angular fragments of volcanic 

rock of boulder size, generally more than 10 feet in diameter. Most 

exposures give ·an exaggerated impression of the number of volcanic 

boulders because they creep down as a mantle over the underlying 

material. 

Much of the mass of debris is nonsorted and nonstratified. It 

resembles till except that it contains boulders and smaller fragments 

that have what appear to be nonabraded shapes. The intimate mixture of various rock types implies differential movement of component 

particles, but exceptions to such mixtures occur. Some large hummocks are completely mantled by boulders of a single kind of volcanic 

rock, evidently formed by breakup, through frost action, of one great 

mass of rock that had previously slumped or slid down from the summit cliff. In the Hickman slide, for example, all the debris on the 
G:Jl]OLOGY OF BOULD'ER MOUNTAIN, UTAH 141 

downstream slope of the largest of the transverse furrows (600 feet 

long) consists of one kind of volcanic rock, whereas all that on the 

upstream side is of a different, agglomeratic type. This difference 

implies that two distinct blocks are at. the surface on the two sides 

of the furrow. 

The thicknesses of the Aquarius landslides are unknown. The 

topography near the toes of the Coleman and Singletree slides suggests 

that their earthflow portions may be as much as 200 feet thick. 

ORIGIN 

Boulder Mountain is strongly susceptible to landsliding. It consists of several hundred feet of flat-lying massive volcanic rocks underlain by several thousand feet of flat-lying sedimentary beds, mostly 

claystone and siltstone. Many complex landslides in other areas 

likewise are present where weak argillaceous rocks are overlain by 

competent caprocks. 

Boulder Mountain would probably fail by landsliding under almost 

any climate. The weak sedimentary rocks, under confined pressure 

caused by the weight of the overlying volcanic rocks, would probably 

lose cohesion and sliding would result. During glacial ages, however, 

sliding in the Aquarius Plateau district was probably enhanced by 

large volumes of melt water that penetrated through the volcanic 

rocks to the underlying sediments. 

Terzaghi (1950, p. 91-100), a keen student of landslides, expressed 

the opinion that the mere weight of water added to rock formerly dry 

is an unimportant causal factor, and that frost action is likewise unimportant because its effects are only skin deep. He stated, however, 

that failure could be caused by a new source of water entering material 

formerly relatively dry and dissolving a soluble binder or cement. 

Terzaghi gives another cause of failure (p. 101): 

Experience shows that the water, which seeps toward steep slopes during rainstorms, does not displace enough air to destroy the apparent cohesion of sand or 

silt. However, if water percolates through the ground toward the slope in large 

quantities and without any intermissions, the air is almost completely expelled, 

the apparent cohesion is eliminated, and the slope fails. 

An additional cause, where clay rather than silt or sand is involved, 

is gradual swelling and softening of clay as it absorbs water, a process 

enhanced by the presence of minute cracks in clay beds that have 

been compressed by loading and expanded by unloading in the geologic 

past (Ward, 1945, p. 185). 

These causes seem adequate to have brought about the Aquarius 

slides, given an extraordinarily large source of water, such as melt 
142 CONTRIBUTIONS TO GENERAL GEOLOGY 

water from snow and glacier ice on the plateau top. The four large 

complex landslides, as well as some of the larger groups of slump blocks, 

are below cusplike peninsulas of the plateau top that apparently 

were not glaciated in Donkey Creek or later time. This distribution 

suggests a possible genetic relationship between landsliding and glaciation: the icecap acted as a protective blanket permitting little percolation of melt water down into the underlying rock. On the nonglaciated 

points, however, melt water from snow, most abundant during spring 

thaw, and summer melt water from the icecap itself percolated downward through vertical joints in the volcanic rocks, saturated, and reduced cohesion in the underlying claystones and siltstone so that 

rupture occurred. 

A part of the downstream earthflow portion of the Singletree slide 

appears to be considerably dissected and perhaps is somewhat older 

than the remainder of the slide. The emplacement of the toe of the 

slide southeast of Lion Mountain may have been followed by an 

episode of dissection, which cut into the underlying bedrock, prior to 

the movement of the remainder of the Singletree slide. 

On the other hand, recent movement is shown by a number of 

features. Leaning trees, including young trees, are common not 

only on many tonguelike complex landslides, but also on much of the 

slope of Boulder Mountain below the summit cliff. In one area 

several very large yellow pines (Pinus ponderosa), still growing, are 

conspicuously bent within 10 to 20 feet of the ground. A sawlog of 

the same kind of pine and of comparable size showed, in section, 320 

growth rings. Hence the bends may record slumps dating from 250 

to 300 years ago. 

One hummock situated about halfway down the length of the Coleman slide exhibits a gaping rift 200 feet long. A large upright fir, 

whose long horizontal roots straddle the rift, has been split in two by 

pulling apart of the roots. When observed in 1952 the fir was not 

yet dead. 

There is much evidence of minor present-day slumping of the lower 

slopes underlain by sedimentary rocks. 

No direct evidence of any particular cause of sliding has been found, 

and the foregoing suggestion is merely a reasonable explanation. 

Mechanically it parallels the explanation given for the recently active 

Cedar Creek slide near Montrose, Colo. (Varnes, 1949). In that slide 

t.he trigger was a new and abundant supply of irrigation water percolating down into a firm caprock overlying a body of shale. The same 

author ascribed two other slides in western Colorado to large amounts 

of water added to shale overlain by a massive caprock. Another 

slide, in shale capped by sandstone, near Durango, Colo., probably 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 143 

was caused by the absorption of a sudden large increment of melt 

water (Vanderwilt, 1934). 

It seems likely that on slopes of the Aquarius Plateau the development and movement of new slump blocks caused rupture of the volcanic rocks along joint surfaces, and that the resulting boulders moved 

downslope as debris-slides. Farther downslope the slump blocks were 

mixed with claystone and siltstone creating a transition from slumping 

to flowing movement. The resulting earthflow was composed of 

till-like material, although some blocks of volcanic rock and even 

large blocks of claystone and siltstone remain. 

Movement of the Aquarius slides probably resembled that of some 

present-day slides. Vanderwilt (1934) described a complex slide 

1,800 feet long near Durango, Colo., which started in 1932. Movement of slump blocks constituting the head of the slide produced 

talus consisting of joint blocks broken from sandstone caprock. 

Maximum measured rate of movement was 30 feet per day. Cracks 

opened and closed, trees were overturned and buried, and in the 

earthflow portion downstream, concentric ridges developed. Farther 

headward "low, rough ridges" developed parallel with the sides of the 

slide. 

The Gros Ventre slide in western Wyoming (Blackwelder, 1912} 

began to move in 1908. Slumping at the head transmitted stresses 

down the slope to old landslide deposits, which "began to press forward, bulge, and crack" in slow flow "like that of a glacier". In. 

1909 the toe "bulged into low irregular domes fretted with open 

crevasses ... " The rate of flow, however, was too slow "to be 

actually seen;" it was inferred from periodic observations. By 1911 

movement had virtually ceased. 

COMPARISON WITH LOBES OF GLACIAL DRIFT 

·Both in form and in component sediments the tonguelike complex 

landslides closely resemble the lobes of glacial drift. Atwood (1909, 

p. 63-65) found that both topographically and internally the two 

kinds of bodies, as they exist in the Uinta Mountains, are very difficult to separate. Blackwelder (1912, p. 491) concluded that "only 

the most painstaking and critical study will serve to discriminate 

the two types of deposits." 

