SHORE PHASES OF THE GREEN RIVER FORMATION IN NORTHERN SWEETWATER 

COUNTY, WYOMING 

By WILMOT H. BRADLEY 

INTRODUCTION 

PURPOSE AND SCOPE OF THE REPORT 

For the last two years the writer has been engaged 

in a detailed study of the Green River formation and 

its oil shale. In order to arrive at an intelligent in-

.,terpretation of this great series of lacustrine beds, the 

field study has been focused upon the marginal phases 

of the deposits and the associated formations, to 

determine, first, so far as possible from the geologic 

and biologic evidence recorded there, .the environmental conditions that prevailed when these beds 

were laid down, such as the geologic history and 

physical configuration of the basin of deposition the 

mode of filling, the sources and nature of the mate · als, 

and the climatic conditions under which the dep sits 

accumulated. From the same evidence the iter 

has also endeavored to determine. the kinds and elative abundance of both plant and animal life hat 

existed in the Green River lake and on the adja ent 

land. Such evidence is fragmentary, as was t be 

expected, but it serves well as a basis for fur her 

study and interpretation. 

The field studies have been supplemented by m·croscopic study of the oil shale and its microorgan sms 

and of the associated rocks, such as the calcar ous 

alga reefs and oolites. Much valuable informa ion 

has also been obtained from an investigation o:f the 

processes of sedimentation that are taking plac in 

modern inland lakes and the kinds of deposits hat 

are produced by these processes. The interpreta ion 

of the organic shale and limestone must de end 

largely upon evidence of this kind. 

This report records the results obtained fro a 

field and office study of shore phases of the G een 

River formation on the northeastern margin of the 

Green River Basin and presents a brief sun:imar of 

the writer's preliminary conclusions regarding the 

origin of the Green Rivet oil shale. 

EARLIER INVESTIGATIONS 

The area described in this report is part of the Green 

River district mapped and studied by F. M. Endlich.1 

In this reconnaissance work theW asatch, Green River, 

I U.S. Geol. and Geog. Survey Terr. Eleventh Ann. Rept., for 1877, pp.131-139, 

pl. 3 (geologic map), 1879; Twelfth Ann. Rept., Ior 1878, pl. 3 (geologic map), 1883. 

I 

and Bridger formations were differentiated and 

mapped. The accuracy of the mapping in part of the 

area here described was materially increased by the 

work of Schultz 2 and Smith 3 in 1907 and 1908. 

FIELD WORK 

In 1923 the writer, assisted by Carle H. Dane, 

mapped this area and studied particularly the phases 

of sedimentation in the Green River formation. The 

:mapping was done largely by :means of plane tables 

and telescopic alidades, on a system of triangulation 

extended from a base line :measured on a level-topped 

ridge just north of Steamboat Mountain. Isolated 

areal features were :mapped in part on a topographic 

base furnished on a few of the General Land Office 

township plats and in part by :means of pace traverses. The mapping was tied to section corners at 

:many points. 

The accompanying geologic map (Pl. LVIII) was 

compiled from the field sheets of Schultz, S:rnith, and 

the writer. Data obtained by Schultz and Smith were 

checked in the field and supplemented by new :material. 

The location of the area is shown in Figure 7. 

ACKNOWLEDGMENTS 

The writer wishes to acknowledge the assistance of 

Mr. John W. Hay, of Rock Springs, Wyo., who supplied the party with saddle horses from his ranch, a 

few miles northeast of the area mapped. He also 

wishes to thank Mr. Banks W. Brady, of Eden, Wyo., 

for his cordial hospitality. 

TOPOGRAPHY 

A belt of shifting sand dunes from 4 to 8 miles wi"de 

extends from west to east across the southern part of 

the area and far out into the Red Desert Basin. 

Steamboat Mountain (altitude 8,630 feet above sea 

level) rises about a thousand feet above the general 

level of these dunes and i~ flanked on the east by a 

slightly lower escarpment, which faces southeast and 

extends northeastward beyond the limits of the area, 

and on the west by a similar escarpment, which faces 

southwest and extends northwestwa-rd. From these 

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, 1920; also 

unpublished field sheets. 

a Smith, E. E., unpublished field sheets. 

121 
122 SHORTER· CONTRIBUTIONS TO GENERAL GEOLOGY, 1925 

escarpments the country slopes gently to the north. 

The western part of the area includes a small portion 

of the Bridger Basin. 

Morrow Creek and its tributaries drain the western 

two-thirds of the area and Alkali Creek the eastern 

third. The Continental Divide separates these two 

drainage basins. 

STRATIGRAPHY 

The exposed rocks in this area belong to the 

Wasatch, Green River, and Bridger formations. 

Toward the north a part of the Green River formation 

is separated from the main body of that formation 

by a tongue of the Wasatch formation, which comes 

upper part consists largely of clay, which is predominantly drab but locally is banded with pink and 

maroon tints. Cross-bedded or massive lenticular 

beds of sandstone of stream-channel origin make up 

the remainder of the upper part. 

The Cathedral Bluffs tongue of the Wasatchformation is more heterogeneous. It consists of clay 

ranging in color from green through -greenish gray, 

gray, and buff to deep red; sandstone; sandy lime-

-stone; and locally thin calcareous alga reefs. Additional facts regarding these deposits· are given under 

the heading "Source of sediments." Measured sections of the Cathedral Bluffs deposits are given on 

page 131. 

FIGURE 7.-Indexmap showingtheloc tioninnorthernSweetwaterCounty, Wyo.,of the areas discussed in this report and locations in Wyoming and Colorado of 

measured sections given in Plate LIX 

in from the north. The terms Tipton tongue of the 

Green River formation and Cathedral Bluffs tongue 

of the Wasatch formation have been applied to these 

tongues 4 and will be used in this paper. Plate LIX 

shows the relations of these tongues to the other 

members of the Green River and Wasatch formations 

and to the overlying Bridger formation. Measured 

sections of the formations are given on pages 129-131. 

WASATCH FORMATION 

Only the upper 450 feet of the main body of the 

Wasatch formation is exposed in this area. This 

• Sears, J.D., and Bradley, W. H., Relations of the Wasatch and Green River 

formations in northwestern Colorado and southern Wyoming: U. S. Geol. Survey 

Prof. Paper 132, pp. 98-99, 1924. 

GREEN RIVER FORMATION 

Tipton tongue.-Light-brown to buff finely laminated 

shale, ostracode-bearing limestone, oolite, and sandy 

limestone make up the bulk of the Tipton tongue of 

the Green River formatio~ in this ~rea. Sandstone, however, is locally conspicuous, either . in , 

persistent well-stratified beds or in massive or crossbedded lenses. Calcareous alga reefs are nillnerous 

in the Tipton tongue. At the base of the Tipton 

tongue throughout this area and beyond there is a 

very persistent limestone in ·which ostracodes are in 

places so abundant as to compose most of the rock. 

