RELATIONS OF THE WASATCH AND GREEN RIVER FORMATIONS IN NORTHWESTERN COLORADO AND SOUTHERN WYOMING, WITH NOTES ON OIL SHALE IN THE GREEN RIVER FORMATION.

By J. D. SEARS and W. H. BRADLEY.

INTRODUCTION. Hayden named the Green River and Wasatch PURPOSE AND SCOPE OF THE REPORT. formations, and the latter name thus has Since the early geologic explorations of priority over the "Vermilion Creek series" of Powell, King, and Hayden the Eocene deposits King and the "Bitter Creek group" of Powell. of the Rocky Mountain and Plateau provinces In 1907 the western part of the Little Snake 5 have been the object of much attention by River coal field was examined by Ball. In 6 stratigraphers. More widespread interest in 1907 and 1908 Schultz mapped in detail the these deposits has been stimulated by the dis­ coal-bearing formations of the Rock Springs covery of vast quantities of oil shale in the uplift. As a result of this work and of later Green River formation of Wyoming, Colorado, reconnaissance to. the south and east, he pre­ 7 and Utah. pared a map covering most of the area The writers have had an opportunity to described in this paper. see the depositional edge of the Eocene forma- FIELD WORK. tions on the northeast flank of the Uinta Mountains and to study the significance of In 1921 and 1922 a large part of Moffat their character along this margin as compared County, Colo., and a few townships in southern with their character farther out in the basin. Sweetwater County, Wyo., were examined by The purpose of this report is to describe the parties in charge of the senior writer. He was lithology, areal distribution, and interfingering assisted in 1921 by K. K. Landes, in 1922 by of the Wasatch and Green River formations in James Gilluly, and in both seasons by the junior northwestern Colorado and southern Wyoming writer. Mapping was done largely by means of and to draw conclusions as to their source of plane tables and telescopic alidades, on a material, mode of origin, time relations, and system of triangulation extended westward and proper nomenclature. The method and place northwestward from the Craig quadrangle, of deposition ~re of special importance in Colorado. Isolated structural and areal fea­ considering the Green River formation, as they tures were mapped by means of stadia or pace largely determine the relative richness of the traverses according to the degree of refinement oil shale found in that formation. desired. The mapping was tied to section EARLIER INVESTIGATIONS. corners at numerous points. The geologic map (Pl. XXIV) accompanying The area discussed in this paper is part of the this report is compiled from the work of Ball, region explored half a century ago by Hayden/ a Ball, M. W., The western part of the Little Snake River coal field 4 Powell, 2 Hague and Emmons,S and King. Wyo.: U.S. Geol. Survey Bull. 341, pp. 243-255, 1909. ' 6 Schultz, A. R., The northern part of the Rock Springs coal field, I Hayden, F. V., U.S. Geol. Survey Terr. Third Ann. RepL, 1869. Sweetwater County, Wyo.: U. S. Geol. Survey Bull. 341, pp. 256-282, 2 Powell, J. W ., Report on the geology of the eastern portion of the 1909; The southern part of the Rock Springs coal field, Sweetwater Uinta Mountains, U.S. Geol. and Geog. Survey Terr., 2d div., 1876. County, Wyo.: U. S. Geol. Survey Bull. 381, pp. 214-281, 1910. s Hague, Arnold, and Emmons, S. F., U. S. Geol. Expl. 40th Par 7 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the Rept., vol. 2, 1877. Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey 4 King, Clarence, idem, vol. 1, 1878. , Bull. 702, pl. 1, 1920. 93 94 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924.

Schultz, and Sears. The location of the area is STRATIGRAPHY. shown in Figure 9. WASATCH FORMATION. The Wasatch deposits were named by Hay­ ACKNOWLEDGMENTS. den 8 because of their excellent exposures on The writers gratefully acknowledge the the eastern slopes of the Wasatch Mountains. cordial assistance and hospitality given by the Their lithologic character in that region is illus­ local ranchers, especially MessrR. Sparks. trated by his brief description of their ap­ Crozier, and Grounds. pearance in Echo and Weber canyons, Utah, where the formation consists of 1,500 to 2,000 TOPOGRAPHY. feet of conglomerate. In a later report Hay­ den 9 described this section more fully, noting In the southwestern part of the area mapped the large size and well-rounded shape of the Cold Spring Mountain and other ridges on the boulders and the predominant red color of the north flank of the Uinta Mountains rise to an sandstones that make up the lower 500 to 800 altitude of about 8,500 feet above sea level. feet of the formation. He noted also the rapid To the north, northeast, and east is the Green lateral changes near the base from fine sand to River Basin, separated by the Rock Springs coarse conglomerate. uplift into the Bridger Basin on the west and It is perhaps unfortunate that the name was the Washakie and Sand Wash basins on the taken from the Wasatch Mountains, where east. Although the Green River Basin is of less the formation has a lithologic character very rr======7,~=~===7.5======::;'ll different from that shown in most other areas. Hayden 10 described the Wasatch at Carter Station, Wyo., as consisting of ·pink, red, and purple indurated sandy clays, alternating with gray and reddish sandstones; this description is --~- ·---·-14'1" more applicable to the formation throughout most of its area of distribution. Hayden believed that the beds were deposited in large fresh-water lakes. Within the area mapped by the writers in 1921-22 the Wasatch consists chiefly of varie­ gated clay shale and irregular, crudely bed­ ded sandstone. The predominant colors of the clay. shale are red and gray, commonly banded with yellow, lavender, pink, brown, pale green, drab, and other shades. Most of the

FIGURE 9.-Index: map showing location of area in northwestern sandstone is gray, buff, or dark brown; a few Colorado and southern Wyoming. beds are white, pink, or red. The ·materials of the sandy beds range in size from very fine altitude than the Uinta Mountains it contains grains to coarse grits, and locally the sandstone here and there high cliffs and isolated peaks; grades into conglomerate carrying boulders as the highest point is Diamond Peak, 9,925 much as 6 feet in diameter. feet above sea level. In the Vermilion Creek basin the middle The major stream of the area mapped is part of the Wasatch contains a few beds of

Green River, which flows southward along its coal, fissile carbonaceous shale, shell marl7 western margin. Green River, with its main and many more beds of sandstone than else­ tributaries, Bitter and Vermilion creeks, drains where in the field. the Rock Springs uplift and a large part of the ' In general the Wasatch formation weathers Washakie Basin. Across the southeast corner into tYJ?ical badlands that suppor~ lit~le or _no of the area runs Little Snake River, which, veget'atwn. Topography of this kind Is varied

with its tributaries, Sand and Powder washes, s Hayden, F. V., U. S. Geol. and Geog. Survey Terr. Third Ann. drains the Sand Wash Basin and part of the Rept., p. 91, 1869. g Idem, Fourth Ann. Rept., pp. 147, 155-156, 1871. Washakie Basin. 10 Idem, p. 147. U. GEOLOGICAL StlllVBY PROFESSIONAL PAPER 132 PLATEXXIV

R . I0 2 W . R . IOI.W . R . IOOW. R. 97 W. R. 10 7 W. R.99 w . R. 98W· R . 92 W, R . 91 W. EXPLANATION SEDIMENTARY ROCKS

Bi hop cong omerat.e (ll'a.IU.-no rued ,._ gwlrtr pcOOI• ruod bovl­

Post-"Laramle" formation rGro.w o.IOd tnvw.o ..,..uw,..; gral' a..d drab Joau. oool W.: oo•g/Dm.rau a.t t.u.J UNCONFORM ITY ~ Gray, white, and brown ndstone ; coal beds; gray shale; eonglom r· ate; variegated day shale [X] Gray thin-bedded lim tonei white cross-bedded sa.ndstone; reo, gray. and drab shale

UNCONFO RMI TY // / ~ s// // / Great thickness of red quartzite and sandstone; some shale and white sandstone and quartzite

IGNEOUS ROCKS } J{ rnBasalt EB s Anticlinal axis EJ Fault GEOLOGIC MAP 10. do..m.t.row: U. "ptJorow) SH WING RE LATION AND DISTRIBl TION OF W SAT H AND GREEN RI\ ER FORMATIONS Boundaries taken from U. S. Geol. Survey Bull. 702, by A. R. Schultz, and from IN NORTHWE 'TERN COLORADO AND SOUTHERN WYOMING Bull. 341, by M. W. Ball By J. D. Sears and W. H. Bradley Scale so6ooo 10 15 20 25 Location of measured section 1924 referred to in the text

