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Home , Atrina, Blackhawk Formation, Book Cliffs, Burro Canyon Formation, Carlile Shale, Cedar Mountain Formation

Cretaceous and Tertiary Formations of the Carbon, Emery, and Grand Counties, , and Garfield and Mesa Counties, By D. JEROME FISHER, CHARLES E. ERDMANN, and JOHN B. REESIDE, JR.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 332

A description of J,OOO feet of strata ranging in age from Early to

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1960 DEPARTMENT OF THE INTERIOR FRED A. SEATON, Secretary

GEOLOGICAL SURVEY Thomas B. Nolan, Director

The U.S. Geological Survey Library has cataloged this publication as follows:

Fisher, Daniel Jerome, 1896- Cretaceous and Tertiary formations of the Book Cliffs, Carbon, Emery, and Grand Counties, Utah, and Garfield and Mesa Counties, Colorado, by D. Jerome Fisher, Charles E. Erdmann, and John B. Reeside, Jr. Washington, U.S. Govt. Print. Off., 1959. iv, 80 p. illus., maps, diagrs., tables. 30 cm. (U.S. Geological Sur­ vey. Professional paper 332) Part of illustrative matter in pocket. Bibliography: p. 76-78. 1. Geology, Stratigraphic Cretaceous. 2. Geology, Stratigraphic Tertiary. 3. Geology Utah. 4. Geology Colorado. I. Erdmann, Charles Edgar, 1897- joint author. II. Reeside, John Bernard, 1889-1958, joint author. III. Title: Book Cliffs. (Series)

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. Pago Page Abstract ______--______-----_-_-_--______1 Tertiary system Continued Introduction ______1 "Wasatch" formation.______22 Location and character of the area.______2 .______22 Fieldwork and acknowledgments.__-_.___--______.. 2 Age and correlation of the formations. -_-_-----_-_____- 22 Previous work in the region._____._____-___-_-_-______4 Standard sequence of Cretaceous of the western The formations.______-___--___-__---____-___ 5 interior region.__-_-__-__----_--__--______22 Pre-Cretaceous formations.____-_--___-_--.______- 5 Lower Cretaceous units__-_-__--_--______24 Cretaceous and Tertiary formations.______6 Dakota sandstone______24 Sources of the nomenclature of the Cretaceous formations _ 6 Mancos shale______---____-_--____-______26 Cretaceous system ______7 Mesaverde group______31 Lower Cretaceous units______---___-__-______7 Blackhawk formation ______31 Dakota sandstone______7 Castlegate .______31 Man cos . --__-___-_--__--_--_---___-____-_- 8 formation (restricted)______31 Mesaverde group_-_____-_____------_-_----_ 9 Buck tongue of ______32 Blackhawk formation.______11 Sego sandstone______33 Formations above Blackhawk formation. ______13 Neslen formation ______33 Utah west of the Green River (western Book Cliffs) _ 13 Farrer formation______33 Castlegate sandstone.______13 Tuscher formation____.-___---_-______34 Price River formation (restricted)______14 Mount Garfield formation and Rollins sandstone Utah east of the Green River and in Colorado member, Bowie shale member, and Paonia (central and eastern Book Cliffs) ______14 shale member of the Mesaverde formation.___ 34 Castlegate sandstone.______15 Hunter Canyon formation and undifferentiated Buck tongue of Mancos shale______15 member of Mesaverde formation.______36 Sego sandstone and included Anchor Mine North Horn and Flagstaff formations undifferen­ tongue of the Mancos shale______15 tiated ______36 Units between the Sego sandstone and the Unnamed sandstone______36 Tertiary formations.______16 Colton and "Wasatch" formations.__-______36 Neslen formation ______17 Green River formation.______36 Farrer formation______-_____---___--. 17 Nonmarine faunas in the sequence.______36 Tuscher formation,______18 Origin of the formations__-_-___-__._--_-______38 Mount Garfield formation. ______19 Lower Cretaceous units______38 Hunter Canyon formation.______20 Dakota sandstone_____----__-----__-______38 Cretaceous and Tertiary systems.______20 Mancos shale and ______38 North Horn and Flagstaff formations undifferen- Post-Mesaverde formations ______40 tiated ______21 Regional relations______40 Tertiary system______21 Local sections ______41 Colton formation______-_----___-_---_-__-_ 21 References______76 Unnamed sandstone__-_-__-----____-----______22 Index.______79

ILLUSTRATIONS

Page Page PLATE 1. Generalized geologic map of Book Cliffs._ In pocket PLATE 5. A, East side of canyon of West water Wash at 2. A, Boulder-strewn shale slope at base of Book the Roberson Ranch, Utah: B, weathered sur­ Cliffs east of Desert, Utah; B, Mancos flat face of upper, white, part of Sego sandstone, south of Beckwith Plateau, Utah; C, Blue- [12 north of Cisco, Utah; C, rippled surface of castle Canyon in Beckwith Plateau, Utah. Follows Castlegate sandstone, northwest of Cisco, 3. A, Southwest edge of Beckwith Plateau, Utah______Follows 28 Utah; B, Gunnison Butte, Utah; C, Book 6. A, Crescent Wash and Crescent Butte, Utah; Cliffs east of Tuscher Wash, Utah __ Follows 12 B, Sego sandstone northwest of Thompson, 4. A, Basal in "Wasatch" forma­ Utah; C, "Wasatch" strata on east side of tion, east side of Nash Wash, northwest of Nash Wash, Utah______Follows 28 Cisco, Utah; B, Castlegate sandstone and 7. A, Book Cliffs, 7 miles north of Woodside, upper part of Blackhawk formation, west Utah, looking northeast; B, Castlegate and face of Beckwith Plateau, Utah; C, Castle­ Blackhawk formations, Nash Wash re-en­ gate sandstone in side canyon of Crescent trant, northwest of Cisco, Utah; C, wide al- [28 Wash, Utah...______. Follows 28 luvial flat, canyon of Saleratus Wash, Utah. Follows m IV CONTENTS

Page Page PLATE 8. Views in Horse Canyon area, Utah. A, PLATE 10. Columnar sections of Book Cliffs and adjacent Castlegate sandstone; B, fault cutting Blue- areas in Utah and Colorado_.______In pocket castle sandstone member of Price River formation; C, Patmos Head; D, contact of 11. Cretaceous strata encircling the Canyon North Horn and Flagstaff formations un- Lands-______-_-_-_-______In pocket differentiated on Bluecastle member of Price River formation.______Follows 36 12. Perspective diagram of correlations from 9. Views in Horse Canyon area. A, view southwestern Utah across east-central Utah looking into Sheep Canyon; B, view of for­ to southwestern Colorado-______In pocket mations in sec. 4, T. 16 S., R. 14 E.; C, con­ tact of Colton formation on North Horn and FIGURE 1. Index map showing relation of Book Cliffs, Flagstaff formations undifferentiated-. Follows 36 Utah and Colorado, to adjacent areas.____ 3

TABLES

Page Page TABLE 1. Correlation of formations in Book Cliffs and TABLE 11. found at various localities in the other areas.______24 Castlegate sandstone______32 2. fossils from the Dakota sand­ 12. Fossils found at various localities in the Price stone ______25 River formation (restricted)______32 3. Fossils found at various localities in the upper 13. Fossils found at various localities in the Buck Greenhorn equivalent.______26 tongue of Mancos shale______._____ 32 4. Fossils found at various localities in the lower 14. Fossils found at various localities in the Sego Carlile equivalent.______27 sandstone.______33 5. Fossils found at various localities in the middle 15. Fossils found at various localities in the Neslen Carlile equivalent______----_-_ 28 formation. ______34 6. Fossils found at various localities in the Ni- 16. Fossils found at various localities in the Farrer obrara equivalent, to base of Telegraph formation ______34 Creek equivalent.______29 17. Fossils found at various localities in the lower 7. Fossils found at various localities in the Tele­ part of the Mount Garfield formation _____ 35 graph Creek equivalent______-____-_____ 29 18. Fossils found at various localities in the upper 8. Fossils found at various localities in the Eagle part of the Mount Garfield formation and equivalents.______35 equivalent- ______29 19. Fossils found at various localities in the un­ 9. Fossils found' at various localities in the differentiated member of the Mesaverde equivalents of the lower part of the Pierre formation ______36 shale.. ______30 20. Fossils found at various localities in the North 10. Fossils found at various localities in the upper Horn and Flagstaff formations undifferenti­ part of the Blackhawk formation ______32 ated- ______------_____-_--_------___ 36 CRETACEOUS AND TERTIARY FORMATIONS OF THE BOOK CLIFFS, CARBON, EMERY, AND GRAND COUNTIES, UTAH, AND GARFIELD AND MESA COUNTIES, COLORADO

By D. JEROME FISHER, CHARLES E. ERDMANN, and JOHN B. REESIDE, JR.

ABSTRACT assigned to the Cretaceous and Tertiary are the North Horn and Flagstaff formations, undifferentiated, in the western The Book Cliffs form a sinuous southward-facing escarpment cliffs and the western part of the central cliffs. The Tertiary that extends in a general eastward direction from the Wasatch formations are an unnamed sandstone in the eastern cliffs, Plateau in central Utah to in western Colorado the Colton formation of Eocene age in the western cliffs, the a distance of 150 miles. The part of the Book Cliffs from the "Wasatch" formation of possible and Eocene age Wasatch Plateau to the Green River may be referred to as the in the central and eastern cliffs, and the Green River formation western cliffs, the part in Utah east of the Green River as the of Eocene age. central cliffs, and the part in Colorado as the eastern cliffs. A comparison with standard sequence for the Rocky Moun­ South of the cliffs and bordering them continuously is a low­ tains region indicates that the Lower Cretaceous formations land locally bearing such names as Castle Valley and Grand are equivalent in age to the Kootenai formation (), the Valley. South of the lowland lie three major structural fea­ Dakota sandstone is early (), the tures : from west to east the , the Salt Valley Mancos shale includes rocks ranging in age from equivalents anticline, and the Uncompahgre uplift, which cause the sinu­ of the lower parts of the Bridge Creek member of osity of the trend of the cliffs. At distances ranging up to the (late Cenomanian or early ) 10 miles north of the Book Cliffs is another escarpment, the to equivalents in the west perhaps of the Sharon Springs mem­ Roan or Brown Cliffs. ber of the and to equivalents in the east of the The lowland, the Book Cliffs, and the consist of Gregory member of the Pierre shale (). The Cretaceous and Tertiary strata that dip gently northward into Mesaverde group generally has not yielded faunas datable the and reach a total thickness of about 7,000 more closely than very late Cretaceous. feet. The age range of the strata is from to The Lower Cretaceous rocks are nonmarine and fluviatile. Eocene. The Dakota is both marine and nonmarine in Colorado and The Cretaceous rocks include, at the base Lower Cretaceous nonmarine and discontinuous in Utah. The Mancos shale is units, the in Utah and the Burro of marine origin, and the lowest parts of the Mesaverde are Canyon formation in Colorado; then, in ascending order, Upper marine and brackish water, but the upper parts are every­ Cretaceous units, the Dakota sandstone, the Mancos shale, and where nonmarine. The Upper Cretaceous beds record the the Mesaverde group. Above the Mesaverde group in the entry into the region from the south and east of marine Book Cliffs are formations of undetermined age that seem to waters that spread rapidly; in these formed an initial deposit include beds which are also found in the Wasatch Plateau, of sandy materials (Dakota). Then, over a long period the where they extend from the Cretaceous into Tertiary; there­ finer materials now composing the main body of the Mancos fore, these formations are here called Cretaceous and Tertiary shale were deposited in the marine waters. These materials, also. Above them are units considered definitely Tertiary. though dominantly fine grained, were variable in character; The Mesaverde group, because of lateral changes in character notable hiatuses may be present. Deposition of the coarser and composition, is divided into three sets of units. In the grained Mesaverde group began much earlier in the west than western cliffs the Star Point formation is not present as such, the east and proceeded with much oscillation of the shoreline, and the Blackhawk formation at the base of the group is over­ recorded by the temporary extension of sandy marine sedi­ lain by the Castlegate sandstone and the Price River forma­ mentary rocks and nonmarine rocks eastward and intervening tion (restricted by removal of the Castlegate). In the central extension of marine finer sedimentary rocks westward, though cliffs the much-thinned Blackhawk formation is overlain in the net movement was a steady eastward retreat of the sea. succession by the Castlegate sandstone, the Buck tongue of The uppermost parts of the Mesaverde group are all non- Mancos shale, the Sego sandstone, the Neslen formation, the marine rocks. The post-Mesaverde rocks are terrestrial. Farrer formation, and the Tuscher formation. In early reports the Sego, Neslen, and the Farrer formations have been con­ INTRODUCTION sidered members of the Price River formation, and the Tuscher formation was not included in the Mesaverde group. This paper is a byproduct of an examination of the In the eastern cliffs the Sego sandstone is the basal unit, con­ mineral resources of the major part of the Book Cliffs taining the Anchor Mine tongue of Mancos shale; the Sego is of Utah and Colorado. The economic findings and overlain by the Mount Garfield formation, containing in the lower part the " measures" with the Rollins sandstone part of the stratigraphic data resulting from the work member and in the upper part the "barren measures"; at the were published in the thirties (Erdmann, 1934; Fisher, top is placed the Hunter Canyon formation. The formations 1936). Important stratigraphic details, particularly CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

those concerning the relatively inaccessible higher be called the western part; the part between the Green strata, had to be left unascertained at that time, and River and the Utah-Colorado boundary, central; and a more detailed report on the was de­ the part in Colorado, eastern. The divide at the south­ ferred in the hope that additional fieldwork could ern margin of the Roan Plateau east of the Green be done. It has not been possible to do this additional River ranges in elevation between 8,000 and well over work, and the information available to the writers is 9,000 feet. The southern margin of the Roan Plateau here assembled. west of the Green River and the Beckwith Plateau, the western Book Cliffs, is relatively even and abrupt; LOCATION AND CHARACTER OF THE AREA the southern margin of the Roan Plateau east of the The Book Cliffs form a great southward-facing Green River, the central and eastern Book Cliffs, is escarpment, at some places several escarpments, ex­ much more irregular; and the cliff front is intricately tending from east-central Utah eastward into western carved into deep canyons separated by remarkable Colorado a distance of some 215 miles along the salients and headlands. The central and eastern Book cliffs, or 150 miles in a direct line. The western Cliffs stand above the shale lowland as a double boundary is the Wasatch Plateau at longitude 111°, escarpment. In Utah the lower part is capped by a and the eastern boundary is the , which bench-making sandstone unit (Castlegate), and the separates the Book Cliffs from the Grand Mesa (fig. upper part is made up of post-Castlegate formations; 1). If the map is held with its west edge down, these in Colorado the lower part is capped by the Sego cliffs appear as a great S-shaped feature extending sandstone, and the upper part is post-Sego formations. from Palisade, Colo., east of Grand Junction, to At distances of as much as 10 miles north of this Castlegate, Utah. At the base of this S is the extensive front set of cliffs, the variegated "Wasatch" strata, area constituting the Wasatch Plateau. The Book capped by the Green River formation, form a second Cliffs are a part of the Colorado Plateaus province, steep ascent, which is called the Roan or Brown Cliffs. the southeastern part of the great Intermontane The Book and Roan Cliffs consist of Cretaceous and Tertiary strata dipping in general northward into Plateaus physiographic division, which lies between the Uinta Basin (fig. 1); to the south, beyond the the and the Sierra Nevada. To­ gether with the Roan Cliffs they form a 'subsection shale flat, older rocks ( and in the main) form the surface, though Cretaceous strata 4 15 miles wide near the northern edge of the Canyon Lands, immediately south of the Uinta Basin. The appear again near the and the sinuous trend of the cliffs is controlled mainly by the La Sal Mountains. San Rafael Swell and the Uncompahgre uplift, two The area is drained by the Colorado and the Green great domal structural features lying to the south, Rivers and their tributaries. Gray Canyon has been and to a lesser extent by Salt Valley, a faulted anti­ cut through the Book Cliffs by the Green River. The cline. Immediately south of the Book Cliffs and only second-class stream is Price River, a western underlain by the Mancos shale is an extensive low­ tributary of the Green; the more important minor land, parts of which at different places from west streams are shown on plate 1, but none of these is to east are known as Castle Valley, Clark Valley, perennial throughout its entire course. Lower eleva­ Gunnison Valley, and Grand Valley. The elevation tions in the region are arid, with an average rainfall of the lowland ranges from some 4,050 feet near Green of between 5 and 10 inches, which results in a sparse River, Utah, to about 6,500 feet north of Clark Valley flora and fauna and large barren areas of well-exposed (west of Sunnyside). Much of it is still mantled strata. The higher parts receive considerably more by remnants of gravel aprons that once extended out­ rainfall and support much more vegetation, even ward from the cliffs. forests. . From this lowland, the Book Cliffs rise majestically FIELDWORK AND ACKNOWLEDGMENTS toward the highlands that form the southern border of the Uinta Basin and that are called the Roan Fisher was engaged during the summers of 1925 Plateau. This plateau is separated into eastern and and 1926 in an examination of the mineral resources western parts by the Green River; the southern ex­ of the Book Cliffs of Utah, south and east of the tension from the western part has been isolated by Sunnyside quadrangle. He was assisted by H. F. Price River and is known'as the Beckwith Plateau. Moses,and K. P. Owen in 1925.and by K. K. Landes These features' are indicated on plate 1. For con­ and R^ M. Leggette in 1926. .Erdmann spent the sum­ venience the Book Cliffs west of the Green River may mer of 1926 and part of that of 1927 in an examination PREVIOUS WORK IN THE REGION 112° . no-

112° no* 108° FIOUHB 1. Index map showing major outcrops of Cretaceous rocks in parts of the Rocky Mountains and regions (after Stose, 1932) and relation of the Book Cliffs of Utah and Colorado to other areas. Position of fence in plate 12 and location of plate 1 are shown. ' of the mineral resources of the Book Cliffs in Colorado. scribing the trip. The party descended the Gunnison He was assisted by W. D. Johnston, Jr., and W. S. River, crossed the Colorado above the mouth of the Glock in 1926 and E. H. Watson in 1927. Erdmann Gunnison, and traveled westward on a route some in 1939 examined the Horse Canyon area, near Wood- miles north of Colorado River. In Utah they ap­ side, Utah. Eeeside and E. M. Spieker had made proximately followed the course of the present-day reconnaissance studies of the whole Book Cliffs in U.S. Highway 50. Beckwith describes the "Roan" 1925, and in 1926 Keeside visited both field parties. or "Book Mountains"; the former name is applied Reeside collected additional data on the basal part especially to the cliff between the Green River and the of the Mancos shale in 1952. "" (Grand Mesa of present usage) Much use has been made of earlier work in adjoin­ because of "the color of its sides." "White River" ing areas both east and west of that covered by the (Price River of present usage) is stated to cut through fieldwork on which this report is based. The western­ the southern point of "Little Mountain," the term most part of the Book Cliffs was examined by F. R. applied to the Book Cliffs west of Green River, though Clark, and the results of his work, published in 1928, two pages farther on it is stated that "sometimes Little have been drawn on in this paper at several points. Mountain from the regular appearance and variegated The region just east of the Book Cliffs was examined color of its strata, like the Roan [Mountain], is called by W. T. Lee, and his results, published in 1912, have Book Mountain." An accurate sketch of the south­ also supplied data. The work of E. M. Spieker (1931, east edge of the Beckwith Plateau is shown, and Beck­ 1946, 1949) on the Wasatch Plateau and other areas, with describes it as follows: chiefly west of the Book Cliffs, has supplied much The mountain wall is very irregular; deep ravines and gorges help toward broad interpretations of features of the extend back into it, giving it, with its regular strata presented Book Cliffs. The writers are grateful to D. M. Kin- to us, where no sign of vegetation exists, the appearance of an ney, A. D. Zapp, and W. J. Hail, Jr., for permission unfinished fortification, on a scale which is pleasing to the imagination, and contrasts the work of men strongly with those to use in graphic form a group of six sections in the of nature. higher beds of the western Book Cliffs. *v Schiel states (1855, p. 102) : PREVIOUS WORK IN THE REGION The wearing and washing away of mountains takes place here on an immense scale, and is the more easily observed, The Franciscan friars, Dominguez and Escalante, as no vegetation of any account covers the country, hiding the did not enter the area during their exploration in destruction from the eye * * * For days before we struck 1776 and 1777, though they did travel around it. Green River, we travelled over a black, clayish, absolutely Later the Spanish Trail between Santa Fe and Cali­ sterile soil, produced by the decaying mountains, and in dif­ fornia, which crossed a small part of the district near ferent places, chiefly at a short distance from where we crossed Green River, we found remnants of those strata in Green River, was well used, but no scientist is known buttes of sometimes considerable height, some of them assum­ to have published any studies bearing on this part ing the shape of huge chimneys. of the route. William WolfskilPs trapping party in Beckwith (1855, p. 65) also notes the Spanish Trail 1830 is supposed to have been the first to follow the is "but seldom used of late ." Spanish Trail. Perhaps the first white man to acquire Powell (1875), in telling of his epic trip down the a detailed acquaintance with the eastern part of the area Green and Colorado Rivers, briefly describes the Book was the trader Antoine Rou'bidoux, who established, and Brown Cliffs in Gray and Desolation Canyons probably in the 1830's, a trading post near the present where the strata of these cliffs cross the Green River. site of Delta, Colo. Some of the goldseekers of 1849 He refers to the shale (lower) part of the Book Cliffs probably followed the trail, but after 1850 the Cali­ as the Azure Cliffs. He does not cite and may not fornia-bound travelers went by way of . have been familiar with Beckwith's description of the In 1853 Capt. J. W. Gunnison, of the United States Book Cliffs to the east. Powell's first trip down these Army, led a party, which included Lt. E. G. Beckwith, rivers was made in 1869, the the Union Pacific west from Fort Leavenworth, Kans. in search of a Railroad was completed. possible railroad route between St. Louis and San The area east of longitude 109°30' was mapped by Francisco near the 38th and 39th parallels. Gunni­ the Hay den Survey (Hayden, 1877) in 1875 and 1876, son was killed by a band of Indians in Sevier Valley, and that to the west by the Powell Survey (Powell, Utah, shortly after crossing the Wasatch Plateau. 1877) in 1876 and 1877. The Hayden maps were Beckwith (1855) and James Schiel (1855), the first published in 1877, and many data from the Powell surgeon-geologist of the party, prepared reports de­ maps appear on a hachure map of the region dated THE FORMATIONS

