NOTES ON THE GEOLOGY OF GREEN RIVER VALLEY BETWEEN GREEN 

RIVER, WYOMING, AND GREEN ;RIVER, UTAH. 

By JoHN B. REESIDE, Jr. 

INTRODUCTION. 

During July, August, and part of September, 

1922, I had the privilege of accompanying a 

party sent out jointly by the Utah Power & 

Light Co. and the United States Geological 

Survey to gather such data as were still needed 

to complete a study of the power resources of 

Green River between Green River, Wyo., and 

Green River, Utah. The chief deficiency to be 

supplied was a continuous topographic map 

of the valley in sufficient detail to permit 

calculation of the storage capacity of any 

reservoir site that might be used, the stream 

gradient, and similar features. Maps on a 

satisfactory scale of a number of isolated 

stretches of the river had already been made 

by public or private agencies, and it was 

necessary to verify them and connect them 

on a uniform datum. Inasmuch as it was 

deemed unlikely that a dam higher than 300 

feet would be constructed anywhere on the 

part of the river to be examined, a plane 

300 feet above the water surface was made the 

upper limit of mapping. Over such parts of 

the valley as had been mapped already the 

progress of the party was naturally very 

rapid, and even where no mapping had previously been done, the 300-foot limit set upon 

the work and the usual narrowness of the valley 

combined to reduce the extent of the area 

to be mapped, so that the speed maintained 

was relatively high. Under this condition of 

rapid movement it was seldom possible to 

make more than the most cursory examination 

of the rocks, though occasionally circumstances 

permitted more or less detailed observation. 

The notes here recorded are therefore mostly 

of a rather generalized character, but as they 

pertain in part to localities that are difficult 

of access and not often visited by geologists, 

and that are at the same time classic in the 

history of American geology, I venture to 

to record them for whatever value they may 

have to other geologists. 

GEOLOGIC NOTES. 

Green River, Wyo., to the mouth of Henrys 

Fork.-Most of the part of Green River valley 

lying between Green River, Wyo., and Henrys 

Fork is cut in rocks .assigned to the Green 

River formation (lower Eocene). This formation includes a lower division of whitish, 

gray, and greenish fissile shale, light-colored 

limestone, and sandstone and an upper division of massive, irregularly bedded brown 

sandstone with some sandy limestone and 

shale-the "Tower sandstone" and "plant 

beds" of Powell. 1 Over much of the way the 

"Tower sandstone" caps the bluffs along the 

river, and the gray mass of shaly beds beneath it forms steep slopes. The dips of the 

beds are low, usually so low that they are not 

apparent to the eye. 

As the mouth of Henrys Fork is approached 

the influence of the Uinta uplift shows in the 

appearance of an appreciable northward dip. 

About 6 miles above the mouth of Henrys 

Fork this dip increases very much, and the 

river, running nearly across the strike of the 

beds, quickly passes out of the Green River 

formation into the beds mapped by Schultz 2 

as Wasatch formation (lower Eocene). These 

beds consist of white to brown sandstone, gray 

shale, and red shale and are said to contain 

some coal. 

From the Wasatch exposures the river 

passes through beds that dip 40°-50° N. and 

have been assigned by Schultz 2 to the Lewis 

1 Powell, J. W., Report on the geology of the eastern portion of the 

Uinta Mountains, pp. 40, 45, U . S. Geol. and Geog. Survey Terr., 1876. 

2 Schultz, A. R ., Oil possibilities in and around Baxter Basin, in the 

Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey 

Bull. 702, pl. 1, fig. 3, 1920. 

35 
36 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, .tl!".:!:3. 

FIGURE 2.-Sketch map of Green River between Green River, Wyo., and Green River, Utah. 
GEOLOGY OF GREEN RIVER VALLEY, WYOMING AND UTAH. 0~ 

01 

shale, Mesaverde formation, and Hilliard shale 

(all Upper Cretaceous). These beds are ·not 

very well exposed immediately adjacent to the 

river, and I had no opportunity to study the 

exposures lying at some distance from the 

river bank. The Hilliard shale, viewed from a 

distance of perhaps a mile, appears to be a 

normal dark-gray marine shale such as one 

would expect to find in this region. Near the 

mouth of Henrys Fork the dip is nearly verticaL 

Boars Tuslc ridge.-The north flank of the 

Boars Tusk, a sharp ridge running southeastward from the river just below the mouth of 

mations, is overturned to the northeast in the 

lower Beckwith and Twin Creek, and appears 

to be nearly vertical in the basal sandstone of 

the Nugget and the underlying red .beds. 

Schultz 3 gives the thickness of the formations 

here as follows: Frontier formation, 125 feet; 

Aspen shale, 135 feet; Beckwith formation, 

850 feet; 4 Twin Creek limestone, 140 feet; 

Nugget sandstone, 1,000 feet; 5 Ankareh shale, 

300 feet; Thaynes ( ~) formation, 290 feet; and 

Woodside shale, 500 feet. 

The Frontier formation here, as understood 

by the writer, consists of a massive browri 

FIGURE 3.-Map showing Green River b etweeu the mouth of Henrys Fork and the mouth of Skull Canyon, Daggatt County, Utah. Shows also 

location of section presented in Figure 5 (line A -B). Adapted in part from Marsh Peak topographic map. 

Henrys Fork, shows at the base the sandstone 

assigned by Schultz 2 to the Frontier formation; above it, topographically, the beds assigned to the Aspen shale (Upper Cretaceous), 

the Beckwith formation (Jurassic and Cretaceous~), the Twin Creek limestone (Jurassic), 

and the Nugget sandstone (Jurassic). The 

south slope shows the red beds assigned by the 

same author 2 to the Ankareh shale (Triassic?), 

Thaynes ( ~) formation (Lower Triassic), and 

Woodside shale (Lower Triassic). The dip is 

nearly vertical in the Frontier and Aspen for2 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the 

Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey 

Bull. 702, pl. 1, fig. 3, 1920. 

coarse-grained cross-bedded quartzose sandstone with some thin included lenses of carbonaceous shale and, as nearly as can be determined, is about 100 feet thick. The Aspen 

shale is a blue-white porcelaneous platy shale 

containing an abundance of imprints of fish 

scales. It is the lithologic equivalent of the 

Mowry shale of the region to the east and north . 

in Colorado and Wyoming. The thickness 

s Schultz, A. R., op. cit., table opposite p. 36, pp. 73-78, and fig. 3. 

4 In the table opposite p. 36 and in fig. 3 Schultz gives this thickness 

as 1,500 feet, but on p. 76 it is given as 850 feet, which I believe to be 

correct. 

~In the table opposite p . 35 and in fig. 3 Schultz gives this thickness 

as 1,600 faet, but on p. 78 it is given as 1,000 feet, which I believe to be 

correct. 
38 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923. 

seemed to be about 225 feet, but the exposures 

are not entirely satisfactory, and it is possible 

that part of the interval should go into the 

Frontier formation. Immediately above the 

Aspen shale in the slope, but below it, in 

stratigraphic position, is a coarse brown conglomeratic sandstone. This sandstone is the 

topmost member of the Beckwith formation 

of Schultz, but from its lithologic constitution 

and its position it would be called the Cloverly 

formation in Wyoming or the Dakota sandstone at many other localities in the Rocky 

Mountain region. The pebbles in the conglomeratic parts are mostly of white and gray 

chert and are as much as an inch in diameter. 