In the southwestern part of this area and to the 

south along White Mountain the Cathedral Bluffs 
U. GE LOGICAL URVEY 

EXPLANATION 

SEDIMENTARY ROCKS 

Bridger 

.. 

formation 

(Gray and drub 3(mdy c y. gray atld brown t611ticula.r nan<Ut.one) 

B-3 

~e 

>'- "-L.4.LL.L.~~·'.I - .£ 

Green River and Wasatch formation 

(Green River formation: Tmc/ ftJurr(M Or '·member 

f¥ujf to brllWn thin-l>edckd itny $G.nd.8tone, limy and 

sandy shah, lim&to1k!, lite, atld co.loo reoll! alga ru[11; Tl, Lctney haU m~. blui8h-whm )indv_ 

laminaUd ~lc3, fi thitl beds of l\~ tmu cr.?W 01l 

•hale; Tt, 1'ipton tqn.gue, buff to brown lannn<Ued wl~. Olltrocode..J>Mring and IXXitic limestOlte, cal<xlrMU alga. reefs and fllndsl~nte lmllu. Wasatch fonnaLion : T cb, Callttdral Blt~,ffs Longue, dra.b1 gree<ti«JJ,.graJI, pink, rtd, cr.'ldla.VCfltUr clay, buff attd. grf t~.­

W. 10.ndito1k! lenMs, and localll{ IICtMY lim&I#M; 

Tw, 1fl4in bod11 of WCIICitckformatwn, till~ clar, o\GftMt •tldltoM ,.,._ ~ atld to~· ff<)1U s ; y ("()(] flrt l"'] 

IGNEOUS ROC KS 

> 

a:: 

< 

i= 

a:: 

w 

1-

--+--

I -t--

~ 

0 --

+ 

Base comprled from freld 

shiHlb nd land piau of 

the General und Offit-.@ 

Anticlinal axis 

Synclinal axi 

Fault 

D, doumthrow 

U, upthrow 

Land corner located 

Dip and strike of strata 

T. 

26 

N. 

Boundaries taken from U. . Geolo · I 

u.rvey Bulletin 702, oy A. K Sc wltz 

and from unpublished field sheets by A. R. Schultz and E. E. mith 

GEOLOGJ MAP OF A POHTJON 

0 

F ~ORTHERN SWEETW TER 

ale 250.000 

3 4 5 6 MILES 

J925 

R . 101 W . 

OMlNG 

Geology by 

W. H. Brant y anrl C. H. Dane Su,. eel rn 1923 

PROFESSIONAL PAPER f PL.A TE LVIII 
U. 8. GEOLOGICAL SURVE Y 

A 

Vicinity of 

Little Snake River, Colo. 

z a:O 

UJ-

(!'to~ 

a: -~ a: mo u. 

Fluviatile and 

lacustrine 

deposits 

Lacustrine deposits 

and oil shale 

B 

Vicinity of 

Lookout Mtn., Colo. 

;,zoo' Laney shale member of 

Green River formation 

-

--

-- Cathedral Bluffs tongue 

of Wasatch formation 

--

--

--

z J:o 

u- t-I-

~~ 

(/)~ 

~a: 

~0 

.... - --= :5===-; - --- - --- ------ - - - _ _ ~o _:._---- Tipton tongue of Green River formation --- --- - -~-----

u.. 

Fluviatile 

deposits / z 0 

-~ -----------

Main body of 

Wasatch formation 

(coal-bearing) 

South 42 ° east from section 70 miles ---- - - - at Green R iver, Wyo. 

0 

Vertical 

1,000 

SECTIONS IN THE GREEN RIVER BJ 

Showing interfingering of Green 

) 
SHORE PHASES OF THE GREE:N" RIVER FORMATION 123 

tongue of the Wasatch formation is not represented, 

and the southern continuation of the Tipton beds is 

more appropriately termed the Tipton shale member 

of the Green River formation. Additional facts regarding the Tipton deposits are given under the 

heading "'Source of sediments, " and measured sections of the deposits are given on pages 129 and 130. 

Laney shale member.-In this area and in White 

Mountain, to the southwest, the deposits overlying 

the Tipton tongue belong to the Laney shale member, 

which here consists entirely of finely laminated shale, 

oil shale, and limestone. The rocks of this member 

without exception weather bluish white and make a 

conspicuous feature of the landscape ~ (See Pl. LX, 

A.) Their relations to the underlying Tipton tongue 

and the Cathedral Bluffs tongue of the Wasatch 

formation are shown in Plate LIX. The thickness of 

the beds is stated under "Source of sediments," and 

the lithology is further described under ''Origin of 

Green River oil shale." 

Tower sandstone lentil and Morrf)W Oreelc member.-

In this area the Laney shale member thins and disappears completely toward the north and east. The 

overlying member of the Green River formation, which 

Powell 5 called the "Upper Green River," continues 

eastward to Steamboat Mountain and northeastward 

to Oregon Buttes and Continental Peak, beyond 

which it was not traced. In Powell's definition of the 

"Upper Green River" he included a basal sandstone, 

which he designated the Tower sandstone, and the 

·overlying plant beds. The Tower sandstone was so 

named because it forms the tops of the weathered 

rock masses known in the vicinity of Green River as 

The Towers. (See fig. 8 and· Pl. LX, B.) It is 

lenticular and is therefore herein designated the 

Tower sandstone lentil of the Green River formation. 

It consists of cross-bedded and massive beds of 

medium to coarse grained brown sandstone which is 

firmly indurated by a limonitic cement. The Tower 

sandstone is not present in the area described in this 

report but occurs farther south, in the vicinity of the 

town of Green River, Wyo. In the northern part of 

Sweetwater County it appears to be replaced by the 

lower part of the plant-bearing beds herein designated 

the Morrow Creek member of the Green River formation, because of their extensive exposures in the 

valley of Morrow Creek. (See Pl. LIX, which 

illustrates the lenticular nature of the Tower sandstone and its relations tb the Morrow Creek member.) 

The Morrow Creek member is a distinct lithologic 

unit easily traceable from this area southward along 

the top of White Mountain to the Union ·Pacific Railroad and thence westward to Green River. It consists largely of buff sandy limestone arul buff sandstone, 

which contrast rather sharply with the underlying 

I 

6 Powell, J. W ., Report on the geotogy of the eastern portion of the Uinta Mountains, p. 45, U.S. Geol. and Geog. Survey Terr., 2d div., 1876. 

bluish-white Laney shale member. Poor bedding and 

chippy fragments are characteristi,c of the exposures 

of these beds~ In addition to the sandstone and 

limestone there is a small amount of light-brown 

paper shale and an occasional alga reef or pisolite. 

Locally plant impressions are abundant. The Morrow Creek member ranges in thickness from 100 to 

300 feet. A measured section of it is given on page 

131. 

BRIDGER FORMATION 

The Bridger formation occupies but a small portion 

of this area. It consists of poorly consolidated coarsegrained sandstone and dull-gray sandy clay. These 

beds weather into pronounced badland forms. 

IGNEOUS ROCKS 

Steamboat Mountain . is capped by two . flows of a 

unique leucite-rich lava called wyom!ngite. According 

to Kemp and Knight 6 the rock consists principally 

of leucite and phlogopite, together with a small 

amount of diopside and hornblende in a gray-green 

.glass. The accessory minerals are rutile and apatite. 

STRUCTURE 

The structure of this area is determined by the Rock 

Springs anticline, the axis of which passes through 

Leucite Mountain. The anticline plunges rapidly to 

the northeast and loses its identity just north of this 

area in a very shallow syncline, which is roughly 

parallel to the major axis of the Wind River Mountains. 

Dips of 1° to 2° NE. prevail east of the anticlinal 

axis. On the west flank the dips are generally steeper 

and the rocks are displaced by a· zone of nearly parallel 

riormal faults that has the same trend as the anticlin~l axis. The faults are marked by rather prominent scarps, a_ fact which perhaps indicates a recent 

origin. 