1878 (Powell, 1879), but none of the quadrangle sheets the westernmost part of the Book Cliffs, adjoining appeared before the next decade; these show the old the area described by Fisher (1936), was published narrow-gage railroad line, completed in 1883. It is by Clark (1928), and one dealing with an area farther interesting to note that within the area here under west and southwest in the Wasatch Plateau was pub­ discussion few of the names applied to the creeks or lished by Spieker (1931). The area of pre-Cretaceous washes on these early maps are now in local use. rocks from Valley City eastward to the Colorado Even the Beckwith Plateau is known locally as Elliot State line has been described by Dane (1935). Young Mountain; indeed, it is so much dissected that it bears (1955), in a paper on sedimentary and inter- little resemblance to a plateau. tonguing in the Book Cliffs dealt especially with the Gannett (1877, p. 346) states: zone of contact of the Mancos shale and Mesaverde The Grand River Valley is limited on the north by the Roan group along the whole length of the cliffs. Stokes, or Book Cliffs. The first name has been given them from their Peterson, and Picard (1955) presented a column for prevailing color, the second from the characteristic shape of "Salt Valley and the Book Cliffs" in a correlation the cliff, which, with its overhanging crest and slight talus chart. In the Guidebook for the Seventh Annual (curved shale slope), bears considerable resemblance to the edge of a bound book. Field Conference of the Intermountain Association of Petroleum Geologists, held in east-central Utah Dutton (1880, p. 161) writes that "Powell named in 1956, a correlation chart by Sanborn, Hill, and the Tertiaries the Roan Cliffs and the Upper Creta­ Arnold and papers by Mitchell, Carter, Katich, Abbott ceous the Book Cliffs." Later Emmons (1894, p. 399) and Liscomb, Johnson, Swain, and La Rocque dealt rather ingeniously invented another reason for the with aspects of the stratigraphy and paleontology of name "Book Cliffs," but unfortunately it applies only the Book Cliffs. Hail, Kinney, and Zapp, (1956) to the Tertiary rocks. He says: discussed problems of correlation of the latest Cre­ The latter (Green River ) are characterized by the taceous and earliest Tertiary of the western Book thinness of their strata and the great definition of their bed­ Cliffs. ding planes, so that their cliffs resemble the leaves of a book, whence the name "Book Cliffs." THE FORMATIONS The first geologic map and report on the Book Cliffs This paper deals primarily with Cretaceous and is by Peale (1878), who described the eastern part. lower Tertiary formations. Generally, the belt of Much later Eldridge (1901) published a small-scale Cretaceous rocks is wide and so also is the belt of geological map that included a little more of the Book Jurassic rocks south of them. At several places, how­ Cliffs area. Taff's brief report (1906) covers a dis­ ever, folding and erosion have exposed rocks much trict mostly to the west. The first and only previous older than Cretaceous within short distances of the geological study of the area as a whole is by Richard­ Cretaceous strata. The San Rafael Swell, the Salt son (1909); it is of reconnaissance nature. In 1909 Valley anticline, and the Uncompahgre Plateau dis­ Forrester (1918) read a paper criticizing some of play these older rocks. Richardson's stratigraphic conclusions. Lee (1912) and Woodruff (1912) examined rocks at the eastern PRE-CRETACEOUS FORMATIONS end of the Book Cliffs. Lupton (1914), Emery (1918), Gilluly (1929), McKnight (1940), and Baker In the San Rafael Swell the exposed rocks range (1946) have prepared reports which cover areas that in age from to and have been near the Green River slightly overlap the district divided into a long series of formations (Gilluly, here discussed. Clark's short report (1914) on an 1929, p. 69-103; 1928, p. 61-110). In the Salt Valley area near Thompson adds nothing to the knowledge anticline, rocks as old as Early reach of the general stratigraphy. Campbell's railroad the surface, and much the same sequence as in San guidebook (1922) gives a very interesting but non­ Rafael Swell is reported (Dane, 1935, p. 24). In technical description of the Book Cliffs region. Win­ the Uncompahgre Plateau, crystalline chester's study of the (1923) and the examina­ rocks are exposed, upon which rest a series of strata tion of bituminous sandstone beds near Sunnyside ranging in age from to Late Jurassic by Holmes, Page, and Averitt (1948) included the (Campbell, 1922; Dane, 1935; Cater, 1955). northern edge of the area. Reeside (1923), Spieker The uppermost Jurassic rocks, the Morrison forma­ and Reeside (1925, 1926), and Spieker (1946) have tion, form a varied series of beds variegated shale, published papers dealing with the Book Cliffs as part conglomerate, sandstone, and minor limestone. The of a larger area. A very thorough description of Jurassic age of the Morrison is established primarily 6 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO by its large reptilian fauna (Baker, Dane, and Reeside, SOURCES OF THE NOMENCLATURE OF THE 1936, p. 58-63); that of the underlying San Rafael CRETACEOUS FORMATIONS group by its marine fauna. The nomenclature of the Cretaceous of the Book Cliffs region is purely a lithologic nomenclature. That CRETACEOUS AND TERTIARY FORMATIONS of the major units has been carried in from other The formations dealt with in this paper range in regions by a rather roundabout procedure. That of age from Early Cretaceous to early Eocene and attain the lesser units is of local derivation. a maximum thickness of 7,000 feet (pi. 10). How­ The name Dakota has been widely used in the ever, because of their lesser economic value, the oldest western interior region of the United States for sand­ and youngest parts of this series of formations were stone that underlies the first marine Upper Cretaceous examined much less thoroughly than the middle part. deposits, though the name originated in what is now In Utah, beds that were long considered the upper­ northeastern . most part of the and of Jurassic Mancos, Mesaverde, and Lewis (which name, though age are now known to belong to the middle part not used in the Book Cliffs, enters into the discus­ of the Early Cretaceous and are called the Cedar sion later) were first applied in southwestern Colorado Mountain formation (Stokes, 1944, 1952; Katich, to, respectively, a marine shale unit that rests upon 1951). In Colorado a similar unit has been called the basal , a succeeding series of coal- the (Stokes and Phoenix, bearing sandstone and shale beds, and a second marine 1948). Little attention was given to these beds in shale unit. The second marine shale is overlain the fieldwork for the present paper, and the account conformably by a sequence of mainly nonmarine sand­ of them is largely drawn from published sources. stone and shale formerly called the Laramie forma­ The lowest unit considered in some detail in this tion but now subdivided in northwestern paper has been called the Dakota sandstone. Over­ into five formations the Pictured Cliffs sandstone, lying the Dakota sandstone is a great marine forma­ , Kirtland shale, McDermott for­ tion, the Mancos shale, which is succeeded in turn by mation, and Ojo Alamo sandstone. In southwestern a series of alternating sandstone and shale beds, in Colorado these names are also used, except that the lesser part of marine origin but in greater part of McDermott is followed by the . nonmarine origin. To the lower part of these sandy In 1906 Fenneman and Gale extended the use of beds has been generally applied the name Mesaverde, the names Dakota, Mancos, Mesaverde, Lewis, and with the rank of either a formation or a group of Laramie to the valley of the Yampa River of north­ western Colorado, thus carrying the southwestern formations. The relations between the Mancos shale nomenclature in one move across the whole length of and the overlying Mesaverde are not simple, for there Colorado. In this usage the units concerned were is a successive loss of sandstone along the outcrop strictly lithologic entities, and the succession of such from west to east by change into shale, such that in units in the valley of the Yampa River .matched that their larger aspect the two units overlap considerably of southwestern Colorado, very closely. Thus, though the higher parts of the Mancos shale of the east were the geographic extension of the nomenclature was formed contemporaneously with the lower parts of large, there was justification for it in the common the Mesaverde of the west. In the Book Cliffs few practice of American geologists then and now. It fossils are known from the higher parts of the sandy can be shown by fossils that the units do not match series, and it is not yet certain how they should be well in a chronological sense, but that is equally true classified. In this paper they have been excluded of many other such extensions of a lithologic nomen­ from the Mesaverde group and viewed as units of clature. undetermined age. Upon this undetermined zone lies In 1907 and 1910 Gale applied Mancos and Mesa­ a series of beds of long accepted as typical verde to the formations of the Danforth Hills and the of the , which in its strictest sense as far south as Colorado River, should be of early Eocene age. Work in areas both having traced the formations southward from the east and west of the Book Cliffs raises some question valley of the Yampa River. In crossing the Axial about their age assignment, though in this paper the Basin anticline, Gale concluded, the Lewis and beds are left under the designation "Wasatch." The Laramie formations had disappeared and their hori­ highest unit is the Green River formation, of Eocene zons were represented by an at the age. top of- a thickened Mesaverde formation. CRETACEOUS SYSTEM Richardson in 1907 and again in 1909, for the Book In western Colorado the Burro Canyon formation Cliffs, and somewhat later Lee (1912, p. 18, 23-47), occupies a position similar to that of the Cedar Moun­ for the Grand Mesa, accepted Gale's interpretation tain formation. It has a basal conglomerate, above and listed Dakota, Mancos, and Mesaverde as major which are beds of limestone, , sandstone, and Cretaceous formations, though Lee stated that the some purplish and much greenish shale, the unit upper part of the Cretaceous section might be of ranging in thickness from 150 to 250 feet. It is over­ Laramie age or even younger but is "referred pro­ lain by strata that include carbonaceous materials and visionally to the Mesaverde." that are assigned to the Dakota sandstone, and it Thus the nomenclature of the Book Cliffs came from rests upon the variegated shale beds of the upper part the by way of the valley of the Yampa of the Morrison formation. River, the Danforth Hills, and the exposures south­ ward from them, all in Colorado. DAKOTA SANDSTONE Hancock in 1925 apparently accepted Gale's con­ Distribution. The Dakota sandstone immediately clusions, but Sears, in work done also in 1925, ques­ underlies the Mancos shale and rests on the variegated tioned them and was led to consider that beds of the beds of the Cedar Mountain formation or on the same age as those of the Lewis and Laramie forma­ Burro Canyon formation. So far as is known, it tions of the Yampa valley were present in the Mesa­ forms a nearly continuous belt along the south side verde sequence on the south side of Axial Basin and of the Mancos shale lowland and is absent at a few that the Lewis shale had passed laterally into beds places and is interrupted by faulting at a few others. predominantly of sandstone. Sears' findings have It has not actually been traced by the writers through­ been accepted by Hancock and Eby (1930). out the whole area, however, and was critically ex­ The present work has not shown by fossils the amined at only a few places. definite presence of strata of Lewis or post-Lewis Lithologic character and thickness. In Utah the age in the Mesaverde rocks of the Book Cliffs, but Dakota sandstone is remarkably variable in both thick­ it is possible that such rocks are included in the ness and lithologic character. It is composed of highest beds. Spieker and Reeside (1925), in defer­ friable to quartzitic sandstone and conglomerate, with ence to the older, purely lithologic nomenclature, interbedded shale and with a very few limy layers. which was considered to be more or less well estab­ It contains some beds of carbonaceous material. The lished, retained the name Mesaverde for the Book sandstone varies from a light-gray fine-grained Cliffs, accepting thus the very broad significance of sugary-textured crossbedded friable rock to hard black the term that has become customary. As commonly pebbly quartzite with a semiconchoidal fracture. The used, even in the San Juan basin, the name is applied conglomerate is locally friable; elsewhere it is firmly to strata both much older (Pike, 1947, p. 13-16; cemented in a silica matrix. The pebbles in it are Sears, 1936, p. 13-14) and much younger (Reeside, as much as 4 inches in diameter and include moder­ 1924, p. 13-16) than those of the Mesa Verde, ately well-rounded pieces of chert of several colors, Colorado, to which Holmes (1877) originally applied white to red quartzite, granite, and other igneous the name. rocks, and less well-rounded pieces of fine-textured CRETACEOUS SYSTEM gray limestone. A limestone pebble collected from LOWER CRETACEOUS UNITS the conglomerate 1^ miles south of Cedar, Utah, As noted on an earlier page, the Cedar Mountain contained Schuchertella chemungensis Conrad?, a formation is assigned to the middle part of the Lower lower species. The shale is commonly Cretaceous (Aptian). It includes the discontinuous light greenish gray, but dark grays are also present. Buckhora conglomerate member of Stokes at the base The lithologic character varies much, both laterally and a shale member above the conglomerate. The and vertically, but dense-textured light-gray limestone conglomerate is particularly marked by chert pebbles, was seen at only one locality, and there as a minor and the shale is variegated and similar to the upper lens. The thickness in the measured sections ranges part of the underlying Morrison formation. The from 2 to 126 feet, the thicker part lying to the east. shale member is said to yield most of the "" Richardson (1909, p. 13) assigns 100 feet of massive that have by some been considered characteristic of white and buff crossbedded locally conglomeratic the Morrison formation. The Cedar Mountain forma­ sandstone to this unit south of Thompson. Gilluly tion approaches 300 feet in thickness at the north end (1929, p. 114, 119) has published two sections of this of the San Rafael Swell but thins eastward. formation in the area under discussion, and Dane 8 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO (1935, p. 113-117) has published several sections from broad east-trending belt immediately south of the the region east of Salt Valley. Lupton (1916, p. 27) Book Cliffs. Topographically the unit makes up the gives a section 3 miles southwest of Mounds, near the lower or buttressing part of the Book Cliffs and the northwest corner of the area. wide expanse of lowland or "flat" extending some In Colorado, as in Utah, the Dakota sandstone is miles to the south. Near the cliffs, are com­ characterized by variability as a unit and in the in­ mon; locally, small box canyons greatly impede dividual strata. Thickness at the surface ranges travel. Plates 2 and 3.4, B show some of these from 25 to 200 feet, and where penetrated by drill features. holes, from 120 to 200 feet, but the maximum may Lithologic character and thickness. The Mancos include some of the beds of the Burro Canyon for­ shale is a well-marked lithologic unit at any given mation. locality, though its content of beds,, in a chronologic In the older literature the Dakota sandstone was sense, may differ with the locality, as described below. construed at many localities to show a threefold litho- The thickness of the formation in the area, as far logic division. as shown by the measured sections, lies between 3,450 The lowermost lithologic division, as so construed, and 4,120 feet in Utah and between 3,908 and 4,150 is not everywhere present and is characterized by feet in Colorado. There is no reason to suspect that greenish sandy shale beds that closely resemble those it is thicker to the southeast in Colorado, but Clark of the underlying Morrison and by a massive brown (1928, p. 13) has reported a thickness of 5,050 feet basal sandstone, much like that at the top of the at a locality a short distance to the west. formation but at many places including lenses of The Mancos is predominantly a monotonously uni­ chert-pebble conglomerate. This unit in recent pub­ form shale drab or bluish gray on the weathered lications has been called the Burro Canyon formation surface and very dark gray when wet. Where fresh and has been removed from the Dakota. cuts are exposed, it is dark gray, limy, and thin Above the lowermost unit usually lies the middle bedded but lacking in pronounced fissility. It-weathers division of carbonaceous shale containing of to a friable semipowdery mass that forms a sticky low rank and grade, some sandstone layers, and usually clay when wet, though water penetrates only a fraction a basal conglomerate. The uppermost division con­ of a foot as the wet surface quickly forms an imper­ sists of a lower part of gray marine shale 20-30 feet vious layer. The fresh apparently smooth shale feels thick, much like the Mancos and containing some slightly gritty to the teeth. Veinlets of gypsum and thin coarse-grained sandstone strata and more rarely are common, and patches or streaks of white basal conglomerate; this division's upper part is mas­ "alkali" are present at many places. Throughout sive brown to buff medium-grained quartzose sand­ the area especially studied in this report and at a stone 20-30 feet thick. The sandstone is also of marine distance of 100-200 feet above the base of the Mancos origin and transitional into the Mancos shale through shale is an interval containing large , which a series of thin sandstone and shale beds that may be are brownish on weathered surfaces and dark gray highly carbonaceous. The two higher divisions are on fresh surfaces; this zone of concretions forms a now considered to constitute the Dakota sandstone. conspicuous element in the sequence. Minor hogback- making sandstone beds are found at different places MANGOS SHALE and horizons, and some soft sandstone beds occur. Distribution. The Mancos shale of the area is In Utah in the northwestern part of the area, near defined as consisting of all strata from the top of Desert, several lenses of cuesta-forming sandstone are the Dakota sandstone to the base of the lowest sand­ present about 150 feet above the base of the Mancos stone unit of the Mesaverde group, which in general shale. In this same area and eastward into Colorado, is the lowest sandstone cropping out in the Book an interval of hard thin platy sandstone layers in Cliffs. The name Mancos was first applied by Cross shale 50 feet or more thick and generally cuesta form­ (1899a) to exposures near the town of Mancos in the ing is usually construed as a relatively weak east­ southwestern part of Colorado. Its use has since ward extension of part of the thick Ferron sandstone been extended, so that it includes the thick shale, member of Lupton (1916, p. 31). This interval is usually in part of Colorado age and in part of from 300 to 500 feet above the Dakota sandstone, and age, found over a large region south of the locally, as along the road south from Crescent, it forms and west of the Rocky Mountains. two cuestas. Somewhat higher sandstone beds are In the present area the Mancos shale crops out in a found near Cliff and Crescent. Similar beds are found CRETACEOUS SYSTEM 9