The thickness of the sandstone is 150 feet. 

species on careful search. This calcareous 

unit is the Twin Creek limestone of Schultz 

and is about 75 feet thick. Above the Twin 

Creek beds in the slope lie red shale 100 feet 

thick, then a yellow sandstone about 100 feet 

thick, then about 300 feet of beds that are not 

well exposed but seem to consist largely of 

sandstone interbedded with layers of red shale, 

all of which together with the overlying sandstone were referred to the Nugget sandstone 

by Schultz. Above these beds and constituting 

the comb of the ridge is the massive white, 

brown, or reddish sandstone forming the base 

of the Nugget. (See figs. 4 and 7 .) 

I did not examine the Nugget sandstone and 

older beds in Boars Tusk ridge with any care 

and made few notes on them. The basal 

member of the Nugget sandstone is a 

thick, massive cross-bedded sandstone 

that resembles both the sandstone 

in the lower part of the Sundance formation in Wyoming and the Jurassic 

sandstone of southern Utah. The red 

beds were not well exposed in the only 

place where I crossed them-the gap 

between Skull Canyon and the drainage north of the ridge. At this locality the red beds are cut off below by 

the great Uinta fault, which extends 

for miles along the northern edge of 

roo' the Uinta Mountain uplift. The beds FIGURE 4.-Section of north slope of Boars Tusk ridge, Daggett County, Utah. On the SOUth side of the fault are the 

Above the sandstone in the slope, but below much older beds described below as the" Uinta 

it stratigraphically, lies a mass of highly formation," the formations normally occurring 

colored, variegated shale and soft sandstone between the red beds and the ''Uinta formaabout 300 feet thick, which strongly resembles tion" having been displaced by the fault. 

the Morrison formation of eastern Colorado (See fig. 5.) 

and central Wyoming. These beds form a It seems hardly possible that the Frontier 

slope and at most places are not well exposed. formation, the Aspen shale, and the uppermost 

The next higher bed in the slope is a second part of the Beckwith formation of Schultz are 

conglomeratic sandstone 50 feet thick, above the exact equivalents of the Frontier, Mowry, 

which more colored shale and soft sandstone, Thermopolis, and Cloverly formations in Wyoabout 300 feet thick and not very well exposed ming, but the similarity of lithologic succession 

at most places, constitute the basal member is striking. That the beds in the Beckwith 

of Schultz's Beckwith formation. Above the formation of Schultz that resemble the Morricolored shale last mentioned (below it strati- son formation are equivalent to that formation 

graphically) lie gray limestone and gray cal- is placed beyond doubt by the occurrence of a 

careous shale. Some of the limestone layers large fauna of Morrison dinosaurs in beds at 

are fairly massive, but most of them are thin the same stratigraphic position near Jensen, 

and platy. Rhynchonella gnathopora Meek and Utah. The Twin Creek limestone of Schultz 

Ostrea strigilecula White were noted, but the is beyond question equivalent to the upper, 

beds would undoubtedly yield many more calcareous zone of the Sundance formation of 
GEOLOGY OF GREEN RIVER VALLEY, WYOMING AND UTAH. 

central Wyoming. Th.ese calcareous beds with 

the beds below them, down probably to the 

base of the Nugget sandstone, I consider to 

represent the interval usually included in the 

Sundance formation in central Wyoming. 

Flaming Gorge, Horseshoe Canyon, Neilsons 

Flat, and Kingfisher Oanyon.-In Flaming 

Gorge the conspicuous rocks are the rim of 

Nugget sandstone and the slopes of red beds 

(Ankareh, Thaynes ( ?) , and Woodside formations of Schultz). At the lower end of the 

gorge the river passes across the trough marking 

the outcrop of the rather soft and unresistant 

upper part of the Park City formation (Permian and Pennsylvanian) into the box c~nyon 

cut in the lower part of the Park City formation and the Weber sandstone (Pennsylvanian) 

and named by Powell Horseshoe Canyon. 

From Horseshoe Canyon the river passes back 

into the trough of Park City beds, where a low 

area near the river is known as N eilsons Flat. 

A 

noted by Schultz. 6 The beds next below the 

unconformity are darker in color-a brickred-and weather differently, their surface 

having a sort of network sculpturing due to 

small regularly arranged cavities, whereas the 

surface of the upper beds is fairly smooth. The 

lower beds are nearly all sandstone and are 

clearly the Thaynes ( ?) formation of Schultz. 

The typical Thaynes formation, 7 near Park 

City, is essentially a calcareous formation with 

gray limestone and sandstone, but there is 

nothing of the sort to be seen here. Beneath 

the cliff of Thaynes ( ?) formation lies a long 

slope underlain by light brick-red sandy shale 

and soft sandstone and broken near the base 

by some harder layers that form small benches 

and by some gray layers interbedded with the 

red. This unit is evidently the yvr oodside 

shale of Schultz and corresponds in a general 

way to the description of the typical Woodside 

shale near P ark City.

8 

"u inta formation" 

Elevetion 7,000' 

,ooo' 

FIGURE 5.-Cross section of ridge east of Boars Tusk ridge, Daggett County, Utah. See Figure 3fJr location. 

From Neilsons Flat the river passes into a sec-

{)nd box canyon cut in Weber sandstone and 

named by Powell Kingfisher Canyon. Kingfisher Canyon is cut off at its lower end by 

the Uinta fault mentioned above, though here 

the surface trace of the fault has passed over 

into older beds and the Weber sandstone lies 

in contact with the "Uinta formation." (See 

fig. 3.) 

The area including the localities just men-

. tioned is a geologic unit, and the geographic 

divisions are made by sharp turns in the river. 

The Nugget sandstone forms a cliff running 

northeastward and lying to the north and 

northwest of the area. Beneath it the Ankareh 

shale of Schultz is composed of dark salmonred sandstone and shale with a minor proportion of yellowish beds. . The upper part of the 

formation appears to contain softer rock and 

forms a slope, but the lower part is harder and 

forms a bench. The formation is bounded at 

the base by a very irregular, wavy surface of 

erosion that I take to be the unconformity 

Schultz gives the thickness of the formations 

as follows: Ankareh, 300 feet; Thaynes, 290 

feet; Woodside, 500 feet. I did not make any 

measurements but believe these figures to be 

about right. (See fig. 6.) 

Boutwell 9 gives the thickness of the Ankareh 

formation at its typical locality near Park City 

as over 1,150 feet, the Thaynes formation as 

1,290 feet, and the Woodside shale as 1,090 

feet. If the beds assigned to these formations 

near Green River are really equivalent to the 

typical divisions near Park City, the ·differences between them and the typical development as described by Boutwell must be 

ascribed to some su·ch change in passing eastward from Park City as occurs in southern 

Utah in the Moenkopi formation, also of Tris Schultz, A. R. Oil possibilities in and around Baxter Basin, in the 

Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey 

Bull. 702, tables opposite pp. 24 and 36, 1920. 

7 Boutwell, J. M., Geology and ore deposits of the Park City district, 

Utah: U . S. Geol. Survey Prof. Paper 77, pp. 5.'"r-88, 1912. 

e Idem, pp. 52-54. 

9 Idem, pp. 52, 56, 58. 
40 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923. 

assic age. 10 The Moenkopi . formation thins 

eastward,. and the proportion of limestone to 

noncalca,reous beds decreases rapidly in the 

same direction. The Ankareh formation suggests, in its position beneath the Nugget and 

its unconformable relation to the underlying 

beds, the Jelm formation 11 of southern Wyoming, which lies beneath the basal Sundance 

sandstone and is unconformable on the underlying Chugwater red beds. The Chugwater 

beds are in turn much like the combined 

Thaynes ( ?) and Woodside formations of Green 

River valley. 