SOURCE OF SEDIMENTS 

At the base of the Tipton tongue throughout this 

area and extending beyond the area as far south as 

Fourteenmile Spring, in sec. 33, T. 21 N., R. 105 W., 

there is a limestone of a surprisingly persistent nature. 

It varies in thickness from place to place but is 

nowhere entirely absent. Most commonly it is 

oolitic or even pisolitic and always carries a great 

abundance of ostracodes (Pl. LXI, B), locally so many 

that they form the greater part of the rock. In 

almost constant association with these features are 

Goniobasis shells and more rarely Unio shells. 

Above this remarkably persistent basal limestone 

there is a noticeable differentiation in the lithology of 

the Tipton tongue in different parts of the area. 

Southeast of a · diagonal line drawn through sees. 1 

and 31, T. 24 N., R. 102 W., the Tipton tongue con6 Kemp, J. F., and Knight, W. C., Leucite Hills of Wyoming: Geol. Soc. America 

Bull, vol. 14, p. 326, 1903. 
124 SHORTER CONTR-IBUTIONS TO GENERAL GEOLOGY, 1925 

EXPLANATION 

Bridger formation 

Green 

-

River formation 

Tmc Morrow Creek member\ Tl Laney shale memher 

Tt Tipkm shale member 

Wasatch formation 

Strike and dip of strata 

0 

R.IOS W. 

2 8 9 MILES. 

R.I04W. 

FIGURE 8.-Geologic map showing the southern extension of the Green River and Wasatch formations in White Mountain, Wyo., and the type locality of the Tower 

sandstone lentil. (From U. S. Geol. Survey: Bull. 702, pl. 1) 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 140 PLATE LX 

A. WHITE LANEY SHALE MEMBER OF GREEN RIVER FORMATION FAULTED DOWN AGAINST 

TIPTON TONGUE OF THE SAME FORMATION IN NORTHWEST CORNER OF SEC. 1, T. 24 N., 

R. 104 W., WYO. 

B. REMNANTS OF TOWER SANDSTONE LENTIL OF GREEN RIVER FORMATION CAPPING "THE 

TOWERS" ABOUT A MILE NORTHWEST OF GREEN RIVER, WYO. 

Photograph by W. T. Lee 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 140 PLATE LXI 

A. LARGE SANDSTONE LENS IN TIPTON TONGUE OF GREEN RIVER FORMATION IN SEC. 1, T. 24 N., 

R. 104 W., WYO. 

B. LARGE BASAL OOLITIC LIMESTONE AND HIGHER SANDSTONE LENSES OF TIPTON TONGUE 

OF GREEN RIVER FORMATION FAULTED DOWN AGAINST VARIEGATED CLAY OF WASATCH 

FORMATION IN E. 1- SEC. 22, T. 25 N ., R. 103 W., WYO. 
U. S. GEOLOGICAL SU~VEY PROFESSIONAL PAPER 140 PLA'l'E LXII 

A. LARGE CALCAREOUS ALGA REEF NEAR TOP OF GREEN RIVER FORMATION IN N. ~ SEC. 12, T . 23 N., R. 102 W., WYO. 

B. CALCAREOUS ALGA REEF INTIMATELY ASSOCIATED WITH OOLITIC AND PISOLITIC LIMESTONE AT BASE 

OF TIPTON TONGUE OF GREEN RIVER FORMATION IN SEC. 22, T. 25 N., R. 103 W., WYO. 

The lower part of the reef is broken and recemented by oolitic limestone 

SHORE PHASES OF THE GREEN RIVER FORMAT10N 125 

· sists of finely laminated shale, ostracode-bearing limestone, limestone, oolite, and alga reefs but no sand-

• stone. Northwestward from that line sandstone becomes more and more abundant. Near the line the 

sandstone is usually limy, micaceous, very fine grained, 

and in thin, relatively persistent beds. Rarely this 

fine limy sandstone shows cross-bedding on a minute 

scale. 

Toward the northwest tlie sandstone becomes more 

massive or more cross-bedded and the sand grains 

become larger until in local lenses the pebbles are as 

much as half an inch in diameter. These pebbles 

and coarser sand grains, largely of quartz and feldspar, are either sharply angular or only slightly 

rounded. The feldspar grains are commonly glassy 

and have bright cleavage surfaces. In this direction 

also the sandstone becomes more and more lenticular 

until in the western part of the area the lenses have 

all the features characteristic of stream-channel 

deposits (Pl. LXI, .A). 

In White Mountai;n, southwest of this area, there 

is a similar lithologic change in the Tipton northward 

from Fourteenmile Spring. (See fig. 8.) 

The numerous stream-channel deposits become 

evenly bedded, finer grained, and thinner to the south 

and southeast and eventually grade into finely laminated shale. These facts clearly indicate that the 

source of the sediments was to the north, and as 

they pass from fluviatile to lacustrine sediments 

in a general southeasterly direction it seems probable 

that the trend of the shore line was northeastward 

in this locality. The shore line could not be located 

accurately, because of insufficient exposures and 

because it evidently migrated with changes in water 

level, but it probably should be placed where crossbedding in the sandstone lenses becomes reduced 

greatly in scale and the greater portion of the sand 

assumes a distinct and fairly regular bedding. It 

was found in the field that where the sandstone 

assumes a lacustrine aspect the lime content increases 

materially. 

· It is probable that the Wind River Mountains, 

about 20 miles north . of this area, constituted the 

land mass from which streams carried these sediments. The arkosic nature of the stream-channel 

deposits as well as the sharp angularity and freshness 

of the individual grains is in harmony with this 

suggestion, for the deeply dissected core of the Wind 

River Range consists of coarsely crystalline granite. 

That the Wind River Mountains were sufficiently 

high above the basin of deposition to furnish abun- · 

dant rock . waste in Eocene. time seems amply proved 

by the studies of Blackwelder/ and it does not 

appear necessary to restate the evidence in this 

paper. 

7 Blackwelder, Eliot, Post-Cretaceous history of the mountains of central-western 

Wyoming: Jour. Geology, vol. 23, pp. 97-117, 193-217, 307-340, 1915. 

Additional evidence that the source of the sediments was to the north is obtained from an examination of the relations between the Wasatch and Green 

River formations in this area. These formations 

interfinger in such a way that the lacustrine sediments 

of the Green River formation either thin or disappear 

entirely toward the north, whereas on the other 

hand the fluviatile sediments of the Cathedral Bluffs 

tongue of the Wasatch formation thin or even disappear to the south. 

The. Laney shale member of the Green River formation thins northward from about 200 feet in sec. 31, 

T. 24 N., R. 104 ·w., to less than 50 feet, and finally 

by the introduction of more and more thin fingers 

of green clay it loses its lithologic identity and passes 

over in sec. 3, T. 25 N., R. 102 W., into the typical 

fluviatile deposits of the Cathedral Bluffs tongue of 

the Wasatch forn1ation. Throughout the remainder 

of the area the Morrow Creek member of the Green 

River formation, which itself.becomes sandy and thins 

northward from nwre than 300 feet to about 100 feet 

in Oregon Buttes, in sec. 12, T. 26 N., R. 101 W., 

rests directly upon the Cathedral Bluffs tongue. 