700-900 feet below the top near Flory, in the vicinity fresh material in most concretions and lenses is a' of Sagers and Nash Washes, in the Cottonwood Creek hard, dense dark-bluish-gray impure limestone. A reentrant north of Cisco, and near the Colorado line. few are ferruginous. Some faces of the concretions In Colorado an irregular group of thin-bedded and exhibit networks of small calcite veins. Upon weather­ platy brown sandstone and sandy shale beds is equiva­ ing, the concretions become tan to reddish brown and lent to the sandstone beds in the lower part of the disintegrate. The surface of the shale in many places Mancos of Utah construed to be an extension of the is littered with small angular fragments of concre­ Ferron. Unimportant showings of gas and oil have tionary material. Many larger concretions have been obtained from these beds in local wells, and spheroidal weathering structures. petroleum geologists have referred to them as the Contact with Mesaverde group. Along the outcrop Frontier sand. Topographically the unit is expressed the upper boundary of the Mancos shale rises strati- as a low ridge north of and parallel to the Dakota graphically toward the east by the successive passing cuesta. Three other similar sandy zones occur in into shale of eastward-pointing tongues of sandstone. the lower 2,800 feet of the formation. The lowest Between the Wasatch Plateau, Utah, and the eastern of these is 50-200 feet thick and lies 800-900 feet end of the Book Cliffs, at Palisade, Colo., the follow­ above the top of the Dakota sandstone. The base ing parts of the Mesaverde group, in the nomenclature of the next higher zone occurs approximately in the followed in this report, in turn form the basal unit: 'middle of the Mancos shale, 2,000-2,100 feet above The Star Point sandstone, Aberdeen sandstone mem­ the base. The thickness ranges from 300 to 400 feet. ber of Blackhawk formation, three successively higher Six hundred feet above the top of this zone is the members of the Blackhawk formation, the Castlegate highest member of the group, whose thickness ranges sandstone, the lower member of the Sego sandstone, from 100 to 200 feet. All are more or less incon­ and the upper member of the Sego sandstone. Ac­ spicuous topographically. Owing to weathering and cepting the local thicknesses, these steps upward are, disintegration of the sandy layers, the surface of the in round numbers, 600, 150, 300, 150, 200, 300, 250, enclosing shale is usually tan or buff. Fossils seem and 350 feet, respectively. According to W. W. Boyer more abundant in these beds than in the finer grained (written communication), a few miles south of shaly layers. Colorado River, in sec. 18, T. 12 S., R. 99 W., the In Utah the upper part of the shale is commonly upper member of the Sego passes into shale, and the sandy, more or less grading into the overlying sand­ Rollins sandstone member becomes the basal Mesa­ stone units of the Book Cliffs. Lenticular beds and verde unit. lenses of impure fine-textured gray limestone up to Young (1955), in his paper on sedimentary facies a foot or so thick are present in many places, espe­ and intertonguing in the Book Cliffs, has dealt par­ cially in the upper part of the formation. The lime­ ticularly with the zone of contact between the main stone weathers yellowish brown, is usually somewhat body of the Mancos shale and that of the Mesaverde resistant, and gives rise to small hogbacks or mounds. group and has expanded the terminology applied to In Colorado the upper thousand feet of the Mancos the Mesaverde sequence to designate 13 tongues or shale is characterized by groups of thin irregular members that toward the east pass successively into layers and overlapping lenses of calcareous sandstone, the Mancos shale. A good case can be made for this concretionary beds, and limestone. The intervals be­ procedure, but the writers have felt it more practi­ tween adjacent lenses, layers, or beds of a given group cable to use in this paper the classification adopted are usually very regular. The thickness of the groups during the active fieldwork. ranges from 4 to 15 feet; the groups are from 25 to MESAVERDE GROUP 200 feet apart and average 90 feet apart. The groups are much more resistant than the enclosing shale beds The name Mesaverde was applied originally by and crop out as low brown ledges, and more rarely as Holmes (1877) to a series of sandstone, shale, and a short steep cliff facing away from a short dip slope. coal beds on the Mesa Verde in southwestern Colorado The concretions range in size from small septaria the that are enclosed between what are now called the size of the hand to large ovoid masses 8 or 9 feet in Mancos and Lewis shales and that constitute equiva­ diameter and 5 or 6 feet thick. Some beds are merely lents of the middle part of the Montana group. In aggregates of concretions, with the intervening spaces the Book Cliffs of Colorado and Utah, the name is occupied by calcareous sandstone and shale. The applied to a sequence of rocks much like that of the 10 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO typical Mesaverde buff to yellow-brown ledge-mak­ including above the lower member a westward- ing sandstone beds, gray shale, and coal beds. The pointing tongue of Mancos shale. This provided sequence rests on the Mancos shale, but throughout the following Mesaverde units: the Book Cliffs there is no overlying counterpart of Price River formation: the Lewis shale; in fact, no later marine beds at all. Farrer non-coal-bearing member The post-Mesaverde rocks are all of fresh-water origin. Neslen coal-bearing member In the eastern part of the Wasatch Plateau Sego sandstone member (Spieker, 1931, p. 16, 21-45) and in the western end Buck tongue of Mancos shale Castlegate sandstone member of the Book Cliffs (Clark, 1928, p. 11, 12, 15, 16), Blackhawk formation the Mesaverde has been recognized as a group and has been divided into the following units, the highest at Erdmann (1934) in the eastern Book Cliffs recog­ the top of the list and the lowest at the bottom: nized the Mesaverde as a group. The Sego sandstone in his area formed the base of the Mesaverde, and he Price River formation: divided the overlying sequence into two units of for­ Non-coal-bearing member Castlegate sandstone member mation rank. The units are Blackhawk formation: Hunter Canyon formation Coal-bearing member Mount Garfield formation Aberdeen sandstone member "Barren measures" Star Point sandstone: "Coal measures," including Rollins sandstone member Spring Canyon tongue Sego sandstone Storrs tongue Upper member Panther tongue Anchor Mine tongue of Mancos shale Only the part of the Blackhawk formation above the Lower member Aberdeen member and the Price River formation of Young (1955), dealing particularly with the rocks this classification extends into the parts of the Book between the main body of the Mancos shale and the Cliffs considered in detail in the present paper. top of the Sego from the Wasatch Plateau to the In the Grand Mesa in western Colorado, Lee (1912, eastern Book Cliffs, did not recognize a Mesaverde p. 19) recognized the Mesaverde strata as a forma­ unit but assigned the post-Mancos rocks to the Star tion in which several members were named, as follows: Point sandstone, the Blackhawk formation, the Price Undifferentiated member, at top River formation, and higher strata. He recognized Paonia shale member, nonmarine 13 littoral marine sandstone tongues or members Bowie shale member, brackish-water and marine separated by westward-pointing tongues of Mancos Rollins sandstone member, at base shale, the whole forming a diagonal belt of littoral Johnson (1948) in the Paonia coal field, a part of marine rocks, the members of which appear succes­ Lee's area, continued to use Mesaverde formation, and sively in the west and give away successively to off­ divided it into members nearly equivalent to Lee's shore marine strata to the east. Above and to the units but did not use the names Bowie and Paonia west of this belt, he recognized a belt of lagoonal because of the difficulty of identifying the units by the rocks cutting across the formations that in the Price conditions under which they were formed. Johnson's River formation he designated as the Neslen facies. classification follows: Above and to the west of the lagoonal facies, he Barren member, at top recognized inland rocks that in the Price River he Upper coal member designated as the Farrer facies. The Castlegate he Lower coal member Rollins sandstone member, at base recognized as a member of the Price River that extends through the inland, lagoonal, and littoral marine Fisher (1936) did not like the term Mesaverde in facies. He shifted the Spring Canyon from the Star the western and central Book Cliffs. Part of the Blackhawk formation is present in his area, and the Point to the Blackhawk formation in the Book Castlegate sandstone extends across the area. West Cliffs. The Colorado terms Mount Garfield and of the Green River the Castlegate was considered the Hunter Canyon he abandoned as unnecessary. Young's basal member of the Price River formation, and the classification is shown in the following table. remainder formed an undivided upper member. East Each member of the Blackhawk and Price River of the Green River the Price River above the Castle­ formations was interpreted as consisting of a cyclical gate member was divided into four named members, repetition of littoral marine sandstone that grades CRETACEOUS SYSTEM 11 westward and upward into lagoonal rocks, including marine shale which fades out westward. The only coal-bearing strata and that is separated from the names applied to these marine tongues were those next higher and next lower sandstone by a wedge of already in use. Section of rocks exposed in the Book Cliffs (after Young, 1956) WEST EAST-

Formation Inland facies Lagoonal facies Littoral marine facies Marine facies

Unnamed units______.__-_--_----__. Cameo member.______Cozzette member______Price River for­ Farrer facies____ Neslen facies____ Corcoran member.______mation. Sego member, including Anchor Mine tongue. Buck tongue of Mancos shale-______Castlegate member Castlegate member.____....______. /'Desert member______Mancos shale. Grassy member.______JSunnyside member.______Blackhawk forma­ Inland facies____ Lagoonal facies _ IKenilworth member.______tion. Aberdeen member.______(.Spring Canyon member.___._-_.____-_____. fStorrs tongue._-______---___-______. Star Point sand­ \Panther tongue.--______.-____.______. stone. Subsequent publications (Stokes, Peterson, and of Mesaverde rocks over the rather long distance Picard, 1955; Sanborn, Hill, and Arnold, 1956; from the Wasatch Plateau along the Book Cliffs to Mitchell, 1956; Katich, 1956; Abbott and Liscomb, Grand Mesa, particularly east of the Green Eiver, as 1956; Swain, 1956; and La Rocque, 1956) have not indicated by the differences in the nomenclatures added material changes except that some of them adopted by various authors, and because the nomen­ show the Tuscher formation to be part of the Mesa­ clature adopted by Young does not seem particularly verde group. useful for the purposes of this paper, the \vriters have Because of the marked changes in the assemblage used the following classification for the Book Cliffs. Sections of the Mesaverde group at selected points in the Book Cliffs [All basal members are underlain by the Mancos shale]

Western Book Cliffs (Utah west of Green River) Central Book Cliffs (Utah east of Green River) Eastern Book Cliffs (western Colorado)

Tuscher formation______Hunter Canyon formation. Farrer formation. 1 Mount Garfield formation: Price River formation: "Barren measures." Bluecastle sandstone member at top. Neslen formation (includes Bluecastle [ "Coal measures," containing Rollins Unnamed member. sandstone member in upper part). J ( sandstone member. Sego sandstone...______Sego sandstone: Upper member. Anchor Mine tongue of Mancos shale: Lower member. Buck tongue of Mancos shale. Castlegate sandstone.______._. Castlegate sandstone. Blackhawk formation______Blackhawk formation: Upper member.______Shale member. Middle sandstone member. Sandstone member. Middle shale member. Lower sandstone member.

Because of these differences in classification in the of the Wasatch Plateau. It is there as much as 900 several parts of the Book Cliffs, it will be necessary feet thick and is enclosed by the Star Point sandstone in the following pages to describe the stratigraphic below and the Castlegate sandstone aboye. Eastward units in part by geographic units, though in general along the Book Cliffs, the Star Point passes into shale the order will be stratigraphic. and does not reach the area under consideration (Clark, 1928, p. 16), as is shown on plates 10, 11 and BLACKHAWK FORMATION 12. The Blackhawk formation of the western end The Blackhawk formation was defined by Spieker of the Book Cliffs consists of three eastward-pointing and Eeeside (1925, p. 443) as the coal-bearing unit sandstone tongues, each of which is overlain by a west- 12 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO ward-pointing tongue of Mancos shale. The lower ern part of the area and along the southwest part sandstone tongue was named the Aberdeen sandstone of the Beckwith Plateau, a thin coal bed is present member by Clark (1928, p. 18). It does not extend in its basal part. It crops out as a steep shale slope as far east as the area under consideration, and the between vertical sandstone cliffs, but its upper part immediately overlying shale is therefore not differ­ grades into the overlying sandstone and so at places entiated from the Mancos shale. For descriptive pur­ constitutes the lower part of a cliff (pi. 2>A}. poses the following terminology, used by Fisher Middle sandstone mem'ber. This member was (1936) in his description of the coal beds, is here traced from the western border of the area to the applied to the remaining parts of the Blackhawk: neighborhood of Saleratus Wash, where it passes into Upper member shale of the Mancos. Where measured, its thickness Middle sandstone member was found to range from 100 to 245 feet. Typically Middle shale member it appears as a massive sandstone that forms vertical Lower sandstone member cliffs (pi. 3). It is medium gray, weathering buff In the part of the area west of the Green River, the except for 1 to 3 zones at the top and in the upper Blackhawk has a thickness up to 700 feet (pi. 2(7). part, which are "white." The three white sandstone All the contacts among these members, as well as the zones are well shown a few miles north of the Price contacts with the enclosing beds, are conformable in River; northwest of that area the middle sandstone the area, though to the west Spieker and Reeside member is commonly reddish, owing to the burning (1925, p. 446) observed an erosional unconformity at of coal beds. It is generally thin to medium bedded the top of the formation in one place, and it is now and even shaly in the lower part and near its eastern known (Spieker, 1946, p. 122, 130-132) that the limits. It is commonly crossbedded, but this is not Castlegate farther west succeeds an important un­ everywhere apparent. The Sunnyside coal seam was conformity. The shale beds grade upward into the interpreted by Fisher (1936, p. 10, 13) to lie 25-75 overlying sandstone beds, but the contacts between feet below the top of this member, but Erdmann, in sandstone and overlying shale beds are at most places his section in the Horse Canyon area (see "Local quite definite, though conformable. sections, No. 5") found it convenient to assign the Lower sandstone member. This member is found coal to the base of the upper member. only in the northwestern part of the area and could Upper member. This unit ranges between 70 and be traced but a short distance east of the Green River. 230 feet in thickness where sections were taken, It dies out very rapidly, not by thinning but by pass­ although the lower figure includes only a part of the ing into shale. This change is well shown on plate 3; member. In the northwestern part of the area, it is along the west and south sides of the Beckwith Pla­ mainly of shale, closely resembling in all respects teau it forms an inaccessible cliff, while at Gunnison the middle shale member; but near the southwestern Butte on the west bank of Green River it is split part of the Beckwith Plateau (pis. 2>A and 45), into three ledges that may be ascended easily. Its it becomes sandy in its upper part. This sandy upper thickness is between 150 and 270 feet. Its contact part continues as far east as the Nash Wash reentrant with the underlying Mancos shale is gradational, but (northwest, of Cisco), where the member within a its upper surface is sharp at most places, though con­ short distance passes into shale of the Mancos. East formable with the overlying shale. It is medium gray, of Saleratus Wash the lower, shale part of the member weathering buff, except for its upper part, which in cannot be differentiated from the Mancos shale, and most places is very light gray ("white"). It ranges the upper, sandstone part in most places makes a from a calcareous argillaceous siltstone to a rather cliff continuous with that of the overlying Castlegate coarse friable sandstone. The lower part is thin bed­ sandstone, from which it is generally separated by ded and crossbedded; the upper part, massive. a locally carbonaceous or coaly, minor shaly unit that Middle shale member. This member was traced is commonly present in its top part. To one somewhat through the same area as the underlying sandstone. casually examining the sandstone beds along the cliffs, Farther east it cannot be distinguished from the what is here called the upper sandy part of this Mancos shale. Its thickness ranges from 100 to 160 member would certainly be lumped with the Castle­ feet. Though it is generally composed of medium- gate ; but if traced carefully along the western edge gray shale quite like the Mancos, varying from gritty of the Beckwith Plateau, particularly through the and limy to soft and laminated, it also contains local southwestern part, it can be clearly seen that the shale thin sandstone and siltstone layers. In places it is beds in the upper part of the member, shown in sec­ black and carbonaceous, and in the extreme northwest­ tion 4 (pi. 10) and also farther to the west, grade GEOLOGICAL STJKVEY PEOFESSIONAL PAPEK 332 PLATE 2

A. BOOK CUFFS ALONG BECKWITH PLATEAU EAST OF DESERT, UTAH Boulder-strewn shale slope showing badland character of Mancos shale, Km, near the cliffs, where it is not protected by gravel aprons, Qg.

. Stiffen,

B. MANCOS SHALE FLAT SOUTH OF BECKWITH PLATEAU, UTAH Limy and sandy layers and lenses in the shale give rise to the "beehives." Photograph by H. F. Moses.

Kpb

Jj2£i$!»-J-SiiS<«*,

C. VIEW WEST UP BLUECASTLE CANYON IN BECKWITH PLATEAU, UTAH Kbls, lower sandstone member of Blackhawk formation; Kbmsh, middle shale member of Blackhawk formation; Kbms, middle sandstone member of Blackhawfc formation; Kbum, upper member of Blackhawk formation; Kc, Castlegate sandstone; Kp, Price River formation, with Bluecastle sandstone member (Kpb) at top. GEOLOGICAL SURVEY PROFESSIONAL PAPER 332 PLATE 3

Kp

Km

Kc

A. I.OOKIXG SOUTH INTO SEC. 32, I. 2(1 >.. I;. 1 > I... U.o.NG SOUTHWEST EDGE OF BECKWITH PLATEAU, UTAH Km, Mancos shale; Kbls, lower sandstone member of Blackhawk formation; Kbmsh, middle shale member of Blackhawk formation; Kbms, middle sandstone member of Blackhawk formation; Kbum, upper member of Blackhawk formation, sandy in upper part; Kc, Castlegate sandstone, here not an important bench maker; Kp, Price River formation.