The Park City formation lies beneath the 

Woodside shale and is only indistinctly separated from it. It is described by Schultz 12 as 

calcareous.' It stands ill Cliffs along the river at 

most places where it is exposed. Schultz gives 

the thickness along Green River as 1,600 feet. 

Hideout and Red Oanyon.-Hideout is a 

rather open area between Kingfisher Canyon 

and Red Canyon. It is perhaps . a mile in 

length n1easured along the river and affords 

relatively easy access to the river on either 

bank. Red Canyon may 'be considered to 

extend down the river from Hideout to a point 

several miles below Red Creek, though it might 

equally well be considered .to end at or above 

Red Creek. The height and inclination of the 

canyon walls varies very much-so much, in 

fact, that perhaps the only uniform character 

is-the constituent rock, the mass of dark-red 

Massive white 

to brown sandstone 

~---=/:: ~~~~ Red and gray 

Ankareh shale · sandstone and shale 

of Schultz. 

300' Salmon-colored 

sandstone 

Woodside 

shale 

500' 

Brick-red 

sandstone 

FIGURE 6.-Diagrammatic sketch of bluff northwest of Neilsons Flat, Daggett County, Utah. 

containing near Flaming Gorge . in the upper 

part a gray calcareous shale or shaly limestone 

200 feet thick, underlain by a massive cherty 

limestone 25 feet thick, a phosphate-bearing 

shale, with chert nodules, 40 to 50 feet thick, 

and a basal member of massive limestone 100 

feet thick resting unconformably on the Weber 

sandstone. These subdivisions are recognizable without difficulty and maintain very nearly 

the thicknesses given. 

The Weber sandstone js a very massive, 

resistant brown sandstone, probably in part 

10 Reeside, J. B., jr., and Bassler, Harvey, Stratigraphic sections in 

southwestern Utah and northwestern Arizona: U.S. GeoL Survey Prof. 

Paper 129, pp. 59-61, 1922. 

u Knight, C. W.,Ageandoriginofthered bedsofsoutheastern Wyoming (abstract): Geol. Soc. America Bull., vol. 28, p. 168, 1917. 

12 Schultz, A. R., A geologic reconnaissance ' of the Uinta Mountains, 

northern Utah: U.S. Geol. Survey Bull. 690, p. 52, 1918; Oil possibilities 

in and around Baxter Basin, in the Rock Springs uplift, Sweetwater 

County, Wyo.: U.S. Ge31. Survey Bull. 702, tables opposite pp. 24 and 

36, 1920. 

to red-brown sediments called by Powell 13 the 

"Uinta group" and by most later geologists 

the "Uinta quartzite" or "Uinta formation," 

though by King and Emmons mistakenly 

identified as Weber sandstone. The name 

Uinta is more correctly applied to the very 

much later Tertiary formation that occurs in 

the Uinta Basin, to the south of the mountains, 

but as no other acceptable name has been 

given to the older unit the name "Uinta formation" will be used with quotation marks for it 

in the present description. 

The "Uinta formation," the only one exposed in Red Canyon, is a succession of deepred to maroon resistant sandstone and conglomerate, with lesser amounts of hard red 

shale. The sandstone is usually dense and is 

1a Powell, J. W ., Report on the geology of the eastern portion of the 

Uinta Mountains, pp. 41, 61, 141, U. S. Geol. and Geog. Survey Terr.~ 

1876. . 
GEOLOGY OF GREEN RIVER VALLEY, WYOMING AND UTAH. 41 

in places changed to a true quartzite in which 

individual grains are not easily distinguished; 

locally the color is a deep brown. The shale 

at some places is greenish. · The beds in the 

upper part of Red Canyon contain more shaly 

beds proportionately than those in the part 

farther downstream, though there are some 

massive beds throughout its length. The 

canyon walls at many places are debris-covered 

slopes; at others, cliffs of bare rock. Powell 

gives the thickness of the "Uinta group" as 

more than 12,000 feet, and· most later writers 

quote his figures. I had no opportunity to 

estimate or measure the thickness, but it is 

certainly very great. 

No fossils have been recorded from the 

"Uinta formation," and it has been assigned 

by various writers to the Devonian, Carboniferous, Cambrian, and pre-Cambrian. I can 

add nothing regarding the age of the formation 

except that search at many places for features 

that would aid in fixing the age revealed only 

obscure trails, mud cracks, and raindrop 

impressions, of no esnecial value for this 

purpose. 

Browns Park and Swallow Canyon.-The 

open valley between Red Canyon and Lodore 

Canyon, called Browns Park, affords few good 

exposures near the river, and as it had already 

been mapped the party's passage through it 

was too rapid even to see much of those. One 

' exposure of soft dove-gray shale or clay not 

far below the upper end of the park is probably 

late river-terrace material, though as far as 

lithology goes it might equally well be of Tertiary . age. Other exposures of brown sandstone are probably part of the late Tertiary 

Browns Park formationY Swallow Canyon, 

on the south side of Browns Park, is a relatively 

shallow canyon cut through the "Uinta formation" by a 4-mile loop of the river which 

abruptly leaves the soft valley deposits to 

plunge into the hard sandstone beds and as 

abruptly returns to the valley. 

Lodore Oanyon.-From Browns park the 

stream passes again into exposures of "Uinta 

formation" in the deep, narrow course of 

Lodore Canyon. These exposures differ in 

no essential respect from those in Red Canyon. 

The formation has perhaps fewer soft layers, 

and the walls stand at high angles with but. 

14 Powell, J. W., op. cit., pp. 40, 44, 168. 

little debris upon them. For the first 12 

miles of the canyon, approximately, no rocks 

except this formation are visible. Then there 

appears at the top of the canyon walls the 

first of the post-" Uinta" formations, the 

Lodore group of Powell. 15 This gradually 

descends down stream until at a point near the 

mouth of Alcove Creek it reaches river level. 

Above the Lodore "group," or Lodore formation, as it would now be called, appear the 

beds designated by Powell "·Redwall group," 

"Lower Aubrey group," and "Upper Aubrey 

group. " 16 These divisions · probably correspond closely to the Mississippian limestone, 

Pennsylvanian limestone, and combined Weber 

sandstone and Park City formation of Schultz. 17 

The Lodore formation, as I interpreted it, 

contains a flaggy basal sandstone of salmon 

color that is sharply separated from the 

underlying "Uinta formation" by an unconformity representing an erosion interval. 18 

This basal sandstone is overlain by a succession 

of variegated red, purplish, and green sandy 

shales and thin sandstones. Possibly there 

are some thin limestone beds at the top that· 

should also be included in the Lodore formation, 

though I tentatively put all the limestones 

into the next higher unit. The shale unit is · 

softer than the underlying beds and the 

succeeding Carboniferous limestone and makes 

a marked slope. The basal sandstone is 

about 150 feet thick and the shale unit about 

300 feet thick. Powell gives 460 feet as the 

thickness of his Lodore "group," and the 

round figure of 500 feet is cited by most later 

writers. No fossils have been recorded from 

the Lodore formation but it is supposed by 

recent writers to be Cambrian, both from its 

position in the section and its resemblance to 

beds in the Tonto group of the Grand Canyon. 

The Carboniferous fossils noted by Powell on 

page 56 of the report cited were very probably 

out of place. 

The beds designated by Powell "Redwall 

group" and "Lower Aubrey group" include in 

the lower part much massive cream-colored to 

brown cherty limestone very similar to the 

Madison limestone (lower Mississippian) of 

15 Powell, J. W., op. cit., pp. 41, 56, 147. 

16 Idem., pp. 41, 54-55, 147-149. 

11 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the 

Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey 

Bull. 702, table opposite p. 36, 1920. 