Near the head of Alkali Brook the Cathedral Bluffs 

tongue is about 200 feet thick, but at Steamboat 

Mountain it is only a little more than 100 feet thick. 

A rnore striking example, however, is to be seen in the 

western part of the area, where the same tongue of 

fluviatile clay thins from 200 feet in the north until 

it pinches out completely between the Laney shale 

member and Tipton tongue of the Green River formation about 16 miles to the southwest. (See Pl. LIX.) 

BIOLOGIC E:VIDENCE OF SHORE PHASES 

From the preceding discussion of the larger relations of the several formations and their lithologic 

character it is clear that these rocks represent the 

marginal phases of lacustrine deposits and the closely 

related shore and fluviatile deposits. Many of the 

life forms associated with these phases of deposition 

are preserved in the deposits and furnish considerable 

information concerning the physical and biologic conditions under which the sediments were laid down. In 

addition they may serve as criteria for the recognition of lake-margin deposits in other areas where 

the lithology alone is not distinctive. 

Calcareous alga reefs, oolites, pisolites, and ostracode-bearing·. limestones are present in abundance in 

the Tipton tongue and Morrow Creek member of the 

·Green River formation in this area and deserve consideration . in such a study of lacustrine sediments 

because of their value ·as indica tors of the physical 

conditions that attended sedimentation. (See Pl. 

LXII, .A.) . 

Calcareous alga deposits of recent or(gin variously 

described as water biscuit, nodular marl, algoid lake 

balls, or marlyte are evidently the modern representa-
126 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1925 

. 'tives of the fossil alga reefs. An examination of the 

mode of occurrence of some of these recent forms is 

instructive. Pollock 8 describes algal pebbles in a 

Michigan lake as being abundant and more or less 

grown together in the shallow water near shore and 

becoming smaller and less numerous as the water 

deepens away from shore. Blatchley and Ashley,9 in 

discussing the deposition of marl in James Lake, say: 

"Along much of the shore of the lake, particularly in 

the shallower water, the marl is markedly concretionary on top and often for 3 or 4 feet down." 

Clarke, 10 Powell,ti and others have emphasized the 

rapidity of growth of such deposits in very shallow 

lake margins. Calcareous reefs, very probably of the 

same origin as the fossil alga reefs in the Green River 

formation, were formed on the wave-cut terraces in 

Lake Lahontan 12 when the lake was deep and of 

broad extent. 

It is perhaps germane to note here that at several 

localities the alga reefs of the Green River formation 

.are broken as if by wave action and that the broken 

fragments are at some places associated with rather 

coarse sand and at others with fine limy sand that 

shows abundant mud curls. Many of the fossil alga 

reefs in this area are immediately overlain by clean, 

well-sorted medium-grained sand, which is locally unconsolidated. Such a deposit of sand at least suggests 

the effects of the currents or waves common in shallow 

water. Again, some of the algal deposit was formed 

around logs, and in sec. 23, T. 25 N., R. 103 W., near 

the top of the Tipton tongue of the Green River. formation, there are a large number of hollow cylinders of 

algal limestone 1 to 2 feet in outside diamet~r, 8 to 10 

inches in inside diameter, and 6 to 8 feet in length. 

The inner surface of these log cases exhibits undoubted 

woody structure. Branching is also common in them. 

The writer believes that the oolites and pisolites ·of 

the Green River formation in this area were deposited 

through the agency of microscopic plants, either algae 

or bacteria, and therefore that they were formed under 

physical conditions at least not widely divergent from 

those which produced the alga reefs. (See Pl. LXII, B.) 

In Ore Lake, Mich., Pollock 13 observed vast numbers 

of minute spherical or subspherical grains, virtually 

a mixed oolite and pisolite, forming in the shallow 

lake margins. Pisolite is now forming at the .shores of 

Pyramid Lake, Nev.,14 a lake which has less than 0.5 

per cent of solids in solution. The formation of oolite 

s Pollock, J. B., Michigan Acad. Sci. Twentieth Ann. Rept., p. 249, 1918. 

9 Blatchley, W. S., and Ashley, G. H., The lakes of northern Indiana and their 

associated marl deposits: Indiana Dept. Geology and Nat. Resources Twenty-fifth 

:Ann. Rept., p. 81, 1900. 4 

to Clarke, J. M., The water biscuit of Squaw Island, Canandaigua Lake, N.Y.: 

New York State Mus. Bull. 39, vol. 8, pp. 195-198, 1900. 

n Powell, C., Observations on some calcareous pebbles: Minnesota Bot. Studies, 

vol. 3, pp. 75-76, 1903. 

u Russell, I. C., Geological history of Lake. Lahontan: U.S. Geol. Survey Mon 

11, p. 191, 1885. • 

ts Op. cit.~ p. 249. 

u Russell,~· C., op. cit., p.l68. 

on the shores of salt lakes and on marine beaches is 

well kno1Vn. Nearly all of the recent oolite that is 

similar to the fossil oolite of the Green River formation in both microscopic and megascopic features is 

being formed either at or very close to the strand line. 

In addition to the calcareous alga reefs and relatively abundant oolite and pisolite in the lacustrine 

deposits of this area there are numerous beds composed 

almost entirely of ostracode shells. Only two of the 

several genera of ostracodes have been identified, and 

they both have a rather general distribution in depth 

and salinity of water, so that in themselves they are 

of little value as indicators of the physical conditions 

of the lake. So abundant are these shells, however, 

that in many places they form loosely consolidated 

beds from 1 to 3 feet thick. Interbedded with such 

pure shell limestones are large quantities of soft, 

finely laminated limy shale in which ostracode valves 

are conspicuous constituents. Such vast numbers of 

these organisms must have lived in the shallow, welllighted, well-aerated, algae-rich .margins of the water 

body in which these sediments were deposited. 

In association with the ostracode-bearing limestone 

and oolite, other evidence of the same marginal conditions is found in the larval cases of trichopterous 

insects. These insects require considerable oxygen in 

the larval stage as well as such microscopic food plants 

as abound in shallow, well-lighted waters. The cases 

of these insect larvae were constructed of ostracode 

valves. Two new species of these fossil insects have 

been described by the writer. 15 

Plant remains, such as the impressions of Equisetum 

stems and the leaves of higher plants, are very common in the Morrow Creek member··of the Green River 

formation and are of sporadic occurrence in the Tipton 

tongue. A few thin beds of carbonaceous shale composed largely of carbonized plant remains also occur 

in the Green River formation of this area. The floral 

evidence from these rocks thus appears to be in 

accordance with the hypothesis that they were deposited near the margins of the ancient lake. 