U. GUNNISON BUTTE, UTAH, FROM THE EAST Symbols as in A.

Km

C. BOOK CLIFFS EAST OF TUSCHER \V.\H! i MHiTMEAST OF GREEN RIVER, UTAH) Note the wide bench surfaced by Castlegate sandstone and the replacement of the middle sandstone member of the Blackhawk formation by Mancos shale. Symbols as in A, CRETACEOUS SYSTEM 13 laterally with some rapidity into sandstone. Section conformable but described a marked erosional bound­ 5, in "Local Sections," shows an intermediate stage, ary at the top. In Clark's area the Castlegate and in section 6 this upper part is markedly sandy. thinned eastward, and the upper member thickened Plate 3J. is a view of the cliffs in the southwestern somewhat, though the total thickness did not change part of the Beckwith Plateau, looking south into greatly. sec. 32, T. 20 S., R. 15 E. The lower sandstone Spieker (1931, p. 44) regarded the Price River of member, grading downward into the Mancos shale, the Wasatch Plateau as of late Montana age, with an makes the lowest cliff, about halfway up. Above this unconformable lower contact to the northwest but prob­ is the slope made by the middle shale member, grading ably a conformable contact in the east. The best cri­ upward into the cliff of the middle sandstone member. terion for the top of the Price River was believed to be Above this second cliff is a minor shale slope (the a limestone conglomerate and highly colored beds mark­ lower shaly part of the upper member), which is ing the Eocene. Later, Spieker (1946, p. 131) indicated overlain by a third sandstone cliff made up of the that the top of the Price River is a gradational con­ Castlegate sandstone resting on the upper sandy part tact, placed where the coarse-grained sandstone beds of of the upper member. The two are separated in the the Price River pass into the variegated finer grained picture by an indistinct carbonaceous zone that appears beds of the North Horn formation. as a notch in the cliff profile. In profile the top of Fisher (1936, p. 9, 14-30), describing the Book the Castlegate sandstone makes a narrow bench upon Cliffs east of Clark's area, subdivided the Price River which rest the younger strata. formation into two members Castlegate sandstone Much of the upper member is shale, and the pres­ member and upper member. He carried this subdi­ ence of a sandstone member in it seems somewhat vision as far as the lower course of Price River, near incongruous. A probable explanation is that during its mouth, but beyond that he found it desirable to the latter part of this stage coarser sediments from a divide the upper member into four members in as­ northerly direction were being laid down over a small cending order, the Buck tongue of Mancos shale, the area, while on either side muds were being deposited. Sego sandstone member, the Neslen coal-bearing mem­ Perhaps it can be pictured best as a southward-pro­ ber, and the Farrer non-coal-bearing member. jecting "peninsula" of sand forming in an otherwise The Castlegate sandstone, the Buck tongue of the shallow, muddy, but open sea. . Mancos shale, and the Price River formation were not recognized as such by Erdmann (1934, p. 22, 31-53) FORMATIONS ABOVE BLACKHAWK FORMATION in the Book Cliffs in Colorado. He recognized, how­ The Price River formation was named by Spieker ever, the Mesaverde group and divided it into three and Reeside (1925, p. 445) from exposures in Price formations in ascending order, the Sego sandstone, River Canyon above Castlegate, Utah. It was de­ the Mount Garfield formation, and the Hunter Can­ scribed as a "succession of predominantly gray sand­ yon formation. stones, grits, and conglomerates, with a minor amount In the present paper the name Price River forma­ of shale," and as including all the sedimentary rocks tion is applied only to the beds above the Castlegate between the Blackhawk formation and the base of sandstone and is carried only as far east as Green what was then called Wasatch formation,.now the base River. East of the Green River the members of the of the North Horn formation. The name Castlegate Price River described by Fisher for Utah are recog­ was adopted by Spieker and Reeside for the lower nized as formations, and those formations used in member of the Price River formation. The thickness Colorado by Erdmann are accepted. These are shown of the formation was given as 900 1,000 feet, and in tabular form on page 11. a later measurement of the type section by Spieker Spieker (1946, p. 122, 131) has shown recently that (1946, p. 130) shows 1,100 feet, of which about half the Price River formation of the eastern Wasatch is included in the Castlegate sandstone. The contrast Plateau passes westward into a .thick series of coarse­ between the fine grain of the underlying beds and grained conglomerate .beds.. The series lies uncon- the grit and conglomerate of the Price River beds was f ormably on beds .of various ages. and underlies beds considered notable and together with evidence of that contain- Late Cretaceous . marked unconformity on the western border of the UTAH WEST OF THE GREEN RIVER (WESTERN BOOK Wasatch Plateau was considered to indicate an im­ . CLIFFS) portant hiatus in the sequence. Clark (1928, p. 20), describing the western end of Distribution. The Castlegate sandstone was named the Book Cliffs, considered the basal contact to be from exposures in Price River Canyon about 2 miles 508471 60 2 14 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO above the town of Castlegate. It crops out in the east coarse-grained (in most places) crossbedded sand­ face of the Wasatch Plateau and at various places stone. It is very light gray on the fresh surface but within the plateau. Farther west, according to Spie- weathers to a buff to light brown, although the upper ker (1946, p. 131), it forms a part of a coarse-grained part is commonly light gray. It is friable and has a conglomerate series in the valley of the Spanish Fork calcareous cement. Locally it contains numerous clay of the Provo River. It extends eastward through the galls up to an inch or so in diameter, which at first area here described to the neighborhood of the Colo­ sight make it appear to be conglomeratic. East of rado-Utah line, where it passes into the Mancos shale. the Green River it is a cliff- and bench-forming unit Lithologic character and thickness. At the type that otherwise differs only in texture as it becomes locality it is about 400 feet thick, and a short distance to progressively finer grained towards the east, especially the west it thickens to about 500 feet (Clark, 1928, in the extreme eastern part of the area. Its upper p. 119). In the area of this report its thickness ranges few feet commonly consist of more firmly cemented up to 190 feet, though it is somewhat thicker near its grains. Plate 45 and C show its appearance in some northernmost exposure in the Gray Canyon of the detail. Green Kiver. In the canyon of Westwater Wash it is about 70 feet thick; eastward from that locality PRICE RIVER FORMATION (RESTRICTED) it thins rapidly, and at the Utah-Colorado State line Distribution. The Price River formation, as re­ it is 30 feet thick, a mere "feather-edge"; at the mouth stricted here by the removal of the Castlegate sand­ of West Salt Creek it is discontinuous. In the eastern stone, extends eastward continuously from the type exposures the lower part gradually becomes more locality of the formation along the Book Cliffs as shaly until a firm thin sandstone ledge at the top of far as the Green River. South of the type locality the member is all that is left. Thus, along the Book in the Wasatch Plateau, it is widespread; and to the Cliffs the Castlegate sandstone ranges from massive west it extends, according to Spieker (1946, p. 130, conglomeratic sandstone near Castlegate to fine­ 131), beyond the divide between Price River and grained siltstone at the east boundary of Utah and Spanish Fork of Provo River to the valley of Spanish passes entirely into shaly beds in Colorado. This Fork, where it forms part of a series of coarse-grained change as seen along the cliffs is not entirely one of conglomerate beds. regular diminution in size of grain and thickness. Lithologic character and thickness. The Price (See pi. 10.) Indeed, this would not be expected River formation in the western Book Cliffs is a se­ unless the outcrop line marked by the cliffs happened quence of gray and buff sandstone beds and gray to cut the sandstone beds in a line parallel to the direction of regular diminution in sedimentation, if shale beds, some 530 feet thick at Horse Creek. Some perchance such a regular diminution ever existed. of the sandstone beds are locally thick and cliff- For the type area Spieker and Reeside (1925, p. forming. 445) state: "The lithologic contrast between the fine­ Fisher (1936, p. 18) found it useful to recognize in grained, predominantly buff beds of the Blackhawk the Beckwith Plateau and a short distance eastward * * * and the coarse, predominantly gray beds of the across the Green River a "Bluecastle sandstone bed" Price River formation is strong." in the upper part of his "Neslen member" of the This distinction does not hold in the present area. Price River formation. This unit has been recognized Between Sunnyside and the Green River, the Castle­ northwest of the area studied in detail by Fisher, gate is not pronouncedly different in any respect from in the Woodside quadrangle, by V. H. Johnson (writ­ the older sandstones of the Blackhawk formation; it ten communication) as the uppermost 300 feet of is simply another cliff-forming sandstone, which, how­ the Price River formation and called the Bluecastle ever, is a very definite continuous unit (pis. 2(7 and sandstone member. It is shown, therefore, to have 34). It makes the upper part of the highest cliff a considerable lateral extent and assumes importance on Gunnison Butte (pi. 35). East of the Green as a local unit in the area adjacent to the Green River. River, extending to Bitter Creek, 3 miles west of the Colorado-Utah line, however, its topographic expres­ UTAH EAST OP THE GREEN BIVER AND IN COLORADO (CENTRAL AND EASTERN BOOK CLIFFS) sion is unique in that it forms the dip-slope surface capping a bench as much as 2 miles wide at the base In Utah east of the Green River, the Castlegate of the second line of the Book Cliffs (pi. 46"). sandstone and subdivisions corresponding to the mem­ West of the Green River then, in the present area, bers of the Price River formation recognized by the Castlegate is a cliff-forming massive rather Fisher (1936, p. 9, 14-30) are used here as formations. CRETACEOUS SYSTEM 15 CASTLEGATE SANDSTONE which includes also the overlying Neslen and Farrer This formation is described on pages 13-14. formations. Plate 65 shows a close view of the two lower units taken a short distance farther east. On BUCK TONGUE OF MANGOS SHALE the east side of Neslen Canyon, the Sego forms two main ledges with an intervening shaly zone containing An eastward-thickening tongue of Mancos shale a third minor ledge. Plate 5A shows the Buck tongue designated by Fisher (1936, p. 10, 15) the Buck and overlying Sego sandstone in the canyon of West- tongue, from the name of a canyon in T. 19 S., R. 23 water Wash, where the former is 340 feet thick. On E., overlies the Castlegate sandstone from the Beck- the whole the Sego sandstone is lithologically very with Plateau to the Colorado-Utah line. Farther similar to the Castlegate in the vicinity of the Green west it fingers into the predominantly sandy phase of River. It is, however, less massive and in only a few the lower part of the Price River formation and is places makes a single continuous cliff, for shaly zones not separable. Since in mapping the Book Cliffs in that cause minor intervening slopes are generally Utah the formations were followed from west to east present. and this shale member was not recognized as a In Utah no single sandstone bed of the Sego is unit until the area east of the Green River was important enough to dignify with a special name. reached, it is not certain just how far west it could be traced, but the beds just above the Castlegate are The shaly partings in the member appear to be fairly lenticular and exist at several or many horizons in very sandy north of the Price River. The thickness different places; the whole is thus treated as a unit of the Buck tongue increases from about 100 feet in the southern part of the Beckwith Plateau to 350 consisting predominantly of sandstone or sandy beds. feet at the Utah-Colorado line; farther east it merges The sandstone weathers buff, often very light gray at the tops of the ledge makers, and is massive to thin with the Mancos shale, owing to the disappearance bedded and shaly. A peculiar detail of weathering of of the intervening Castlegate sandstone. Lithologi- this quartz sandstone is shown in plate 55; this cally, in general, it cannot be distinguished from the honeycomb appearance is not untypical of the top of Mancos shale. (See pis. 5A and 6A and 65). The the member at many places. It is thought to depend carving of a bench on the top of the Castlegate sand­ upon the solvent action of water on the calcareous stone east of the Green River, and not to the west, cement, which probably has an irregular distribution is accounted for mainly by the greater thickness of and results in the loosening of the sand grains, which this shale zone in this region. Its upper contact is are scooped out of the hollows by the abrasive action gradational into the overlying Sego sandstone. Its of torrential waters and possibly wind action. origin is similar to that of the Mancos. The In Colorado the Castlegate sandstone is not recog­ content is shown in table 13, and the question of age and nizable; the Buck tongue has become an integral part correlation is discussed with that of the Sego of the Mancos shale; and the Sego sandstone rests sandstone. directly upon the Mancos shale. The upper surface SEGO SANDSTONE AND INCLUDED ANCHOR MINE TONGUE OF of the Sego is relatively smooth and is the most per­ THE MANCOS SHALE sistent and easily recognizable stratigraphic horizon Distribution. Overlying the Buck tongue, and in the Colorado part of the Book Cliffs. The outcrop, recognizable as a unit from the Beckwith Plateau especially toward the east, is usually a bold vertical eastward into Colorado, is the marine cliff-making cliff. In Colorado the Sego sandstone is subdivided sandstone, the Sego, named by Fisher (1936, p. 9, 15) into the upper sandstone member, the Anchor Mine from the Utah settlement of that name in T. 20 S., tongue of Mancos shale, and the lower sandstone R. 20 E. member. Lithologic character and thickness. In Utah the Lower member of the Sego sandstone. The lower average thickness of the Sego sandstone is 175 feet, member of the Sego sandstone begins to show clearly and only one section east of the Green River differs as a unit in Utah near the State boundary. Its thick­ from this average by more than 40 feet. It makes ness is irregular, reaching a maximum for Colorado from 1 to 4 minor cliffs in the basal part of the at the mouth of the canyon of East Salt Creek, where second escarpment of the Book Cliffs. In Crescent it is 110 feet thick. At Hunter Canyon it is 90 feet Canyon it makes 2 or 3 cliffs. Plate QA shows a view thick, though between East Salt Creek and Hunter looking northwest across the juniper-bearing Castle­ Canyon it is much less. Between Hunter Canyon and gate bench at Crescent Butte. The Buck tongue and sec. 12, T. 10 S., R. 100 W., it passes into shale. Near Sego sandstone form the base of the escarpment, East Salt Creek the lower member of the Sego is 16 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO typical in its lithologic character, a little less massive ber of the Sego is about 75 feet thick, with a more than it is to the west and more massive than it is to massive middle zone (40 feet), a thin-bedded basal the east. Both upper and lower boundaries are part (20 feet), and a gray-white upper part (15 markedly transitional and are more irregular than feet). It maintains this general constitution to East those of the upper member of the Sego. The nature Salt Creek, then thins to 43 feet in sec. 10, T. 8 S., K. of the lower boundary has been noted in some detail 102 W., where it is divided into upper and lower in connection with the Mancos shale, as has also massive beds by a stratum of carbonaceous shale and the base of that part of the upper member that over­ coal. At Hunter Canyon the upper bed is massive, laps the lower member. gray white, about 25 feet thick, and the lower part is The general lithologic character of the lower mem­ thin bedded; eastward to the Book Cliffs mine there ber is given in a stratigraphic section of the unit is little change in thickness, though the unit decreases taken at East Salt Creek. (See "Local Sections," in prominence. At the Book Cliffs mine the member Section 20.) Here the upper part of the member is 31 feet thick, massive, and gray white, but a mile contains two massive medium-grained buff to yellow- north of the Book Cliffs mine there is an additional brown sandstone beds that are 30 and 12 feet thick, lower zone of thin sandstone and sandy shale 73 feet respectively, and are separated by a thinner bedded thick. At the Garfield mine the thickness increases sandstone that is 15 feet thick, the whole sequence abruptly to 100 feet. At the Biverside mine, near being about 60 feet thick. The lower part consists the Colorado River, the thickness is 40 feet. To the of sandstone, sandy shale, and clay shale in beds up east of this locality the member becomes less promi­ to 2^ feet thick, the whole about 50 feet thick. These nent, and in sec. 28, T. 12 S., R. 97 W., it is a suc­ lower beds are lenticular and at places contain mud cession of platy, calcareous sandstones in shale that pellets and fragments of carbonaceous matter. is hardly recognizable as a unit. It is reported by Anchor Mine tongue of Mancos shale. The general W. W. Boyer (written communication) to disappear character of the Anchor Mine tongue in the western south of Colorado River. part is shown by a section at the mouth of the canyon The sandstone of the Sego is medium grained, has a of East Salt Creek (see "Local Sections," Section 20), sugary texture, and is soft and friable. It is largely where the relation of the tongue to the enclosing composed of quartz, but in some localities an abun­ sandstone units is as definite and as well exposed as dance of ferromagnesian minerals gives it a grayish at any place on its outcrop. Here the tongue is 115 tone. Some red jasperlike grains are also present. feet thick, the gray sandy clay shale containing in Throughout most of its extent, the upper 10 or 15 the upper 30 feet and the lower 50 feet thin beds of feet is lighter than the underlying buff and brown medium-grained gray sandstone. Where it is thinnest, strata. The variations in thickness that are so ap­ near Salt Wash, the whole unit is carbonaceous and parent are due to lateral changes in lithology at the dark, the Anchor coal bed occupying a zone 5 feet base and to lack of definition of the top of the Mancos. thick about 11 feet above the lower member of the Sego. Near Hunter Canyon the uppermost and lower­ UNITS BETWEEN THE SEGO SANDSTONE AND THE most parts of the Anchor Mine tongue are carbona­ TERTIARY FORMATIONS ceous and contain thin layers of coal, but most of Above the Sego sandstone different units are the unit is gray sandy shale and thin-bedded sand­ recognized and different names are applied in Utah stone. Farther east the unit resembles the Mancos and Colorado. This difference in usage has two shale. sources differences in the sequence of rocks, natur­ Upper member of the Sego sandstone. The upper ally expectable in exposures covering great distances member of the Sego sandstone is recognized, with at a high angle to an old shoreline; and a lack of considerable range in thickness, from Utah near the precise information, particularly as regards significant State boundary eastward into Colorado as far as fossils, concerning the upper part of the sequence. Grand Mesa. In general, this member appears as a It has seemed more useful for practical purposes to massive gray cliff somewhat lighter in color than use the boundary between Colorado and Utah as an the Mancos shale below. When viewed closely it arbitrary line of separation between the two nomen­ consists of a great number of thin irregular or platy clatures, though the strata are, of course, continuous beds of sandstone, usually laminated and in many across it, and for some distance on either side the places crossbedded. It is more massive toward the units of the respective areas might be discriminated. west, and toward its eastern end contains more shale. In Utah the Sego sandstone is overlain, in sequence, Near the Utah-Colorado State line, the upper mem­ by the Neslen formation and the Farrer formation of CRETACEOUS SYSTEM 17 definitely Late Cretaceous age and the Tuscher for­ coal is not burned, the Neslen sandstone beds weather mation of possible Tertiary age but here arbitrarily light gray to buff; and the noncarbonaceous shales, included in the Late Cretaceous. In Colorado the to drab or medium light gray. The strata are notably Sego sandstone is overlain, in sequence, by the Mount different from those of the Blackhawk formation Garfield formation, containing the Rollins sandstone (which contains all the coal west of the Green River) member, of Late Cretaceous age, and the Hunter in the conspicuous absence of continuous cliff-making Canyon formation, which is essentially equivalent to sandstone beds and in the inferiority of the coal beds, the Tuscher formation. The Hunter Canyon forma­ which are thinner and of lower rank and grade. The tion is overlain in turn by a unit to which the non- appearance of the unit is shown in plate 6J., in which commital designation Tertiary sandstone has been its top is about halfway up the cliff, at the top of the applied. In the southeastern part of the Grand Mesa light-colored zone. While in distant view its upper field, Lee (1912, p. 19, 30) found the Rollins sandstone contact is fairly well marked, it is seen on closer in­ member to be the base of his Mesaverde formation spection to be gradational. Because this upper and recognized above it the Bowie shale member, the boundary is somewhat indefinite and because of the Paonia shale member, and an unnamed upper member, lithologic heterogeneity of the unit, its thickness as upon which rests a conglomeratic sandstone unit cor­ mapped ranges over rather wide limits. Sections related by Lee with the Ohio Creek conglomerate of measured show values between 250 and 410 feet, with the area of Colorado, but not named an average of 350 feet. Many details of its lithologic in this paper. Johnson (1948) adopted essentially character are given in the section entitled "Local Lee's units, but used lower and upper coal members Sections." for what Lee called Bowie and Paonia members and About 200 feet stratigraphically above the base of called the upper member the barren member. In the formation, in the Beckwith Plateau and a short both Utah and Colorado the next higher unit was distance east of it, a cliff-making sandstone bed was long believed on lithologic grounds to be equivalent recognized as a unit, mainly because it forms the to the Wasatch formation, of Eocene age, but Patter- dip-slope surface on the top of the Beckwith Plateau son (1934, p. 99) has shown that in Colorado upper (pi. 2tf). It was called by Fisher (1936, p. 18, 19) the Paleocene beds are present at least locally in the lower "Bluecastle sandstone bed," after the canyon of that part of it. In eastern Utah no other name than Wa­ name which nearly bisects the Beckwith Plateau, and satch has been used, but in Colorado the name Ruby was later called the Bluecastle sandstone member of formation was applied by Lee and others, perhaps the Neslen formation (Cobban and Reeside, 1952). It erroneously. To the upper Paleocene part of the has a thickness of 100 feet, or slightly more, on the sequence, Plateau Valley beds has been applied by plateau but thins rapidly to the east, where it loses Patterson (1936). its identifying characteristics, as is indicated on plate NESLEN FORMATION 10. In the Woodside quadrangle, northwest of the area studied by Fisher, the Bluecastle member was Distribution. The Neslen formation lies between recognized by V. H. Johnson (written communica­ the Sego sandstone and the Farrer formation and tion) as the uppermost 300 feet of the Price River takes its name from Neslen Canyon, in which the town formation. (See section 5, p. 183-201.) It thus ap­ of Sego is located (Fisher, 1936, p. 9, 16-19). The pears to be wedge shaped, thickening northwestward formation contains all the coals of importance found into an important unit. Aside from the characteristics in the central Book Cliffs. As a unit it has not been already mentioned it is similar to most of the other traced west of the Green River, though all post-Sego Neslen sandstone beds namely, it is crossbedded, strata of the Beckwith Plateau would fall within it. medium to fine grained, and weathers buff to gray. Farther to the northwest it merges into the Price Two other minor sandstone units (Thompson Canyon River formation. To the east it appears to be equiva­ lent to part of the Mount Garfield formation. sandstone bed, Sulphur Canyon sandstone bed), to­ Lithologic character and thickness. The Neslen gether with the coal beds of the Neslen formation, formation is composed of alternating sandstone and were also described by Fisher (1936, p. 18, 19). shale beds that appear in outcrop as minor ledges FARRER FORMATION with intervening slopes; the two are in about equal proportions. As a whole the formation is relatively Distribution. Above the Neslen formation is found light colored, contrasting therefore with the overlying a series of somber-appearing Cretaceous shale and somber beds of the Farrer formation. Where the sandstone beds grouped by Fisher (1936, p. 9, 19) 18 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO as the Farrer formation (pronounced fair-er), the localities and have never been studied in any detail. name coming from a local mine of that name in the They were tentatively grouped by Fisher (1936, p. canyon of Coal Creek (T. 20 S., R. 17 E.), above 9,20) as a separate formation under the name Tuscher, which it stands as a pronounced escarpment. It also after the canyon in T. 20 S., R. 17 E. The forma­ forms the upper half of the cliffs in plate 6J.. It has tion makes a continuous unit in the Book Cliffs of been followed from the Green River to the Utah- Utah east of the Green River. Colorado line. It appears to be equivalent to the As a unit, and at some distance, the formation upper part of the Mount Garfield formation and stands out from the underlying somber-appearing possibly to part of the Hunter Canyon formation of beds and the overlying varicolored but notably red Colorado. West of the Green River, the recognition "Wasatch." The absence of interbedded varicolored of the Bluecastle sandstone member of the Neslen shale beds was the main reason for not grouping the formation in the top of the Price River formation in Tuscher formation with the "Wasatch" when the the Woodside quadrangle and assignment of the over­ unit was established by Fisher. The positions of the lying beds to the undifferentiated North Horn and actual contacts are, however, obscure in many places. Flagstaff formations suggests that the Farrer and The individual beds thicken and thin and cannot as Tuscher formations may be missing. a rule be traced far. On the Green River the thick­ Lithologic character and thickness. The Farrer for­ ness was found by Spieker (1946, p. 140) to be 215 mation was examined only at intervals, since it is feet; east of the Green River the thickness ranges not readily accessible at many places and time suffi­ between 267 and 600 feet. The unit is composed cient to make a careful study was not available. Its largely of massive sandstone beds; these are separated thickness shows notable variation; in 7 sections it by thinner beds of buff to gray shale layers that in ranges from 410 to 1,095 feet, averaging 690 feet. It many places show a light-greenish cast. The sand­ is not sharply distinguished from either the under­ stone is typically crossbedded, friable, light gray to lying or overlying beds. It has, however, certain creamy white, cliff making, weathering to rounded unifying characteristics. It is nearly non-coal-bearing surfaces; but local variations were noted. The com­ although it does carry a few unimportant lenses of position is largely colorless quartz in medium-sized coal at several horizons. The sandstone beds, consti­ well-rounded to angular grains generally weakly tuting about two-thirds of the whole, in the main cemented by calcium carbonate. White feldspar in weather into brown-stained blocky ledges or cliffs amounts up to 10 percent and dark minerals in amounts separated by medium-gray clay shale beds with a of 2 percent or less are present. Some layers are pro­ distinct olive-greenish tinge. This olive green of the nouncedly conglomeratic, carrying minor amounts of shale beds is the best single criterion for placing the quartz and black chert pebbles up to 1 inch in basal contact. Locally, where the shale beds are diameter. sufficiently bolstered with sandstone layers, the for­ The character of the exposures and the presence mation forms an impressive and unscalable cliff. The of slump materials make it difficult to determine the whole presents a notably somber appearance, contrast­ nature of the contacts with the adjacent formations. ing with the enclosing lighter-colored beds. The While a pronouncedly unconformable surface has not sandstone beds show excellent crossbedding of the been seen, both upper and lower contacts are thought current type and carry lenses of clay gall "con­ to mark disconformities. These are indicated by the glomerate." True pebbles are quite rare, though great variations in thickness of both the Tuscher present. The rock consists largely of subangular to formation and the Farrer formation. In places on poorly rounded medium-fine quartz grains in a firm the east side of the Nash Wash reentrant a thick basal calcareous cement but contains 3-10 percent of feld­ conglomerate immediately overlies the formation. spar, 2-10 percent of dark minerals, and a very small As previously noted, Erdmann (1934, p. 33, 51) amount of white mica. suggested that the Tuscher formation passes east­ ward into the Hunter Canyon formation of Colorado, TUSCHER FORMATION and recent examination of aerial photographs by In Utah east of the Green River above the Farrer Fisher has made this correlation very probable. formation and below the varicolored, though pre­ Little direct evidence of the age of the Tuscher dominantly red, "Wasatch" strata is found a series formation is available, but since it seems to be es­ of light-colored sandstone beds separated by minor sentially equivalent to the Hunter Canyon formation shale beds. These have been examined at only a few and appears to be older than the undifferentiated CRETACEOUS SYSTEM 19