Bu. compiled from fo.td aheeta G.otoay compolod from the work of and rrom townahip plata of the A. R.. Schultz, M. W . Ba ll, and J. D. S..ra G.neral LAnd Office Surveyed in 1907-t9n

R. 92 W . WASATCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 95 by low escarpments and benches where the The Green River formation is peculiarly sandstone is comparatively resistant. resistant to weathering and rises in high, steep GREEN RIVER FORMATION. cliffs of monotonous buff, gray, or bluish-white tints, contrasting sharply with the brightly Remarkable exposur~s along Green River colored badlands. of ·the Wasatch. Almost as. led Hayden 11 to apply the name of that stream striking is the contrast between the Green to the series of shale and sandstone overlying River and the overlying Bridger, which weathers his Wasatch "group." The type locality of into fantastic badlands of ash or bluish gray, the formation is at the town of Green River, Wyo., where, according -to W:lnchester,t2 an varied by dark-green and light-bluish sand­ stones and a few patches of red and orange­ incomplete section has a thickness of 755 feet. colored clay shale. Other sections near by/3 in Tps. 17 and 19 N., R. 106 W., show a thickness of approximately STRUCTURE. 1,350 feet. In all these sections a coarse, The southern margin of the field is the north massive brown sandstone, 125 to 245 feet flank of the Uinta Mountain-Axial Basin arch. thick (the " Tower sandstone" of Powell), is West of Little Snake River the Eocene beds, included in the top of the formation. The dipping away from the mountains, rest with remainder of the formation at the type locality marked angular unconformity upon the up­ consists almost entirely of finely laminated turned edges of Mesozoic rocks, showing that shale, some of which is rich oil shale. A few uplift of the Uinta region both preceded and beds. of thin platy sandstone and sandy shale followed Eocene deposition. Farther south­ occur at wide intervals in these sections. A east no angular unconformity is found below very striking feature of the Green River in · the Wasatch and Green River, a fact which this part of the field is its bluish-white color on indicates that · movement of th~ Axial Basin weathered surfaces. anticline began after the end of Eocene time. Farther southeast, in the outcrops sur- North of this great uplift is the broad rounding the Washakie and Sand Wash basins, Green River Basin, which in the area here the formation shows a somewhat different mapped is divided by the north-south Rock lithology. The "Tower sandstone" of Powell Springs uplift into two synclinal depressions. was not recognized by the writers in the southern The western depression, known as the Bridger. part of this area, but it may be represented by Basin, is partly within this area. The eastern one or more of the sandstones in the upper depression is separated by one or two east­ part of their Green River. The contact west arches into the Washakie Basin on the between this formation and the overlying north and the Sand Wash Basin· on the south. Bridger was difficult to determine; it was drawn The present southern edge of the Eocene in the field at the horizon considered to mark outcrops is determined partly by the original most plainly a change . in conditions of sedi- limits of deposition and partly by structure. mentation. This mapping includes at the top At the southwest it is marked in part by the of the Green River about 135 feet of beds that great Uinta fault,· which extends for many resemble somewhat the overlying as well as the miles westward from the northwest corner of underlying rocks. The Green River in this Colorado; some if not all of the movement part of the field is about 1,200 feet thick and along this fault was post-Wasatch. It is consists principally of finely laminated shales, possible that the fault between the Cretaceous many of which are very limy, and some beds of and the Wasatch rocks, extending from Dia­ low-grade oil shale. The formation weathers mond Peak southeastward to a point beyond to a characteristic buff color. In the upper East Fork of Vermilion Creek, is a continuation 500 or 600 feet there is a greater amount of of the Uinta fault, but their relation is con­ clay shale and thin-bedded to massive sand- cealed by recent debris. stone. A few thin beds of oolitic limestone, From Vermilion Creek southeastward to generally silicified, and calcareous alga reefs Sand Creek· the margin of Eocene deposits is are scattered through the section. marked by a zone of en echelon faults and sharp anticlines. These and other faults u Hayden, F. V., U. S. Geol. and Geog. Survey Terr. Third Ann. Rept., p. 90, 1869. farther out in the basin have no bearing on 12 Winchester, D. E., Oil shale of the Rocky Mountain region: U.S. the character and relations of theWasatch and Geol. Survey Bull. 729, p. 125, 1923. 1a Idem, pp. 124-126. Green River and need not be described here. 96 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924.