On the Aquarius Plateau the two groups are alike in that both 

may (1) originate at cliffs, (2) occupy valleys or other pre-existing 

depressions, (3) consist of nonsorted, nonstratified materials, and 

(4) possess tonguelike form, subparallel longitudinal ridges, and 

knolls and basins. The differences, therefore, are of detail rather 

than of general form and composition; not all are applicable to any 
144 CONTRIBUTIONS TO GENERAL GEOLOGY 

one landslide or drift lobe. Some of the differences listed in the 

table below are depicted in figure 29. 

Comparison of features of landslides and drift lobes around Boulder Mountain 

Tonguelike complex landslides Glacial drift lobes 

External form and position 

May head in nonglaciated areas including those below peninsulas of the 

plateau top. 

Massive transverse ridges in headward 

part (slump blocks). 

May have longitudinal ridges upstream. 

Concentric transverse ridges are confined to vicinity of toe and are not 

continuous with marginal ridges. 

Possess nearly straight, transverse 

fractures and radial fractures at toe. 

Lack outwash body beyond toe. 

Head in reentrants and (or) glaciated 

areas or above former regional snowline. 

Sinuous transverse ridges in headward 

part (terminal moraines). 

Lack longitudinal ridges except at 

lateral margins (lateral moraines). 

Concentric transverse ridges (terminal 

moraines) may be continuous with 

lateral ridges (moraines) and are not 

restricted to toe. 

Lack fractures. 

Commonly have small outwash body 

beyond toe. 

Internal composition 

Material derived only from rocks present on the local slope. 

Fragments include very large masses 

of weak bedrock and joint-faced 

boulders of strong rock. 

Material may be derived from any or 

all rocks in glaciated area upstream. 

Fragments are comminuted and mixed; 

include fragments with abraded 

surfaces. 

Very few striations were seen on rock fragments in drift on the 

Aquarius Plateau, and none were seen on rock fragments in the 

landslides. During reconnaissance of the Wasatch Plateau, Flint 

observed abundant striations on limestone fragments in both drift 

and landslides; furthermore Vanderwilt (1934, p. 168), among others, 

noted striations on the surface of rupture beneath landslides. Striations, therefore, are not a means of discriminating between drift 

and landslides. 

The features cited in the table are developed ideally and may give 
GEOLOGY OF BOULD'ER MOUNTAIN, UTAH 145 

the impression that landslides are more easily discriminated from 

drift lobes than they actually are. The differences listed are often 

difficult to apply, as is indicated in these examples: 

1. Slumping in the headward part of a drift lobe, as in the Donkey 

Creek lobe in the Fish Creek valley, may give the false impression 

that the lobe is a complex slide. 

2. Exposures of the slides and drift lobes are so rare that their 

internal character generally must be inferred from the surface material. 

3. Leading away fron1 the toe of the Coleman slide is a nearly 

plane, inclined surface immediately underlain by alluvium. Deep 

exposures are lacking. Whether the underlying material was outwash could not be determined. The Coleman mass was identified 

as a slide on other evidence. 

4. Slides may incorporate in their masses preslide glacial drift; 

hence the presence (for example, in the Singletree slide) of fragments 

having a glacially abraded appearance does not prove that the body 

of debris is glacial drift. 

5. On a basis of the features listed in the table on p.l44 the Miller 

Creek lobe (p.l28) is identified as a drift lobe rather than a complex 

slide; however, the critical features are less well developed, and identification rests on less firm ground than that for the drift lobes on the 

north side of the plateau. Comparison of the Miller Creek lobe with 

the Coleman slide is made below. 

Comparison of surface features of Miller Creek drift lobe and Cowman slide 

Topographic features Miller Creek lobe Coleman slide 

Hummocks and basins_ Abundant, especially in south Scarce except near 

part of lobe. terminus. 

Lateral ridges _________ Well developed on flanks of Rare; some present on 

canyon portion; compare northwest flank at 

favorably with those in head of Bullberry 

Fish Creek lobe of Donkey Creek. 

Creek drift. 

Transverse, longi- Absent. Abundant. 

tudinal, or radial 

cracks. 

Dissection _____________ Slight. Slight. 

LANDSLIDE MANTLE 

Bouldery deposits of undetermined origin (pl. 6) are chiefly a 

mantle of landslide debris that covers much of the area of the plateau 

slopes. The mantle has no distinct form. Its surface is a jumble of 
146 CONTRIBUTIONS TO GENERAL GEOLOGY 

knolls and depressions (some of which are basins) having many sizes 

and shapes but with a preferred lineation paralleling the contour of 

the plateau slope. Some knolls reach 100 feet in height, and some 

basins have closures as great as 30 feet. The landslide mantle has 

reduced the relief of the Plateau slopes by partly filling or wholly 

obliterating small valleys. The positions of most of the small valleys 

have been determined by the relief of the landslide mantle itself. 

The surface is covered generally with vegetation and exposures 

are scarce. Masses of sedimentary rock, in places much deformed, 

with a few fragments of volcanic rock are visible in the banks of small 

streams. Abraded cobbles, presumably glaciated, occur at a few 

localities, implying that the mantle postdates at least one glaciation. 

TIME OF MOVEMENT 

Information as to the time of movement of the landslides is scattered 

and inconclusive. At least a part of the landslide mantle antedates 

some of the tonguelike slides. Some groups of slumps along the 

summit cliff were formed in stages separated by intervals of stability. 

The slump blocks farthest away from the cliff are broken up, their 

boulders are exfoliated, and they are partly covered by soil and vegetation, whereas those near the cliff are intact and are not forest 

covered. 

The toe of the Hickman slide (fig. 25) projects into the side of the 

Donkey Creek drift lobe showing that the slide postdates the moraine. 

Some large slump blocks in the vicinities of Blind Lake and Donkey 

Lake appear to antedate Blind Lake drift. Other slump docks in the 

Blind Lake area, situated as much as half a mile beyond the toe of 

the summit cliff but no lower in altitude, indicate substantial recessionof the cliff since the slumping. The latter slump blocks imply a 

pre-Donkey Creek date of movement because post-Blind Lake recession has been slight. 

Lack of continuity in most of the drift lobes, at and below the 

base of the summit cliff, suggests landsliding (chiefly slumping) since 

the lobes were deposited. Analogous discontinuity within drift 

bodies is present around the summit cliff of Grand Mesa, Colo., and 

has been explained in a similar way (Retzer, 1954). 

The data above suggest intermittent sliding over a long time and 

repeated movement in the same slide. Except for very recent move~ 

ment, however, they do not establish within close limits any major 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 147 

movement within any particular slide. The data are not inconsistent with the view that sliding was especially active during the 

times of glaciation. Some slumping along the sides of the large reentrants drained by Fish, Pleasant, and Boulder Creeks may have 

taken place when glaciers melted and exposed cliffs and slopes oversteepened by glacial erosion. 

ALLUVIAL, COLLUVIAL, AND LACUSTRINE DEPOSITS 

Alluvium occurs along the principal streams and was deposited by 

them. Colluvium occurs at the base of steep slopes and was derived 

from them by rills, minor streams, sheet runoff, and mass movements. 