1s Powell, J. W., op. cit., pp. 144-145. 
42 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923. 

central Wyoming; and in the upper part a 

succession of red, pink, and purplish shale and 

sandstone and gray and pinkish limestone, all 

in relatively thin layers and as a mass much 

like the beds commonly assigned to the Amsden formation (Pennsylvanian and upper Mississippian) in central Wyoming. I estimate 

the thickness of the upper and lower divisions 

as 1,000 to 1,200 feet each. 

Above the beds of Powell's "Lower Aubrey 

group" comes the Weber sandstone, here as 

in Horseshoe and Kingfisher canyons a very 

massive, much cross - bedded yellow :.. brown 

quartzose sandstone that rises in sheer unbroken walls for hundreds of feet. 

At the extreme lower end of Lodore Canyon, 

just at the edge of Echo Park, a fault, visible 

on the right bank of the river and striking in a 

direction somewhat east of north, brings the 

lower part of Powell's "Red wall group" into 

contact with the extreme top of his "Lower 

Aubrey group." The extension of this same 

fault southward is clear in Mitten Park and the 

basin of Pool Creek. (See below.) 

Echo Parle, Pool Greek, and Mitten Parlc.-

Green River, on leaving Lodore Canyon, follows 

for some miles a course shaped like a narrow U 

with the . open end to the north. The east 

limb of this U receives Yampa River from the 

east, and the bend receives Pool Creek from 

the south. The narrow open bottom adjacent to the mouths of these streams is Echo 

Park or Pat's Hole. Farther downstream, at 

the top of the west limb of the U, another small 

open bottom is known as Mitten Park. From 

Mitten Park the river passes abruptly into 

Whirlpool Canyon. 

Echo Park is walled in by sheer cliffs of 

Weber sandstone, which likewise forms Steamboat Rock, the great mass that fills the area ir.. 

the center of the U. The lower course of Pool 

Creek is a narrow box canyon, likewise in the 

Weber sandstone, though in about 2 miles the 

creek bed rises above it, through the Park City 

beds, and runs upon red beds. These red beds 

lie in a small basin bordered on the west by 

the fault mentioned above and possibly by 

another on the south. The Woodside shale 

appears to be much as on the north side of the 

mountains, and · the Thaynes 0) about the 

same except for the occurrence of some heavy 

beds of brown sandstone. I believe that . the 

supposed Ankareh and later beds have been 

removed here by erosion. 

In Mitten Park the rocks are tilted to a high 

angle in proximity to the fault and are even 

overturned. The downthrow is on the east 

and the upthrow on the west, bringing above 

the river level several hundred feet of the upper part of the "Uinta formation." 

I made no estimate of thicknesses in this 

region, though the Weber sandstone Is certainly in excess of 1,000 feet. 

Whirlpool Oanyon.-At the upper end of 

Whirlpool Canyon the uppermost several hundred feet of the "Uinta formation" appears 

west of the fault described above. The normal 

succession of formations appears above it-Lod9re formation, "Red wall group," and" Lower 

Aubrey group." The Lodore formation has 

about the same constitution and thickness as 

in Lodore Canyon; likewise the lower Madisonlike part of Powell's .divisions and the upper 

Am·sden-like part. The irregular contact of 

the Lodore formation on the "Uinta formation" is especially well shown. The formations dip downstream, and at the lower end of 

the canyon the Weber sandstone appears. It · 

is bent sharply downward and cut off by a 

fault, which runs about parallel to that of the 

upper end, with the downthrow on the west 

and the upthrow on the east.19 Whirlpool 

Canyon therefore seems to cross an uplifted 

fault block, with the Mitten Park fault on • 

the east and the Island Park fault on the 

west. 

Island Parle.-The area along the river between Whirlpool Canyon and Split Mountain 

Canyon is divided by the local residents and 

on some maps into three small parks. These 

are merely large bottoms separated by low 

ridges and are called, in order downstream, 

Island Park, Rainbow Park, and Little Park. 

The rocks of this area, often called as a whole 

Island Park, lie in an unsymmetrical syncline 

with axis plunging a little south of east and 

with the eastern tip truncated by the fault at 

the eastern edge of Island Park. The formations present extend from the Weber sandstone to the Hilliard shale, inclusive. The 

character of the rocks is best shown in the 

following section: 

19 See Schultz, A. R., A geologic reconnaissance of the Uinta Mountains, northern Utah: U.S. Geol. Survey Bull. 690, pl. 5, 1918. 
GEOLOGY OF GREEN RIVER VALLEY, WYOMING AND UTAH. 43 

Section measured in Island Park. 

[See also fig. 7.] 

Measured northwest of Rainbow Park. 

Hilliard shale. 

Frontier formation of Schultz: 

Sandstone, massive, gray to yellow ________ _ 

Shale, yellow, sandy _____________________ _ 

Sandstone, massive, gray to yellow ________ _ 

Shale, yellow to gray, in part sandy .. ______ _ 

Aspen shale of Schultz: Shale, hard, platy, 

bluish-white, with abundant fish scales. Exactly like Mowry shale in Wyoming _________ _ 

Beckwith formation of Schultz: 

Sandstone, massive, brown to gray, coarse, 

containing few lenses of pebbles the size of 

wheat. (Where measured the upper part 

of this unit is in almost direct contact 

with Aspen shale, but along the strike the 

upper 50 feet changes to very dark shale)._ 

Shale, brown to dark gray, with some thin 

beds of brown sandstone. Not as dark as 

might be expected at this horizon. ______ _ 

Sandstone, coarse, brown to gray. No 

pebbles seen __ ... _ . _____ . ______________ _ 

Shale, variegated purple, green, gray; sandstone, soft, whitish; and sandstone, brown, 

hard. Contain bone fragments and gastroliths at a number of horizons. Beds 

change rapidly both vertically and horizontally. Possibly some of the basal beds 

may belong to . the underlying marine 

Jurassic, but they did not furnish clear 

evidence of marine origin. Thickness calculated from topographic data. __________ _ 

Measured 1 mile west of Ruple ranch. 

Twin Creek formation of Schultz: 

Shale, greenish gray, with layers of platy 

argillaceous sandstone and some lenses M 

soft yellow sandstone. Not sharply separated from overlying unit. Sandstone 

layer 10 feet above base contains Rhynchonella gnathophora Meek, Ostrea sp. undetermined, Tancredia warrenana Meek and 

Hayden, Trapezium? sp ________________ _ 

Sandstone, blocky, light brown, fine-grained; 

contains Rhynchonella, Ostrea, and other 

fossils very poorly preserved ____________ _ 

Sandstone, soft, gray-white, cream-colored to 

yellow, argillaceous; at most places weathers back like shale, at others stands out as 

ledges; contains lenses of greenish shale. 

No fossils seen .. ____ .......... _ ........ . 

Shale, greenish gray, with thin layers of 

sandy brownish limestone and nodules of 

dense blue limestone. Contains Cidarisf 

sp., bryozoan, Parallelodon? n. sp., Pinna 

sp., Eumicrotis eurta (Hall), Ostrea strigileeula White, Cardinia? n. sp., Trigonia 

quadrangularis Hall and Whitfield, Camptonectes platessijormis White, Modiola pertenuis Meek and Hayden, Pleuromya newFeet. 