ORIGIN AND RELATIONS OF THE WASATCH fication, grades laterally within less than a AND GREEN RIVER FORMATIONS. mile to the north and east in to carbonaceous THE UINTA MOUNTAINS AS A SOURCE OF shale, shell marl, and coarse but regularly MATERIAL. bedded sandstone-the typical Wasatch assem­ blage of this vicinity. The interfingering of Powell 14 noted the occurrence of thick con­ these several types is clearly exposed eastward glomerates in the basal part of his "Bitter in the bluffs along Talamantes Creek and to the Creek group" (Wasatch formation) .on the north in deep tributary gulches. There can be north side of the Uinta Mountains from Rich­ no doubt that the material was derived from ards Peak, Wy6., to a point east of Bruce the Uinta uplift, as the conglomerate thins Mountain, Colo. The conglomerate consists away from the mountains and consists prin­ of boulders and pebbles of sandstone and cipally of gray cherty limestone identical with limestone; in the vicinity of Richards Peak the massive Carboniferous limestone now the limestone boulders contain Jurassic fossils. exposed high on the flank of Cold Spring From these facts Powell inferred that in Mountain, less than 2 miles to the southwest. Wasatch time erosion of the Uinta Mountains Evidently the Carboniferous_rocks of the uplift had in places reached the Carboni£ erous rocks; were being eroded during at least a part of that the conglomerate referred to was formed Wasatch time. from sandstone and limestone of Mesozoic age, Westward from Sugarloaf Butte the Wasatch and, to a lesser extent, of Carboniferous age; contains near its base several beds of conglom­ and "that the badland rocks of Mesozoic age eratic sandstone consisting of abundant white were carried from the Uinta region and redis­ sugary-textured quartzite pebbles and boulders tributed as badland beds of the Bitter Creek as much as 8 inches in diameter in a white or period. " 15 Powell 16 noted also' that near the gray sandy matrix. These white quartzites Uinta uplift the Green River formation " is are very similar to the Weber and older much thickened, and the shales are replaced Pennsylvanian quartzitic sandstones exposed by sandstones and conglomerates of fine in the Uinta Mountains. Eastward from pebbles" ; from this he inferred that the Green Sugarloaf Butte as far as East Fork of V er­ River was " derived from the Uinta region, milion Creek conglomerates in the lower and that the material was supplied from lime­ Wasatch are characterized by pebbles of black stones and sandstones 'of Carboniferous age." chert; the source of the chert is unknown, but Additional evidence pointing to the Uinta the pebbles strongly resemble those of the Mountains as -a source of material was collected Dakota in color, roundness, and high polish, by the writers in 1922. Conglomerates in and they may have been reworked from that both the Wasatch and the Green River are formation. thickest and carry the largest boulders near Eastward from Godiva Ridge several con­ the mountains and thin rapidly toward the glomeratic sandstones near the base of the basin. The most conspicuous example is at Wasatch contain many well-rounded chert Sugarloaf Butte, in sees. 15 and 16, T. 11 N., pebbles less than half an inch in diameter; R. 101 W., where there is in the lower part of these pebbles, predominantly white and to a the Wasatch an. alternating series, 150 to 200 lesser extent red and black, may have been feet thick, of very coarse conglomerate, ·grit, derived either from the Uinta Mountains or and lenses of coarse cross-bedded friable buff from the Park Range, to the east. to white sandstone. Most of the boulders The developEent of conglomerate close to are well rounded by stream action, but some the mountains is illustrated also in the Green are angular and subangular; the largest boul­ River formatio . Along Canyon Creek from ders are 6 feet in diameter. (See Pl. XXV, A.) sec. 18, T. 12 N., R. 101 W., westward to Pine This notable aggregation of coarse detritus, in Mountain the upper 300 feet of the Tipton which there is only the crudest kind of strati- tongue of the Green River formation is repre­ sented by massive medium to coarse grained H Powell, J . W ., Report on t he geology of the eastern portion of the "Uinta M ountains, pp. 162-164, U.S. Geol. and Geog. Survey T err., 2d sandstones separated by very thin partings of -div., 1876. hard greenish shale. In these sandstones, ~~ Idem, p . 165. 16 Idem, p . 166. especially in the upper ones, are zones of WASATCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 97 . pebbles and boulders as large as 6 inches. in . Wasatch and Cretaceous rocks in the Axial diameter, of white and brown quartzite, Basin anticline, showing that that arch was angular red chert, hard shale, and cherty lime­ not uplifted at the earliest until after Green stone; a few boulders consist of red quartzite River time. · lithologically identical with the red quartzite that forms the core of the Uinta Mountains. BROAD VARIATIONS AWAY FROM THE SOURCE. Schultz 17 noted these conglomeratic sand­ In addition to the local changes within the stones on Canyon Creek and says: "Upstream formations near the mountains, there are on Ruby Creek toward the mountains the large-scale lateral variations in the sediments percentage of conglomerate and the size of the farther out in the basin of deposition. pebbles rapidly increase. Within a mile boul­ In the basin of Vermilion Creek the upper ders as large as 2 feet are encountered.'' North­ part of the Wasatch is principally variegated ward from the Canyon Creek coal mine, in sec. clay shale in which red is the predominant 17, T. 12 N., R. 101 W., the conglomeratic color. The lower part consists largely of gray sandstone grades laterally into gray fissile and buff clay shale and sandstone; it includes shale that is characteristic of the Tipton also some brightly colored clay shale, a few tongue. bed~ of coal which in places are thick enough Another type of evidence pointing to the to be mined for local use, thin-bedded car­ Uinta Mountains as a source of material may bonaceous shale and interbedded shell marl be summarized as follows. An erosional window (which superficially resemble the Green River in the Browns Park formation, in T. 9 N., R. formation), and at least one calcareous alga reef. In the vicinity of East Fork of Vermilion 100 W., exposes the Bridger resting with Creek, northeastward from sec. 4, T. 10 N., marked angular unconformity upon Mancos R. 100 W., a zone of clay shale and sandstone and older Mesozoic rocks dipping northeast­ near the top of the lower Wasatch grades ward on the flank of the Uinta Mountain arch. The Bridger is very conglomeratic, laterally into gray fissile shale of Green River appearance. Farther north this zone includes the boulders consisting largely of gray cherty beds of low-grade oil shale; it thickens from limestone containing Carboniferous fossils. In­ about 200 feet in sec. 3, T. 10 N., R. 100 W., asmuch as a few n1iles farther north there is no to nearly 400 feet in sees. 27 and 28, T. 12 angular unconformity between the Bridger N., R. 99 W. The method of thickening is and Green River, the fact that in T. 9 N., illustrated at the base of the fissile shale in R.100 W., the Bridger restsdirectlyuponMeso­ sees. 34 and 35, T. 11 N., R. 100 W., where a zoic rocks seems to s'4ow that the Wasatch long wedge of papery, low-grade oil shale re­ and Green River were not deposited this far places toward the north a band of gray and south, and that the Bridger was laid down as buff clay shale, and the whole Green River an overlap beyond the margins of the older zone thickens 100 feet in about a mile. Similar Eocene beds. This conclusion, together with examples were noted elsewhere along the out­ the conglomeratic nature of the Bridger, indi­ crop. cates that the east end of the Uinta Moun­ Thus the Wasatch is split northward into tains was never buried under Eocene beds but two parts by a wedge of very different material. was the site of erosion that furnished the The thickness of the lower part is unknown, Eocene sediments. On the other hand, it as the base is not exposed. The upper part, seems probable that the Wasatch and Green called by Schultz 18 the Cathedral Bluffs red River formations (and possibly the Bridger) beds member of the Green River formation, is of the Green River and Uinta basins were 1,200 feet thick at Lookout Mountain and 600 continuous around the east end of the moun­ feet thick northwest of the Washakie Basin; tains; this inference is drawn from the narrow westward and northwestward, according to interval (14 n1iles) now separating the north­ Schultz, it merges laterally into typical Green ern and southern Wasatch and Green River River shale. The wedge of fissile shale and outcrops east of Cross Mountain and from oil shale was named by Schultz 19 the Tipton the lack of angular unconformity between shale member of the Green River formation.

17 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the 1s Idem, p. 28. Rock Springs uplift, Sweetwatoc County Wyo.: U. S. Geol. Survey 19 Idem, p. 30. Bull. 702, p. 31, 1920. 98 $HORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924. On the east side of the Washakie-Sand Wash rapidly northward into a coarse-grained sand­ depression a similar change northward occurs stone with a limy cement. Just west of Little in the Wasatch. Godiva Ridge is capped by Snake River, near the center of T. 8 N., R. the main body of the Green River formation, 97 W., two or three thin beds of coal and which in this area is the Laney shale member. numerous beds of partly humified plant re­ Below this is exposed the entire Wasatch mains occur in the Laney shale several hun­ formation, 5;600 feet thick, consisting of dred feet above the base. The coal beds are brightly colored clay shale and subordinate. bony and very lenticUlar, ranging from a sandstone, with no beds of Green River type. few inches of carbonaceous material to beds North of Baggs, Wyo., the Tipton tongue of 3 feet thick Toward the north the Green the Green River enters in the midst of the River formation contains· fewer and thinner Wasatch beds, thickens northward, and, encir­ sandstones, and its buff color changes gradually cling the north end of the Washakie Basin, to the more characteristic bluish-white tone, unites with the Tipton to the west. Thus · probably owing to an increasing richness of the outcrop of the Tipton tongue has the the oil shale. shape of the letter U with the open side toward the south . . The Tipton lake may have ex­ NOMENCLATURE. tended southward to a line between Baggs The early explorers believed that the Green and East Fork of Vermilion Creek; and there Rive.r formation is not only different from the is a possibility that much of the Cathedral Wasatch in lithology but is also distinctly Bluffs tongue of red beds, deposited as this younger throughout. Such a belief is justified lake retreated, was derived from the east and in the Bridger Basin, where the Wasatch was southeast. followed by continuous Green River deposi­ In contrast to the relations described above, tion. Farther east, however, in the Washakie­ Green River deposition on the east rim of Sand Wash depression, this belief led them to the Bridger Basin was evidently not inter­ draw the boundary at the base of the beds later rupted by a temporary regression of the lake, named Laney shale member by Schultz, thus as the Wasatch and Green River show no including in the Wasatch the deposits here interfingering, even close to the mountains. called the Tipton tongue of the Green River In this area the lake probably reached the formation and the Cathedral Bluffs tongue of foot of the mountains, but as the finely lami­ the Wasatch formation. The boundary was nated shale and oil shale of the Green River drawn at the same horizon by Schultz 20 in his indicate deposition in very quiet water, mate­ reports on the coal fields of the Rock Springs rial must have been carried out from the uplift. In a later report, however, Schultz 21 mountains very slowly if at all. described the northwestward gradation of his On the rim of the· Washakie-Sand Wash Cathedral Bluffs red beds member into shale of depression the main body of the Green River Green River type and suggested that his Tipton formation (Laney shale member) undergoes shale member might die out toward the south­ a very gradual northward change. Near the east, causing an interfingering of the two forma­ mountains it is prevailingly buff and much tions. He believed that the Green River west of its shale is limy and poor in oil-yielding of the Rock Springs uplift is the time equiva­ organic matter. Although sandstones are nu­ lent of all beds east of the uplift between the merous, only one conglomerate was observed. base of the Tipton tongue and the base of the This conglomerate, about 5 feet thick, con­ Bridger, and hence he treated the Tipton tains small · subangular pebbles of black and tongue and the Cathedral Bluffs tongue as green chert and of coarse-grained red quartzite, members of the Green River formation. some grains of glassy quartz, and a few com­ pact clay balls. The pebbles average a quar­ 20 Schultz, A. R., The northern part of the Rock Springs coal field, Sweetwater County, Wyo.: U. S. Geol. Survey Bull. 341, pp. 256-282, ter of an inch in diameter; a few pebbles of 1909; The southern part of the Rock Springs coal field, Sweetwater black chert are an inch in diameter. This County, Wyo.: tr. s. Geol. Survey Bull. 381, pp. 214-281, 1910. 21 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the conglomeratic lens, near the top of the Laney Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey shale member in 'i.'. 9 N., R. 100 W., passes Bull. 702, pp. 25, 28-31, 1920. WASATCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 99 Although the time equivalenc.e suggested by arch and carried great amounts of sediment out Schultz is essentially correct, the writers believe over the lowlands. Alluvial fans of poorly that ·his classification does not adequately ex- sorted boulders were built up at the foot of the press the time and depositional relations of the mountains by torrential streams; flood-plain Wasatch and Green River. The interfingering silts and stream-channel deposits, which later of these formations, now proved to exist, may became colored clay shale and coarse, irregu­ be better indicated by the use of the term lar sandstone, were laid down farther out in the ''tongue," introduced by Stephenson.22 The basin. Here and there swamp conditions per­ names Cathedral Bluffs tongue of the Wasatch mitted the) accumulation of plant remains, formation and Tipton tongue of the Green which later became carbonaceous shale and River formation are therefore here used to re- coal. To the east and west these deposits of

Vicinity of Vicinity of Lookout Mountain, Little Snake River, Colo. · Colo.