In addition to the evidence already stated, . there 

exists some ~ore or less fragmentary evidence-,-for 

example, in sec. 30, T. 25 N., R. 101 W., the mingling 

of the bones of aquatic and terrestrial vertebrates in 

a thin but persistent grit which the writer believes is 

a beach deposit in the Tipton tongue of the Green 

River formation. The bones associated there are the 

teeth and vertebrae of fish and fr~gments identified 

by J. W. Gidley as belonging to Parameryx, a small 

camel. Near the top of both the Tipton tongue and 

the Morrow Creek member of the Green River formation petrified wood is rather abundant. The value 

of petrified wood as an indicator of lake-margin conditions, however, is rather doubtful. 

u Bradley, W. H., Fossil caddice-fly cases from the Green River formation of 

Wyoming: Am. Jour. Sc.i., 5th ser.; vol. 7, pp. 31Q-312, 1il24. 
I 

SHORE PHASES OF TI E GREEN RIVER FORMATION 127 

ORIGIN OF THE GREEN RIV. ER. OIL ~HALE ancy. There is considerable evidence to indicate that 

OIL SHALE OF THE LANEY SHALE MEMB::!:R the Eocene representatives of the plankton flora were 

similar in this respect. As the zooplankton depends 

Description of the Laney shale member of the Green largely upon the phytoplankton for food, there was 

Ri:ver f.ormation has. purpose~~ been defe~ed up 1 to v-ery probably an abundant microscopic fauna,. but it 

this pmnt, because Its depositiOn was evidently at- remains to be demonstrated to what extent It contended by physical conditions. that differed fr?m thp~e tributed to the organic ooze that became oil shale 

which produced the underlying and overlpng sedi- . when it was subsequently lithified. The only micro-

:ments. Thi~ :member con~ists entir~ly .of exc~e~ingly scopic animal remains so far known in the Green 

fine-grained sedi:ments whiCh contain In additiOn / to River oil shale are very rare fragments of insects. In 

the clastic mineral matter varying proportions of or- the associated beds, however, a large invertebrate and 

ganic.matter. The ?rganic content ranges from almest vertebrate fauna has been found. 

none ill the barren lnny shale t~ as T?-uch as 36 per .ce~t Pollen and spores constitute a much smaller part of 

in the richest oil shale found In this area. On distil- the organic matter than the remains of plankton, and 

lation this rich shale yielded oil a~ the rate of 315.5 as they were transported by the wind they are irregugallons to the ~hort to~. All grada~wns between th1

ese larly disseminated through the deposit. Nevertheless 

two extremes ill organic content exist, but the ~re~t~r they produce oil upon distillation, and consequently 

part of the shale in the Laney shale :member In this where they occur in abundance the shale is enriched. 

area is relatively poor in organic matter. The salllfple The more highly organized plants that grew. on the 

th~t yielded 3.5.5 gallo_ns of oil to the ton came frOlf a land adjacent to the shores and the larger . aquatic 

thill bed of ml shale .In sec. 2, T. 24 ~., R: .104 W. plants that inhabited the shallow lake margms conNorth and east of this place the organic c?ntent 1

de- tributed very little to the organic shale. Aside from 

creases rapidly, and for the last several ~ules of t~e the pollen and spores which these plants produced 

La:ney shale :member. all the shale and h~eston~ ~s they are represented in the oil shale by o:o.ly scattered 

qmte barren of organic matte~.. The physical co~di- fragments of a lignified or suberized cell, or group of 

tions that attended the depositiOn of the ~arren p1

art cells. Such fragments of higher plants are usually 

of the Laney shale member of the Green River forma- somewhat strongly humified or even carbonized and 

tion ':~re probably .similar to those that attendedJhe yield little if any oily distillate. · Precipitated ~umin 

deposi~IOn of the Tip to~ tongue of the Green. ~Iver acid, also poor in oily distillates, is apparently Inco?-

formatwn already described. The mode .of ongi~. of spicuous in the Green River oil shale. Under certam 

that part of the Laney shale :m~mber w~ch contains conditions jn small ponds and in the shallow margins 

an apprec~able con~ent of orga~I~ matter I~volves the of large lakes a type of oil shale has formed which 

more specific questiOn of the ong1n of the ml shale. contains in addition to the plankton material considerPRELIMINARY CONCLUSIONS / able humified debris and probably also precipitated 

. Regarding the conditions of deposition of the Gr1een 

River oil shale, the preliminary conclusions from the 

field and microscopic study of the last two years on 

the oil shale and microscopic flora of the Green River 

formation may be stated briefly at this time. The 

detailed evidence upon which these conclusions 1

are 

based will be presented in another paper, the comple- · 

tion of which awaits more extended field observation and microscopic study. I 

ORGANIC CONSTITUENTS 

Evidence of several kinds leads the :writer to ~el eve 

that the dominant part of the organic :matter In the 

oil shale of the Gre~n River. formation. cons.ists of lthe 

remains of planktoniC orgamsms that hved In the surface waters of the ancient lake. Probably :most of 

these organisms, which after death accumulated( on 

the lake bottom as a pu~r~scent ooze, ':ere microsc~pic 

plants. Many of the hVIng planktomc algae are pch 

in a fatty gr oily substance which is the product of · 

their :metabolism and may also serve in part for buoy1 

humin acid, both of which were derived from the m~re 

highly organized land and aquatic plants. Such an 

oil shale is likely to be of only local occurrence and 

therefore of only small commercial importance. An 

oil shale of this kind occurs in the Fuson formation 

near Cambria, Wyo. 

The evidence thus far accumulated by the writer 

suggests that there are two entirely distinct typ~s of 

oil shale the characteristics of which are determined 

largely by the depth of water in which the original 

deposit formed. . . . 

That type of oil shale which In the Green River 

formation of both the Green River and Uinta basins 

yields the most oil upon distillation B:ppears to ha~e 

resulted from a periodic concentratiOn of organic 

matter due to a very pronounced reduction in volume 

of the water body. This shale is characteristically 

black on the fresh surface and weathers bluish white. 

The lake or lakes as the case may be, in which this ' . oil shale formed were probably less than 100 feet In 

depth at the initiation of any given cycle and supported a luxuriant plankton · flora and fauna. It 
128 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1925 

seems probable that the reduction in depth and volume 

of the lakes was accompanied by stagnation and an 

increase in temperature of the water, factors both of 

which would stimulate a vastly greater production of 

the plankton and hence increase the volume of t:Q.e 

organic ooze. The facts indicate that such periodic 

reductions of volume accompanied by the augmented 

production of plankton proceeded in most places until 

there remained only a sirupy or gelatinous mass of 

putrescent organic matter on the bottoms of the lake 

basins. \ 

Desiccation appears to have been the :final phase of 

some of these periodic reductions in volume, for some 

of the oil shale is mud cracked and brecciated, and in 

places the bedding planes are studded with molds of 

salt crystals. In the samples of this brecciated oil 

· shale so far examined no pyrite has been found, but 

many of the other rich oil shales of otherwise similar 

character contain pyrite ·in varying amounts disseminated in minute grains and blebs. When these shales 

were formed reducing conditions evidently persisted 

until lithification occurred, whereas the brecciated 

shale was probably exposed for a short time at least 

to oxidizing conditions. The absence of pyrite in the 

brecciated shale, although not conclusive, is suggestive 

of exposure to air. 

Bacterial decomposition of the organic matter must 

have been effectively checked prior to lithification. 

It is not yet known whether this putrefactive decomposition was inhibited by the concentration of inorganic salts in solution or the concentration of toxins 

in the form of organic acids (the products of bacterial 

activity) or by the paucity of available water necessary 

to continued bacterial life. It seems probable that 

more than one of these factors or perhaps all acted 

simultaneously to produce the aseptic state necessary 

to the preservation of the organic matter. 

The ·other type of oil shale-the ordinary lean and 

commonly limy shale of the Green River forma.tion-as 

a rule yields an appreciably smaller quantity of oil to 

the ton on distillation. It is usually light brown or 

even dark chocolate-brown but rarely if ever black, 

and it weathers buff rather than bluish white. The 

intimate and consistent association of remains of freshwater aquatic plants, insect larvae, crustaceans, and fish 

with this lean oil shale suggests that it accumulated 

in water bodies of a more pen:nanent nature but at 

the same time of moderate depth, perhaps not exceeding 60 feet. This shale, then, probably derived 

its organic content from the accumulation on the 

bottom ·of planktonic organisms similar to those which 

constitute the water bloom of existing fresh-water 

lakes. 