North Horn and Flagstaff formations, it is here as­ lithologic unit in the "coal measures" is the Rollins signed to the Mesaverde group and arbitrarily con­ sandstone member. It is similar to the Sego sand­ sidered of Late Cretaceous age. stone and has been at times confused with it. The weathered surface is light yellow gray and brown; the MOUNT QARFIELD FORMATION fresh surface, grayish white to white. It is cross- Distribution. The Mount Garfield formation was bedded, coarse grained, and of sugary texture. Locally named by Erdmann (1934, p. 32) from Mount Gar- the upper part contains rusty-brown concretions as field, about 3 miles northwest of Palisade, Colo. It much as 30 inches in diameter, with which are at is recognized along the Book Cliffs from the Utah- some places associated Halymenites major Lesquereux. Colorado State boundary as far as Grand Mesa. No other fossils were found. The unit is not identifi­ Lithologic character and thickness. The Mount able west of the Book Cliffs mine, about 10 miles Garfield formation ranges in thickness from 970 to northwest of Palisade. 1,070 feet and contains most of the coal beds in the Upper part of "barren measures" Erdmann (1934, Book Cliffs of Colorado. The lower part, ranging p. 44) describes these beds as follows: in thickness from 305 to 666 feet, constitutes the "coal The lithology of the "barren measures" of the Mount Garfield measures"; the upper part, ranging from 405 to 665 formation closely resembles that of the "coal measures." The feet, constitutes the "barren measures." In the lower "barren measures" contain very little coal, and the total amount part, in the vicinity of the Colorado River, a promi­ of carbonaceous shale has been reduced from 15 to 6 percent. Though there is somewhat less sandstone, the beds are in nent sandstone bed has been designated the Rollins general slightly more arkosic and more massive. They also sandstone member, as it is believed to be the unit show more decided characteristics of fluviatile origin, especially so named by Lee (1912, p. 30) in the Grand the cross bedding. In color, structure, and size of grain Mesa area. Southeast of the Colorado River the beds (averaging 0.01 inch [0.25 mm]) the sandstones are similar of the lower part of the Mount Garfield formation to those of the "coal measures." The shaly beds in the "barren below the Rollins sandstone member pass into measures" are like those below, but locally they are much thicker. These deposits are considered to be of continental marine shales indistinguishable from the Mancos origin. shale, and the Rollins becomes the basal unit of the Mesaverde group. The Mount Garfield formation Relations of the Mount Gar-field formation to the is conformable with the Sego sandstone below and the Bowie and Paonia shale members of the Mesaverde Hunter Canyon formation above. The upper bound­ formation. Resting on the Rollins sandstone member ary is somewhat arbitrary, the Hunter Canyon for­ of the Mesaverde formation of Lee (1912, p. 32-4Y) mation differing chiefly in its more numerous, coarser, in the Grand Mesa field lie in ascending order the grayer, and more massive sandstone beds and its lack Bowie shale member, the Paonia shale member, and of carbonaceous shales. the undifferentiated upper Mesaverde. Lee dis­ Lower part, or "coal measures" Erdmann (1934, tinguished the Bowie shale member as of marine and p. 40-48) has described the lower part or "coal meas­ brackish-water origin and the Paonia member as of ures" of the Mount Garfield formation in detail in his fresh-water origin, both containing coal; the un­ report on the coals of Garfield and Mesa Counties. It differentiated part does not contain coal. The Rollins consists of sandstone, shale, sandy shale, carbonaceous sandstone member was said by Lee to rest on the shale, and coal beds. Continental rocks predominate, Mancos shale throughout the Grand Mesa region. The but brackish-water rocks nearly equal them in amount. Paonia member rests, according to Lee, on the Rollins The sandstone beds are of several sorts white, mas­ sandstone member in the western part of the Grand sive, apparently littoral beds; irregular but massive Mesa area, but toward the east the Bowie member buff sandstone beds of fluviatile origin with partings appears and gradually increases in thickness eastward. of shale and shaly sandstone; and thin irregular According to W. W. Boyer (written communication), sandstone layers intercalated in beds of gray shale. Lee misidentified his units in the western part of the The massive sandstone beds have grains averaging Grand Mesa field. The upper member of the Sego 0.25 millimeters in diameter; the thin sandstone layers sandstone of this paper was mistaken for the Rollins, in shale are hard, fine grained, and ripple marked. and the strata between the upper Sego and Rollins The clay shale beds are generally gray; the carbona­ were referred to the Bowie shale member. The upper ceous shale beds are generally associated with the part of the "coal measures" of the Mount Garfield for­ coal beds and range from reddish brown to black. mation and the "barren measures" are together equiva­ Rollins sandstone member. The most conspicuous lent to the Bowie and Paonia shale members, and the 20 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO Hunter Canyon formation is equivalent to the un- CRETACEOUS AND TERTIARY SYSTEMS differentiated upper Mesaverde. In the Wasatch Plateau the beds above the Price HUNTER CANYON FORMATION River formation were formerly classified as three members of the Wasatch formation. These three Distribution. The Hunter Canyon formation was units are now called the North Horn formation, the named by Erdmann (1934, p. 33, 48-53) and described Flagstaff limestone, and the Colton formation in detail. The type locality is in Hunter Canyon, (Spieker, 1946, p. 120-122, 132-136). The lower part north of Grand Junction, Colo. The formation has of the typical North Horn formation has been shown been identified over the whole length of the Colorado by Gilmore (1946) to contain of Late Creta­ part of the Book Cliffs. ceous age, and the upper part has been shown by Lithologic character and thickness. The formation Gazin (1938, 1939, 1941) to contain of consists of massive brown-buff and gray sandstone early Paleocene age. The typical Flagstaff limestone and soft gray shale beds and ranges in thickness from is assigned to the late Paleocene and possibly early 375 to 1,400 feet. It is distinguished from the Mount Eocene by La Rocque (1951) on the basis of the non- Garfield formation chiefly by the character of its marine mollusks. In later papers La Rocque (1953, sandstone beds, which are more numerous, coarser, 1956) reaffirms the assignment and also definitely grayer, and more massive than those of the Mount assigns the Colton to the Eocene. Garfield by the virtual absence of carbonaceous shale, Spieker (1946, p. 140-142) carried out a reconnais­ and by the presence of some greenish shale beds. sance examination eastward from the Wasatch Plateau These differences are much like those that separate as far as the Green River in an attempt to trace the the Neslen and Farrer formations in Utah, but it is North Horn, and other formations from the Wasatch believed that the Hunter Canyon and Farrer are only Plateau into the Book Cliffs. The effort was not in small part equivalent. The upper boundary is an entirely successful because, with the equipment and evident disconformity, the erosional relief being small time available, important parts of the line of outcrop locally but in larger aspect attaining 1,100 feet. The could not be reached. He did, however, conclude that overlying unit is a chert pebble conglomerate or con­ the Colton, North Horn, and Flagstaff formations glomeratic sandstone. extend into the western Book Cliffs; that certain beds Sandstone makes up about 60 percent of the for­ which occur on the Green River represent the Colton mation, the remainder being gray shale with some and North Horn formations, and that below these is thin sandstone layers. Carbonaceous shale layers probably the Tuscher formation of Fisher. constitute only about 1 percent. The sandstone beds In a section measured in 1925 in the canyon of Horse are medium to coarse grained and in beds 10-40 feet Creek, south of Sunnyside, Fisher assigned a thickness thick but locally aggregating as much as 300 feet. of 650 feet to the Price River formation above the The bedding is generally regular, but even thick beds Castlegate sandstone and thought the overlying 131- may finger into shale abruptly. Crossbedding is com­ foot unit largely of sandstone might belong t'o the mon, and channeling fairly common. The basal parts Tuscher formation. However, Reeside considered that of many beds are characterized by accumulations of this unit together with the overlying 655-foot largely mud pellets and lumps ranging in longest dimension shale unit might represent the North Horn formation. from 1/4 to 4 inches. Gray and greenish-gray shale In a section measured in the same area at a later and sandy shale are abundant. They contain thin cal­ time Erdmann (written communication, 1940) assigned careous sandy layers and some concretions. Fossils with doubt essentially the same sandstone bed to the are rare. Tuscher formation and suggested that it and an overly­ As noted above, the Hunter Canyon formation ap­ ing bed might constitute the North Horn formation. pears to be equivalent to the undifferentiated upper Recent reexamination of the sections in the canyon members of the Mesaverde formation of Lee (1912, of Horse Creek and Tuscher Canyon by Hail, Kinney, p. 43) in the Grand Mesa coal field. Erdmann (1934, p. 33, 51) suggested, in proposing the name Hunter and Zapp (1956 and written communication) support Canyon, that the unit is equivalent to part of the correlations made by Spieker, Fisher, and Erdmann the Farrer formation and part or all of the Tuscher except that the beds between the Price River and formation of Utah (discussed above). Recent examina­ Colton formations seem better assigned to an un­ tion of air photographs by Fisher indicates that differentiated North Horn and Flagstaff unit and probably the Tuscher and Hunter Canyon are es­ except that the Tuscher formation is not recognizable sentially equivalent units. in the canyon of Horse Creek. TERTIARY SYSTEM 21 In Colorado a unit designated the "unnamed sand­ River formation, both of Eocene age. In the central stone" was mapped by Erdmann from the Colorado- and eastern Book Cliffs, some of the higher part of Utah boundary to the Colorado River. Though the the sequence is of dubious age and has been somewhat age of this unit is dubious, it is assigned somewhat arbitrarily assigned. The Tuscher formation has arbitrarily to the Tertiary. been placed in the Late Cretaceous, and the unnamed sandstone has been placed in the Tertiary. A still NORTH HORN AND FLAGSTAFF FORMATIONS UNDIFFERENTIATED higher part, long called Wasatch, is almost certainly all of Tertiary age. This part for convenience is According to Spieker (1946, p. 140), though the called here the "Wasatch" formation and may contain North Horn formation extends through the western both Paleocene and Eocene beds. Book Cliffs, the Flagstaff limestone thins eastward Patterson (1934) has demonstrated that the beds and does not appear to be a well-defined entity near adjacent to the Colorado River near Debeque, Colo., Sunnyside. Recent examination of sections in the essentially the eastern end of the Book Cliffs, that western Book Cliffs by Hail, Kinney, and Zapp were called "Ruby" formation by Lee (1912, p. 49, 51) (1956 and written communication) indicates that the contain upper Paleocene deposits overlain by Eocene North Horn and Flagstaff are not readily separable beds with and other . To the in this area, though equivalents of both are probably Paleocene deposits, Patterson (1936, p. 397) has given present. A thickness of 1,095 feet was assigned the the name Plateau Valley beds. Just how these beds combined unit in Willow Creek; 1,040 feet, in the can­ fit into the Book Cliffs sequence has not been de­ yon of Soldier Creek; and 530 feet, in the canyon of termined. Whitmore Creek. South of Sunnyside in the Horse COLTON FORMATION Canyon area, a gray unit 260 feet thick (units 175-197 of sec. 5) contains beds of gray limestone that make up In Utah only the basal part of the beds above those about one-sixth of the thickness and become more sandy assigned to the Price River or Tuscher formations in the lower part. (See pis. SO and Z>, and 9#.) was examined by the writers, except in the canyon of Beneath it at the canyon of Horse Creek is a unit Horse Creek (section 5), where the sequence for 3,300 310 feet thick (units 150-174 of sec. 5) of tan to green­ feet above the Price River formation was measured. ish-gray shale beds and soft light-gray salt-and-pep- Hail, Kinney, and Zapp (1956 and written com­ per sandstone beds, with very minor limestone layers. munication) have examined sections in the western (See pi. SB.) These two units, totaling 570 feet, Book Cliffs from Willow Creek, north of Price, Utah, seem better interpreted as containing together the to the canyon of Tuscher Wash, east of the Green North Horn and Flagstaff formations. This unit has River. They identified the Colton formation in this been traced by Fisher on aerial photographs into the area as succeeding the undifferentiated North Horn gray unit 395 feet thick identified by Spieker (1946, p. and Flagstaff formations and as intertonguing in its 140) as the North Horn formation on the Green River. upper part very extensively with the Green River Beneath his North Horn, Spieker identified a possible formation. In Willow Creek and the canyon of Tuscher formation and beneath it in turn three units of Soldier Creek, about 1,700 feet of beds are assigned sandstone and shale (his units 6, 7, and 8) that are here to the Colton, with about 500 feet of interbedded included in the Price River formation. East of Tuscher Colton and Green River above it. In the canyon of Canyon the terms North Horn and Flagstaff have not Whitmore Creek the Colton is about 1,300 feet thick, been used, and, if present, beds equivalent to these but the zone of interbedding is nearly 1,700 feet thick. units have been included in the "Wasatch" formation. In the canyon of Horse Creek all of this interval is of Colton type, and the thickness of the Colton is TERTIARY SYSTEM more than 3,000 feet. Between the Green River and As indicated on page 13, the lowest part of the the Utah-Colorado State boundary, the Colton is sequence above the Price River formation in the included in the "Wasatch" formation, and the thick­ Wasatch Plateau is definitely of Cretaceous age, but ness is not known. succeeding beds are in part of Paleocene age and in The Colton formation is described as composed of part of Eocene age. Some of these units can be traced gray salt-and-pepper sandstone, greenish-buff sand­ into the western Book Cliffs and perhaps beyond the stone, siltstone that commonly weathers golden brown, Green River. The North Horn and Flagstaff forma­ and shale ranging from deep red to variegated and tions have already been discussed. Above them, in gray. Individually, the strata are irregular and dis­ succession, lie the Colton formation and the Green continuous and are of flood-plain and channel origin. 22 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

UNNAMED SANDSTONE bright colors. The color is in the shale beds, where, besides grays, are seen brick reds, purples, yellows, In the Colorado Book Cliffs a conglomeratic sand­ and other shades. The unit contains important stone rests upon the Hunter Canyon formation and amounts of cliff-making sandstone, as exhibited at a seems to be equivalent to the unit that on Grand locality in the Nash Wash reentrant (pi. 6(7), where Mesa was designated by Lee (1912, p. 48) as the the lower 800 feet of the unit is present. At this Ohio Creek conglomerate. This name was taken locality the base of the "Wasatch" is marked by a by him from the typical Ohio Creek of Eldridge, 50-foot cliff-forming conglomerate bed (pi. 4J.). A a unit of the Anthracite-Crested Butte area farther similar conglomerate is present 110 feet above the southeast in Colorado. It was identified by Lee with base of the unit in the canyon of Saleratus Wash. the Ohio Creek largely because of its stratigraphic No such conglomerate was found in the Tuscher position and supposedly similar lithologic composi­ Canyon section. tion. Lee did not trace the unit, and it appears from In the Colorado part of the Book Cliffs the a reconnaissance examination by W. S. Burbank and "Wasatch" formation consists of variegated clays of B. S. Butler (oral communication) that his use of fluviatile or lacustrine origin, with a few sandstone the name is very dubious. Erdmann (1934, p. 53) and limestone layers. It is particularly susceptible to did not apply a formal name to this unit in the Book erosion and forms highly sculptured outcrops. The Cliffs, and none is applied in this paper. chief characteristic of the formation is its bright The unnamed sandstone of the eastern Book Cliffs coloring, particularly reddish tints, though gray and has as its base a conglomerate or conglomeratic sand­ yellow-brown and greenish tints are also present. stone bed 10-40 feet thick, characterized by rounded It forms the lower part of the Roan Cliffs. Sub­ pebbles of gray and black chert. Pebbles of other ordinate sandstone occurs as thin slabby masses and kinds of chert, quartz, and rarely jasper and lime­ as irregular lentils and is generally fine grained. The stone are also present. The pebbles range from 1/4 to beds of limestone are gray and fossiliferous. The 2 inches in diameter, and the matrix is gray to yellow thickness of the formation ranges from 280 feet at sand. The basal conglomerate beds grade upward the head of West Salt Creek to 790 feet at the head into a coarse-grained gray sandstone contain­ of Hunter Canyon. The lower boundary is transi­ ing thin stringers and lenses of pebbles. The tional from the underlying unnamed sandstone for­ whole unit ranges from 155 to 370 feet in thickness. mation. The sandstone is in beds separated by beds of shale GREEN RIVER FORMATION ranging from 10 to 50 feet in thickness, predominantly gray but with a greenish tone. Clay-pellet con­ Over most of the area examined in Utah, the Green glomerate also occurs in the sandstone beds. The River formation lies so far behind the Book Cliffs base is a major erosional unconformity, and Erdmann escarpment that it was not studied. In Colorado the thinks the unit is more closely related to the over­ basal Douglas Creek member of the formation forms lying beds than to the underlying beds. the upper part of the Roan Cliffs and was examined at many places. It is an assemblage of sandstone, "WASATCH" FORMATION fresh-water marlstone, and shale that reaches a maxi­ In the western Book Cliffs the former Wasatch for­ mum thickness of 1,200 feet. An abundance of mation, now divided, forms the higher parts of the calcareous material is characteristic of the member cliffs. From Sunnyside eastward to the Green River, as a whole. Its aggregate color is a whitish gray. the main body of the unit lies well behind the front, AGE AND CORRELATION OF THE FORMATIONS though "Wasatch"-capped spurs project toward the escarpment and in these areas bring the formations STANDARD SEQUENCE OF THE CRETACEOUS OF THE to a position not far back of the Book Cliffs escarp­ WESTERN INTERIOR REGION ment. On the east side of Nash Wash reentrant, In considering the intrarelations of the Cretaceous northwest of Cisco, the "Wasatch" again makes up deposits of the western interior of the United States, it the higher part of the escarpment. East of Nash is desirable not only that they be compared within such Wash the formation stands up as the Roan or Brown limited regions as the Book Cliffs, but also that some Cliffs of the Powell maps, some miles behind (north sort of comparative standard be set up to which all the of) the Book Cliffs. deposits may be referred. Cobban and Reeside (1952) In Utah east of the Green River the beds that are have proposed such a standard reference sequence of grouped as "Wasatch" are characterized by their Cretaceous formations for the western interior region AGE AND CORRELATION OF THE FORMATIONS 23 and have suggested a suite of f aunal zones to accompany cluding the Virgin Creek member is middle and late this standard sequence. These, with several minor Campanian, and the Mobridge and Elk Butte mem­ emendations, are as follows: bers of the Pierre shale and the Fox Hills sandstone are Maestrichtian. The Hell Creek is traditionally as­ Formations Faunal zones signed to the , but there is little evidence for Upper Cretaceous series: Hell Greek formation______Triceratops and nonmarine . this except position at the top of the sequence, and Fox Hills sandstone: Unnamed members...----_... No zonal fossil. the usual assumption that the Danian is Cretaceous. Timber member..____ Discoscaphites nebrascensis. For comparison between the sequences of forma­ Trail Olty mombor______Discoscaphites nicolletii. Piorro shalo: tions in the Book Cliffs and those in three other areas Elk Butto member.._... -- No zonal fossil. in the western interior region, table 1 shows the for­ Baculites clinolobatus. Mobrldgo mombor______Baculites grandis. mations of these areas referred to an abbreviated form Baculites baculus. of the standard sequence. Baculites eliasl. Virgin Crook mombor... Bacums compressus s. L Nonmarine faunas are found at horizons in the Vorondryo mombor... Baculites corrugatus s. L DoGroy mombor..... Baculites crickmavi. western interior sequence but are best characterized in Crow Crook member._____ Baculites scotti. the oldest and youngest beds. The equivalents of the Gregory member..______Baculites gregoryensis. Peterson and Draney contain a consider­ _ , . Baculites n. spp. Sharon Springs member.. Baculites obtusus able fauna; the fresh-water equivalents of the Skull Scaphites hippocrepis. Creek shale, such as the Bear River formation, have : Desmoscaphites bassleri. Eaglo sandstone equivalent..... Desmoscaphites erdmanni. a varied fauna; the fresh-water equivalents of the Telegraph Crook formation c Clioscaphites choteauensis. Gregory member of the Pierre shale, such as the equivalent. Clioscaphites vermiformis. member. Scaphites depressus. Judith River formation, have a somewhat smaller Inoceramus involutus. assemblage; and the Hell Creek formation has a Fort Hays limestone member... Inoceramus deformis. large fauna, some of it, however, rather long ranging. Carl 11 o shalo: Sago B roaks member.. ____ Prionocyclus guadratus. In the Book Cliffs region, species characteristic of Scaphites nigricollensis. some of the older zones were not noted, and these Prionocyclus wyomingensis. Turner sandy member... Scaphites ferronensi3. zones may be thin or missing. In the upper part of Scaphites warreni. the Book Cliffs sequence, relatively few fossils are Blue Hill shalo member...... hyatti. Falrport chalky shale momber.. Collignoniceras woollgari. known, and these are nonmarine; satisfactory assign­ Groonhorn limestone: ment may not be possible. Attention will be called Bridge Greek limestone mom- \Inoceramus labiatus. bor. [Sciponoceras gracile. to all of these features in discussing the several stra- _.,,,,, , \Dunveganoceras albertense. tigraphic units. xlartlancl snaio momoer...... ![Jjunveganoceras T^ condituTTi.... Lincoln limestone momber . Dunveganoceras pondi. Since in the Book Cliffs a given chronologic horizon \Acanthoceras? wyomingense. may lie in strata of marine origin in the east and in Bollo Fourcho shale.. \Acanthocerast amphibolum. [Calycoceras sp. strata of nonmarine origin in the west and since the Lower Orotacoous series: contemporaneous marine and nonmarine strata may Mowry shalo. __ . Neogastroplites sp. Newcastle sandstono...... U comancheanus. be of differing lithologic composition and hence bear Skull Greek shalo.. . J Fall River sandstone... No zonal fossil. differing names, it is not easy to present the picture Gannett group: of the relations of the zones to the lithologic units Unnamed red shale_ No zonal fossil. O Dranoy limestone.. 1 without some degree of repetition. In the following Bochlor conglomerate. \Protelliptio douglassi. pages the fossils from the Lower Cretaceous beds and Potorson limestone J Ephrnlm conglomerate.... No zonal fossil. those from the Mancos shale are presented by refer­ ence to the standard units shown on preceding pages, In terms of a commonly accepted European chrono­ without respect to lateral equivalents of other name logic scheme it is believed that the zone containing or facies. Then in ascending order are given the Protelliptio douglassi and its associates is Aptian, the Skull Creek shale and the Newcastle sandstone faunas of the accepted divisions of the Mesaverde are middle , and the is late Albian. group, which chronologically overlap the upper part The Belle Fourche shale and the two lower members of the Mancos shale. The faunas from higher beds of the Greenhorn limestone are Cenomanian; the are given last. upper members of the Greenhorn are early Turonian. The relations of the f aunal units to the lithologic The is middle and late Turonian, and units in the Book Cliffs are shown graphically in plate the Niobrara formation is , , and 10, in a columnar diagram. The relations of the Cre­ early Campanian. The Pierre shale up to and in- taceous units over a wider area are shown in plate 11, 24 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