35 

33 

40 

130 

80 

75 

38 

8 

700 

40 

3 

85 

Twin Creek formation of Schultz-Continued. 

toni Whitfield, Astarte packardi White, Tanaedia? inornata Meek and Hayden, Dosinia 

jurassica Whitfield, Quenstedticeras? hoveyi 

Reeside, Cardioceras cf. C. cordijorme (Meek 

and Hayden), Cardioceras sp., Belemnites Feet. 

densus Meek and Hayden ......... _. __ ._._ 50 

Nugget sandstone of Schultz: 

Sandstone, platy, gray to cream-colored, 

with thin shale layers. Grades into overlying beds ........... _ ........... _. _ _ _ _ _ _ 15 

Sandstone, massive, cream-colored; cross- bedded .... ____ .. _. ___ . ____ . ___ ... __ .____ 20 

Sandstone, platy, gray, interleaved with 

thin layers of green, gray, and purple shale. 

The lower part contains clay-pellet conglomerates, and the base is a sinuous line. 

Probably no unconformity of much magnitude, as both these beds and the underlying beds are shallow-water deposits. 

Sandstone, massive, cream-colored to brown, 

cross-bedded, in a single bed. Crossbedding seems to be of the current type.. 75 

Measured in Little Park. 

Shale, brick-red with some gray streaks .... _ 200 

Sandstone, gray to yellow, locally salmoncolored, cross-bedded, very massive._..... 560 

Sandstone and shale, alternating in thin beds, 

red and white .... _ .. _ ... ____ .. __________ 14 

Ankareh shale of Schultz: 

Shale, sandy, red with some white streaks 

and gray layers .. _________ .. _ .. __ ... _ . _ _ _ 50 

Sandstone, salmon-colored, massive, medium 

grained ........ ____ ... _ . __ . _ . _ .. _ .. __ . . . . 15 

Shale and soft sandstone, mostly brick-red.. 160 

Grit, coarse, white, yellow, and pink, with 

lenses of pebbles of quartz and chert 1 inch 

or less in diameter; basal part has pebbles 

as much as 2 inches in diameter. _ ... ____ . 30 

Unconformity. 

Thaynes (?) and Woodside formations of Schultz: 

Shale and sandstone, brick-red, without any 

prominent subdivisions; estimated at~ ...... : 1, 000 

Park City formation. 

Split Mountain Oanyon.-The rocks exposed 

in Split Mountain Canyon (sometimes locally 

called Black Mountain Canyon) form a sharp 

unsymmetrical anticline whose axis runs about 

due west. The river enters the canyon at 

right angles to the strike ·of the rocks on the 

north limb but on reaching the axis of the 

fold runs parallel to it for about 5 miles, then 

at right angles to the strike across the south 

limb. The upper end of the canyon is in 

Weber sandstone, but the dip is steep and 

soon brings up the upper part of the "Lower 

Aubrey group" of Powell (Amsden-like beds) 

and in places along the axis Powell's "Red wall 

group" (Madison-like beds). On the south 
44 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923. 

limb the reverse succession is present, and the 

canyon ends at the top of the Weber sandstone. 

Wonsits Valley.-The name Wonsits Valley 

was applied by Powell 20 to the region extending from the lower end of Split Mountain 

Canyon to the mouth of Duchesne River. It 

is here extended arbitrarily southwestward to 

include the valley as far as the mouth of 

Willow Creek. 

Immediately following the Weber sandstone 

at the lower end of Split Mountain Canyon 

comes a succession of red beds, Nugget sandstone, etc., nearly identical with that in Island 

Park. These beds dip very steeply but are not 

as well exposed near the river as in Island 

Park. Owing to the steep dip the river passes 

through the older beds in a short distance and 

then runs upon the Cretaceous a considerable 

distance, but the exposures are rather poor 

because of the abundance of river-terrace 

material. Along this part ofthe river a number of attempts have been made to exploit 

the river terraces for placer gold, but they 

have not yet been wholly successful. 

At a point about 6 miles above Jensen the 

. river approaches closely the outcrops of the preCretaceous rocks. Near this point the Carnegie 

Museum of Pittsburgh, Pa., has for years been 

taking dinosaur remains from a quarry in beds 

of Morrison age. A stratigraphic section in the 

neighborhood of the quarry is as follows: 

Section measured at Carnegie Museum dinosaur quarry, above 

Jensen.· 

[See also fig. 7.] 

River-terrace materials, underlain by Hilliard shale. 

Frontier formation of Schultz: 

Sandstone, fairly coarse, gray to brown, cross- bedded ................ _ ...... __ . _________ _ 

Shale, yellow, sandy, with thin layers of gray 

Feet. 

22 

Beckwith formation of Schultz-Continued. 

Shale, gray, violet, and greenish, with lenses 

of greenish argillaceous sandstone, grit, and 

conglomerate that weather to a chocolatebrown; highly variable unit ............... . 

Sandstone, greenish, conglomeratic; weathers 

brown. Horizon of dinosaur quarry ....... . 

Shales and sandstone, variegated; like second 

unit above ................ __ ............. . 

Twin Creek formation of Schultz: 

Sandstone, fine grained, fissile, beautifully ripple marked and rain pitted, greenish gray, 

with considerable interbedded shale. Some 

layers contain Ostrea sp ...... : .. __ ......... . 

Sandstone, platy, ripple marked, gray, fine 

grained; contains Rhynchonella gnathophora 

Meek and Tancredia warrenana Meek and 

Hayden ......... _ ............... _ ........ . 

Shale, greenish gray, with some platy sandstone of same color_ ...................... . 

Sandstone, brown, limy; contains Ostrea strigilecula ..... _ .......... ..... ... _ ........... . 

Shale, dark gray, almost black, containing dense 

blue limestone in concretions .... _ ... _ ... _ ... 

Limestone, gray, coarse, sandy; contains Eumicrotis curta (Hall), Ostrea strigilecula White, 

Camptonectes platessiformis White, Astarte 

packardi White, Tancredia? inor:nata Meek 

and Hayden, Tancredia sp., Dosinia furassica 

Whitfield?, Cardioceras russelli Reeside, Cardioceras hyatti Reeside, Cardioceras cordiforme 

Meek and Hayden, Cardioceras aff. C. wyomingense Reeside, Cardioceras sp ............ _ 

Shale, greenish gray, with limestone in nodules 

and containing Ostrea strigilecula White and 

Eumicrotis curta (Hall) .................. _ .. 

Nugget sandstone of Schultz: 

Sandstone, very massive, cross-bedded, medium grained, yellow to gray .. -_ ... _ ...... . 

Shah~ and platy sandstone, yellow to gray .... . 

Sandstone, massive, gray to yellow, crossbedded, medium grained ................. . 

Shale, variegated, gray and brick-red ........ . 

Sandstone, very massive, yellow to gray; forms 

here an impassable ridge; must be some hundreds of feet thick. 

Feet. 

279 

10 

506 

40 

2 

65 

1 

42 

1 

27 

91 

12 

120 

107 

sandstone __ . _ ....... _ . ____ . _ . ___ . _ . _ .... _ . 158 For a short distance below the . dinosaur 

quarry there are very good exposures of 

50 Hilliard shale dose to the river, but over much 

37 of the way to Jensen the exposures are poor. 

Aspen shale of Schultz: 

Shale, bluish gray, hard, platy; contains many 

fish scales ............... __ . ............... . 

Shale, yellowish, sandy .................. _ .. . 

Beckwith formation of Schultz: 

Sandstone, gray to brown, locally weathering 

pink, coarse, conglomeratic, cross-bedded . . . 

Shale, rusty brown and drab_ ... __ . _ ......... . 

Sandstone, gray to brown, in thin beds ... _ ... . 

Shale, rusty brown and drab ................. . 

Sandstone, ripple-marked, coarse, cross-bedded, 

brown to gray; rusty in places. This bed 

seems to be variable in thickness arid may 

even be absent a short distance to the west .. 