The cessation of bacterial acti~ty in such an organic 

ooze would be dependent only upon the exclusion of 

sufficient water and oxygen for putrefaction, which 

would result from the compression due to the weight 

of later deposits. It is significant that the organic 

matter in this generally 1ean oil shale has been completely disorganized, presumably through the activity 

of bottom-dwelling organisms, such as certain fish, 

crustaceans, and nematodes, and of bacteria and fungi, 

whereas in the richer type of oil shale many of the 

microorganisms, spores, and pollen grains that go to 

make up the organic part of the shale have retained 

their original form and a few of them· even their 

internal structure. 

Conditions approaching those outlined above accompanied the deposition of part of the Tipton tongue 

of the Green River formation in this area and resulted 

in several beds of very low grade papery oil shale. 

These shales will yield less than 10 gallons of oil to 

the short ton on distillation. In other parts of the 

Green River Basin the Tipton tongue of the Green 

River formation . contains oil shale of a higher grade. 

Whatever kind of organic matter accumulated on 

the substratum, it was subjected to a more or less 

thorough but slow putrefaction, in which bacteria, 

saprophytic fungi, and similar microorganisms effected 

a selective decomposition, the more cellulosic parts of 

the organisms and plant parts being removed and the 

fatty, waxy, and resinous parts remaining as resistant 

matter, to be later lithi:fied and thus preserved as oil 

shale. 

CHEMICAL CHANGES 

The original organic ooze has undergone complex 

and probably numerous chemical changes since its 

accumulation on the lake bottoms. Very ·little is 

known regarding these changes except that the trend 

was evidently toward the elimination of oxygen with 

a corresponding relative increase in hydrogen and 

carbon. Part of this change may have occurred 

during the accumulation of the dead organisms on 

the substratum, through the agency of bacteria. The 

remainder of the series of changes may have occurred 

very gradually subse·queilt to lithification as purely 

chemical reactions, perhaps assisted or even entirely 

controlled by the presence of inorganic matter in a 

colloidal state. 

E. T. Erickson, of the United States Geological 

Survey, is at present engaged in a protracted study 

of the chemistry of these complex changes. Lacustrine 

organic oozes form the starting point of some of these 

investigations. · 

MINERAL CONSTITUENTS 

Concomitantly· with the accumulation of the 

organic constituents occurred· the deposition of 

varying amounts of finely divided aluminous material, 

calcium carbonate, and minute particles of quartz: 

In the Laney shale member of the Green River formatiqn the quantity of calcite far exceeds that of the 

other mineral constituents. The calcite is distributed 
SHORE PHASES OF THE GREEN RIVER FORMATION 

pretty uniformly through the shale in very fine 

particles and may have been deposited indirectly 

through the agency of bacteria. According to 

Kellerman 16 the precipitation of calcium carbonate 

may take place "by the combined action of ammonia, 

produced by bacteria either by the denitrification of 

nitrates or by the fermentatio·n of protein, together 

with carbon dioxide, produced either through the 

respiration of large organisms or the fermentation 

of carbohydrates by bacteria." There was certainly 

sufficient ammonia and carbon dioxide in a~sociation 

with the putrefying plant and animal matter at the 

bottom of the Green River lake to effect such a 

precipitation, if there was an adequate supply of 

lime salts. Kellerman's experiments 17 showed that 

ordinary crystals of calcite could be produced by a 

growth of mixed cultures of bacteria in either salt 

or fresh water. 

CLIMATE 

The climate that attended the deposition of the 

Green River. formation must have been warm and 

moist enough to support a luxuriant vegetation and 

yet of such a. seasonal nature that it alternately 

favored and inhibited the growth of woody plants. 

It appears also that the area was subject to periodic 

droughts of sufficient' length to produce very decided 

changes in the volume of la:r.-ge inland water bodies. 

MEASURED SECTIONS 

The folloWing sections, measured by the writer and 

C. H. Dane, set forth in greater detail the lithologic 

character of the several parts of the Green River and 

Wasatch formations and their lateral variations. 

Beds described as low-grade oil shale yield less than 

10 gallons • of oil to the ton. 

Sections of Tipton tongue of Green River formation in northern 

part of Sweetwater County, Wyo. 

Locality 1, sec. 1, T. 24 N., R. 100 W. 

Shale, flaky, greenish gray; contains thin beds of 

ostracode limestone and abundant fish-bone frag- ments ________________________________________ _ 

Ostracode limestone; contai~s fish-bone fragments __ _ 

Shale, flaky to lumpy, brown to chrome-yellow _____ _ Interval concealed ________________________ :. ______ _ 

Calcite parting, cone-in-cone structure ___________ :---

. Shale, laminated, brown to greenish gray; contains 

a few thin beds of impure limeston·e _______ -. _____ _ 

Clay, olive-brown _______________________________ _ 

Clay, greenish gray ______________________________ _ 

Shale, flaky, greenish gray; alternates with brown 

laminated shale and thin beds of impure limestone:.. 

Limestone, buff; contains abundant ostracodes, 'fishbone fragments, and clay balls __________________ _ 

Shale, flaky, greenish; alternates with brown paper 

shale and thin beds of sandy limestone; ostracodes numerous ______ :. _____________________________ _ 

Ft. in. 

4 9 

6 

3 

5 2 

1 

28 

1 

4 

4 6 

3 

4 6 

16 Kellerman, K. F., Relation of bacteria to deposition of calcium carbonate: 

Science, new ser., vol. 41, pp. 507-508, 1915. 

17 Idem, p. 508. 

Limestone, sandy __________________________ - --- --

Shale, flaky to laminated, greenish gray and brown __ 

Limestone, finely crystalline, yellowish gray; contains • 

many mud balls and 'mud curls ______________ ___ _ 

Interval concealed ________________ ----- _____ ------

Limestone, banded, hard ____________________ ---_-_ 

Limestone, oolitic _______________________________ _ 

·Shale, flaky, greenish gray _______ "' ________________ _ 

Alga reef, mixed with sandy limestone ______________ _ 

Shale and shaly limestone, lamina ted, gray _________ _ 

- Alga reef ______________ - - - - - - - - - - - - - - - - - - - - - - - - - -

Shale, flaky, greenish graY-------------.,------------

Limestone, oolitic; contains mud curls _____________ _ 

Shale, flaky to lumpy, gray green _________________ _ 

Shale, papery _____________________ - ________ - ____ _ 

Limestone, dense, sandy; concretionary ____________ _ 

Shale, laminated, soft, limy, brown; ostracodes numerous; contains few beds of low-grade oil shale ____ _ 

Limestone, sandy and oolitic _____________________ _ 

Shale, alternately flaky and laminated, brown to gray; containsostracodes ____________________________ _ 

Interval concealed, probably soft limy shale _________ _ 

Alga reef; ostracodes between the nodes ___________ _ 

Shale, papery, bluish white _______________________ _ 

Limestone, platy; contains many large gastropods, 

U nios, and ostracodes _________________________ _ 

18 

25 

1 

13 

3 

f ---

179 5 

Locality 2, sec. 1, T. 23 N., R. 102 W. 