The distinction between alluvium and colluvium is based largely on 

topography. Alluvium is mapped where the surface of the deposit 

slopes parallel with the main drainage. Colluvium is shown where 

the surface of the deposit slopes from the adjacent hills toward a 

main drainage line. Only the larger bodies of alluvium are shown 

on plate 6, and colluvium is mapped only in the Teasdale-Torrey 

lowlands, principally in small areas along the Fremont River between 

the outwash fans at the mouths of Carcass, Fish, and Donkey Creeks. 

Other bodies of colluvium are included with alluvium. Lacustrine 

deposits are scarce. None are shown on plate 6. 

The alluvium is composed of different mixtures of gravel, sand, 

silt and clay. The material is derived chiefly from adjacent surficial 

deposits and sedimentary rocks, and in places contains varying 

amounts of volcanic debris. The fragments of rock range from a fraction of an inch to about 3 feet in diameter; the material is noticeably 

finer grained than outwash, terrace gravel, or pediment veneers. The 

matrix is sandy in areas of sandstone, and dominantly silty in areas 

of siltstone and shale. It is generally calcareous throughout and 

locally contains abundant gypsum. The material is not well sorted; 

the sands are commonly silty and the silts gritty. The gravels 

contain both angular and somewhat rounded fragments of rock. 

Where the local bedrock is thin bedded, the gravels contain numerous 

small flagstones. 

Stratification of coarser grained alluvium is irregular, and channel 

fillings and disconformities are visible in many sections. Commonly 

the finer grained alluvium is evenly stratified, with 1- to 2-inch beds 

traceable along the strike for hundreds of feet (table below). The 

maximum observed or inferred thickness of alluvium is about 20 feet. 
148 CONTRIBUTIONS TO GENERAL GEOLOGY 

Section of alluvium exposed along Boulder Creek about 1 mile east of Teasdale 

(pl. 6, loc. 2) 

Top. 

Slumped----------------------------------------------------

Sand, coarse-grained, and gravel, fine-grained, pinkish-gray, calcareous; bedded; layers from~ to 2 inches thick; contain volcanic 

and sedimentary pebbles as much as ~ inch in diameter, a few 

fragments of charcoal, a few lenses of silt, and 1 or 2 small lenses 

of crossbedded gravel as much as 6 inches across _____________ _ 

Silt and fine-grained sand, gray and brown, mottled, massive, 

highly calcareous; contain carbonaceous material and numerous snail shells _______________________________________________ _ 

Silt, gray to white, massive, calcareous; few carbonaceous seams; 

contains irregularly cemented masses, and black carbonaceous 

veinlets (roots?) _____________ ~ ________________________ -- __ _ 

Silt, white, and fine-grained, gray sand, thin-bedded; contain 

irregularly cemented masses of silt, gray to black carbonaceous 

layers that range from ~ to 1 inch in thickness, carbonaceous 

veinlets (roots?), and a few thin lenses of very fine grained 

gravel----------------------------------------------------

Silt, white, and fine-grained gray sand, thin-bedded to massive ___ _ 

Silt, white, and fine-grained gray sand, bedded; contain numerous 

thin lenses of carbonaceous material; base not exposed ________ _ 

Total------------------------------------------------

Base. 

Feet Imhe11 

2 

5 

2 

2 

4 

3 

19 

0 

6 

4 

0 

8 

0 

0 

6 

In a few places the alluvium contains buried layers that are mixtures of organic and mineral matter, and that may be remnants of 

soil profiles. Bedded sand, which has lenses of gravel and includes the 

remnants of two possible buried soil profiles, is exposed along Bull berry 

Creek about 1 mile west of Teasdale (fig. 30). At the southeast end 

of the section, bedrock (Navajo sandstone) is overlain by bouldery 

gravel and sand. Gravel, sand, and silt lap over onto the northwest 

side of this bouldery material. The remnants of buried soil profiles 

shown were not exposed in the creek bank about 100 feet west of the 

northwest end of the area shown in figure 30. These buried layers 

are not continuous along the strike and are believed to record minor 

episodes of relative stability during alluvial deposition. 

Almost no fossils or artifacts were found in alluvium. Snail 

shells were found in sandy alluvium exposed along Boulder Creek 

about 1 mile east of Teasdale (preceding table), and one artifact 

(a stone point) was found at a depth of 6 feet in pebbly gravel and 

sand exposed in the bank of a small arroyo near the Fremont River 

just south of the mouth of Donkey Creek. 

It is impossible to assign any precise date to the alluvium. The 

fine-grained bedded sand and silt east of Teasdale (table above) are 
NW. SE. 40' 40' 

20 '-t~·~:~~tr~·-,:;,~,~::;~·{;;,:;/_;;~;;.:-:·/,~-~~~;~~;~;~j-;_~;-;·;~~;-;;·i--~-~:-::-~-~:i;):~)~~·i-~f;·;~i-~=e:i;i~i('!~':'~':!~ 20' 

Loamy fine sand (unitY) 

Loamy fme sand (unit Zl 

0 0 

50 0 100 Feet 

FIGURE 30.-Alluvium including two possible buried soil profiles exposed along Bullberry Creek about 1 mile west of 

Teasdale (pl. 6, loc. 1). Vertical exaggeration 2~ times. 

c 

tr:l 

s 

~ 

0 

l'%j 

t:x:l 

g 

~ ~ 

8 

J 

d 

~ 

......... 

~ 

c:o 
150 CONTRIBUTIONS TO GENERAL GEOLOGY 

certainly no older than the rock glaciers and probably record swampy 

conditions. The gravel and sand west of Teasdale (fig. 30) are also 

doubtless of recent date; perhaps unit Z, with its weakly developed 

horizon of lime and gypsum (soil profile), represents a relatively dry 

interval such as the Thermal Maximum, the overlying materials 

(units X and Y) being younger. . 

Alluvial, colluvial, and some lacustrine deposits are exposed along 

the Fremont River from the mouth of Donkey Creek, eastward to 

Carcass Creek. The colluvium is red and gray silty sand, in places 

containing lenses of flaggy or pebbly gravel. It underlies slopes that 

rise steeply toward the adjacent bedrock wall of the valley (fig. 26). 

In places the content of gravel is greater near the valley wall than 

toward the center of the valley; elsewhere the deposit is almost free 

of gravel within a few tens of feet of the adjacent bedrock slope. In 

many places colluvium is overlain by slide-rock. 

A small mass of colluvium along the south side of the Fremont 

River between Fish and Carcass Creeks is shown on plate 6. This 

colluvium is as much as 30 feet thick and is underlain by silt, sand, 

and gravel that rest in places on Carcass Creek(?) till (fig. 28). The 

reddish silty sand and flaggy colluvium apparently were derived from 

the adjacent slopes, whereas the underlying gray silt, sand, and 

gravel are fluvial and probably lacustrine deposits, perhaps of glacial 

origin. The colluvium showing in figure 28 and observed in other 

exposures in the vicinity demonstrate that valleys at least 30 feet 

deep were excavated in the till before deposition of the overlying 

beds. Other exposures show that before deposition of the red silty 

sand and flaggy colluvium there was an erosion interval during which 

the underlying fluvial and lacustrine deposits were dissected to depths 

of at least 20 feet. 

Similar lithologic units arranged in a more complex fashion are 

exposed (fig. 27) in the small tributary valley that joins the Fremont 

River from the north and that is followed by the Torrey-Grover road. 