TABLE 1. Correlation of Cretaceous formations in Book Cliffs and other areas

Standard sequence Book Cliffs, Utah and Colorado Northern San Juan basin, Central Central Montana Colorado

Hell Creek formation Animas formation (part) Hell Creek formation Fox Hills sandstone McDermott formation Pierre shale: Nonmarine upper part of Mesaverde group; exact Kirtland shale Elk Butte member equivalency not known Fruitland formation Lewis shale Mobridge member Pictured Cliffs sandstone Bearpaw shale Virgin Creek member Verendrye member DeGrey member Mesaverde group Crow Creek member Lewis shale Gregory member Sego sandstone Judith River formation Sharon Springs member Lower part of Mesaverde Claggett shale group in west Mesaverde group Steele shale Eagle sandstone Niobrara formation: Telegraph Creek formation Smoky Hill chalk mem­ ber Fort Hays limestone Niobrara formation member Carlile shale: Carlile shale Sage Breaks member Mancos shale Turner sandy member Mancos shale in west Mancos shale in east Blue Hill shale member Fairport chalky shale member Colorado shale Greenhorn limestone: Bridge Creek limestone member Hartland shale member Lincoln limestone mem­ ber Dakota sandstone or hia­ tus in west Dakota sandstone equiv­ Belle Fourche shale Dakota sandstone in east alents not definitely determined Mowry shale Mowry shale Newcastle sandstone Hiatus Hiatus Thermopolis shale Skull Creek shale Fall River sandstone Gannett group: Unnamed red shale Cedar Mountain forma­ Burro Canyon formation Cloverly formation Kootenai formation Draney limestone tion Bechler conglomerate Peterson limestone Ephraim conglomerate which includes the Cretaceous deposits that encircle yielded plant remains that are assigned by Brown the Canyon Lands of southeastern Utah. (1950) simply to the Lower Cretaceous. These plants include the distinctive fern Frenelopsis varians Fon- LOWER, CRETACEOUS UNITS taine, and also Cycadeoidea sp., Brachyphyllum cras- At or near the type locality, Cedar Mountain forma­ sicaule Fontaine, and Sphenolepis kurriana (Dunker). tion (Stokes, 1944, p. 966) has yielded bones, The flora is marked by the absence of dicotyledonous the fresh-water pelecypod Eupera onestae (McLearn), species. Invertebrates have been reported from a undetermined ostracodes, and the fern single locality in the Burro Canyon formation (Kee- minor Bead and Brown (Katich, 1951, p. 2049; side, 1957) and include, beside Nippononaia asinaria Stokes, 1952, p. 1Y69). The pelecypod is widespread Reeside, the widespread Aptian forms Protelliptio in the western interior region in fresh-water Lower douglassi (Stanton) and Lampsilis farri (Stanton). Cretaceous deposits of Aptian age (Gannett group, DAKOTA SANDSTONE and Lower Blairmore, Kootenai, and Cloverly forma­ tions), and the fern is found in the Mowry shale and The name Dakota was intended originally to apply equivalents. Eupera onestae has been found at an­ to an introductory Upper Cretaceous sandstone unit other locality south of Thompson, Utah, together with in the Missouri Valley, and its use has been widely undetermined gastropods and scales and with extended. So much confusion exists in the wide use ostracodes determined by E. E. Peck (Stokes, 1952, of the name Dakota, however, that it has come to p. 1768) as Metacypris angularis Peck, Cypridea cf. mean simply brown sandstone beds near the boundary C. ~brevicornis Peck, and C. wyomingensis Jones and between the Lower and Upper Cretaceous series. For the charophyte oogonium Clavator harrisi Peck. a time the U.S. Geological Survey attempted to ex­ In Colorado the Burro Canyon formation has press this confusion by using a query with the name AGE AND CORRELATION OF THE FORMATIONS 25 in many regions, but even in the type area there is but better assigned to the Calycoceras. These doubt as to what is to be included in the Dakota and fossils are of early Late Cretaceous age (Cenoman­ as to its exact age (Tester, 1952), and the query is ian). The species found at the several localities are now omitted. The Dakota sandstone, as the name is shown in table 2. here applied, is believed to rest unconformably on the Lower Cretaceous deposits, and it is apparently TABLE 2. Invertebrate fossils from the Dakota sandstone conformable with the overlying Mancos shale, which USGS locality ' in its basal part contains a late Greenhorn fauna (early Turonian). 4198 13710 9251 9252 9253 13707 23960 In Utah, determinable fossils are scarce in the Da­ X Inoceramus aff. /. prefragilis Stephen- kota. Fragmentary pelecypods were found by Fisher X at one locality. Petrified wood is fairly common, and X in places large tree trunks are present. Near Elgin X X X X X X and near Woodside, Richardson (1909, p. 14) collected 1 Descriptions of localities follow. 4198. Point between Colorado and Qunnison Rivers, near Grand Junction, Mesa fossil plants that were determined by F. H. Knowlton County, Colo. (sec. 23, T. 1 S., R. 1 W., Ute principal meridian). Car­ bonaceous shale at top of coal of Dakota sandstone. Collector, W. T. Lee, as typical Dakota forms; these included the ferns Pec- 1907. 9251. One-third of a mile west and one-eight of a mile south of SE. cor. T. 4 S., R. opteris striata Heer? and Gleicheniaf sp.; the coni­ 3 E., 7M miles west of Delta, Delta County, Colo. Upper 20 feet of Dakota sandstone. Collector, Q. H. Stone, 1915. fers Torreya oblanceolata Lesquereux and Pinus sp.; 9252. One-eighth of a mile southwest of loc. 9251; upper 20 ft of Dakota sandstone. Collector, G. H. Stone, 1915. and the dicotyledons Laurus proteaefolia Lesquereux, 9253. Three-fourths of a mile southwest of loc. 9251; upper 20 ft of Dakota sandstone. Collector, G. H. Stone, 1915. L. modesta Lesquereux?, Liquidambar integrifolium 13707. North bank of , 7^ miles west of Delta, Delta County, Colo. Shale beneath uppermost sandstone of Dakota. Collector, J. B. Ree­ Lesquereux, Andromeda linearifolia Lesquereux?, and side, Jr., 1926. 13710. Highway 50, 8 miles west of Delta, Delta County, Colo.; 1 mile north of loc. Salix proteaefolia Lesquereux. This flora, with a 13707. Uppermost sandstone of Dakota. Collector, J. B. Reeside, Jr., 1926. 23960. Same locality as 13707.; uppermost sandstone of Dakota. Collector, J. J. varied dicotyledonous element, is assigned to the early Carroll and J. B. Reeside, Jr., 1952. Late Cretaceous (Cenomanian). The problematical marine fossil Halymenites major Lesquereux is com­ The fauna of the marine part of the Dakota sand­ mon at some places, though it has no significance in stone of western Colorado, though small, resembles correlation. Katich (1951) reports Inoceramus co- that of the lower part of the of the mancheanus Cragin from the Dakota, which, if cor­ foothills of the of central Colorado, rectly determined, would be of Albian age (late Early which has yielded from a zone 60 feet above the Cretaceous). The close relationship with the Mancos Dakota sandstone of that region a considerable num­ shale and the fossil plants suggest strongly that, at ber of species, including ammonites of the genus Caly­ least at most places, the Dakota sandstone in the Utah coceras (Dane, Pierce and Reeside, 1937, p. 210). The part of the region is to be placed in the Late Creta­ difference in the horizons of the fauna in the two areas ceous (Cenomanian). suggests that the two sandstone formations are merely In Colorado the coal-bearing lower part of the Da­ homogenetic, not strictly equivalent units. The exact kota sandstone has yielded fossil plants assigned by relation of either to the typical Dakota sandstone of Brown (1950) to the early Late Cretaceous. These northeastern Nebraska is unknown. include the ferns Asplenium sp., flfatonidium ameri- The present record thus leaves the Dakota sand­ canum Berry, and Bolbitis coloradica Brown, and the stone in a somewhat uncertain status. The fossils of dicotyledons Juglans crassipes Heer, Ficus daphnoge- the Cedar Mountain and Burro Canyon formations noides (Heer), Nelumbium sp., Mahonia furnaria are believed to indicate an Aptian age. The plants Brown, Sassafras cretaceum Newberry, Platanus new- reported by Richardson and Brown and the inverte­ berryana Heer, Celastrophyllum stokesi Brown, Ster- brates reported by Reeside are believed to indicate a culia towneri (Lesquereux), and Gapsulocarpus dako- Cenomanian age. The only indication of intermediate tensis Berry. Brown says that these are . Albian beds is the Inoceramus reported by Katich, chiefly species that occur in the large flora * * * from the which would be of middle Albian age. Certainly at brownish Dakota sandstone of and Nebraska, in the many places there would seem to be no strata to rep­ Woodbine formation of , the Dakota of the , resent the Albian (including equivalents of the Mowry S. Dak., and the Upper Cretaceous rocks of Greenland. shale). The writers are inclined to believe that in the The upper part has yielded a few marine inverte­ Book Cliffs region a Cenomanian Dakota sandstone brates, notably Inoceramus aff. /. prefragilis Stephen- rests unconformably on the Aptian Cedar Mountain son and an ammonite formerly called Acanthoceras formation or the Burro Canyon formation and that aff. A. rhotomagensis (Defranee) by Reeside (1927), equivalents of the post-Aptian Lower Cretaceous beds 26 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO are missing. It is possible that in central Utah the TABLE 3. Fossils found at various localities in the upper Green­ discontinuous Dakota sandstone is in part equivalent horn equivalent l to the early Greenhorn zones that in western Colorado USQS Mesozoic loc. are found in the basal part of the Mancos shale, though the evidence for this is scant, and that the 13255 15553 23958 3769 Lotl 13660 9249 23962 Cenomanian, as well as the Albian, is poorly repre­ Inoceramus aft. I. prefragilis sented or missing. Gryphaea newberryi Stanton, X X X X X X Oryphaea newberryi Stanton, MANGOS SHALE X At its type locality in southwestern Colorado, the 1 See list at the end of table 9 for descriptions of localities. Mancos shale was estimated by Cross (1899b) to be early Turonian age and is associated with fossils char­ about 1,200 feet thick, but a measurement by Pike acteristic of an upper part (lower part of Bridge (1947, p. 9) shows it to be about 2,200 feet thick. Creek limestone member) of the Greenhorn lime­ The lower part contains fossils representing zones stone Metoicoceras whitei Hyatt, Kanafoiceras, and of Colorado age, whereas the upper few hundred Sciponoceras gracile (Shumard). Katich (1951) re­ feet contains fossils representing the lower zones of ports Inoceramus nahwisi McLearn in the basal part Montana age. The belt of outcrop that includes the of the Mancos shale. If correctly identified, this would type locality extends along the margins of the San indicate a late Albian age and equivalence to the Juan basin some distance to the east in Colorado and Mowry shale;, this assignment conflicts with the ap­ to the south into New Mexico (Reeside, 1924, p. 9). parent age of the underlying Dakota sandstone and In all this area it is overlain by rocks assigned to the with the accepted age of Gryphaea newberryi. The Mesaverde group. Eastward from the type locality, writers know no other evidence of the presence in the lithologic boundary, by the passage of Mesaverde the section of an equivalent of the Mowry shale. sandstones into marine shales, rises somewhat with No faunal evidence is known to the writers of the respect to the faunal zones; southward from the type presence in the Mancos shale of the Book Cliffs region locality, the lithologic boundary descends by the re­ of beds equivalent to the upper part of the Belle verse process, so much so that it passes well down into Fourche shale and to the two lower members (Lincoln beds of Colorado age (Pike, 1947, p. 13-25; Sears, and Hartland members) and the uppermost part 1936, p. 13-14; Sears, Hunt and Hendricks, 1941, p. (upper part of Bridge Creek member) of the Green­ 108-110), and the Mancos includes only the older horn limestone. The Belle Fourche shale and the beds of Colorado age. lower members of the Greenhorn limestone are gen­ The Mancos shale of the Book Cliffs, though much erally considered equivalent to the later Cenomanian thicker than at the type locality, nevertheless includes of Europe; and the upper members of the Greenhorn in the western part of the area about the same chrono­ limestone, to the early Turonian. of Europe. In the logic units as does the type exposure faunal zones western interior the highest member of the Greenhorn of Colorado age and of earlier Montana age. East­ limestone contains Inoceramus labiatus (Schlotheim), ward, younger beds are included progressively until Thomasites, and other ammonites. These have not strata are present (equivalents of the Gregory member been found in the Book Cliffs, but it is possible that of the Pierre shale) somewhat younger than are a very thin barren representative of the rocks in the known in the Mancos of the San Juan basin. The interval is present and unrecognized. equivalents of the Mancos shale in the standard se­ Two faunal zones, marked particularly by species quence, so far as may be determined from available of the ammonite genus Gollignoniceras (Prionotropis collections of fossils, are shown graphically on plate of literature), are found in the Mancos shale above the 10, and the accompanying tables list the species found. zone containing Gryphaea newberryi. The species Widespread at or near the base of the Mancos found in these zones are shown in table 4. Elsewhere shale in eastern Utah a zone a few tens of feet thick these species mark the lower part of the Carlile shale. contains an assemblage marked by Gryphaea new- A lower zone with Collignoniceras woollgari (Man- berryi Stanton; in western Colorado this species is tell) has been recognized at localities in eastern Utah found 60-90 feet above the Dakota sandstone. West and western Colorado in the lower part of a persistent of Green River, Utah, it has not been found. The interval of rocks, marked by large concretions. The collections from this zone available to the writers are unit is as much as 50 feet thick, and its base ranges shown in table 3. In other parts of the western in­ from 100 to 150 feet above the base of the Mancos terior, this species has been commonly considered of shale. This zone corresponds in age to the Fairport AGE AND CORRELATION OF THE FORMATIONS 27

TABLE 4. Fossils found at various localities in the lower Carlile equivalent

U.S.G.S. Mesozolc loo.

Collig- Collignoniceras woollgari zone noniceras hyatti zone

12834 23952 23953 13256 23946 3767 13254 23942 23948 23943 23949 23944 23947 23963 23422

? X X X X X X X X X (Atrina) afT. P. (A.) lakesi Whito...... X X X X X X X X X X art. /. labiaius (Schlothoim)...... _ ...... _ . X X X X Pteria (Phelopterla) gastrodes (Meek) __ ___ .. ___ _ .... X? X X X X sp...... X X X X X X X X X X ? X X X ? ? X X X X ? X X X ? X X X X v X X X ? X X X X X X ? ? ? X

X X X X X X X X X X? X X X X X X X X X sp -X ? X X X X ? hyatti (Stanton) s. s...... X X X X X X

i See list at the end of table 0 for descriptions of localities. chalky shale member of the Carlile shale. The upper tive fossils have not been found east of the one known zone, with Collignoniceras hyatti (Stanton), has been locality. recognized at only one locality, southeast of Price, Two faunal zones, marked particularly by species Utah; and its stratigraphic relations to the localities (see table 5) of the ammonite genus Prionocyclus and cited in the lower zone are not well known.1 This associated scaphites, are found in the Mancos shale zone corresponds to the Blue Hill shale member of above the Collignoniceras zones. A zone of platy cal­ the Carlile shale. Possibly the zone with G. hyatti careous sandstone beds separated by shale beds, 80-100 is represented in eastern Utah and western Colorado feet thick and referred to in some of the descriptions in the upper part of the persistent interval of large of the Book Cliffs region as the Ferron sandstone concretions or in the overlying shale, but the distinc- member of the Mancos shale, extends across eastern Utah into western Colorado, generally as a low cuesta J Thls locality was found by Dr. P. J. Katlch, who kindly permits along the outcrop. South of Crescent, Utah, there are the writers to record It here. two cuestas in this sandstone zone. The base of this 28 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO TABLE 5. Fossils found at various localities in the middle Carlile equivalent l

U.S.Q.S. Mesozolcloc.

Prionocyclus macombi zone Prionocyclus wyomingensis zone

CD o o lO 8 to o> CO 00 CD 0> s s? 10 CO £ 1 CO' CO CO CO 3 *o co CO 35 1 82 i r- r- i s CO CO§ CO r-» CO CO § 00s 00 00 100 00 00 CM8 CO 1 1 1 i 00 00 00 00 £5 1 1 § 1 s 1 Leda? sp ______X X X -- X X -- X X X X X X X X X X perplexus Whitfield ______? X X X X X howelli White ______X X X ? f X X X ? n. sp. aff. /. labiatus (Schlo- X X sp-_._ ___ _ X X X X X X X X X X X X X X X X X X sp X X X X X X X X X X X -- X f Cyrena? sp ______X X X X X X -- X X X ? ? X ? X X X X X ? ? X X X V X X X ? ? Corbula kanabensis Stanton _ _ _ _ X X X X X Teinostoma? sp______X Eulimella? sp______X Gyrodes depressa Meek ______X X X Lunatia aff. L. concinna (Hall and Meek) ______X Pugnellus? sp______X Volutoderma ambigua (Stanton) ?____ X X gracilis (Stanton) ?______X Baculites sp ______X X X X V Scaphites ferronensis Cobban _ _ _ _ X X whitfieldi Cobban ______X X V X X X f X sp______.______X X X X Prionocyclus macombi Meek______X X X X X -- -- X X X X X X X X .. X -- X X X X sp______X X X Fish remains, indet ______X X X X See list at the end of table 9 for descriptions of localities. zone of shale and sandstone lies, around the San Ka- equivalents of the Niobrara formation. The typical fael Swell, from 600 to 400 feet above the Dakota Niobrara formation of the has not been sandstone, with the greater measurement in the west. interpreted in the past to contain equivalents of the East of the swell in both Utah and Colorado, the base Telegraph Creek and Eagle formations of Montana, is about 300 feet above the Dakota. A lower zone but recent evidence tends to support the thesis that with Prionocyclus macombi Meek, /Scaphites warreni they are present, but perhaps with a facies not indi­ Meek and Hayden, and their associates is found in cative of an environment favorable to the faunas the lower part of the shale, and 'sandstone zone. An characteristic of the Montana formations. In the upper zone with Prionocyclus wyomingensis Meek and western Book Cliffs the lower and middle parts of its associates is "found in the upper part and in the the Niobrara equivalent below that of the Telegraph overlying shale.beds. Inoceramus. dimidius White and Creek are as much as 1,600 feet thick, and in the Ostrea lugubris Conrad are very common in these eastern Book Cliffs they are 1,000 feet. Scattered zones. An equivalent of the uppermost parts of the collections, shown in table 6, indicate the presence Carlile shale has not been identified in the Mancos of lower Niobrara fossils (Inoceramus exogyroides shale, and it is not known whether the sequence is Meek and Hayden and /. unibonatus Meek and Hay- complete but barren or whether unnoted interruptions den, both of which may be /. involutus Sowerby, and are present. Scaphites depressus Reeside) and lower middle Nio­ Above the Carlile equivalents, beds that are gen­ brara fossils (Clioscaphites vermiformis (Meek and erally more calcareous contain faunas that identify Hayden) and Inoceramus stantoni Sokolow). Farther GEOLOGICAL ST.'KVKY PROFESSIONAL PAPEK 332 PLATE 4

B. WEST FACE OF BECK\VITU 1'LATEAU EAST OF DESERT, UTAH Castlegate sandstone, Kc; and upper, sandstone, part of upper member of A. ViAsAiUl" lOKAIAIlU.N Blackhawk formation, Kbiim. Detailed view of basal conglomerate shown in plate 6C.