Limestone, oolitic, thin bedded, buff; contains a few 

thin beds of sandy and limy shale ______________ _ 

Shale, platy, sandy, and limy ______________ ______ _ 

Shale, thin, uniform bedding, soft, grayish green ____ _ Alga reef, calcareous ____________________________ _ 

Sandstone, very fine grained, soft; contains thin beds 

of buff paper shale ____________________________ _ 

Alga reef, concentric shells of large stools and pillars 

10 inches high and 2 to 5 inches in diameter; reef is 

slightly silicified ______________________________ _ 

Shale, papery, soft, light brown; contains small amount 

of low-grade oil shale _____________________ ,.. ____ _ 

Limestone, oolitic, in part almost unconsolidated; 

ostracodes abundant in lower few inches _________ _ 

Shale, laminated and papery; contains some beds of 

carbonaceous shale and small amount of low-grade oil shale _____________ ____________ . ____________ _ 

Ostracode-bearing limestone, thick beds, gray to buff_ 

Shale, papery, brown; replete with ostracodes _____ .,. _ Clay, soft, greenish gray _________________________ _ 

Sandston~, clayey and limy, dark gray; bedding is 

very irregular and evidently indicates current or 

wave agitation at time of depositiori. ______ _, ___ J. __ _ 

Clay, light gray------------- ____ ~--- ____________ _ 

Shale, flaky, soft, brown _____ _: _________ -'---------...: 

Shale, laminated, hard, bluish gray; low-grade oil 

shale------------------------------ ---------- Oolite; contains half-inch layer of alga deposit_ ______ -

Shale, laminated, blue-gray to buff; contains ostracodes------------------------ ----------------- Alga reef __________________ ---------------------

Shale, papery, blue-gray; low-grade oil shale _____ "'--

Shale, papery; low-grade oil shale; contains numerous thin beds of ostracodes ___________ _____________ _ 

Ostracode-bearing limestone, buff _________________ _ 

Shale, papery, blue-gray; low-grade oil shale ________ _ 

Shale and ostracode-bearing limestone; consists of 

alternating thin beds of laminated shale and ·ostracodes ___ _____________________________________ _ 

Ft. in. 

6 

5 

3 

1 6 

4 

5 

8 

3 

11 

2 

8 

3 

11 

5 

15 

5 

8 

6 

3 

1 4 

10 

1 

1 

2 6 
130 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1925 

Ostracode-bearing limestone, stained with limonite; 

contains many fish7bone fragments and edgewise 

conglomerate of shale pieces ___________________ _ 

Shale, soft, gray; contains many ostracodes __ .., ___ _ _ 

Limestone, sandy, gray to faint buff; contains gastropods, ostracodes, and Unios------- ----------

Locality 3, sec. 25, T. 25 N., R. 102 W. 

Shale, limy, white ______________________________ ~_ 

Limestone, white _____________________ ___ _______ _ 

Shale, papery ____________ ___ _____ __________ _____ _ 

Limestone, banded, mud cracked _________________ _ 

Shale, papery ___________ _______ _________________ _ 

Alga reef, marbleized ______________ ___________ ___ _ 

Shale, papery _____ _______ ___ ____________________ _ 

Sandstone, cross-bedded on a small scale; contains 

beds of coarse angular quartz, grit, and stringers 

of small pebbles; bones of Parameryx and fish 

associated in the grits; beach deposit __ · __________ _ 

Interval concealed _______________________________ _ 

Clay, gray ___ _________ ______________________ ___ _ 

Shale, limy, brown _______ _______ _____ ,.. __________ _ 

Limestone, thin bedded, sandy, white _____ ________ _ 

Interval concealed ______ __ __________ ________ _____ _ 

Limestone, thin bedded, sandy, white ________ _____ _ 

Interval concealed ______ ____________________ __ ___ _ 

Shale, papery; contains thin beds of ostracode-bearing limestone ______ ____ _____________ ________ __ ___ _ 

Limestone, massive; contains gastropods and ostracodes ________________________________________ _ 

Locality 4, sec. 18, T. 24 N., R. 102 W. 

Top of bluff, approximately top of Tipton. tongue. 

Limestone, hard, yellow-brown to gray; in part 

ostracode-bearing limestone ___ _________________ _ Shale, sandy _____________________ ___________ ___ _ 

Sandstone, crudely bedded, limy, fine grained, yellow- brown ____________________________ ___________ _ 

Sandstone, thin bedded, shaly, fine grained, gray ____ _ 

Sandstone, crudely bedded, hard, micaceous; contains 

large fragments of alga reef ____________________ _ 

Sandstone, platy, micaceous, very fine grained, greenish gray _________________________________ _ 

Alga reef; breaks into fragments resembling goose-egg shell ______________________________ ___________ _ 

Shale, fissile, sandy and limy, micaceous, greenish 

gray _______ ___ ______________________ _________ _ 

Limestone, porous, sandy; contains some ostracodes __ 

Shale, papery, soft, yellowish brown _______________ _ 

Shale, papery, slate-gray _____________ .,. __________ _ _ 

Ostracode.,bearing limestone, sandy, buff __________ _ 

Limestone, dense, white ____________ · _____________ _ 

Sandstone, massive, fine grained, micaceous; contains 

round brown concretions and lenses of dark-brown 

grits which consist of angular grains of quartz and 

fresh feldspar _________________________________ _ 

Shale, very sandy, platy, hard, gray _______________ _ 

Sandstone, crudely bedded and cross-bedded, fine 

grained, micaceous, light gray to buff ____________ _ 

Limestone, shaly, poorly bedded, hard, light gray to 

white. This zone persists through several townships surrounding this place_ .. __________________ _ 

Ft. in. 

1 

115 

Ft. 

1 

3 

4 

1 

13 

4 

5 

4 

6 

21 

5 

22 

5 

2 

98 

Ft. 

1 

8 

4 

1 

2 

2 

1 

2 

4 

4 

14 

37 

8 

6 

9 

in. 

1 

2 

5 

2 

6 

6 

6 

6 

5 

in. 

6 

4 

5 

6 

6 

6 

6 

6 

1 

Shale, thin regular bedding, somewhat clayey, soft, 

brown to greenish gray _______________________ _ _ 

Shale, papery, limy, soft, brown to buff ____________ _ 

Alga reef; large well-rounded 'stools ________________ _ 

Shale, papery, soft, brown _______________________ _ 

Alga reef __ _______________________________ -· ___ - - -

Shale, flaky, very soft, brown to light gray __ . _______ _ 

Ostracode-bearing limestone, buff _______ __________ _ 

Shale, bedding obscure, sandy, light gray __________ _ 

Ostracode-bearing limestone ______________________ _ 

Limestone, massive or platy, hard, rather coarsely 

crystalline, buff; contains abundant ostracodes ____ _ 

Sandstone, limy, fine grained, hard ________________ _ 

Locality 5, sec. 18, T. 24 N., R. 103 W. 