The rocks lie in a syncline plunging to the west, 

35 as shown by Gale 21 and Schultz.22 An anti27 cline, also plunging westward and with its axis 

10 passing close to Jensen, brings up Frontier 

37 sandstone just east of the town. · Downstream 

from Jensen the river passes through higher 

and higher beds. About 6 miles southwest 

37 of Jensen sandstone and shale containing 

20 Powell, J. W., Map of Green River from the Union Pacific Railroad 

to the :i:nouth of White River, 1873; Exploration of the Colorado River 

of the West and its tributaries, explored in 1869 ,1870 ,1871 ,and 1872, 

p. 44, 1875. 

21 Gale, H. S., Coal fields of northwestern Colorado and northeastern 

Utah: U.S. Geol. Survey Bull. 415, pl. 21, 1910. 

22 Schultz, A. R., A geologic reconnaissance of the Uinta Mountains, 

northern Utah: U. S. Geol. Survey Bull. 690, pl. 5, 1916. 
GEOLOGY OF GREEN RIVER VALLEY, WYOMING AND UTAH. 45 

many red beds appear. These beds are 

relatively soft and lack the hard sandstones 

present in the Wasatch. I take them to be 

the Tertiary beds assigned to the Bridger 

formation (middle and upper Eocene) and 

dip northward. From that point on to a 

locality some distance above Ouray only these 

red beds are visible, but at this locality gray 

beds appear at river level and the red element 

is less striking. 

~..><: 

·- $ ~() 

!l 

:;· .c 

() 

r:n 

.... 

0 

...., 

<l) 

bO 

bO 

:;:1 

z 

.... 

0 

t: 

"' p. 

.... 

<l) 

p. 

p. 

~ 

Flaming Gorge Island Park Dinosaur quarry 

300 

75 

100 

300 

Hilliard shale 

Brown coarse-grained 

sandstone with some carbonaceous shale 

--- --- Mostly ---blui~·white · fish-scale shale. -...._ Not well exposed, -...._ possibly in part 

Frontier 

Hilliard shale FEET 

Gray to yellow sandstone - -zz 

Sandy shale 

Massive gray to yellow sandstone 158 

- - -. fish-scale sha\e 37 

B\uish-whlte ---35 -- 27 

Coarse brown conglom- Conglomeratic sandstone ~~ eratic sandstone.· 

Pebbles of white and 38 Shale, brown to gray _ ~ gray chert -.·_.____,,.._._- - ----- _ - - - - 8 Sandstone, coarse, .browri 

Variegated, highly 

colored shales and 

soft sandstones 

Conglomeratic sandstone 700± 

Variegated shales 

and soft sandstones 

Yell ow sandstone, not well exposed 

Apparently sandstone 

and some red shale, not well exposed 

Variegated, highly colored 

shales ami soft sandstones. Bone fragments and gas- troliths at many horizons. 

Possibly some of basal part 

should go with Twin Creek 

* Shale:&-reenish gray 

279 

10 

506 

'-Sandstone, gray, hard· - - _ Sandstone, soft, _gray- 40 

white, argillaceous 2 

Shale, greenish gray 

Sandstone, platy, gray 

Sandstone;massive, gray_ 41 

Sandstone, platy, and shale- _ 

Sandstc;me, massive, 2 gray and brown ~I 

* Marine Jurassic fossils 

Hilliard shale 

Yellow sandstone, fairly coa.rse 

Shale, sandy, and 

thin sandstone 

Hard bluish::White 

fish-scale· shale 

Shale, yellow, sandy 

Sandstone, broWn:-conglomeratic 

Shale, brown to drab 

Sandstone, brown, thin 

·Shale, brown and drab _ ~J!<!S_!OE~ r~tY.!_ V~.!!_b~ __ 

Variegated shale, highly 

colored, with soft sand- stones that weather 1!. 

chocolate-brown 

Sandstone. Horizon of 

1dinosaur quarry 

Variegated shale, highly 

colored, and chocolatebrown sandstones 

Sandstone, platy, greenish---- gray, and shale 

Sandstone, platy 

·Shale, greenish gray -Sandstone, brown 

Shale, very dark, with 

limestone concretions 

\\.Limestone, gray, sandy 

\~ale, greenish gray, with 

limestone concretions 

Sandstone, massive, 

yellow to gray 

Shaie and piaty sandstone 

Sandstone, massive, gray to yellovv 

· Shale, brick-red 

Massive. sandstone Of Nugget 

FIGURE 7.-Diagram showing correlation of sections n ear Flaming Gorge, Daggett County, and in Island Park and near the Carnegie Museum 

dinosaur quarry, Uinta County, Utah. 

Uinta formatio.n (upper Eocene). This is the 

real Uinta formation. These beds have a 

south dip at their northern edge. Farther 

downstream they lie practically flat, but about 

at the neck of Horseshoe Bend they begin to 

33372°-25--4 

Upper Desolation Canyon.-The name Desolation Canyon was applied by Powell 23 to the 

s'tretch of valley from a point somewhere in the 

23 Powell, J. W., Exploration ofthe Colorado River of the West and its 

tributaries, explored in 1869, 1870, 1871, and 1872, pp. 46-50, 1875. 
46 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923 

neighborhood of Indian Pasture downstream 

to the Roan Cliffs. For the present description the stretch of valley between Willow 

Creek and Minnie Maud Creek is taken arbitrarily as Upper Desolation Canyon, though it 

is much less a canyon than a sharply limited 

valley, and the valley below it to the Roan 

Cliffs is taken as Desolation Canyon proper. 

Near the mouth of Willow Creek much sandstone is present in short lenses. The shale between and around the sandstone lenses is of a 

sort of mauve color, and the sandstones themselves a coffee-brown. The whole mass has a 

purple tone when seen in the distance. Near 

the mouth of Desert Spring Wash the purple 

beds are replaced in part by gray and yellowish 

beds. The dip is low, but the replacement 

is thought to be due to the rising of older beds 

to river level. A few miles below Desert 

Spring Wash the walls of the valley are all of 

gray and yellowish beds of unmistakable 

Green River aspect. Sandstone is present 

but only in short lenses, and the bulk of the 

rock is shale. At Indian Pasture the shaly 

beds are very conspicuous and the slopes look 

as if all shale. The change from the purple 

beds to the gray beds appears to mark the 

change from the Bridger and Uinta formations 

to the Green River formation. There seems 

to be no break. I did not estimate the thickness of the purple-red beds. 

Winchester 24 places the base of the Bridger 

beds some distance above Desert Spring 

Wash-in fact, beyond the area covered by 

his map-but he must have had some su~h 

distinction in mind as that· stated above. 

The zone of rich oil shale appears at river level 

about 3 miles above the mouth of Minnie 

Maud Creek, according to Winchester, and is 

mapped by him along the walls of the canyon 

for many miles below, rising southward until 

high up on the walls it turns to the east and 

west somewhere near Chandler Creek. 

Desolation Oanyon.-Desolation Canyon is 

here considered to extend from Minnie Maud 

Creek to the Roan Cliffs below the McPhe:tson 

ranch. 

Near Minnie Maud Creek the walls of the 

canyon appear to be largely shale, gray to 

2t Winchester, D. E., Oil shale of the Uinta Basin, northeastern Utah: 

U.S. Geol. Survey Bull. 691, pl. 12, 1919. 

yellowish, with only a minor amount of sandstone, but downstream some miles near Tabby 

Ah Guy Canyon, much more sandstone appears-fine grained, yellow to brown, platy. 