C. CASII.L.c.^ll, SANDSTONE IN A SIDE CANYON OF CRESCENT WASH, UTAH Note irregularity of bedding. Photograph by E. M. Spieker. GKOl.tKIICAT, SURVEY PROFESSIONAL PAPER 332 PLATE 5

A. EAST SIDE OF CANYON OF WESTWATER WASH AT ROBERSON RANCH, UTAH Kc, bench of Castlegale sandstone; Kbt, Buck tongue of Mancos shale; Ks, Sego sandstone; Kn, Neslen formation. .

_ .

«« ** B. SEGO SANDSTONE NORTH OF CISCO, UTAH Detailed view of weathered surface of upper, "white," part as seen in SW1^ sec. 4, T. 19 S., R. 23 E.

t . i.v.^M.f,(,\II. >\M)STONE, NORTH OF CISCO, UTAH Rippled surface 4 feet below top, near southwest corner sec. 2, T. 20 S., R. 22 E. Right side of view is on the west. Average wave­ length is 0 inches and average amplitude is 1 inch. GEOLOGICAL SURVKY PROFESSIONAL PAPKIJ 332 PLATE 0 Crescent Butte

r

A. CRESCENT BUTTE,LOOKING NORTH ACROSS CRESCENT WASH View of the butte in T. 20 S., R. 19 E., where it rises to 1,450 feet above the wash. Kc, bench of Castlcgatc sandstone, dotted with junipers; Kbt, Buck tongue of Mancos shale; Ks, Sego sandstone; Kn, Neslen formation, lower part hidden behind Sego cliff; Kf, Fairer formation.

B. SEGO SANDSTONE AND BUCK TONGUE OF MANCOS SHALE Sego sandstone, Ks, nearly 200 fpet thick, in spur northwest of Thompson, Utah; Kbt, Buck tongue.

C. "WASATCH" STRATA, NORTHWEST OF CISCO, UTAH Lower 800 feet of "Wasatch" strata, Tew, exposed on east aide of Nash Wash reentrant. GEOLOGICAL SURVEY PROFESSIONAL PAPER 332 PLATE 7

Coal in Sunnyside coal Kbum

HBW*&7-« .«,mdS»Ki A. LOOKING NORTHEAST AT BOOK CUFFS, 7 MILES .NOKTII OF WOODSIDE, UTAH A dissected alluvial pediment cut on Mancos shale and sloping away from cliffs. Note narrow fragments of whole face of lower sand­ stone slumping off. Km, Mancos shale; Kbls, lower sandstone member, Blackhawk formation; Kbmsh, middle shale member, Black- hawk formation; Kbms, middle sandstone member, Blackhawk formation; Kbum, upper member, Blackhawk formation; Kc, Castlegafe sandstone.

B. CASTLEGATE AND BLACKHAWK FORMATIONS, NASH WASH REENTRANT, NORTHWEST OF CISCO, UTAH View, looking northeast from sec. 9, T. 20 S., R. 21 E., showing how large sandstone blocks from 140 feet of Castlegate and Black- hawk formations break off the cliff front. Km, Mancos shale; Kc, Castlegate sandstone arid upper 50 feet of Blackhawk formation; Kp, undifferentiated formations; Tew, "Wasatch" formation.

C. WIDE ALLUVIAL FLAT, CANYON OF SALERATUS WASH, UTAH Flat with meandering stream, owing to weakening of strata by faulting, looking down canyon, 13 miles east of Green River, Utah, from sec. 7, T. 21 S., R. 19 E. Km, Mancos shale; Kbum, sandy upper part of upper member of Blackhawk formation; Kc, Castlegate sandstone. AGE AND CORRELATION OF THE FORMATIONS 29 TABLE 6. Fossils found at various localities in the Niobrara TABLE 7. Fossils found at various localities in the Telegraph Creek equivalent, to base of Telegraph Creek equivalent l equivalent 1

U.S.O.S. Mesozoic loc. U.S.G.S. Me ozolc loc. as £ CO «o en 383 co « S 1 s 1 Si § « % 8 s CO CO i-~ O5 S s CO CO CO II

X X X X X X -- X X X X X X X X X X -- X -- X X X X X X - X X .. X ? X X X X X -. X cr\ X X X .. X X X X X - X X X X X X See list at the end of this series of tables for descriptions of localities. X X X X -. X X X -- X X X -- X -- X X X TABLE 8. Fossils found at various localities in the Eagle equivalent* X X ... X ClioscapMtes vermiformis (Mock and Hay- X X X X- U.S.O.S. Mesozoic loc. X X

TABLE 9. Fossils found at various localities in equivalents of lower part of Pierre shale

U.S.G.S. Mesozoic loc.

13318 13332 13683 13693 13714 13715 4189 4206 4208 4209 4213 4216 4217 4490 4496 4498

X X X X X Yoldia evansi (Meek and Hayden).... ___ . _ .-.-----.-.. v X Inoceramus "barabini Morton" of Meek. ____ _.-__--_-_-_-_ X X X X X X ? X X X X X X X X X X linguiformis (Evans and Shumard)...-. ______...... X X X X X X X X X X X X X X X X Thetisf circularis (Meek and Hayden). .. __ ...... X v X X X ? X X

X v Baculites asperiformls Meek. ______...... ? X X X X X X X

See list at the end of this series of tables for descriptions of localities.

Descriptions of localities in tables 8-9 8758. SW%SE% sec. 9, T. 15 S., R. 12 E. 8759. NE%SW% sec. 4, T. 15 S., R. 12 E. 8760. SW% sec. 15, T. 15 S., R. 11 E. Lot 1. Near Home Oil Company's wells, in sec. 4, T. 19 S., 8761. SE%NW% sec. 7, T. 15 S., R. 12 E. R. 25 B., Grand County, Utah (Dane, 1935, p. 116) 8762. NW % sec. 21, T. 15 S., R. 12 E. 3754-3773. Book Cliffs coal field, Utah and Colorado. Collected by 8763. NW%NW% sec. 6, T. 15 S., R. 12 E. G. B. Richardson, 1906. 9249-9250. Western Colorado; collected by G. H. Stone, 1915. 3754. Bluff on south bank of Grand [Colorado] River, 1% 9249. West of Delta; less than 50 ft above base of Mancos shale. miles east of Grand Junction, Colo.; Mancos shale. 9250. West of Delta; 300-400 ft above base of Mancos shale. 3759. Hill one-fourth of a mile east of reservoir near narrow 10276. Eastern Utah; collected by J. W. Young, 1920. Railroad cut gage railroad, 10 miles west of Mack, Colo.; Mancos about 100 yd west of depot at Green River; thin calcareous shale. sandstone layers in shale. 3766. 7 miles south of Thompson, Utah; near base of Mancos 12S34. Eastern Utah; collected by James Gilluly, 1924. Summerville shale. Wash, sec. 13, T. 18 S., R. 13 E.; 150 ft above top of 3767. 2 miles southwest of Green River, Utah; base of shale Dakota sandstone. bluff in Mancos shale, half a mile from top of Dakota 13240-13264. Eastern Utah; collected by E. M. Spieker and J. B. sandstone. Reeside, Jr., 1925. 3769. 2 miles east of Cisco, Utah; base of Mancos shale. 13240. 1 mile south of Desert (sec. 11, T. 20 S., R. 14 E.) ; 3773. Hill immediately south of D. & R. G. W. R.R., between 20 ft above "Ferron sandstone." Fruita and Mack, Colo.; near base of Mancos shale. 13241. Half a mile south of Desert. 90 ft above "Ferron 4189-4498. Grand Mesa coal field, Colo.; collected by W. T. Lee, 1907. sandstone." 4189. Sec. 1, T. US., R. 98 W., near Palisade; near top Mancos 13242. Half a mile south of Desert, 110 ft above "Ferron shale. sandstone." 4206. Sec. 4, T. 14 S., R. 96 W., 9 miles northwest of Delta; 13243. Half a mile east of Desert in layer about near top of Mancos shale. 975 ft above base of Mancos. 4208. Sec. 36, T. 13 S., R. 95 W., 10 miles northeast of Delta; 13244. 1 mile east of Desert in orange-brown limestone layer 400 ft below top of Mancos shale. about 1,600 ft above base of Mancos. 4209. Sec. 21 T., 13 S., R. 95 W., 12 miles north of Delta; 13245. Same locality as 13244 and 10 ft above it. near top of Mancos shale. 13246. 1 mile east of Desert, in shale between 2 limestone 4213. Sec. 20, T. 13 S., R. 95 W., 12 miles north of Delta; bands, about 1,630 ft above base of Mancos. near top of Mancos shale. 13247. 1 mile east of Desert. Concretion in shale, 1,710 ft 4216. Sec. 30, T. 13 S., R. 95 W., west of Fairview mine, 10 above base of Mancos. miles north of Delta; about 200 ft below top of Mancos 13248. 1 mile east of Desert. 1,750 ft above base of Mancos. shale. 13249. 1 mile east of Desert. 1,900 ft above base of Mancos. 4217. Sec. 21, T. 13 S., R. 95 W., 12 miles northeast of Delta; 13250. 1 mile east of Desert. 1,920 ft above base of Mancos. about 400 ft below top of Mancos shale. 13251. 1% miles east of Desert. 2,200 ft above base of Mancos. 4490. Sec. 5, T. 14 S., R. 90 W., Minnesota Creek, 7 miles east 13252. 1% miles east of Desert. In a gritty sandstone 2,175 of Paonia; near top of Mancos shale. ft above base of Mancos. 4496. Sec. 5, T. 14 S., R. 90 W., 7 miles east of Paonia; top 13254. 1 mile south of Green River. 100 ft above base of of Mancos shale or base of Mesaverde formation. Mancos shale. 4498. Sec. 8, T. 14 S., R. 90 W., 7 miles east of Paonia; top 13255. 2 miles south of Green River, along road to Hanks- of Mancos shale. ville. Very near base of Mancos. 8135-8139. Farnham anticline, Utah ; associated with "Ferron sand­ stone" ; collected by F. R. Clark, 1912. 13256. Half a mile southwest of Desert, along Cottonwood 8135. Sec. 15, T. 15 S., R. 11 E.; 850 ft above base of Mancos Springs road, 100 ft above base of Mancos. shale. 13257. 1 mile south of Desert; 60 ft above "Ferron sand­ 8136. Sec. 2, T. 15 S., R. 11 E.; 700 ft above base of Mancos stone," 380 ft above base of Mancos. shale. 13258. 1 mile south of Desert; 80 ft above "Ferron sand­ 8137. Sec. 36, T. 14 S., R. 11 E.; 700 ft above base of Mancos stone," 400 ft above base of Mancos. shale. 13259. Near Desert. 780 ft above base of Mancos. 8138. NW% sec. 6, T. 15 S., R. 12 E.; 700 ft above base of 13260. Half a mile east of Desert. 970 feet above base of Mancos shale. Mancos. 8139. Center sec. 6, T. 15 S., R. 12 E.; 700 ft above base of Mancos shale. 13261. 1 mile east of Desert. 1,350 ft above base of Mancos. 8758-8763. North of Mounds, Utah; associated with "Ferron sand­ 13262. 1 mile east of Desert. 1,460 ft above base of Mancos. stone," 700-900 ft above base of Mancos shale; collected 13263. East of Desert. 1,525 ft above base of Mancos. by F. R. Clark, 1913. 13264. East of Desert. 1,550 ft above base of Mancos. AGE AND CORRELATION OF THE FORMATIONS 31

1331.8-13340. Eastern Utah; collected by H. F. Moses, 1925. 23951. Same locality as 23950; upper of 2 zones of platy sand­ 13318. 6 miles northeast of Woodslde (sec. 14, T. 17 S., R. 14 stone, about 250 ft above base of Mancos shale. E.). About 500 ft below top of Mancos. 23952. 1 mile W. 20° N. of Cliff, in SB. cor. sec. 5, T. 19 S., 13319. 3 miles north of Woodslde (SE%, sec. 29, T. 17 S., R. R. 14 E.; basal part of zone of large dirty concre­ 14 E.). From a coarse-grained gray-brown, 6-in. tions, 115 ft above base of Mancos shale. limestone bed, 3,200 ft below top of Mancos. 23953. Same locality as 23952; hard, cuesta-forming sandstone 1.3323. 4 miles southeast of Woodslde (SW& sec. 25, T. 18 S., 165 ft above base of Mancos shale. R. 14 E.). 500-600 ft below top of Mancos. 23954. Same locality as 23952 ; base of 30-ft zone of ridge- 13324. One quarter of a mile south-southwest of 13323 In the forming platy sandstone beds, 295 ft above base of same quarter section. 500-600 ft below top of Mancos shale. Mancos. 23955. Same locality as 23952 ; middle of 30-ft zone of sand­ 13325. 4 miles south of Woodslde (NE% sec. 4, T. 19 S., R. stone, 310 ft above base of Mancos shale. 14 E.). 2,750 ft below top of Mancos. 23956. Same locality as 23952 ; top of 30-ft zone of sandstone, 1332G. 6 miles northwest of Green River (SE% sec. 14, T. 20 325 ft above base of Mancos shale. S., R. 15 E.). About 800 ft below top of Mancos. 23957. On road to Uvanco mine, 11 miles southeast of Thomp­ 13328. 3 miles northeast of Green River (NE% sec. 2, T. 21 S., son, in NW%NE% sec. 25, T. 22 S., R. 21 B., pro­ R. 16 E.). 1,400 ft above base of Mancos. jected ; thin-bedded sandstone beds 300 ft above base 13330. 4 miles northeast of Green River (SB'4 sec. 28, T. 20 of Mancos shale. S., R. 16 E.). 1,950 ft above base of Mancos. 23958. 1 mile west of road to Uvanco mine, 11 miles south­ 13331. 3 miles northeast of Green River (SW% sec. 33, T. 20 east of Thompson, in NE&NW% sec. 26, T. 22 S., S., R. 16 E.). About 1,400 ft above base of Mancos. R. 21 E., projected ; lowest 10 ft of Mancos shale. 13332. Bast branch of Tuscher Wash (SB. cor. sec. 13, T. 20 23962. Near Highway 50, 7 miles west of Delta, western Colorado ; S., R. 16 E.). 350 ft below top of Mancos. 140 ft above base of Mancos shale; collected by P. J. Katich, 13340. 4 miles northeast of Solitude (NW% sec. 18, T. 21 S., 1952. R. 1.8 E.). About 700 ft below top of Mancos. 23963-23964. Western Colorado; collected by J. B. Reeside, Jr., J. J. 18658-13605. Western Colorado ; collected by J. B. Reeslde, Jr., 1926. Carroll, and J. De A. Ramos, 1952. 13058. North of west end of Grand Junction; lowest yellow 23963. Road north from Highway 50 to Lee Brisuma Ranch, 7 layer, 1,800 ft beneath top of Mancos shale. miles west of Delta; concretions 200 ft above base 13659. North of west end of Grand Junction; yellow layer of Mancos shale. 1,350 ft beneath too of Mancos shale. 23964. Same locality as 23963; platy sandstone beds 250 ft 13660. 2 miles north of Whltewater; 80 ft above Dakota (?) above base of Mancos shale. sandstone. 13663. Same locality as 13660; 330 ft above Dakota(?) sand­ stone. 13664. Same locality as 13660; 400 ft above Dakota(?) sand­ MESAVERDE GROUP stone. 13665. Same locality as 13600; 410 ft above Dakota (?) sand­ stone. BLACKHAWK FORMATION 13666-13693. Eastern Utah. 13666. 1% miles northwest of Floy (SE% sec. 32, T. 21 S., R. 18 E.). 600-700 ft below top of Mancos. Collected Fossil mollusks were found in only the upper mem­ by D. J. Fisher, 1926. 13683. Sagers Canyon In sec. 5, T. 21 S., R. 21 B. About 400 ber of the Blackhawk formation. These are domi- ft below top of Mancos shale. Collected by R. M. Leggette, 1926. nantly brackish-water forms, mostly of long range, 13691. About 3 miles south of Sagers, near the NB. cor. sec. 7, T. 22 S., R. 21 B. From middle of Mancos shale. and associated with them are a few fresh-water forms. Collected bv R. M. Leggette, 1926. 13692. 300 yd south of 13691 and about 75 ft lower strati- It is probable that the mixture is wholly mechanical. grnphically. Collected by R. M. Leggette, 1926. 13093. 3 miles north of Sagers (sec. 4, T. 21 S., R. 21 B.). The relations of the fresh-water and brackish-water About 750 ft below top of Mancos. Collected by J. H. Hengst, 1926. faunas are discussed under the heading, "Nonmarine 13695-13715. Western Colorado; collected by J. B. Reeslde, Jr., 1926. 13695. 2 miles north of Whitewater; 453 ft above base of faunas in the sequence." The best that can be said Mnncos shale. 13696. 6 miles north of Grand Junction; lowest yellow layer, now of the fauna is that it represents a Late Creta­ about 2,350 ft beneath top of Mancos shale. ceous age. However, the eastward passage of the 13697. 6 miles north of Grand Junction; 2,100 ft beneath top of Mancos shale. Blackhawk into marine shale whose relative position 13098. 6 miles north of east end of Grand Junction; 2,200 ft boneuth too of Mnncos shale. is known affords a better dating than the brackish- 13714. NE% sec. 31, T. 7 S., R. 102 W., on Rangely road just above Brown's lower ranch; 250 ft below top water fossils. The species found are shown in of Mancos shale. v 13715. Same locality as 13714; 200 ft below top of Mancos table 10. shale. 15553. Eastern Utah ; collected by A. A. Baker, 1930. About 2% miles southeast of Hanksville road, in sec. 15, T. 22 S., R. 15 E.; CASTLEGATE SANDSTONE base of Mancos shale. 23422. Eastern Utah; collected by P. J. Katlch and others, 1951: Highway 50, 16 miles east of Price; 330 ft above base of Mancos shale. A few fossils, as shown in table 11, were col­ 23942-23958. Eastern Utah; collected by J. B. Reeside, Jr., J. J. Carroll, and J. De A. Ramos, 1952. lected from the Castlegate sandstone in the area east 23942. Hanksville road, half a mile south of Green River in NE%SE% sec. 16, T. 21 S., R. 16 E.; light-gray con­ of the Green River. The species present are indica­ cretions 100 ft above base of Mancos shale. 23943. Same locality as 23942; base of zone of large dirty- tive of brackish-water to marine conditions, except brown concretions 130-185 ft above base of Mancos shale. for fragments of a trionychid found near 23944. Same locality as 23942; upper part of zone of large concretions. Crescent Wash, which fossil may have been trans­ 23045. Same locality as 23942; basal part of ridge-making zone of platy sandstone 330 ft above base of Mancos ported from its normal fresh-water habitat. The shale. 2394.6. Hnlf a mile west of Desert, in SB% sec. 10, T. 20 S., species do not in themselves afford an exact age R. 14 E.; sandy zone 160 ft above base of Mancos shale. assignment. 23947. Half a mile west of road to "Geyser" and 4 miles southeast of Green River, in center sec. 30, T. 21 S., R. 17 B.; base of concretion zone, 100 ft above base PRICE RIVER FORMATION (RESTRICTED) of Mancos shale. 23948. Hanksville road, 2 miles south of Green River, in SEyt SW% sec. 20, T. 21 S., R. 10 E.: lowest con­ cretions, 100 ft above base of Mancos shale. In the part of the Book Cliffs where the Price River 23949. Same locality as 23948; base of zone of large dirty concretions 130 ft above base of Mancos shale. formation, restricted by removal of the Castlegate 23950. Highway 160, from Crescent to Moab, 4 miles south of Valley City, in SE%SWi4 sec. 13, T. 23 S., R. 19 E.; sandstone, is recognized, few fossils were collected lower of 2 zones of platy sandstone, about 150 ft above base of Mancos shale. from the formation. The age of the formation is 32 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO fixed, however, by the passage eastward of the lower TABLE 12. Fossils found at various localities in the Price River part into marine beds of Late Cretaceous age equiva­ formation (restricted)1 lent to part of the Pierre shale and by the occurrence U.S. G.S. U.S.G.S. Mesozoic Mesozoic above it, in the North Horn formation of the Wasatch loc. loc. Plateau, of a Late Cretaceous dinosaur fauna. The 12247 8140 12247 8140 species noted are all fresh-water forms and are shown in table 12. cf. U. priscus Meek X X X X Unio cf. 17. amarillensis Campeloma cf. C. amaril- X X sp...... X X Sphaerium cf. S. planum Goniobasisf subtortuosa TABLE 10. Fossils found at various localities in the upper part of X X the Blackhawk formation 1 v

TJ.S.G.S. Mesozoicloc. i Descriptions of localities follow. 8140. Sec. 14, T. 13 S., R. 10 E., canyon of Deadman Creek, Wellington quad­ rangle, Utah; base of formation; collected by F. R. Clark, 1912. 7395 7398 7399 7397 7393 7394 13327 13333 12247. 1 mile above Castle Gate on Price River; base of formation; collected by E. M. Spieker and J. B. Reeside, Jr., 1923. Fresh-water species: X BUCK TONGUE OF MANCOS SHAUB X X X X X v Goniobasis aff. 0. convexa (Meek and The Buck tongue of the Mancos shale has yielded Brackish-water species: a marine fauna of considerable variety that is most X X X X v comparable to that of the Gregory member of the X X X X X X X X Pierre shale. The species found are shown in table 13. X Corbicula cytheriformis (Meek and X X TABLE 13. Fossils found at various localities in the Buck tongue ? SP - X X v of the Mancos shale 1 X X X X X X en X U.S.G.S. Mesozoicloc. : O5 CO N S 8 N CO CO S 3 i All localities in Utah; 7393-7399 collected by F. R. Clark, 1911; 13327 and 13333 by 1 D. J. Fisher, 1925. X 7393. 3 miles south of Sunnyside, in sec. 17, T. 15 S., R. 14 E.; 560 ft above Mancos X (upper member of Blackhawk formation). 7394. 4 miles south of Sunnyside, in NWJ4 sec. 20, T. 15 S., R. 14 E.; 560 ft above X X Mancos (upper member of Blackhawk formation). 7395. 3 miles northwest of Sunnyside, in sec. 24, T. 14 S., R. 13 E.; 520 ft above Man- cos (upper member of Blackhawk formation). 7397. 1^ miles southeast of Sunnyside, in SE^4 sec. 5, T. 15 S., R. 14 E., from dump X X of Mine No. 3 in Water Canyon; 480 ft above Mancos (middle sandstone v member of Blackhawk formation). X 7398. Near tunnel of Sunnyside mine No. 1, from railroad cut in mouth of No. 2 v Canyon, in sec. 32, T. 14 S., R. 14 E.; 480 ft above Mancos (middle sand­ X stone member of Blackhawk formation). X 7399. At Sunnyside, In SWJ4 sec. 32, T. 14 S., R. 14 E.; 480 ft above Mancos (middle sandstone member of Blackhawk formation). X 13327. North of Green River, from the SW)4 sec. 6, T. 20 S., R. 16 E.; 11 ft below top of middle sandstone member of Blackhawk formation. X 13333. Southeast tributary of Tuscher Wash, SE. cor. sec. 13, T. 20 S., R. 16 E.; 30 ft below top of middle sandstone member of Blackhawk formation. v v v TABLE 11. Fossils found at various localities in the Castlegate X sandstone l v Tuba? sp ____ I __ _ X X ' U.S. G.S. Mesozoicloc. X X ....