·Fluviatile and fresh-water Vicinity of lake deposits Green River, Wyo. -­ 1,100' --·-­ Fresh-water __ -----Laney shale member of lake deposits _-- Green River formation and oil shale lake deposits ___ --- _.... ______.._ ---- ....::­ 1,350± -=-==- ~~ --Cathedral Bluffs tongue .-.=;;::".:-- of Wasatch formation ~-==--:::.-=------~ Tipton tongue-;;[(};~ Rlv-;------Fluviatile deposits

FIGURE 10.-Sections from northwest to southeast in the Green River Basin, Wyoming and Colorado, showing interfingering of the Wasatch and Green River formations. place the members of Schultz. The relations early Wasatch time merged with material of these tongues are shown diagrammatically in brought from the Park and Wasatch ranges. Figure 10. As erosion cut deeper into the mountain mass, older rocks were exposed and fragments of Car- SUMMARY OF GEOLOGIC HISTORY. boniferous limestone were carried into the The,geologic events bearing on the deposition basin. Scattered shallow ponds swarmed with and relations of the Wasatch and Green River organisms such as Unio and Goniobasis, as is in this area may be summarized as follows: attested by the abundant shell marl inter- After Cretaceous time the Mesozoic and spersed in lenses of finely laminated carbona­ older rocks were lifted many thousands of feet ceous shale. The increasing thickness of the in the Uinta Mountain arch, and ori the north Wasatch deposits caused an encroachment side part of this movement resulted in great upon the lower flanks of the mountains, as illus­ faulting. Streams began a vigorous attack on trated on Vermilion Creek by the overlap of the the Mesozoic rocks forming the surface of the Wasatch upon beds ranging in age from Mesa­ verde to Twin Creek. East of the Uinta 22 Stephenson, L. W., Tongue, a new stratigraphic term, with illustra­ Mountains the Wasatch was laid down upon tions from the Mississippi Cretaceous: Washington Acad. Sci. Jour., vol. 7, pp. 243-250, 1917. practically horizontal Cretaceous rocks. 100 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924.

Over these flood-plain deposits spread grad­ OIL SHALE IN THE GREEN RIVER FORMATION. ually a broad, shallow lake. Toward the west this lake reached the foot of the Uinta Moun­ PHYSICAL PROPERTIES. tains; here its transgression marked the end of The oil shale in the Green River formation Wasatch sedimentation, as the lake main­ may be divided into tw.o distinct varieties, be­ tained its position until the end of Green River tween which there are many gradations. One time. Farther east the margin of the lake variety is hard and tough. On fresh surfaces was a line between East Fork of Vermilion it is chocolate-brown to black and generally Creek and Baggs, Wyo. Into the quiet waters shows no distinct lamination. When weathered of this lake was transported fine sediment, it is predominantly of a bluish-white color, and which became mixed with varying amounts of its finely laminated structure is indicated by the organic matter and formed the gray fissile alternation of thin dark-gray bands with bluish­ shale and oil shale of Green River type. white layers. (See Pl. XXV, B.) The frac­ Some coarser debris was carried into the edges ture is commonly subconchoidal; freshly broken of the lake, as shown by the conglomerate in faces have a vitreous or pitchy luster in the the Tipton tongue on Canyon Creek. Mean­ richest grades and are dull in the leaner grades. while sedimentation of Wasatch type was con­ The other variety has very pronounced bedding tinuing over the flood plains not transgressed of paper thinness and is commonly called by the lake. papery shale. Its laminae, which are re­ After the deposition of several hundred feet markably flexible, separate very readily. (See of shale, forming the Tipton tongue, the margin Pl. XXV, 0.) Fresh samples are light to of the lake gradually receded to a line roughly dark brown or less commonly black; weathered marked to-day by the axis of the Rock Springs surfaces are light blu~sh gray or white. In uplift. Within the limits of the restricted general, the tough, massive variety yields more lake the formation of Green River sediments oil than the papery shale. continued, while over the fine silt left exposed by its retreat was deposited the brightly col­ CHEMICAL PROPERTIES. ored clay shale of the Cathedral Bluffs tongue. After the formation of 600 to 1,200 feet of Oil shale contains little or no petroleum as sediments composing the Cathedral Bluffs such, and only a small percentage of the organic . tongue Wasatch deposition came to an end matter can be extracted with common pe­ by a new advance of the Green River lake, troleum solvents such as · carbon tetrachloride which this time encircled the east end of the carbon bisulphide, and benzene. The per mountains and united with the lake of the centage extracted varies with the cha;racter of Uinta Basin. The much smaller thickness of the shale and the solvent, but according to a the entire Green River formation at Green table prepared by Gavin 23 the average amount River, Wyo., compared with the thickness of extracted by six solvents fr<;>m three samples of its age equivalents-the Tipton and Cathedral Green River shales was only 1.3 per cent of the Bluffs tongues and Laney shale member (pos­ weight of the samples. sibly including representatives of the "Tower Upon destructive distillation the organic sandstone" and plant beds of Powell)-at matter in the shale yields a crude oil. Accord­ Lookout Mountain, may be partly ,accounted ing to Steuart,24 Prof. Crum Brown gave the for by a gradual southeastward tilting that name ''kerogen" to this organic matter of may have been an important factor in the indefinite and variable chemical composition. second transgression of the Green River lake. The economic value of the shale depends Later folding and faulting have changed the upon the character of the kerogen and the attitude of the .Wasatch and Green River but proportions of kerogen and clastic mineral have not affected their relations. 25 matter. McKee and Goodwin · show that Two questions may be outlined as problems for future study. What was the mode of dis­ 23 Gavin, M. J ., Oil shale-an historical, technical, and economic study: U.S. Bur. Mines Bull. 210, p. 28, 1922. appearance of the Green River lake~ Are the 24 Steuart, D. R., Oil shales of the Lothians, pt. 3, The chemistry of the earliest Green River beds of the Uinta Basin oil shales, 2d ed., p. 159, Scotland Geol. Survey Mem., 1912. 1 the age equivalents of the basal Tipton tongue 25 McKee, R. H., and Goodwin, R . T., A chemical examination of the organic matter in oil shales: Colorado School of Mines Quart., vol. 18, or the basal part of the Laney shale member~ No. 1, pp. 8, 20, 1923. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 132 PLATE XXV

A. CONGLOMERATE IN THE LOWER PART OF THE WASATCH FORMATION AT SUGARLOAF BUTTE, SEC. 15, T. 11 N., R. 101 W., COLO. Compare size of boulders with height of man on right side of photograph