The northwestern half of this section contains a sequence of beds 

similar to those shown in figure 26 except that the sequence occurs 

at altitudes about 50 feet higher relative to the Fremont River than 

do those sequences to the south. The flaggy colluvium is near the 

same height above the Fremont River as the outwash of Carcass 

Creek age about half a mile southeast. The southeastern half of the 

section (fig. 27) shows similar beds (gravel overlain by colluvium) deposited after at least part of the sequence to the northwest had been 

dissected. 

The sandy reddish flaggy colluvial deposits along the Fremont River 

between Donkey and Carcass Creeks may have been derived from 

the adjacent slopes and deposited on the eroded top of the underlying 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 151 

glacial(?) deposits. The colluvium is perhaps in part reworked 

eolian sand blown from the Teasdale-Torrey lowlands during Donkey 

Creek or later times and deposited on the sides of the Fremont valley, 

whence it was moved downslope by mass-wasting to its present position. Doubtless much eolian sand was deposited on the Fremont 

River flood plain and was carried on downstream. This hypothesis 

explains the occurrence of loamy sand close to steep bedrock slopes 

where coarser colluvium would be expected if the material had been 

derived directly from adjacent bedrock. The fact that a buried soil 

with caliche was not found in the reddish silty sand favors the hypothesis that this deposit postdates the Carcass Creek drift. The sliderock that overlies the reddish colluvium is perhaps no older than the 

rock glaciers (post-Thermal Maximum of Flint and Deevey, 1951). 

The slide-rock records a time interval when the adjacent cliffs yielded 

considerable fragments of rock and finer material, perhaps as the result 

of more vigorous frost action than takes place at present. All these 

deposits are now being dissected. 

Silt and sand, probably of lacustrine origin, are exposed in a few 

places along the Fremont River (figs. 26 and 28). Stream gravel, 

perhaps outwash, and lake deposits, exposed in the first arroyo east 

of the mouth of Fish Creek, about half a mile south of Fremont River, 

are described below. These well-beclded silts and sands were probably 

deposited in standing bodies of water, dammed perhaps by drift or by 

ice at the mouth of Carcass Creek. 

Section of surficial deposits exposed along first arroyo east of mouth of Fish Creek, 

about half a mile south of Fremont River (pl. 6, Zoe. 7) 

Top. 

Gravel, pebbly and cobbly, sandy matrix, gray, dominantly of volcanic 

rock; pebbles and cobbles are subangular (outwash?) ________________ _ 

Sand, fine-grained, pinkish-gray; silty in upper part (outwash?) _________ _ 

Gravel, pebtly, gray, contains well-rounded pebbles of volcanic rock and 

of quartzite (outwash?) _______________________ ---- __ --------------

Silt, white, thin-bedded; contains a few thin seams of clay (lacustrine?) ___ _ 

Gravel, pebbly and cobbly, dominantly of volcanic rock; base not exposed __ 

Total------------------------------------------------------

Base (bottom of arroyo, 112 feet above mouth of arroyo along Fremont River). 

Feet 

6 

15 

3 

40 

2 

66 

The fluvial and lacustrine deposits along the Fremont River 

probably were laid down in slack or ponded water formed by drift 

dams at the mouths of Fish and Carcass Creeks; they are rather well 

sorted and may include considerable outwash. The bedded silt and 

fine sand may be lacustrine deposits in temporary ponds on the 

flood plain or outwash plain of the Fremont River. 
~152 CONTRIBUTIONS TO GENERAL GEOLOGY 

We do not know to what substage or substages. the Fremont River 

.depositsbelong. Apparently those south of the r!ver and west of the 

Torrey-Grover road (fig. 26) record a gradeline of the Fremont River 

·about 40 to 50 feet above that of today, whereas the Grover lobe 

~outwash at the mouth of Fish Creek is graded to an altitude about 

100 feet above the river. This discrepancy in height suggests that 

.. some Fremont River deposits perhaps belong to Donkey Creek or 

Blind Lake times. Two intervals of alluviation separated by erosion 

. are suggested by the relations shown in figure 27. Soils with caliche 

similar to those developed on drift of the Fish Creek-Grover lobe were 

not seen on top of, or buried by, these alluvial, colluvial, and lacustrine 

deposits along the Fremont River. If we assume that the soils with 

caliche on the Carcass Creek drift were formed prior to deposition of 

. the Donkey Greek drift, it would be logical to conclude that their 

absence suggests that these deposits date from post-Carcass Creek 

time (table, p.158). We might suppose that the interval between the 

times of deposition of Carcass Creek and Donkey Creek drifts was a 

time of erosion by the Fremont River and that an indefinite amount 

of Carcass Creek drift could have been removed during the interval. 

In summary, the deposits along the Fremont River suggest at least 

two episodes of alluviation separated by an erosion interval, they 

are probably no older than the Carcass Creek drift and no younger 

than the Thermal Maximum (Flint and Deevey, 1951, p. 275). 

EOLIAN FEATURES 

Sand, believed to be eolian, together with ventifacts and lag concentrates of pebbles left after the removal of fines by the wind are 

found in the Teasdale-Torrey lowlands. No eolian deposits are shown 

on plate 6. Coarse-grained loose sand, in places silty, occurs as a 

widespread mantle and as isolated patches. The sand is generally 

pink but ranges from white to red. No stratification is visible, and 

the sand is fresh. A few inches of brownish oxidized(?) material 

may be present just beneath the organic surface horizon, but no 

horizon of caliche was noted. The maximpm observed thickness of 

sand is about 3 feet, but at some localities thicknesses as great as 

. 10 feet can be reasonably inferred. The sand has no .. distinct topographic expression of its own; no ancient or modern dunes were 

observed. Most of the sand appears to be stabilized at present, 

although some wind movement probably takes place on flood plains 

and on patches of bare ground on pediment surfaces in the TeasdaleTorrey lowh:mds. The sand occurs on pediment veneers at altitudes 

of as much as several hundred feet above the present drainage and 

overlies soils with caliche developed on drift of the Fish Creek-Grover 
GEOLOGY OF ·BOULDER MOUNTAIN, UTAH. 153 

lobe. The sand is, therefore, younger than Carcass Creek time and 

is ass"llffied to postdate the Carcass Creek-Donkey Creek interval. 

W c:, suspect that the eolian(?) sand is partly of late Pleistocene and 

partly of Recent age. 

In the Teasdale-Torrey lowlands many boulders of volcanic rock 

on the ground surface have been grooved or polished by sandblasting. 

Grooves or flutings are best developed on vesicular volcanic rocks, 

probably because the wind-driven sand enlarged the vesicles. However, grooves occur on volcanic rock that is not vesicular. Some 

sandblasted surfaces are partly covered by crustose lichens and have 

been slightly weathered since sandblasting. Many ventifacts have 

been partly exfoliated or have been broken into smaller fragments. 

In some places, such as the lowlands north of Torrey, ventifacts are 

free of lichens and have the glistening coating of black oxides called 

desert varnish. The freshness of such ventifacts suggests that they 

may be ancient forms now being reworked by sandblasting. The 

partial destruction of the vegetative cover exposes patches of bare 

sand that is being picked up and transported by present-day winds. 

Sandblasted boulders of volcanic rock are found on Carcass Creek 

drift (till and outwash), on terraces along Fremont River, and on 

pediment veneers. They occur on surfaces several hundred feet 

above present drainage lines, such as the mesa about 2 miles east of 

Teasdale. The degree of weathering and exfoliation of ventifacts and 

their association with eolian(?) sand suggest that they are no older 

than the Donkey Creek drift. The ventifacts on top of the mesa 

east of Teasdale probably were cut by wind-driven sand blown from 

the lowlands to the southwest, up over an escarpment about 150 feet 

high. 