The sandstone layers in weathered faces are 

often masked by debris but in clean vertical 

faces are very evident. Some of the sandstone has probably come in by lateral change 

from shale, some of it by rising above river 

level. Near Temple Canyon the lowest beds 

are nearly all sandstone, yellow and rusty 

brown, with a minor amount of maroon and 

greenish-gray shale. Above these sandy beds 

the shaly gray Green River beds like those of 

Minnie Maud Canyon appear, but they are so 

high on the canyon wall that, considering the 

low dip, it is very unlikely that they could have 

simply risen. I believe that there has been 

some lateral change in lithology. 

Near the mouth of J ~ck Creek the rocks for 

perhaps 1,000 feet above the river are brown 

sandstone with a minor amount of red and 

greenish shale. Above these beds are oolitic 

cream-colored limestone and light shale and 

sandstone, such as are present in the more 

typical Green River beds. How inuch, if any, 

of the mass of brown sandstone and colored 

shale are Green River formation and how 

much Wasatch formation I am unable to say. 

Down near the river level at Jack Creek some 

striking deep-red beds appear. Downstream 

these red beds near the river become progressively thicker, and there is a fairly sharp plane 

of division between them and the overlying 

mass of brown sandstone and colored shale. 

The distinction is not ideally sharp, as some 

red coloring occurs in the rocks above, and 

there is no evidence of any break in sedimentation. The top of the marked red series 

might well be considered the top of the W asatch formation, though here, as has been 

noted at other places in the region by various 

observers, the position of the boundary between the Wasatch and Green River formations offers ground for wide difference of 

op1mon. These reddish beds make up more 

and more of the canyon walls downstream 

until they finally include practically all the 

rock visible from the river. Near Three Canyon Creek there is much conglomerate of small 

chert pebbles in the fallen blocks along the 
GEOLOGY OF GREEN RIVER VA~LE"Y, WYOMING AND UTAH. 47 

river, though I did not see the rock in place. COMPARISON OF THE LITHOLOGIC SUCCESSION 

Just below the McPherson ranch at river level IN GREEN RIVER VALLEY, SOUTHWESTERN 

UTAH, AND CENTRAL WYOMING. 

appear gray shale, thin brown sandstone, and 

dark fresh-water limestone crowded with Viviparus, Unio, and other fossils. Beneath these 

beds are gray shale with streaks of red and then 

plain gray shale and brown sandstone. I 

supposed the red and gray shales associated 

with the fresh-water limestone to be the base 

of the Wasatch and the gray shale and brown 

sandstone beneath them to be the Mesaverde 

formation of the region. The outcrop of the 

red beds turns away from the river here to 

form the Roan Cliffs, and Gray Canyon begins. 

Gray Canyon.--:Gray Canyon is cut in a succession of. alternating massive brown sandstone 

and gray shale-the Mesaverde formation of 

the region. Coal beds are present in the lower 

part of this series, but I did not have time to 

locate any definitely. There is little change in 

character of the rocks above the end of the 

canyon, where the outcrops of the sandstones 

turn off to the east and west to form the Book 

Cliffs, and the river runs through lowlands of 

Mancos shale. 

The lithologic succession in Green River 

valley affords an interesting comparison with 

that of southwestern, Utah and that of central 

Wyoming. In general, the information available would not justify a statement that the 

units compared are strictly chronologie equivalents, for in the greater parts of the respective 

stratigraphic colwnns close paleontologic correlations are not possible. A similarity in the 

succession of lithologic units may be pointed 

out, however. The thicknesses of the individual 

lithologic units compared with one another 

may differ greatly, owing to differences in the 

length of the time interval represented by the 

units compared or to differences in the contemporaneous rate of deposition in the respective areas or to both causes at once. 

It has seemed the best method to make such 

a comparison by arranging the names in current 

use in three vertical columns with horizontal 

lines including the units compared and with 

such comment as may be made appended as 

notes. 

Comparison of the series of lithologic units recognized in Green River valley with those in southwestern Utah and central 

Wyoming. 

Age. I Southwestern Utah. Green River valley. Central Wyoming. Not£>. 

I 

Uinta formation. Uinta formation . 

Bridger formation. Bridger formation. 

Pink Cliff series of Dutton. Green River formation. I Wind River (a) 

Tertiary Wasatch formation. 

(Eocene). formation. 

I 

Wasatch formation. I 

"Post-Laramie' ' formation. Fort Union formation. .I 

--- ---------- -- -- (b) 

Tertiary? "Laramie'' formation. Lance formation. 

······· ··· · -·---- Lewis shale. Lewis shale. (c) 

Mesaverde formation . Mesaverde formation . (d) 

Shales and sandstones vari- I 

--

Cretaceous. ously named. e Steele shale. Hilliard shale. Niobrara formation. 

I 

Carlile shale. 

Frontier formation of Schultz. Frontier formation. (!) 

Aspen shale of Schultz. Mowry shale. 

I (g) Thermopolis shale. 

I I 

-- (See footnotes on pp. 48, 49.) 
48 SHORTER CONTRIBUTIONS . TO GENERAL GEOLOGY, 1923. 

Comparison, of the series of lithologic units recognized in Green River valley with those in southwestern Utah and central 

Wyoming-Continued. 

Age. Southwestern Utah. Green River valley. Central Wyoming. Note. 

Cretaceous. Beckwith for- Dakota(?) for-

............................. Sandstone. mation of mation. Cloverly formation. (h) 

Cretaceous? Variegated shale. Schultz. Morrison for- Morrison formation. 

mation . 

...................... .. ........ ·· - --

Marine 'Upper Jurassic. Twin Creek limestone of 

Schultz. 

Jurassic. 

Sundance formation. ( i) 

White Cliff sandstone. Nugget sandstone of Schultz. Vermilion Cliff sandstone. 

Chinle formation . Ankareh shale of Schultz. J elm formation·. (i) Shinarump conglomerate. 

Triassic. 

Thaynes(? ) formation of 

Moenkopi formation. Schultz. Chugwater formation. ( k) 

Woodside shale of Schultz. 

- -

Kaibab limestone. 

Permian. Coconino sandstone. Phosphoria formation. Hermit shale. Park City formation . ( Z) .. .. .......................... 

Absent(?). 

Pen?syl- Supai formation. van1an. Weber sandstone. Tensleep sandstone. (m) 

Pennsylvanian limestone. Amsden formation. (n) 

--

Mississippian. Red wall limestone. Mississippian limestone. Madison limestone. 

-- Muav lime- (?) Gallatin limestone. stone. 

Cambrian. Tonto group. Bright Angel Lodore formation. Shale. Gros Ventre shale. (o) shale. I 

Tapeats sand- Sandstone. Flathead quartzite. stone. I 

--

Pre-Cam- Pre-Cam brian. "Uinta formation." Pre-Cam brian. (P) brian. 

q The exact equivalent in time of the Pink Cliff series 

of Dutton is uncertain, but it probably represents some 

part of the Wasatch formation with possibly some later 

beds. The Green River formation and the Wind River 

have little in common except stratigraphic position; it is 

also probable that the Wasatch and Wind River formations 

are in part contemporary. 

contain the Fort Union flora . The "Laramie" formation 

contains the Laramie flora and the Lance formation the 

Fort Union flora and are supposed on that ground to differ 

in age. Beds older than Dutton's Pink Cliff series and 

younger than Creta~eous are not known in southwestern 

Utah. 

c The Lewis shale is a somewhat doubtful unit on Green 

River. There is no well-defined shale unit between the 

Wasatch beds of the Roan Cliffs and the Mesaverde formab The "post-Laramie" formation and the Fort Union 

formation, besides having a ftimiiar stratigraphic position, 
GEOLOGY OF GREEN RIVER. VALLEY, WYOMING AND UTAH. 49 

tion of the Book Cliffs, south of the Uinta Mountains, that 

could be called Lewis shale. North of the mountains 

such a unit is mentioned by Gale (U.S. Geol. Survey Bull. 