B. OIL SHALE IN THE GREEN RIVER FORMATION,- SHOWING CHARACTERfSTIC THIN, REGULAR BEDDING Photograph by D. E. Winchester

C. PAPERY OIL SHALE, SHOWING FLEXIBILITY Photograph by D. E. Winchester

WASATCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 101 the chemical composition of the kerogen and also near shore at places where little clastic hence of the oil distilled from it differs in material was being supplied, the proportion of different shales and even from place to place organic debris was much larger; and the shale in the same formation. For example, shale is far richer in the oil-yielding kerogen. The oil from the Green River formation in Colorado variation is strikingly shown by comparison of has a mixed paraffin and asphalt base, whereas sections of the Tipton tongue in T. 10 N., shale oil from a locality in Utah has an asphaltic R. 100 W., Colo., and T. 12 N., R. 102 W., base. The yield of oil is to some degree Wyo., with a section on Shell Creek in T. 12 dependent upon the chemical composition of N., R. 99 W., Colo.; it is indicated also by the shale, but is determined far more by the comparison of sections of the Laney shale mem­ amount of kerogen present. ber in T. 8 N., R. 97 W., and T. 10 N., R. 100 W., with those in T. 13 N., R. 99 W., and T. EFFECT OF VARYING CONDITIONS OF FORMATION 17 N., R. 106 W. These sections, given on Researches of numerous careful students 26 following pages, show a gradation northward; indicate that kerogen was formed by the ac­ as the sandstones and the more limy and cumulation in fresh water of spore exines, pol­ sandy shales disappear the percentage and len grains, the more resinous parts and some­ richness of oil shale in~rease. what macerated cuticles of larger plants, and MEASURED SECTIONS AND TESTS. the remains of various types of algae, particu­ larly the more gelatinous and filmy types. The following sections, measured by the The low orders of plant life, both sessile and writers except as otherwise noted, indicate the planktonic, the drift material, and the parts character of the formation at different locali­ of higher plants would be distributed in vary­ ties and present more detailed data concerning ing amounts through a body of fresh water lateral changes. Results of distillation tests according to depth, cun·ents, wave action, are given opposite the descriptions of the beds source of supply of extraneous material, pre­ sampled. Beds described as low-grade oil shale vailing winds, and other factors. Where clas­ yield less than 10 gallons to the ton. tic material was being carried into the lake Sections of Tipton tongue of Green River formation in the organic content of the shale formed would Moffat County, Colo., and Sweetwater County, Wyo. be relatively smaller and the value of the shale Locality 1, sec. 3, T. 10 N., R. 100 W. Ft. in as an oil producer would be lessened. Where Sandstone, buff, hard, medium grained ___ _ 2 6 the organic debris could accumulate without Sandstone, brown, thin bedded, inter- much influx of inorganic material the resultant bedded with hard gray-green shale ______21 shale would be very much richer in kerogen. Sandstone, gray, massive, medium grained. 2 8 Shale, gray-green, platy ______2 6 From this reasoning it is easily understood Sandstone, brown, medium grained ______2 why the oil shale of the Green River formation Shale, greenish brown, platy to lumpy ___ _ 8 near the east end of the Uinta Mountains is of Sandstone, brown, platy, medium grained_ 3 very low grade. Much clastic material was Shale, gray-green, platy ______. 3 carried out from the mountains and deposited Sandstone, reddish brown, medium grained, undulating bedding planes ______in the shoreward portion of the Green River 1 6 Shale, greenish brown, sandy, platy ______8 6 lake; the proportion of included organic ma­ Sandstone, brown, very fine grained ______2 terial was small. Farther out in the lake, and Shale, gray-green, platy ______2 Sandstone, brown, very fine grained ______4 26 Bertrand, C. E., Les charbons humiques et les charbons des purins: Shale, gray-green, platy ______4 Lille Univ. Trav. et Mem., vol. 6, Mem. 21, pp. 13-178, 1898; Con- ferences sur les charbons de terre: Soc. beige geol. Bull., vol. 11, p. 287, Sandstone, brown, very fine grained_----- 6 1897. Davis, C. A., On the fossil algae of the petroleum-yielding shales Clay shale, light gray------3 ofthe Green River formation of Colorado and Utah: Nat. Acad. Sci. Shale, gray-green, soft, platy ______6 Proc., vol. 2, pp. 114-119, 1916; quoted in Winchester, D. E., Oil shale in Sandstone, yellow-brown, thin bedded, fine northwestern Colorado and adjacent areas: U. S. Geol. Survey Bull. 641, p. 165, 1916; Oil shale of the Uinta Basin, northeastern Utah: u. s. grained __ ------8 Geol. Survey Bull. 691, pp. 46-47, 1918. Jeffrey, E. c., The nature of Shale, gray-green, platy to lumpy ______5 6 some supposed algal coals: Am. Acad. Arts and Sci. Proc., vol. 46, pp. Shale, brown, carbonaceous, papery; trace 273-290, 1910. Thiessen, Reinhardt, and White, David, The origin of of oiL ______5 6 coal: U. S. Bur. Mines Bull. 38; pp. 199-203, 1913; Origin of certain oil S shales: Econ. Geology, vol. 16, pp. 289-300, 1921. White, David, Late hale, gray to light brown, flaky------31 theories regarding the origin of oil: Geol. Soc. America Bull., vol. 28, Shale, chocolate-brown, carbonaceous; trace p. 730,1917. I of oiL ______3 6- 102 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924.

Ft. in. Ft. in Shale, gray, flaky----- ______3 Sandstone, blue-gray, soft, fine grained ___ _ 9 Sandstone, buff., cross-bedded, medium Sandstone, light gray, very coarse grained, grained ______10 locally cross-bedded and conglomeratic __ 10 Shale, brownish gray, papery; contains Sandstone, massive to platy, medium to many humified plant fragments ______24 fine grained ______7 Sandstone, buff, cross-bedded; upper 3 feet Shale, sandy, platy ______6 platy with shaly partings ______19 Sandstone, greenish gray, massive, sugary Shale, dark brown, papery, brittle, car­ textured, medium grained ______3 6 bonaceous; contains abundant humified Shale, sandy, interbedded with thin-bedded plant fragments ______56 medium-grained sandstone ______4 6 Wasatch formation. Shale, hard, brown; low-grade oil shale; 227 contains small limy concretions ______- 5 Locality 2, sec. 15, T. 12 N., R. 102 W. Sandstone, soft, medium to coarse grained Sandstone, brown, cross-bedded, very and slightly cross-bedded; several 6-inch coarse grained, locally conglomeratic, partings of hard shale ______24 carrying red and brown quartzite Shale, laminated to lumpy; contains sandy boulders as much as 5 inches in diameter __ 15+ lenses ______2 3 Sandstone, hard, gray; irregular thin bed- Sandstone, reddish brown, massive, medium ding ______2 6 grained ______2 6 Sandstone, light gray, cross-bedded, medium Shale, greenish gray, hard, lumpy ______2 6 to coarse grained ______2 Shale, hard, brown; low-grade oil shale; Sandstone, gray, very hard, thin bedded, weathers blue-gray_~ __ ------3 fine grained ______7 6 Sandstone, soft, medium to coarse grained __ 4 Interval concealed, probably fine-grained Sandstone, thin bedded; interbedded with lumpy sandstone ______7 shale ______5 Sandstone, cross-bedded, from medium Sandstone, brown, medium grained ______9 grained to conglomeratic ______3 Shale, dark brown, laminated; low-grade Sandstone, hard, fine grained ______4 oil shale ______-_---_ 3 Sandstone, brown, massive, coarse grained __ 2 6 Sandstone, brown, coarse grained ______;.._ 8 Sandstone, hard, massive, fine grained ___ _ 10 Shale, hard, brown, massive; low-grade oil Sandstone, massive, coarse grained; carries shale ______.______. 10 a few pebbles ______· ___ _ 2 Sandstone, brown, medium grained ______8 Shale, hard, sandy, interbedded with thin- Shale, chocolate-brown, hard, massive; low- bedded sandstone ______24 grade oil shale ______..:. ______15 Sandstone, platy, interbedded with thin, -Sandstone, red-brown, massive to thin hard, impure limestones ______6 bedded, medium to fine grained; carries Sandstone, hard, platy, very fine grained __ 4 leaf impressions; numerous thin partings Sandstone, gray, soft, thin bedded to cross- of sandy shale ______69 bedded, medium grained ______Shale, sandy, gray; few thin platy sand- Sandstone, greenish gray, hard, irregularly stones ______14 bedded; contains numerous soft white specks ______Shale, brown, papery; few thin sandstones; 5 trace of oiL ______11 Sandstone, buff, massive, fine. grained ____ _ 5 6 Concretionary zone; probably calcareous Sandstone, greenish gray, hard, irregularly alga reef ______2 bedded; contains numerous soft white Sandstone, soft, coarse grained, cross-bedded; specks ______11 lower part sandy clay shale ______30 Sandstone, gray, cross-bedded, in part con- glomeratic ______Sandstone, brqwn, thin bedded, fine grained 4 9 Clay shale, hard, gray ______9 Sandstone, thin bedded, fine grained, in­ Sandstone, brown, soft and friable, coarse terbedded with hard brown low-grade grained ______oil shale ______18 8 6 Clay shale, blue-gray ____ ---- ___ -----_-- 15 Sandstone, basal 3 feet conglomeratic, Shale, papery; low-grade oil shale ______10 carrying pebbles of white quartz, hard Clay shale, sandy, hard and lumpy ______shale, red and gray chert, and limestone; 18 remainder fine grained and irregularly Shale, brown, papery; low-grade oil shale __ 11 thin bedded ______22 Clay shale, gray; few thin sandstones ___ _ _ 5 Shale, very low-~rade oil shale, interbedded Shale, chocolate-brown, papery; low-grade oil shale ______~ ______with numerous fine-grained platy sand- 17 stones ______6 Sandstone, "limy; full of Goniobasis shells __ 2 Sandstone, brown, slightly cross-bedded; Gray and maroon clay shale of Wasatch carries subangular- white and pink formation. quartzite pebbles ______12 509+ W ASAXCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 103