All the larger ventifacts in the Teasdale-Torrey lowlands are 

boulders apparently not rotated sin~e sandblasting. The orientations 

of these suggest that the sand-laden winds came from the adjacent 

highlands. Thus the grooves and the orientation of the pitting of the 

larger ventifacts south of the Fremont River indicate southwest winds 

from Boulder Mountain, whereas the ventifacts north of Torrey 

suggest northwest winds from Thousand Lake Mountain. 

Pediment sand and gravel in the Teasdale-Torrey lowlands are 

covered by a lag concentrate of volcanic boulders and pebble-sized 

fragments of rock. The fragments are of quartzite and chert, highly 

polished, together with spalls from adjacent boulders of volcanic 

rock. The underlying materials contain only a relatively small percentage of pebbles. The veneer of fragments is believed to have 

resulted from removal of fine sediment by wind. 
154 ; CONTRmUTIONS TO GENERAL GEOLOGY 

PEDIMENTS AND TERRACES 

Pediments, now greatly dissected, slope radially outward from 

Boulder Mountain on its northern, eastern, and southern slopes (pl. 6). 

To the west, pediments are absent, and a pronounced scarp separates 

the mountain from the Awapa Plateau and Rabbit Valley. The 

pediments are rock-cut surfaces veneered with sand and gravel; they 

form long, gently sloping surfaces (1 °-4 °) indented by broad, shallow 

swales as much as 30 feet deep and as much as several hundred feet in 

diameter, trending down the regional slope. The pediments are 

dissected and lie from 50 to several hundred feet above the adjacent 

streams. Pedinients in the Teasdale-Torrey lowlands are distinctly 

fan shaped. 

The gravel and sand that comprise the pediment veneers are composed predominantly of fragments of volcanic rock together with 

varying proportions of diverse sedimentary rocks (see table below). 

The fragments are mostly unweathered, but a few are stained throughout or crumble between the fingers. The matrix ranges in texture 

from silt to sand and generally is highly calcareous. Thin seams of 

clay were observed in some exposures. The rock fragments are subangular to slightly rounded, and range in size from pebbles to boulders 

as much as 15 feet in diameter. There is a slight decrease in maximum 

size of the boulders from the apex of a pediment downslope toward the 

main drainage line. 

Pediment veneers range from strongly bedded to nonstratified 

bodies. Texture changes vertically and horizontally over short distances. Crossbedding and channelling are visible in many sections. 

Where the base of the gravel is exposed along the Bicknell-Torrey road 

about 1}~ miles north of Teasdale the maximum observed thickness 

is about 30 feet. Exposed thicknesses of 10 feet are numerous. The 

maximum inferred thickness is about 70 feet. 

Section of pediment veneer capping mesa about 2 miles east of Teasdale (pl. 6, loc. S) 

Thickness Depth 

Top. 

Slumped, surface covered with boulders of volcanic rock _____ -- __ -

Gravel, pebbly, calcareous, contains pebbles of volcanic rock, limestone, and sandstone; upper 3 feet is highly calcareous, white __ -

Sand, reddish, stratified, cemented, calcareous; contains few small 

pebbles and a few seams of gray sand, silt, and clay ___________ _ 

Gravel, pebbly and bouldery; contains fragments of volcanic rock, 

conglomerate (Shinarump), and sandstone (Moenkopi); base of 

pediment veneer not exposed ____________________ ---·-- __ -----

Total------------------------------------------------

Base. 

(feet) (feet) 

10 Q-10 

6 10-16 

10 16--26 

3 26--29 

29 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 155 

On the basis of their internal characteristics the pedilnent veneers 

are indistinguishable from outwash. Pediment gravel and sand are 

shown on plate 6 where the material mantles a rock.-cut surface but 

lacks drift near its apex. Small bedrock mesas that rise several 

hundred feet above present-day arroyos are capped by sand and 

gravel. The caps are mapped as pediment veneers but may be 

outwash derived from glaciers whose drift sheets have not been 

recognized. The pediment veneers near Teasdale are perhaps outwash of the Carcass Creek glaciation, the associated till being unrecognizable because of subsequent landsliding, such as that represented 

by the Coleman slide. 

In the Pleasant Creek drainage, pediment remnants lie about a 

mile north and a mile south of the terminal segment of the Pleasant 

Creek drift lobe. Both remnants have thin veneers of · bouldery 

sediment, and both stand high above present drainage and appear to 

antedate the drift lobe. Pediment remnants having an apparently 

similar relation to the Boulder Creek drift lobe occur in the vicinity 

of Boulder (fig. 24). 

The pediment remnants slope with the main drainage lines~ 

Although minor drainage adjustments have occurred during and following pediment formation, the principal streams probably occupied 

about their present positions at the time the highest pediment was 

formed. The establishment of the course of the Fremont River through 

the north end of Miners Mountain and Capitol Reef appears to antedate any existing pediment remnants. Most of Miners Mountain 

drains eastward toward Capitol Reef, the drainage divide lying close to 

the west base of the mountain. The northern part of Miners Mountain 

has no surficial mantle. It is a broad anticlinal ridge of bare rock 

without the scattered fragments of volcanic rock that are widespread 

on the slopes of Boulder Mountain. The distribution of boulders of 

volcanic rock suggests that streams which cut a pediment on Lion 

Mountain flowed either northward to the Fremont River or southward into Sulphur Creek, and that the drainage divide along Miners 

Mountain was present then although doubtless somewhat east of its 

present location. An unlikely alternative is that erosion has stripped 

off any surficial covering on Miners Mountain related to streams 

that cut the Lion Mountain pediment. However, it is probable that 

the volcanic rocks that cap Boulder and Thousand Lake Mountains 

originally were one body of rock that extended at least as far eastward as Miners Mountain, and probably much farther. It is likely 

that Miners Mountain at one time had a surficial mantle of volcanic 

debris that has since been completely removed. Such stripping is 

almost certainly pre-Carcass Creek and probably is older than 

Sangamon time (Hunt, 1953, p. 204). 
156 CONTRIBUTIONS TO GENERAL GEOLOGY 

The range in altitude of pediment remnants above present streams 

suggests that several episodes of planation occurred in Pleistocene 

time, probably both before and following the Carcass Creek glaciation. The soils developed on the pediment veneers are not markedly 

different from those developed on Carcass Creek drift. Elsewhere 

in the Western United States surficial deposits and land surfaces 

believed to be of pre-Wisconsin (Sangamon and older) date .have 

weathering and soil profiles very different from those on younger 

deposits or land surfaces (Hunt and Sokoloff, 1950; Richmond, in 

preparation). The pre-Wisconsin soils have marked similarities over 

a wide range of altitudes and parent materials. Jlowever, none was 

seen in the Aquarius Plateau district, although Hvff (oral communication) found what may be such a profile on till(?) about 2 miles 

east of the Wildcat Ranger Station (p. 124). 

Thus the ages of the several pediment remnants are largely 

unknown. The lowest remnants (Qpg3, pl. 6) grade to a line not 

more than 40 feet above the Fremont River and, therefore, may be 

no older than Carcass Creek drift. The higher pediment remnants 

(Qpg2 and Qpg1) are tentatively assigned to Sangamon and older times. 