Sandstone, limy, thin bedded and cross-bedded, 

micaceous, white to yellowish gray ______________ _ 

Sandstone, limy, soft; contains some oolite _________ _ 

Limestone, thin but very irregular bedding __ _______ _ 

Sandstone, limy, pale green; has a spherulitic texture 

due to grouping of sand grains __________________ _ 

Sandstone, massive and cross-bedded, limy _________ _ 

Limestone, poorly bedded, white _______ -------- ___ _ 

Limestone and limy shale, white to yellowish gray ___ _ Interval concealed ________ . ______________________ _ 

Oolite, bedded; contains the fossil larval cases of 

trichopterous insects _______________ - __ ~-- __ - _-- Pisolite ___________________________________ _____ _ 

Oolite; contains layers of ostracodes and a few gas- tropods ______________________________________ _ 

Alga deposit; consists of an aggregate of small sphe- . 

roidal lumps as much as 1 inch in diameter, which 

strongly resemble the so-called algoid lake balls of 

modern lakes ________________ · _________________ _ 

Limestone, clayey, light g1ay; contains abundant 

ostracodes ____ _______________________________ _ 

Limestone, massive, hard, light gray; contains large 

quantities of ostracodes and near the top many gastropods _________ __________________________ _ 

Locality 6, sec. 25, T. 25 N., R. 103 W. 

Sandstone, medium grained, thin regular bedding, 

limy, hard, light yellow-gray. Some of the thin 

beds are cross-bedded on a minute scale. Toward 

the top the sandstone becomes more massive and 

cross-bedding is more conspicuous __ -_-_ --- _----- Interval concealed ____________________ __________ _ 

Shale, very sandy, thin bedded, gray_.., __ --_ :._- ___ -_ 

Clay, soft, gray; alternates with thin beds of uncon- solidated sand ________________ ________________ _ 

Clay, soft, limy, gray and brown __________________ _ 

Shale, very limy, thin bedded to papery, gray to brown 

Clay, laminated, light greenish gray ________ ~ ______ _ 

Alga reef; in part broken and recemented __________ _ 

Clay, soft, green ___________ -_ - _------_--_---_----

Limestone, oolitic, white to buff; contains great 

numbers of ostracodes and a few gastropods ______ _ 

Ostracode-bearing limestone, hard, buff; contains some oolites and many gastropods ______________ _ 

Ft. in. 

7 6 

3 6 

2 

10 

1 

1 4 

8 

2 

2 

5 

1 

109 6 

Ft. in. 

1 6 

2 

8 

2 

9 

2 

21 

22 

1 

1 

14 

1 

1 

2 

87 6 

Feet. 

51 

12 

11 

6 

15 

16 . 

11 

2 

2 

7 

7 

140 
SHORE PHASES OF THE GREEN RIVER FORMATION 131 

Sections of Cathedral Bluffs tongue of Wasatch formation in . 

northern part of Sweetwater County, Wyo. 

Locality 7, sec. 21, T. 24 N., R. 101 W. 

Top of ridge; approximate base of Morrow Creek member of Green River formation. 

Clay, hard, gray ________________________________ _ 

Clay, mauve _______ ____________________________ _ 

Clay, hard, gray ___ :- ___________________ ~ ________ _ 

Limestone; caliche (?) _________________________ __ _ 

Clay, hard, yellow __________________ _ Limestone, caliche (?) _______________ -------------

Clay, hard, yellowish gray ___________ ~~~~~~~~~~~~~ Clay, platy, hard, limy, gray _____________________ _ 

Clay, soft, gray to yellowish gray _________________ _ 

Clay, hard, very limy; breaks into chips ___________ _ 

Sand, unconsolidated, yellowish gray ______________ _ 

Clay, greenish gray; contains turtle-bone fragments __ 

Clay, greenish gray; contains beds of reddish sand- stone ________________________________________ _ 

Locality 8, sec. 14, T. 25 N., R. 102 W. 

Clay, carbonaceous, nearly black __ -- _____________ _ Clay, gray-green ________________________________ _ 

Clay, irregularly platy, white _____________________ _ 

Clay, massive, hard, white _______________________ _ 

Clay, soft greenish gray, alternating with hard white 

claY------------------- ----------------------- Clay, dense; has conchoidal fracture 

Clay, limy, white; breaks into flat chi;s-----~==~=~~~~= Clay, light greenish gray _____________ ____________ _ 

Clay, banded, dark and light greenish gray _________ _ 

Clay, hard, white, blocky fracture ________________ _ 

Clay, dark greenish gray _________________________ _ 

Interval concealed ______ _ 

Clay, soft, gray; contains ~~~-;i~~l~t;d-;t~~~~-of-~~1~ careous alga reeL ___________ _ 

Cia y, greenish gray ____________ = = = = = = = = = = = = ~ ~ ~ ~ ~ ~ Clay, sandy, greenish gray _____________________ ___ _ 

Sandstone, very friable, distinct but irregular bedding 

light yellowish gray_---------------- __________ ~ 

Ft. 

2 

3 

7 

4 

1 

37 

1 

11 

5 

6 

8 

27 

115 

Ft. 

1 

5 

2 

14 

1 

10 

5 

16 

2 

5 

5 

6 

2 

8 

7 

in. 

5 

6 

6 

6 

7 

6 

in. 

5 

6 

6 

6 

6 

6 

6 

6 

6 

6 

93 11 

Section of Morrow Creek member of Green River formation at 

locality 9, sec. 17, T. 23 N., R. 102 W., in northern part of 

Sweetwater County, Wyo. 

Wyomingite flow capping Steamboat Mountain. 

Shale, very limy, hard, platy ____________________ _ 

Pisolite, ·completely silicified _____________________ _ 

Sandstone, very . fine grained, limy, gray to buff, 

regularly bedded _____________________________ _ 

Limestone, hard, slightly sandy, thin bedded, gray 

to faint buff _________________________________ _ 

Shale, sandy, and fine-grained sandstone, brownish 

graY------------------------------~---------- Alga reef, completely silicified ___________________ _ 

Sandstone, almost unconsolidated, medium to fine 

grained, gray; contains conspicuous amount of) 

biotUe-------------------------~-------------

Limestone, shaly, hard, irregularly platy; carries 

plant impressions ____________________________ _ 

Sandstone, limy, fine grained, soft, buff banded with 

limonitic stain ____________________ ~ __________ _ 

Interval concealed, probably soft shaly sandstone ___ _ 

Limestone, sandy at base, grading upward into shaly 

limestone, ash-gray; carries abundant plant re- mains ______________________________________ _ 

Sandstone, almost unconsolidated, fine grained, buff __ 

Sandstone, very limy, fine grained, irregularly bedded. 

Shale, flaky, crudely laminated, greenish gray ______ _ 

Shale, very soft, paper-thin laminae, buff __________ _ 

Shale, finely laminated, light brown _______________ _ 

Limestone, shaly, hard, irregularly bedded, buff _____ _ 

Shale, rather thick laminae, pale greenish gray ______ _ 

Shale, limy, soft, laminated; bedding planes wavy ___ _ 

Clay, hard, blocky, greenish buff _________________ _ 

Limestone, shaly, irregularly bedded _____________ _ 

Shale, soft, limy, paper-thin laminae; contains a few 

thin beds of low-grade oil shale ________________ _ 

Shale, flaky, greenish gray ______________________ _ 

Shale, papery, brown ___________________________ _ 

Limestone, sandy __ ____________________________ _ 

Shale, carbonaceous, black; contains abundant plant fragments ___________________________________ _ 

Ft. 

3 

70 

5 

12 

1 

10 

15 

142 

2 

1 

5 

4 

1 

4 

3 

5 

2 

1 

25 

5 

3 

in. 

6 

6 

3 

8 

6 

10 

6 

6 

6 

,i 

6 

324 3i