Ft. in. Locality 3, sees. 27 and 28, T. 12 N., R. 99 w. Ft. in. Sandstone, coarse grained, thin bedded ___ _ 2 Red and green clay shale and sandstone of Shale, sandy, interbedded with thin sand­ the Cathedral Bluffs tongue of Wasatch stones; both carry abundant mica flakes __ 8 formation. Sandstone, white, very friable, coarse grained ______Shale, greenish gray; upper part clayey; 5 lower part laminated low-grade oil shale_ 14 Shale, dark gray, fissile ______6 Sandstone, brown, soft, thin bedded, fine Shale, dark brown, papery; tough; low-grade oil shale ______grained; ripple-marked at top ______4 6 9 6 Shale, greenish gray, hard, laminated ____ _ 2 Shale, sandy, and thin sandstones ______2 Sandstone, brown, thin bedded, fine grained, Sandstone, white, friable, medium grained, interbedded with sandy shale ______6 micaceous ______~ ______6 6 Shale, sandy, hard ______6 7 Shale, dark chocolate-brown, soft ______1 4 Sandstone, light gray, soft, thin bedded, Shale, sandy, and thin soft sandstones ___ _ 6 6 interbedded with sandy shale ______3 Sandstone, white, very soft and sugary, me- Shale, hard and sandy, interbedded with dium grained, micaceous ______8 thin fine-grained micaceous sandstones __ 6 2 Sandstone, dark reddish brown, hard, coarse Sandstone, brown, hard, medium grained, grained, cross-bedded ______2 6 in part cross-bedded; abundant mica Sandstone, buff, massive, fine grained ____ _ 6 flakes ______8 Sandstone, dark brown, much cross-bedded, Sandstone and interbedded bluish-gray medium grained ______2 shale; both micaceous ______8 Clay shale, light brown ______3 Zone of hard brown sandy concretions ___ _ 8 Sandstone, buff, soft, coarse grained ______6 Sandstone, dark gray, much cross-bedded, Shale, sandy _____ 7" ______2 fine grained; distinct parting planes of Sandstone·, brown, irregularly bedded, fine grained ______mica flakes ______1 6 Shale, light gray; few thin micaceous sandy Shale, gray, soft, flaky ______10 lenses ______10 Shale, very dark brown, hard, tough (sam- Alga reef, calcareous ______2 ple IV-53; 7.5 gallons) ______5 Shale, hard, dark gray, papery; low-grade Shale, gray to brownish, flaky ______14 oil shale ______6 Shale, dark chocolate-brown, papery; low- Sandstone, buff, medium grained; numerous grade oil shale ______8 partings of hard sandy shale ______5 6 Clay shale, greenish gray, sandy ______M Sandstone, buff, very thin bedded ______1 4 Shale, dArk brown to nearly black, papery; Shale, dark gray, papery; trace of oiL ___ _ 5 low-grade oil shale ______15 Shale, sandy, interbedded with irregular Limestone, hard, shaly ______6 thin sandstones ______2 3 Shale, dark chocolate-brown, papery, some­ Shale, hard, sandy, interbedded with hard what carbonaceous; low-grade oil shale __ 18 light-gray shale that shows trace of oiL_ 2 Clay shale ______6 Shale, sandy, and thin sandstone ______1 6 Concealed, apparently sandy shale ______40 Shale, bluish gray, hard, flaky; shows trace Sandstone, fine grained, thin bedded ______10 of oil ______1 6 Clay shale, light gray ______5 Shale, sandy, and thin sandstones ______10 Limestone, hard, shaly ______6 Clay shale, sandy ______8 Shale, chocolate-brown, papery, tough; low- Sandstone, brown, medium grained, irregu- grade oil shale ______4 8 larly bedded ______7 Shale, greenish gray, sandy, flaky ______4 Shale, gray-green, hard; trace of oil; few Shale, dark brown, papery, flexible laminae; thin lenses of very fine sand ______6 6 low-grade oil shale ______6 Sandstone, brown, soft, fine grained, mas- Shale, sandy, flaky ______sive, micaceous ______4 2 Shale, dark brown, papery; low-grade oil Shale, bluish gray, sandy ______2 6 shale ______14 Sandstone, buff, soft, medium to coarse Clay shale, sandy, and thin sandstones ___ _ 4 grained, massive, micaceous ______7 Shale, nearly black, papery; low-grade oil Shale, gray, hard, sandy; few thin sand­ shale ______32 stone lenses; carries a few plant frag- ments ______Silicified bed of small Goniobasis shells ____ _ 2 9 Sandstone, gray, medium grained, thin bed- Sandstone, drab, soft, medium grained, mi- caceous ______6 ded; carries a few larger Goniobasis shells_ 1 4 Shale, dark gray, sandy, fissile ______10 Wasatch fm;mation, main body. ---- 388 4 104 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924.

Sections of Laney shale member of Green River formation Ft. in. in Moffat County, Colo., and Sweetwater County, lVyo. Clay shale, light gray; contains water- rounded clay balls ______· 1 8 Locality 4, sees. 22 and 27, T. 10 N., R. 100 W. Marl, shaly; irregular bedding; carries pele- Sandstone, limestone, and clay shale of cypod shells ______8 Bridger formation. Alga reef, calcareous, in part silicified; Sandstone, greenish brown, medium to Ft. in. carries some oolites ______·__ _ 1 3 coarse grained, micaceous, cross-bedded __ 1 6 Clay shale, greenish gray, lumpy ______8 4 Clay shale, sandy ______7 Sandstone, very friable, very fine grained __ 21 Sandstone, greenish brown, medium grained, Shale, carbonaceous; partly humified plant cross-bedded ______2 2 remains abundant______1 8 Sandstone, greenish brown, medium grained, Shale, gray, flaky and lumpy ______6 2 platy ______6 Shale, calcareous, hard, platy ______3 Clay shale, sandy ______3 6 Shale, gray-green, flaky ______2 6 Shell marl, largely Goniobasis shells ______2 Shale, very carbonaceous ______1 Clay shale, greenish gray ______7 Clay shale, gray ______6 Sandstone, dark brown, medium grained, Sandstone, massive, medium grained ______1 6 crudely bedded ______1 8 Sandstone, extremely friable, very fine Clay shale, gray ______5 grained ______15 Sandstone, brown, medium grained ______6 Sandstone, medium grained ______1 Clay shale, greenish gray, hard ______9 6 Sandstone, soft, very fine grained ______~_ 2 6 Sandstone, brown, platy ______10 Concealed, probably clay shale ______13 Clay shale, gray ______11 Shale, gray, flaky ______7 6 Sandstone, hard, limy, medium grained; Limestone, shaly, hard, buff ______8 carries Goniobasis shells ______3 Concealed, probably soft sandstone and Clay shale, sandy ______5 clay shale ______52 Sandstone, dark brown, platy ______1 8 Shale, buff, hard, platy; trace of oiL ______7 Alga reef, calcareous; some calcareous Shale, brown, hard, limy ______8 shale ______2 6 Clay shale ______-- - -- ~ - ______7 Clay shale, gray ______21 Clay shale, sandy ______11 Sandstone, gray, fine grained ______4 Sandstone, brown, very friable, medium Clay shale, greenish gray ______8 6 grained ______1 Sandstone, brown, shaly ______20 Clay shale, greenish gray ______1 4 Limestone, shaly, buff ______1 Sandstone, gray, fine grained, banded ____ _ 2 Shale, brown, flaky ______2 Shale, brown, carbonaceous; thin shell Shale, hard, limy ______8 marls ______3 5 Shale, buff, blocky ______15 Clay shale, sandy; lenses of soft sand- stone ______Sandstone, light gray, sugary textured, 28 medium grained, friable, massive ______22 Clay shale, gray-green ___ ------2 6 Clay shale, sandy, pale green ______7 Shale, brown to black, carbonaceous ______10 Sandstone, greenish gray, fine grained ____ _ 2 Concealed, probably clay shale ______17 Clay shale, greenish gray ______8 Shiny black, soft, earthy matter; yields Sandstone, gray, medium grained ______1 some oiL ______4 Clay shale, greenish gray ______6 Concealed, probably clay shale ______33 Shale, calcareous, platy ______10 Clay shale, gray-green, sandy ______2 Clay shale, gray ______.:. _____ ~ __ 1 Clay shale, gray ______4 Shale, calcareous, platy"'"------4 Shale, papery; poorly exposed______6 Clay shale, gray ______1 Shale, dark chocolate-brown, hard, tough Shale, calcareous, hard, platy ______4 (sample 0114-A; 10 gallons) ______2 7 Clay shale, gray; contains lenses of loose Shell marl, containing flat gastropods, fish fine to coarse sand ______21 vertebrae, and bone fragments ______3 Limestone, buff, shaly, hard, blocky ______10 Shale, limy, brown; carries plant fragments; Shale, yellowish brown, lumpy ______1 low-grade oil.shale ______19 6 Limestone, brown, hard, impure, in part Shale, limy, hard ______1 4 crystalline ______5 Shale, chocolate-brown, hard, tough; low- Shale, gray to brown, platy and flaky ____ _ 12 grade oil shale ______11 4 Sandstone, light gray, friable, medium to Clay shale, gray ______1 coarse grained ______11 Shale, reddish brown, carbonaceous, very Clay shale, greenish gray, lumpy and fissile; numerous plant fragments ______8 flaky ______7 Sandstone, friable, very fine-grained car- Limestone, shaly, buff, hard, blocky ______1 4 bonaceous partings ______1 3 Clay shale; contains water-rounded clay Clay shale, gray ______1 balls ______10 Shale, brown, platy ______3 6 Shale, buff, hard, platy ______1 7 Shell marl; Goniobasis and Unio shells ___ _ 2 1 WASATCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 105