Small remnants of terraces occur in some places but have been 

mapped (pl. 6) only along the Fremont River. Gravel and sand that 

underlie terraces are similar to pediment veneers except that terrace 

gravels are dominantly pebbly whereas pediment veneers may contain . numerous cobbles and boulders. The terraces range in height 

from about 50 to 80 feet above the Fremont River. Near the power 

plant south of Torrey a soil with caliche is developed on bouldery 

gravel that forms a terrace about 80 feet above the Fremont River 

and about 20 feet below the base of the outwash t.o the south. These 

facts suggest that the terraces along the Fremont River are not older 

than Carcass Creek time and probably are considerably younger. 

CORRELATION WITH THOUSAND LAKE MOUNTAIN 

Thousand Lake Mountain lies north of Boulder Mountain1.between 

the Canyon Lands on the east and Rabbit Valley and the Fish Lake 

Plateau on the west (fig. 24). In topography and geology the mountain 

closely resembles Boulder Mountain. A cap of volcanic rock overlies 

a thick sequence of Tertiary{?) and Mesozoic sedimentary rocks. The 

volcanic rocks on each mountain may originally have been a continuous sheet. The cap rock forms a steep, even precipitous, escarpment from which great masses of rock have slumped and moved 

downward and outward in all directions. A shelf or gently· sloping 

bench extends outward from the base of the escarpment for nearly a 

mile, beyond which the slopes descend more steeply to the adjacent 
GEOLOGY OF BOULD·ER MOUNTAIN, UTAH 15't 

lowlands. Pediment remnants at several altitudes are present on 

the lower slopes. 

The principal difference between the two mountains is the area of 

the cap of volcanic rock. The summit of Thousand Lake Mountain 

has a total area of only about 2 square miles compared with an area of 

about 70 square miles for the summit of Boulder Mountain. An 

examination of aerial photographs of Thousand Lake Mountain and a 

reconnaissance trip to its scimmit did not reveal evidence of late 

Pleistocene glaciation similar to that on Boulder Mountain. We 

believe that the ice tongues on the sides of Boulder Mountain were 

probably offshoots of its icecap; the apparent absence of such ice 

tongues on Thousand Lake Mountain indicates that the area of the 

latter's "summit was too small to nourish an icecap, at least in late 

Pleistocene (Donkey Creek or Blind Lake) time. 

The base of the escarpment is mantled with slide-rock but no rock 

glaciers were found close to it. The surface of the adjacent bench 

is covered in many places by ancient boulder fields, and it is surprising 

that remnants of rock glaciers were not found on Thousand Lake 

Mountain. Perhaps they existed formerly, and were destroyed by 

subsequent mass movements. 

QUATERNARY HISTORY 

The late Quaternary history of the northeastern part of the Aquarius 

Plateau is summarized in the table below. The facts do not permit 

firm correlation with the Quaternary features of other areas in the 

Western United States. The deposits suggest that a warm episode 

and two cold episodes followed the deposition of Blind Lake drift; 

the three episodes are presumably of Recent date. The warm episode 

is doubtless the Thermal Maximum, but proof that it antedates the 

formation of the rock glaciers is lacking. 

In terms of glaciation the Aquarius Plateau, like other highlands 

in the Cordilleran region, is probably a marginal area. Glaciers 

could have flourished on it only when temperatures were lower and 

when summer-season ablation, perhaps owing to greater cloudiness, 

was less than at present. Such glacial conditions can be expected tohave existed at times of increased frontal_ activity associated with 

low-index (Willett, 1944) atmospheric circulation. A slight change 

from higher toward lower index circulation might have had only a 

small effect on the melting Laurentide Ice Sheet in and north of the 

Great Lakes region, while exerting at the same time a marked influence at the top of the Aquarius Plateau. Very likely this is the reason 

why the relative distances between the borders of the successive drift. 

sheets are greater in the Aquarius Plateau district than in the region. 

of ice-sheet glaciation. 
Quaternary history of Boulder Mountain, Utah 

Elloch Events in Boulder Mountain region 

Formation of slide-rock at base of cliffs surrounding Boulder Mountain; slight dissection; slight reworking of eolian deposits and of ventifacts; locallandsliding; deposition of alluvium. 

Recent Formation of rock glaciers, from accumulations of snow along base of cliff around 

plateau top, at altitudes of about 10,500 to 10,700 feet; locallandsliding; continued 

eolian activity; probable deposition of slide-rock along Fremont River. 

Glaciers absent from Boulder Mountain; probable continued eolian activity. 

Deposition of Blind Lake drift close to base of cliff around top 

of plateau by glacier ice from plateau top; glaciers descend 

to altitudes as low as 9,900 feet; possible deposition of Probable deposition 

outwash in valley of Fremont River; movement of Hick- of red sandy and 

man slide southwest of Fish Creek and probable sliding flaggy colluviull'!. 

elsewhere. along Fremont 

Erosion(?) River and of 

Possible correlation with events in Rocky Mountain region (Holmes and Moss, 

1955) 

Little Ice Age (Matthes, 1939). 

Temple Lake stage (Howard 

and Hack, 1943). 

Thermal Maximum (Flint and 

Deevey, 1951, p. 275). 

Pinedale stage. 

....... 

~ 

~ P.:1 

~ 

ttl 

§ 

~ Ul 

8 

0 

'-l 

t:':l 

~ 

~ ti« 

0 

t:':l 

0 

~ 
Deposition of Donkey Creek drift on upper slopes of Boulder eolian(?) sand in 

Mountain by glacier ice from plateau top. Glaciers descend Teasdale-Torrey 

to altitudes as low as 8,200 feet; possible deposition of out- lowlands; abrasion 

wash in valley of Fremont River; possible movement of of ventifacts. 

large slump blocks near Blind and Donkey Lakes and 

Pleistocene probable landsliding elsewhere. 

Glaciers of Boulder Mountain are small or absent; assumed time of formation of soils 

with caliche; widespread dissection. 

Deposition of Carcass Creek drift by glacier ice from the plateau top; along Fremont 

River includes outwash and perhaps lake beds; glaciers descend to altitudes as low 

as 6,600 feet; landsliding including probable movement of the tonguelike complex 

landslides. 

Formation of pediments and bouldery accumulations of undetermined origin; possible 

deposition of drift near mouths of Fish and Carcass Creeks and in valley of Pleasant 

Creek by glaciers from the plateau top. 

-----· ···---~----------------~-- ------

Bull Lake stage. 

Buffalo and pre-Buffalo stages 

(Sangamon? and older). 

~ 

s 

~ 

0 

~-:~j• 

t:d 

i 

t:d 

I 

> 

~ 

d 

~ 

"""'-

Ot 

0 
160 _CONTRmUTIONS TO GENERAL GEOLOGY 

The summit of the neighboring Fish Lake Platea.u is more than 

11,000 feet high and is glaciated; plateaus at lower altitudes were 

not glaciated (Hardy and Muessig, 1952). Thousand Lake Mountain, 

altitude 11,000 feet, is the only exception. The diHerence implies 

that during glaciation the regional snowline lay somewhat below 

11,000 feet. 