341, p. 310, 1909), and by Schultz (U.S. Geol. Survey Bull. 

702, fig. 3, 1920), but no description is given. A correlation of the Lewis shale of the Green River region with that 

of central Wyoming, and of either with the typical Lewis 

shale in southwestern Colorado is simply a loose grouping 

of large shale units of upper Montana age and does not imply identity in time of deposition. 

d It is not known that the Mesaverde formation of the 

Book Cliffs occupies the same time interval as the Mesaverde formation north of the Uinta Mountains, nor that 

either is the same as the Mesaverde formation of central 

Wyoming or of the typical region in southwestern Colorado. This name, like Lewis, has been loosely used and 

is made to apply practically to any coal-bearing formation 

within the Montana group. 

e The Upper Cretaceous deposits of southern Utah are 

variable in constitution and have been classified differently by different geologists. Much still remains to be 

learned, and I do not venture to make detailed correlations. There are beds that in a loose way might be called 

Frontier, others that might be called Mesaverde, and still 

others that may require other names. 

f The Frontier formation of the Green River region 

is a thin sandstone unit very low in the Colorado group. 

It can hardly be really the same as the much thicker 

Frontier formation of other areas except under the loose 

application of the name to any sandy unit in the lower part 

of the Colorado group. 

g The Aspen shale on Green River has exactly the 

lithologic character of the Mowry shale of Wyoming but is 

very thin and rests almost directly on the preceding sandstone (Dakota?) without ant' suggestion of an intervening 

shale like the Thermopolis shale. 

h The Beckwith formation as delimited by Schultz 

on Green River contains as its upper member a conglomeratic sandstone that would certainly be mapped as 

Cloverly formation in Wyoming or Dakota sandstone in 

Colorado. Whether it is equivalent only to the Dakota 

sandstone proper or contains also, like the Cloverly formation, beds of probable Lower Cretaceous age, can not be 

determined in the absence of fossils. The Beckwith beneath this upper sandstone contains three members which 

together seem to me to be the Morrison formation of Colorado and Wyoming. Schultz offers two different correlations for his Beckwith formation. In one (U. S. Geol. 

Survey Bull. 702, tables opposite ·pp. 36 and 82, 1920) 

he indicates that the Dakota sandstone and Cloverly formation are both probably absent and that the Beckwith 

formation is all ~1orrison in age. In the second (idem, pp. 

75-77) he expresses the belief that the upper sandstone is 

equivalent to the Dakota sandstone of some regions and 

upper Cloverly of others, that the upper shale and middle 

conglomerate are equivalent to the middle and lower parts 

of the Cloverly formation, and that the lower shale alone is 

Morrison. The position of the dinosaur fauna near Jensen 

and the lithology of the Cloverly formation, so far as I 

know it, are both against the correlation of the two middle 

members with the Cloverly formation. It seems also very 

doubtful to me whether the Beckwith formation of the 

Green River region is really comparable to the beds to 

which the name Beckwith is applied farther west in Utah 

and in Idaho. 

i W. T. Lee, in a paper now awaiting publication, has 

adduced abundant evidence to indicate that the Sundance formation of Wyoming, as usually defined, contains 

in the lower part the equivalent of the Nugget sandstone of 

the Green River region and of the thick Jurassic sandstone 

unit of southern Utah believed to include the White Cliff 

and Vermilion Cliff sal'l.dstones. Some writers on Wyoming stratigraphy have included the sandstone in the 

upper part of the Chugwater formation, but its structural 

relations ally it more with the overlying than the underlying beds. The Twin Creek limestone of the Green 

River region is the lithologic and faunal equivalent of the 

calcareous beds in the upper part of the Sundance. It is 

very likely that the Twin Creek formation of the Green 

River region is equivalent to only a small part of the beds 

to which the name was originally applied. No evidence 

of any other marine Jurassic formation than the Sundance 

was observed on Green River. 

j The correlation suggested by stratigraphic position and 

structural relations between the Shinarump and Chinle 

formations, the Ankareh shale of Schultz, and the Jelm 

formation is largely conjectural. All three are separated 

from the preceding beds by an unconformity. The 

Shinarump is regarded as probably Upper Triassic; the 

Chinle and Jelm contain vertebrate remains of Upper 

Triassic age; the Ankareh ·formation in the typical region 

contains in the lower part marine invertebrates of Lower . 

Triassic age. Whether the Ankareh formation of the 

Green River region is the same as the typical Ankareh 

may well be questioned. 

k A correlation of the Moenkopi formation and the 

Woodside and Thaynes(?) formations of the Green River 

valley rests on the assumption that the latter beds are 

really the equivalent o{the marine Lower Triassic formations of the same names that occur in the western Uinta 

region. It seems to me that the. assumption is very probably valid, at least in a broad sense, even though continuous tracing between the two regions i~ not possible. The 

relation of the Chugwater formation to those just named 

is more doubtful, though · the presence of a marine limestone in the upper part of the Chugwater is difficult to 

account for except as an eastward extension of the marine 

Lower Triassic strata. Another point of difference is 

that the Moenkopi formation is unconformable on the 

preceding beds, whereas the Woodside and Chugwater 

formations appear to be conformable. 

l The equivalence of the Kaibab limestone, Coconino 

sandstone, and Hermit shale on the one hand and the· 

Park City formation on the other is not supported by 

direct evidence. The Coconino and Hermit are placed 

in the Permian on the basis of fossil plants in the Hermit. 

formation and an unconformity beneath it. The Kaibab 

limestone has a marine fauna of Permian age, and so has. 

the Park City formation, in its upper (Phosphoria) part, 

but there are very few species in common. It is possible· 

that the upper (Phosphoria) part of the Park City formation may be entirely later than the Kaibab limestone, 

though still Permian, as the Kaibab is followed by an 

unconformity and the upper part of the Park City is 
50 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923. 

believed to be conformable with the succeeding beds. 

An unconformity is known in places in southeastern 

Idaho at the base of the Phosphoria formation. 

m The Tensleep sandstone, Weber sandstone, and Supai 

formation are somewhat variable sandy formations that in 

some phases are very much alike and in others quite different. They are assigned to the late Pennsylvanian 

(Supai, possibly also including Permian) and probably 

do not differ greatly in age. 

n The Redwalllimestone, as originally defined from its 

occurence in northern Arizona, contained beds of both 

Pennsylvanian and Mississippian age, but in recent classifications the Pennsylvanian part has been added to the 

Supai formation. In southern Utah a considerable thickness of calcareous strata beneath the sandy beds assigned 

to the Supai formation contains Pennsylvanian fossils. 

It is possible also that there are iri Green River valley 

beds of upper Mississippian age, which in Wyoming in 

places occur in the lower part of the Amsden formation 

and above the Madison limestone (lower Mississippian). 

o There is no specific evidence for correlating the Lodore 

formation with either the Tonto group or the Flathead, 

Gros Ventre, and Gallatin formations of central Wyoming. 

All three have a sandstone at the base followed by shales, 

the gross lithologic features of which are similar. If there 

is any limestone in the upper part of the Lodore formation, its analogy to the Tonto and Deadwood would be 

complete. In the field I considered any limestone beds 

to belong to the overlying Carboniferous, but I may have 

been mistaken. 

P There is no specific evidence to show that the "Uinta 

formation" is Cambrian nor that it is pre-Cambrian . 

•