Ft. in. 1 Ft. Ill. Shale, platy; carries ostracodes ______11 Limestone, buff, shaly, hard ______1 2 Shell marl; Goniobasis shells ______1 Clay shale, light brown ______------10 Shale, dark gray; some plant fragments; Shale, limy, papery, light brown, soft ____ _ 9 6 interbedded thin shell marls ______29 Alga reef ( ?) ______------2 Limestone, shaly, hard ______6 Sa.ndstone, medium grained ______------.. 9 ShaJe, dark-brown, hard; carries ostra- Shale, light brown, laminated; trace of oiL 12 10 codes; low-grade oil shale ______14 4 Sandstone, medium grained ______.:. ______4 Shell marl, limy; largely ostracodes ______6 Limestone, gray, hard ______--- 8 Shale, dark brown, hard, platy ______10 Clay shale, gray ______------7 Shell marl, sandy; mostly small pelecypods_ 10 Shale, limy, papery ______- _--- 7 Shale, gray-brown; plant fragments ______5 7 Sandstone, buff, limy, medium to coarse Clay shale, dark greenish gray, waxy ____ _ 1 10 grained ______2 6 Shale, gray-brown, soft, fissile; carries Clay shale, gray ______------3 5 ostracodes and fragments of fish teeth __ 13 Shale, limy; faint bedding ______1 2 Shale, dark brown, papery ______3 4 Shale, dark gray, papery; trace of oiL ___ _ 5 Limestone, blue-gray, hard, lenticular ____ _ 5 Sandstone, buff, medium to coarse grained; Shale, hard, pale green, blocky (sample carries few small pebbles; locally cross­ 086-A; 4 gallons) ______21 bedded------~------9 8 Limestone, gray, hard ______4 Sandstone, shaly, blocky ______5 Shale, brown, hard, locally papery; low- Sandstone, buff, soft, friable, coarse grained 3 1 grade oil shale ______83 Sandstone, limy, buff, fine grained ______1 5 Limestone, buff, shaly, hard ______5 Shale, greenish, limy ______3 Shale, brown, hard, platy; some beds are Shale, limy, light yellow-brown, laminated_ 22 3 low-grade oil shale ______43 Shale, limy, hard, not laminated ______1 Sandstone, limy; carries Goniobasis shells_ 3 Shale, limy, light yellow, papery ______4 Shale, brown, soft, platy ______7 Limestone, shaly, lenticular ______2 Shale, dark brown, carbonaceous ______10 Shale, sandy and limy; plant fragments __ _ 4 2 Sandstone, limy, hard ______3 Clay shale, gray ______1 6 Shale, dark brown, hard, platy; low-grade Shale, light brown, papery ______18 oil shale ______87 3 Clay shale, dark gray ______1 Sandstone, platy ______10 Sandstone, buff, fine grained ______1 Shale, greenish brown, soft______16 Clay shale, gray; grades up into gray Limestone, sandy; carries ostracodes ______1 papery shale ______2 9 Shale, brown, soft______2 6 Clay shale of Cathedral Bluffs tongue of Shale, yellowish brown; abundant plant 1 Wasatch formation. fragments ______13 1, 199 11 Shale, limy, soft, laminated ______8 Shale, light brown, laminated; low-grade Locality 5, sec. 20, T. 8 N., R. 97 W. oil shale ______5 Top of bluff. Shale, gray, flaky ______1 Sandstone; carries Goniobasis and U nio Shale, limy, yellow-brown, papery, soft_ __ _ 5 shells. Ft. in. Shale, light gray, hard, platy ______23 6 Sh:a.le and thin sandstones ______11 10 Limestone, sandy, crystalline ______1 3 Sandstone, coarse grained ______2 Shale, light brown, soft______5 Shale and thin sandstones ______28 6 Shale, limy, yellowish gray, soft; traces of Shale, limy, buff; trace of oiL ______5 oil ______36 Shale, carbonaceous and clayey ______6 Limestone, shaly, hard ______4 Sandstone, fine grained, thin bedded ______3 Shale, gray, flaky ______2 1 Shale, carbonaceous and clayey ______21 8 Sandstone, yellow, coarse grained ______2 Shale, limy, hard ______2 3 Shale, limy, yellow-brown, platy ______13 8 Shale, gray, carbonaceous and clayey ____ _ 41 6 Limestone, sandy, lenticular ______3 Shale, greenish; plant fragments ______4 Clay shale, gray ______5 Limestone, shaly, gray ______1 6 Shale, limy, light brown, papery, soft_ ___ _ 9 1 Cla.y shale, gray ______2 Limestone, buff, shaly, hard ______9 Shale, limy, hard ______3 Shale, limy, light yellowish brown, papery __ 19 Shale, light brown, platy; low-grade oil Clay shale, reddish gray ______30 shale ______23 7 Alga reef, calcareous; abundant ostracodes_ 1 Clay shale, sandy; contains thin beds of Limestone, oolitic, hard ______· ______3 coal ______16 6 Shale, limy, yellow brown ______1 .5 Sandstone, brown, coarse grained ______5 Limestone, gray, hard ______3 Shale, black, carbonaceous ______3 Shale, limy, gray ______2 Shale, limy, soft______1 4 Clay shale ______3 Shale, brown; some plant fragments ______8 106 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1923-1924.