Sharp (1942, p. 500) approximated the altitude of the late Wisconsin 

-orographic snowline (the regional snowline as m~ified by local 

topography) on San Francisco Mountains, Ariz., by comparing the 

caltitudes of glaciated and nonglaciated peaks. The value, 11,000 to 

11,300 feet, he compared with the value of 10,000 feet derived by 

Atwood for the comparable feature in the Uinta Mountains. The 

gradient between the two points gives a value for the Aquarius Pia .. 

teau, 190 miles north of San Francisco Mountains on a direct line to the 

Uintas, of 10,400 to 10,700 feet. That value is consistent with the 

-distribution of the Donkey Creek and Blind Lake drifts of the Aquarius Plateau slopes. 

The existing snowline cannot be far above the highest point on 

the plateau, because during the summer of 1952 snowbanks were ob-

·served as late as August 10 on the open little-protected plateau top. 

_Although snowfall during the preceding winter had been unusually 

heavy, it is believed that lowering of the snowline by only a few 

hundred feet would be sufficient to restore glacier ice to the Aquarius 

Plateau. 

No direct evidence was found as to whether the icecap disappeared 

entirely from the plateau during the intervals between successive 

·glaciations. However, because of its small size and areal position 

the icecap probably disappeared during the Carcass Creek-Donkey 

·Creek interval and very likely disappeared also during the interval 

between the Donkey Creek and Blind Lake glaciations. During the 

·subsequent cold episode, when most of the rock glaciers accumulated 

against the summit cliff, snowbanks or even small glaciers may have 

-developed on the plateau top, but no evidence of their existence has 

been found. 

REFERENCES 

.Atwood, W. W., 1909, Glaciation of the Uinta and Wasatch Mountains: U. S. 

Geol. Survey Prof. Paper 61. 

-Blackwelder, Eliot, 1912, The Gros Ventre slide, an active earthflow: Geol. 

Soc. America Bull., v. 23, p. 487-492. 

Bryan, Kirk, and Ray, L. L., 1940, Geologic antiquity of the Lindenmeier site 

in Colorado: Smithsonian Misc. Coli., v. 99, no. 2. 

·Capps, S. R., 1910, Rock glaciers in Alaska: Jour. Geology, v. 18, p. 359-375. 

nixon, Helen, 1935, Ecological studies on the High Plateaus of Utah: Bot. 

Gazette, v. 97, p. 272-320. 
GEOLOGY OF BOULDER MOUNTAIN, UTAH 161 

Dutton, C. E., 1880, Report on the geology of the High Plateaus of Utah, with 

atlas: U.S. Geog. and Geol. Survey Rocky Mtn. region: Washington, Govt. 

Printing Office. 

Flint, R. F., and Deevey, E. S., 1951, Radiocarbon dating of late Pleistocene 

events: Am. Jour. Sci., v. 249, p. 257-300. 

Goddard, E. N., and others, 1948, Rock-color chart, prepared by Rock-color 

Chart Committee, Nat. Research Council, Washington. 

Gould, L. M., 1939, Glacial geology of Boulder Mountain, Utah: Geol. Soc. 

America Bull., v. 50, p. 1371-1380. 

Gregory, H. E., and Anderson, J. C., 1939, Geographic and geologic sketch of 

the Capitol Reef region, Utah: Geol. Soc. America Bull., v. 50, p .. 1827-

1850. 

Hardy, C. T., and Muessig, Siegfried, 1952, Glaciation and drainage changes 

in the Fish Lake Plateau, Utah: Geol. Soc. America Bull., v. 63, p. 1109-

1116. 

Howard, E. B., and Hack, J. T., 1943, The Finley site: Am. Antiquity, v. 8, 

p. 224-241. 

Holmes, G. W., and Moss, J. H., 1955, Pleistocene geology of the southwestern 

Wind River Mountains, Wyoming: Geol. Soc. America Bull., v. 66, p. 629-

654. 

Hunt, C. B., 1953, Geology and geography of the Henry Mountains region, 

Utah: U. S. Geol. Survey Prof. Paper 228. 

--- 1954, Pleistocene and Recent deposits in the Denver area, Colorado: 

U. S. Geol. Survey Bull. 996-C, p. 91-140. 

Hunt, C. B., and Sokoloff, V. P., 1950, Pre-Wisconsin soil in the Rocky Mountain 

region, a progress report: U.S. Geol. Survey Prof. Paper 221, p. 105-123. 

Hunt, C. B., Varnes, H. D., and Thomas, H. E., 1953, Lake Bonneville: Geology 

of northern Utah Valley, Utah: U. S. Geol. Survey Prof. Paper 257-A, p. 

1-99. 

Kessell, J. E., 1941, Rock streams in the Sierra Nevada, California: Geog. Rev., 

v. 31, p. 203-227. 

Martin, W. P., and Fletcher, J. E., 1943, Vertical zonation of great soil groups 

on Mt. Graham, Arizona, as correlated with climate, vegetation, and profile 

characteristics: Ariz. Univ., Agri. Expt. Sta. Tech. Bull. 99. 

Matthes, F. E., 1939, Report of Committee on Glaciers: Am. Geophys. Union 

Trans., v. 20, p. 518-523. 

Nikiforoff, C. C., 1937, The inversion of the great soil zones in western Washington: Geol. Rev., v. 27, p. 20Q-213. 

Retzer, J. L., 1954, Glacial advances and soil development, Grand Mesa, Colorado: 

Am. Jour. Sci., v. 252, p. 26-27. 

Roots, E. P., 1954, Geology and mineral deposits of the Aiken Lake map area, 

British Columbia: Geol. Survey of Canada Mem. 274. 

Sharp, R. P., 1938, Pleistocene glaciation in the Ruby-East Humboldt Range, 

northeastern Nevada: Jour. Geomorphology, v. 1, p. 296-323. 

---1942, Multiple Pleistocene glaciation on San Francisco Mountain, Arizona: 

Jour. Geology, v. 50, p. 481-503. 

Sharpe, C. F. S., 1938, Landslides and related phenomena: New York, Columbia 

Univ. Press. 

Smith, J. F., Jr., and Albritton, C. C., Jr., 1941, Solution effects on limestone as 

a function of slope: Geol. Soc. America Bull., v. 52, p. 61-78. 

Spieker, E. M., and Billings, M. P., 1940, Glaciation in the Wasatch Plateau, 

Utah: Geol. Soc. America Bull., v. 51, p. 1173-1198. 
162 CONTRIBUTIONS TO GENERAL GEOLOGY 

Terzaghi, Karl, 1950, Mechanism of landslides; Geol. Soc. AmericA, Berkey_ 

volume, p. 83-123. 

Thorp, James, 1931, The effects of vegetation and cliQlate upon soil profiles in 

northern and northwestern Wyoming: Soil Science, v. 32, p. 283-297. 

Troll, Carl, 1944, Strukturboden, solifluktion und frost klimate der erde: Geol. 

Rundschau, band 34, p. 545-694. 

U. S. Dept. Agriculture, Soil Survey Staff, 1951, Soil Survey Manual, Agriculture 

handb. 121. 

Vanderwilt, J. W., 1934, A recent rockslide near Durango, in La Plata County, 

Colorado: Jour. Geology, v. 42, p. 163-173. 

Varnes, H. D., 1949, Landslide problems of southwestern Colorado: U. S. Geol. 

Survey Circ. 31. 

Ward, W. H., 1945, Thestabilityofnaturalslopes: Geog. Jour., v.105, p.170-197. 

Washburn, A. L., 1950, Patterned ground: Rev. Canadienne de geog., v. 4, p. 5-54. 

Willett, H. C., 1944, Descriptive meteorology: New York, Academic Press, p. 

143-149. 

Woolley, R. R., 1947, Utilization of surface-water resources of Sevier Lake basin, 

Utah: U.S. Geol. Survey Water-Supply Paper 920. 
INDEX 

Page· 

Alluvium ••• _---------------------------- 147-152 

.Aquarius Ranger Station--------------------- 129 

.Aquarius Ranger Station landslide: ...... ..: •• 137,138 ~._. ___ , ________________ ;;:"-------------- 148 

lllind L.ake drift__ __ 114, 12(125-126, 128, 130,146, 160 

Boulder Creek drift lobe ____________ 127-128, 131, 155 

·:l3oukier · Mountam, correlation with. Thousand Lake Mountain .•••••••••• 156-157 

·Boulders, ·exfoliation ••..••• .., .. --------------- 113-114 

undetermined origin----~----~------------ 136 

.J3nllberryJan~lide ___ ---------·-----------~ 137, 138 

Carcass Creek drift, age __ ----------~------- 119, 156 drainage ________________________________ 122-123 

erosion ___ ------------------------------ 123-124 

exfoliated boulders________________________ 113 

probable substage________________________ 121 

internal character------------------- 122,152,153 

outwash---------------------------------- 123 

sons_----------------------------------- 123-124 

stratigraphy __ -------------------------- 124-125 

topographic expression____________________ 122 

weathering_---------------------------- 120,123 

Cedar Creek slide._-------------------------- 142 

Chert. ___ ------------------------------------ 153 

Climate.----------------------------------- 108-109 

Coleman landslide __________ 137,138,140,141,142,145 

;page 

Fisher Creek-Grover drift lobe; Bllnd Lake · drift ____________________________ ~126 

Carcass Creek drift._,~----·----~-·---- 1~1~ ~29 

dimensions.-----------------------... ~--- 122, 131 

·D-onkey dreek drift·- -~----~-~-~--------125-126 eolian features ______________ .. .::_.;.__________ 152 

Fossfls ___________________________________ ;.,.:..,.w 148 

Geography, physical __________ ~------------· 104-109 

Geology, bedrock--------------------.--··-·- _107-108 

Glacial ~!ft, plateau sides _____ :-:----~-,-- .. --·118-131 

relation to bedrock topography_---------- 120 

topography-----------------:-------------:- 120 weathering_· ___ -____ ::_____________________ 120 

Glacial features, plateau tOP---------------- 115-117 

Glaciation, Blind Lake _________________ 127,136,160 

Carcass Creek ______________________ 127, 129, 156 

Donkey Creek ______________ 125, 126, 127, 130,160 

history._------------------------------- 157-160 

substages------------------------------- 121-122 

Gros Ventre landslide________________________ 143 

Gypsum ..• --------------------------------- 147,150 

Hickman landslide _________________ 137,138,140,146 

Hinrichs, E. N., acknowledgment____________ 104 

Huff, L. C., acknowledgment._______________ 104 

Hunt, C. B., acknowledgment________________ 104 

Colluvium _____________________ 133,134, 135, 147-152 Lacustrine deposits------------------------- 147-152 

Deposition, glacial __________________________ 115-117 

Donkey Creek drift.------------------------- 113, 

121, 125, 127, 130, 137, 145, 146, 152, 160 

Donkey Creek drift lobe ________________ 13G-131, 145 

Drift lobes, age _____________________________ 119-120 

altitudes __ -------------------------------_ 119 Boulder Creek __________________ 127-128, 131,155 

description_---------------------------- 122-131 

dimensions_----------------------------__ 119 

Fish Creek-Grover __ ----------- 122-126,129,131 

location_--------------------------------- 117 Donkey Creek ______________________ 13G-131, 145 

Miller Cr-eek._--------------------- 128-129,145 Pleasant Creek _____________________ 126-127,131 

Station Creek __________________________ 129-130 

Dutton, C. E., quoted________________________ 105 

Eolian features _____________________________ 152-153 

Landslide mantle ___________________________ 145-146 

Landslides, comparison with lobes of glaci3I drift ____________________________ 143-145 

composition.--------------------------- 140-141 

distribution. __ --------------------- 117, 137-138 independent slumps ____________________ 136-137 

origin ___________ -----_____ ._------------ 141-l 43 

thickness------------------------------- 140-141 

t.ime of movement.--------------------- 146-147 

tonguelike complex _____________________ 137-145 

topography------------------------- 138-140, 141 

vegetation ____ .---________ ------------ __ .- 142 

See also individual slides. 

Laurentide Ice Sheet------------------------- 157 

Lime----------------------------------------- 150 

Lion Mountain landslide _______________ 137,138,142 

Lion Mountain pediment ____ ---------------- 155 

Leudke, R. G., acknowledgment_____________ 104 

Exfoliation of boulders ______________________ 113-114 Melt water.-------------------------------- 123,147 

Erosion, glaciaL--------------------------- 115-117 Miller Creek drift lobe _________________ 128-129, i45 

163 
164 INDEX 

Page 

Miller Creek glacier_------------------------- 129 Moraines _______________ 115-117, 121, 125, 126, 128, 130 

Nikiforo1f, C. C., acknowledgment___________ 104 

Patterned" ground. __ ----------------------- 114-115 

Pediments---------------------------------- 154-156 Pleasant Creek drift lobe _______________ 12tH27,131 

Pleistocene _____ 116,117,119,133, 136,103,156,158-159 

Quartzite_____________________________________ 103 

Quaternary .history------------------------- ~57, 160 

Recent •. ---------------------------- 136,103,158-159 Rlchmond,·G. M., acknowledgment__________ 104 Rock glaciers; __________ .; ____________ ,; ______ 131-133 

Singletree landslide _____________ 137,138,141,142,145 

snde-rock_--·--------·------------------------ 151 

Page 

Soils, Lion Mountain.---------------------- 111-112 

pediment--------------------------------- 156 

profiles in Boulder Mountain region______ lOt vegetation __________________ ;;. ___________ 111,113 

with,'c8liche- ------------------- 100:.112,124,152 without caliche _________________________ 112-113 

Solution of boulders._------------------------ 114 

Station Creek drift lobe.------------------- 129-130 

Talus _______________________________________ 133-136 

Tel'r8CeS-----------------------------------· 154-156 T~hitKarl, .qtttlted .•••••••••••••••••• ;.... 141 

Thern:i8I·Maxmi.um_' _______________ 133,150,152,157 

Thousand Lake Mountain, correlation with 

Boulder Mountain------~------ 156-11)7 

Till.-------------------------------- 118-119,126, 153 Topography _________ .; __ .; __________________ ._ 104-107 

Slumps, Independent •• --------------------- 136-137 Vegetation.-------------------- 104-107,111,113,142 

Smith, J. Fred, Jr., acknowledgment_________ 104 Ventifacts. &t Eolian features. 

Bolls; A horizon---------------------------- 110,112 Volcanic rock _______________ 123,126,153,154, 155;156 

B horizon.------------------------- 110,112,124. buried profileS-------------------------- 148, 149 Weathering, profiles ________________ ;. ________ .;. 109 

C horizon.----------------..:-------------- 112 Wildcat Ranger Station. ---------------····:-• 156 

U. S. GOVERHMEHT PRiffTIHG OFFICE1 1958