Ft. in. Ft. in· Clay shale, gray and pink ______,______12 4 Limestone, shaly, hard, buff ______4 Sandstone, gray, hard, platy, thin bedded __ 4 7 Shale, gray to buff, hard, platy to papery; Shale, limy, buff, platy ______41 some beds of low-grade oil shale ______83 6 Shale, limy, buff, hard; trace of oiL ______6 Shale, dark gray; fragments of shells; will Shale, gray; lower 48 feet limy; upper part probably yield some oiL ______2 low-grade oil shale ______61 6 Shale, black, soft ______8 1 Shale, brown to black, carbonaceous ______6 Clay shale(?), soft, yellow, waxy ____ _: ___ _ 2 Shale, sandy, gray ______4 5 Shale, gray, soft------~------4 Sandstone, fine to medium grained_ ·- ____ _ 9 6 Limestone, shaly, gray, hard ______1 Shale, sandy, hard ______2 Shale, gray, sandy and limy, flaky ______1 8 Shale, limy, hard, buff ______3 7 Sandstone and sandy shale, thin bedded __ _ 33 6 Sandstone, gray, fine grained ______4 6 Shale, limy ______27 Shale, sandy, fissile ______.,. __ _ 1 8 Sandstone, thick bedded to massive ____ ;.. __ 38 4 Shale, carbonaceous ______1 Shale, limy, platy __ _: ______14 2 Shale, limy ______~ ______3 6 Sandstone, irregularly thin bedded to mas- Shale, gray, hard; low-grade oil shale __ __ _ 20 sive ______6 8 Shale, gray, soft; trace of oiL ______52 6 Shale, gray, papery ______4 4 Shale, brown, hard; low-grade oil shale ___ _ 79 10 Sandstone (base of Green River) ______11 Shale, limy, hard, barren ______3 Shale, brown, laminated; low-grade oil 814 3 shale ______8 8 Locality 6, sec. 3, T. 13 N., R. 99 W. Shale, very limy, brown; low-grade oil shale 1 6 Shale, limy, hard, barren ______8 [According to Schultz.27] Top of bluff. Ft. in. Shale, brown, laminated, hard_} · ~ 3 Shale, limy, hard (not sam- (sample 11- Sandstone, coarse grained, not massive ___ _ 50 Sandstone, containing fossil shells ______4 8 5 6 Sandstone, coarse grained, thin bedded ___ _ 10 15 2 Sh~~:~;;~;~~~~~i~~t~d~ h~;d~ :~~~!~~· Covered, probably sandy shale ______35 Shale, limy, hard, barren ______10 Sandstone, coarse ______8 Shale, gray to brown, hard, laminated; low- Covered, mostly shale ______30 grade oil shale ______2 10 Shale, papery, drab, lean ______5 Limestone, shaly, buff, hard ______5 Shale, thin, barren, and sandstone ______72 Shale, gray to brown, hard, laminated; low- Shale, drab, thin, lean ______grade oil shale ______8 3 Shale, thin, drab, barren ______Limestone, shaly, buff, hard ______3 20 Shale, brown; weathers papery; low-grade Shale,thin,lean ______~------30 oil shale ______2 Sandstone, concretionary ______1 9 Shale, thin, lean ______Shale, black, carbonaceous ____ -'- ______2 14 Shell marl, silicified ______1 2 Oolite and chert. Shale, thin bedded, lean ______14 · Sandstone, gray, hard, fine grained ______1 2 6 Shale, piaty, silicified ______8 Shale, thin bedded; weathers blue; rich ______2 Shale, brown, fis'sile; low-grade oil shale __ _ 1 3 Shale, silicified ______7 Shale, gray, sandy (not in- . ) (sample1; 1 Shale, gray, fissile ______2 c 1u d e d m samp1 e ------7 Shale, limy, hard ______6 Sandstone, yellow (not in- 30 gal­ eluded in sample) ______lons.) 1 Shale, dark brown, hard, tough; low-grade oil shale __ ~ ______Shale, thin bedded; weathers 25 4 blue; rich ______Shale, silicified ______3 1 112 Shale, yellow, sandy ______Shale, gray to brown; low-grade oil shale __ _ 28 Shale, limy, hard ______5 Shale, papery, lean ______40 Shale, drab, fissile ______10 Shale, dark brown, hard, platy; low-grade 7 oil shale ______13 10 Sandstone, concretionary ______1 Limestone, silicified ______5 Shale, drab, 'papery (over 15 gallons) ____ _ 13 Oolite ______Shale, brown to buff; trace of oiL ______14 6 Clay shale, greenish ______2 2 Shale, drab, papery (over 15 gallons) ______10 Sandstone, oolitic ______Shale, gray, soft______"" ______8 4 3 Shale, drab, fissile ______12 Shale, dark gray, hard; low~grade oil shale_ 8 6 Sandstone, micaceous ______. Shale, gray, hard, blocky; trace of oil; inter- 1 Sandstone, yellowish ___ .__ .:. ______bedded with few thin hard shaly lime- 3 stones ______4 4 Shale, drab; thin sandstone lenses ______26 .Shale, gray, papery; limy shale interbedded_ 5 Sandstone, shaly, yellowish_ :- ______1 ·Clay shale, greenish, waxy------1 2 27 Schultz, A. R., Oil possibilities in and around Baxter Basin, in the Shale, limy, yellow, hard ______9 Rock Springs uplift, Sweetwater County, Wyo.: U. S. Geol. Survey .Shale, light brown, laminated ______8 Bull. 702, p. 54, 1920. WASATCH AND GREEN RIVER FORMATIONS IN COLORADO AND WYOMING. 107

Ft. in. Ft. in.[ . Shale, drab, papery, barren ______5 Shale, hard, nch (over 15 gal~ons) ______10 6 Shale, sandy ______Sandstone, shaly; yellowish ______1 118 Shale, greenish drab ______37 Sandstone, graY------~------4 Shale, sandy, greenish ______Cathedral Bluffs tongue of Wasatch forma- 6 tion. Sandstone, gray, thin bedded ______1 489 4 Shale, sandy, green ______27 Locality 7, sees. 17 and 19, T. 17 N •• R.106 W. Shale, sandy, thin bedded, gray ______21 [According to Winchester.2SJ Sandstone and shale, green, in· beds 2 feet Ft. in. thick; sandstone concretionary ______58 Sandstone, massive, brown, coarse ("Tower Shale, sandy, gray, slope ______97 sandstone" of Powell) ______125 Sandstone, massive, cross-bedded, forming Sandstone, thin bedded ______35 ledge and capping hill ______5 Sha~e, papery, gray ______25 Shale, forming slope __ ------43 Sandstone, shaly, gray ______32 Sandstone, rather massive, forming ledge __ _ 10 Shale, sandy, lean ______65 Shale, soft, thin, platy, barren ______30 Shale, hard; contains fish remains (sample Shale, medium hard, rather thin, very lean_ 4 11 120; 14 gallons) ______5 Shale, medium hard (sample 116; 4 gallons)_ 4 10 Shale, lean ______20 Shale, sandy, lean to barren ______70 Shale, thin, with lenses of very rich waxy Shale, medium hard, very lean ______10 Shale, lean ______shale ______~--~------55 4 6 Shale, hard ______15 Sandstone, brown, persistent_ __ ~ ______8 Shale, hard (sample 119; 12 gallons) ______5 Shale, lean ______3 6 Shale, hard, lean ______12 Shale, hard to mediu.m hard (sample 115; 9 Shale, gray, sandy ______20 gallons) ______------4 6 Shale, hard, rich (more than 15 gallons) __ _ 1 4 Shale, lean to barren ______- ______75± Shale, gray, sandy, thin sandstones, and a Shaly sandstone, barren ______15 few 1 to 3 inch beds of rich shale ______90 Shale, sandy, forming slope, lean ______47 Shale, hard, thin, medium rich ______1 6 Shale, hard (sample 114, lower 4! feet; 11 Shale, barren ______15 gallons) ______5 6 Shale, medium, with large gypsum crystals_ 1 6 Shale, hard (sample 113; 10 gallons) ______5 3 Shale, thin, barren ______80 Shale, hard ______} { 1 4 Shale, medium, with gypsum crystals ______8 Sandstone ______(sample 112; 3 Shale, gray, sandy ______26 Shale, fairly soft, thin bedded_ 9 gallons)__ · 2 9 Shale, medium, with gypsum crystals ____ _ 1 6 Shale, hard ______------1 Shale, hard, rich (over 15 gallons) ______10 Shale, hard, rich (sample 111; 19 gallons) __ _ 5 4 Sandstone, thin, gray ______8 Shale, hard, rich (sample 110; 19 gallons) __ _ 6 3 Shale, hard, rich (over 15 gallons) ______10 Shale, soft ______} { 7 Shale, gray, sandy ______17 Shale, hard, rich ______(sample 109; 2 5 Shale, hard, rich (over 15 gallons) ______2 Shale, soft ______-- - - 11 gallons)_ 6 Shale, thin, gray, sandy ______9 2 Shale, hard, rich ______2 3 2s Winchester, D. E., Oil shale of the Rocky Mountain region: U.S. Geol. Survey Bull. 729, pp. 124, 125, 1923. 1, 360 ±