Lotl 13680 13684 13685 or* X X .... X .... cr\ X X X X X v i Descriptions of localities follow. X Lot 2, unnumbered. East of the Green River, Utah; about 500 ft above top of Man- X cos shale, in upper part of tongue; collected by G.B. Richardson, 1906; identified by X ? J. W. Gidley. 13239. Green River, 20 miles above Green River, Utah, in SEJ4 sec. 1, T. 19 S., R. 16 E.; 60 ft above base; collected by E. M. Spieker and J. B. Reeside, Jr., 1925. i Descriptions of localities follow: 13265. Canyon of Westwater Wash., Grand County, Utah, on road; 50 ft above base; Lot 1 (loc. 26). North of Crescent, in NWJ4 sec. 16, T. 21 S., R. 19 E.; 10 ft below top; collected by E. M. Spieker and J. B. Reeside, Jr., 1925. collected by D. J. Fisher, 1926. 13266. Canyon of Westwater Wash, Grand County, Utah, on road; 100 ft above base; 13680. East wall Thompson Canyon, In sec. 15, T. 21 S., R. 20 E.; from float blocks collected by E. M. Spieker and J. B. Reeside, Jr., 1925. from upper part of formation; collected by J. H. Hengst, 1926. 13712. Diamond Canyon, north of Cisco, Grand County, Utah, in sec. 18, T. 19 S., 13684. West side Sagers Canyon, in NWJ4 sec. 8, T. 21 S., R. 21 E.; from top of mem­ R. 23 E.; 100 ft above base; collected by J. B. Reeside, Jr., 1926. ber; collected by D. J. Fisher, 1926. 24411. 1 mile west of the Anchor mine 1, in sec. 27, T. 8 S., R. 101 W., Mesa County, 13685. 2 miles north of Oscar Turner's ranch (Nash Wash) from the NEH sec. 3, Colo.; collected by P. J. Katich, 1952. ' T. 20 S., R. 21 E.; slump from Castlegate sandstone; collected by D. J. 24412. North side of canyon, Cottonwood Creek, in sec. 18, T. 19 S., R. 23 E., Grand Fisher, 1926. County, Utah; collected by P. J. Katich, 1952. AGE AND CORRELATION OF THE FORMATIONS 33 SEGO SANDSTONE table 14. Two f acies are represented one of chiefly The Sego sandstone conformably underlies the beds brackish-water species, accompanied at some locali­ of the Neslen formation in. Utah and the Mount ties by a few fresh-water species; the other more Garfield formation in Colorado. At most places the strictly marine. The marine species are most com­ contact is definite, but where the basal beds of the parable to those of the Gregory member of the Pierre Neslen are sandy, the exact position is doubtful. Fos­ shale, but some of the most distinctive forms of the sils collected from the Sego sandstone are shown in Gregory have not been noted in the Sego. The assem­ blage is notable in containing an element that brings TABLE 14. Fossils found at various localities in the Sego sand­ to mind the faunas of the Late Cretaceous of the gulf stone l region, a feature noted also at certain localities in U..S.Q.S. Mesozolc locality southern Wyoming (Steele shale of Laramie Basin), to t^ in the northern Front Range in Colorado (lower 8 S COIf S % IS S CO CO e> 3 8 8 rr 1 $ 8 CO CO §CO cc co CO PO CO§ CO 8 sandstone members of the Pierre shale), and in north­ ern New Mexico (Mesaverde group). Frosh-wator spoclcs: Viaiparus cf. V. panguitchensis White.. X _ _ .. X Brackish-water species: NESUEN FORMATION Membranipora n. sp.... __ _ .... _ . X X X ? ? X X Anomla gryphorhynchus Meek and A fresh-water fauna was found in the lower beds in Haydon...... X X X X X the western exposures and in higher beds in the sp...... X Corbicula cytheriforrrils (Meek and eastern exposures. A brackish-water fauna with a ? X X few marine species also occurs in the lower beds, X Marino species: particularly toward the east. Equivalents in Colorado Boring sponge (Cllona?) ____ ...... X X of the middle beds of the Neslen formation are marine. Hemiaster humptireysianus Meek and X The age of the Neslen faunas cannot be placed more X Y closely than Late Cretaceous. Several plants as well X ? Y Barbatia cf. B. barbatula White...... X as fragments of reptiles were found. Pinna lakesi White.. ___ ...... X X X Table 15 shows the fossils collected from the Neslen X X Y y X X formation. Pteria linguaeformls (Evans and Shu- FARRER FORMATION X X Y BP...... -...... -. X X X X X The fossils of the Farrer formation include the X X X fresh-water mollusks shown in table 16, remains of a X X sp...... X turtle found in canyon of Saleratus Wash (bed 35 Modiolus attenuatus (Meek and Hay- X of section 10), and plant remains noted in Tuscher X X Canyon (bed 34 of section 8) and north of Cisco X X (beds 51 and 53 of section 14). The fauna is of rather X Cardium (Ethmocardium) whitei Ball _ . ------X X -- X -- X X X X X X --: late Cretaceous age. Protocardia subquadrata (Evans and Shumard)...... X X X X i Descriptions of localities follow. v X X 13236. Green River, Utah, 26 miles above the town of that name, In NEJ£ sec. 19, X T. 18 S., B. 17 E.; about 200 ft above Castlegate sandstone (Sego horizon); X collected by J. B. Reeslde, Jr., and E. M. Spleker, 1925. X 13237. Same locality and collectors as 13236; loose on surface above horizon of 13236- X Mactraf sp...... X 13253. Neslen Canyon, opposite Sego schoolhouse. Utah; probably from lower part - X of formation; collected by J. B. Reeside, Jr., and E. M. Spieker, 1925. ------_ X 13267. Canyon of Westwater Wash, Utah, on road; collected by J. B. Reeside, Jr., X and E. M. Spieker, 1925. X X 13268. Canyon of Westwater Wash; SWJ£ sec. 32, T. 17 S., R. 24 E., or NWJ£ sec. 5, ------X - - - - T. 18 S., R. 24 E., Utah; from brown limy sandstone at or near top; collected X by J. B. Reeside, Jr., and E. M. Spieker, 1925. X 13320. Price River, near center sec. 18, T. 18 S., R. 15 E., Utah; 115 ft above Castlegate X -1 sandstone (Sego horizon); collected by D. J. Fisher, 1925. X 13329. Canyon of Tuscher Wash; SWJ£ sec. 8, T. 20 S., R. 17 E., Utah; 17 ft below X - - X top; collected by D. J. Fisher, 1925. Fasdolaria cf. F. cheyennensis (Meek 13336. Canyon of Tuscher Wash- NWJi sec. 9, T. 20 S., R. 17 E., Utah; 12 ft below - - - X top; collected by D. J. Fisher, 1925. . . X 13337. Same locality and collector as 13336; 34 ft above base. X 13675. West branch of Saleratus Wash; sec. 31, T. 20 S., R. 19 E., Utah; 50 ft below X top; collected by D. J. Fisher, 1926. X X 13676. Same locality and collector as 13675; 15 ft below top. X X X - 13677. Same locality and collector as 13675; 5 ft below top. - - - - - X X X 13679. Northwest of Thompson; sec. 5, T. 21 S., R. 20 E., Utah; 53 ft below top; . ; . . . X collected by D. J. Fisher. 1926. X X 13687. Canyon of Westwater Wash; SWJ< sec. 5, T. 18 S., R. 24 E., Utah; 64 ft below - - - - X ? - - X ? top; collected by D; J. Fisher, 1926. - X X 13690. 2 miles west of Colorado; sec. 31, T. 16 S., R. 26 E., Utah; 165 ft below top; - - - collected by D. J. Fisher, 1926, 34 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

TABLE 15. Fossils found at various localities in the Neslen TUSCHER FORMATION formation * The Tuscher formation has yielded no significant U.S.O.S. Mesozoic loc. fossils. Its equivalence to the Hunter Canyon for­ mation in Colorado does not help to date it closely, Tf 35 X) rf CO % & § 3CO +3o COi s 1 1 & CO S 00 1 1 for this unit is also placed only as Late Cretaceous. It resembles the overlying "Wasatch" more in litho- Fresh-water species: X X X X logic character than the underlying beds, and the X X X nature of the contacts with both adjacent units is Tulotomops laevibasalis Yen. _____ . __ ...... X X X - -- - usually difficult to determine. It could be latest X X Cretaceous or earliest Tertiary, but it is here desig­ X X nated somewhat arbitrarily Cretaceous and part of Brackish-water and marine species: X the Mesaverde group. X X X X -- Y X MOUNT GARFIELD FORMATION AND ROLLINS SAND­ STONE MEMBER, BOWIE SHALE MEMBER, AND V PAONIA SHALE MEMBER OF THE MESAVERDE X FORMATION Cardium afl. C.whitei DalL. ______v v Corbula subtrigonalis Meek and Hayden. __ --.-. - X X - - - V Only a few collections of invertebrate fossils are Vertebrates and plants: available from the Mount Garfield formation of the X X Book Cliffs proper. However, from the equivalents of this formation southward and southeastward, the Rollins, Bowie and Paonia members of the Mesaverde i Descriptions of localities follow. formation, Lee (1912, p. 29-47) collected fossils noted Lot 3, unumbered. Above Ballard's prospect in Neslen Canyon, in sec. 27, T. 20 S., R. 20 E., Utah; about 175 ft above base; collected by G. B. Richardson; in table 17. The lower part of the Mount Garfield identified by F. H. Knowlton, 1906. Lot 4, unnumbered. North of Cisco, In NW>4 sec. 3, T. 19 S., R. 23 E., Utah; loose yields only marine fossils. Toward the south and sandstone slab 220 ft above base; collected by D. J. Fisher, 1926. 13334. Canyon of Tuscher Wash; NW>4 sec. 9, T. 20 S., R. 17 E., Utah; in lower 10 ft; collected by D. J. Fisher, 1925. southeast, as stated in previous pages, most of this 13339. Northeast of Solitude, from SWJ4 sec. 6, T. 21 S., R. 18 E., Utah; about 20 ft above base; collected by D. J. Fisher, 1925. part passes into the upper part of the Mancos shale. 13674. East branch from canyon of Horse Creek, SW^4 sec. 2, T. 21 S., R. 18 E.; about 25 ft above base; collected by D. J. Fisher, 1926. The upper part of the Mount Garfield formation in 13678. West side of canyon of Saleratus Wash; sec. 31, T. 20 S., R. 19 E., Utah; 35 ft above base; collected by D. J. Fisher, 1926. the Book Cliffs has yielded only fresh-water fossils. 13681. Northwest of Thompson; sec. 31, T. 20 S., R. 20 E., Utah; 4 ft above base; col­ lected by R. M. Leggette, 1926. Toward the south and southeast, however, the Bowie 13686. East side of Diamond Canyon; sec. 18, T. 19 S., R. 23 E., Utah; 120 ft above base; collected by R. M. Leggette, 1926. shale member replaces the lower beds of the upper 13688. East canyon of Westwater Wash; sec. 10, T. 17 S., R. 24 E., Utah; 304 ft above base; collected by D. J. Fisher, 1926. Mount Garfield and contains both brackish-water and 13689. North branch of canyon of Sulphur Wash; sec. 24, T. 18 S., R. 23 E., Utah; 325 ft above base; collected by D. J. Fisher, 1926. marine fossils. The Paonia shale member replaces 13709. West side of canyon of Saleratus Wash; NWj£ sec. 32, T. 20 S., R. 19 E., Utah; 15 ft above base; collected by J. B. Reeside, Jr., 1926. still higher beds but contains dominantly fresh-water fossils. The marine fossils are of longer ranging species, as are also the brackish-water forms, but the TABLE 16. Fossils found at various localities in the Farrer fresh-water types are elsewhere best known in strata formation l of very late Cretaceous age. Lee lists fossil plants from shales of the Bowie and U.S.G.S. Mesozoic loc. Paonia members and gives an analysis of the collec­ 13673 13682 Lot5 tions by F. H. Knowlton. Knowlton concludes that the fossil plants indicate an age later than the Montana Mollusks: X epoch; that is, later than the time of deposition of X X the Fox Hills sandstone. Because some of the oc­ X X currences with which comparison is made are now X X generally accepted as very late Cretaceous (though Plants: X some of them, such as the Arapahoe and Denver X or\ X formations, were considered Tertiary by Knowlton), X X and because some occurrences are well down in the Montana sequence, it is doubtful that the plants are i Descriptions of localities follow. Lot 5, unnumbered. About 8 miles north of Thompson, Utah; probably from a hori­ really distinctive of more than a general Late zon near top; collected by G. B. Richardson, 1906; identified by F. H. Knowl­ ton. Cretaceous age. 13673. East fork ofHorse Canyon, in sec. 3, T.21S..R. 18 E.,Utah; 110 ft above base; unidentified fossil leaves also found here; collected by D. J. Fisher, 1926. The fossils of the Mount Garfield formation and 13682. North of Thompson, in SE H sec. 32, T. 20 S., R. 20 E., Utah; 30 ft above base, from a lens of limy sandstone in shale; collected by D. J. Fisher, 1926. equivalents are shown in tables 17 and 18. AGE AND CORRELATION OF THE FORMATIONS 35 TABLE 17. Fossils found at various localities in the lower part 4205. Point east of Rollins mine, 75 ft above base of Paonla shale. of the Mount Garfield formation 1 4218. 14 miles northeast of Delta, Colo.; 100 ft above base of Paonia shale. U.S.O.S. Mesozoic loc. 4 miles northeast of Cedaredge, Colo.; 200 ft above base of Paonia shale. 6 miles north of Hotchkiss, Colo.; 100 ft above base of 4185 4186 4192 4203 Paonia shale. 4264. Conine mine, 3 miles northwest of Paonia, Colo.; 40 ft above base of Bowle shale. X 4265. 3 miles north of Paonia, Colo.; base of Bowie shale. X X 4266. Same as 4265 ; base of Bowie shale. X 4268. 1 mile west of Bowie, Colo.; base of Bowie shale. X ? ? 4269. One half of a mile north of Bowie, Colo.; base of Bowle X X shale. X 4271. Same as 4269 ; base of Bowie shale. X 4274. Hubbard Creek, Colo.; slide rock near top of Bowie shale. X 4275. Same as 4274; 20 ft above base of Bowie shale. X 4276. Bast side Hubbard Creek, Colo.; about 300 ft above base of Bowie shale. i See list at the end of this series of tables for descriptions of localities. 4487. Waneta mine near Bowie, Colo.; 25 ft above base of Bowie. Descriptions of localities in tables J7 and 18 4488. Near Bowie, Colo., in sec. 15, T. 13 S., R. 91 W.; 50 ft above base of Bowie. 4184-4504. Collected by W. T. Lee, 1907. 4492. Minnesota Creek, in sec. 5, T. 14 S., R. 90 W., Colo.; base 4184. 3% miles southeast of Palisade, Colo.; 250 ft above Rol­ of coal. ling sandstone. 4493. Same as 4492. 4185. 4 miles southeast of Palisade, Colo.; 25 ft above base of 4494. Same as 4492 ; 90 ft higher. Mount Gar field. 4495. Same as 4492; 275 ft higher. 4180. 3Ya miles southeast of Palisade, Colo.; 25 ft above base 4497. Same as 4492; 200 ft higher. of Mount Garfleld. 4499. Same as 4492 ; base of Bowie shale. 4192. Same as 4186; 125 ft above base of Mount Garfield. 4500. Same as 4492; near base of Bowie shale. 4195. 3Mi miles southeast of Palisade, Colo.; 150 ft above Rolling 4501. Same as 4492; near top of Bowie shale. sandstone. 4503. Coal Creek, Colo.; near top of Bowie shale. 4197. 4 miles southeast of Palisade, Colo.; 150 ft above Rolllns 4504. Same as 4503 ; near base of Paonia shale. sandstone. 13970. NW. cor. SW% sec. 29, T. 7 S.( R. 104 W., Colo.; 40 ft 4203. 7 miles southeast of Palisade, Colo.; 25-200 ft above above highest Carbonero coal, 375 ft above top of base of Mount Garfield formation. Sego sandstone; collector, C. E. Erdmann, 1926. TABLE 18. Fossils found at various localities in the upper part of the Mount Garfield formation and equivalents U.S.G.S. Mesozoic loc. in the Mount Bowie shale member of Mesaverde formation Paonia shale Qarfleld member of Mesaverde formation formation Marine Nonmarine

13970 4184 4195 4197 4495 4497 4501 4503 4264 4265 4266 4268 4269 4271 4274 4275 4276 4487 4492 4493 4494 4499 4500 4205 4218 4220 4263 4488 4504

Fresh-water species: X X cf. U. briinkattensis Stanton cf. U. brachyopisthus White. X X » X X cf. 17. endlichi White. X X X X X X X X Sphaerium cf. S. planum Meek X X X X .... X Campeloma cf. C. amarillensis X X X X X X X X X X y X X Goniobasis cf. O. tenuicariuata X X X X ? Mesolanistes reesidei (Stanton). X X Brackish-water species: Ostrea subtriyonalis Evans and X X X X X v X X X y X X "x" X "x" X "x" - X X Brachydontes regularis (White) . X X X laticostata (White)...... Corbicula cytheriformis (Meek v X X .... X X occidentalis (Meek and X on X X X "x" X "x" X ...... X X undifera White...... X X X X subtrigonalis Meek and X X X X X ? X X X v Marino species: Inoceramus "barabini Morton"

Cardium (Ethmocardium) whitei J)M...... X X Lamna sp... . ___ ...... X X ' See list at the end of this series of tables for descriptions of localities. 36 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

HUNTER CANYON FORMATION AND TTNDIFFEREN- TABLE 20. Fossils found at various localities in the North Horn TIATED MEMBER OF MESA VERDE FORMATION and Flagstaff formations undifferentiated 1

The Hunter Canyon formation proper has yielded U.S.G.S. Mesozoic loc. no fossils and is undated. The presumably equivalent beds to the southeast, the undifferentiated member of 13317 Lot 6 13234 13235 13338 the Mesaverde formation, has yielded only a few invertebrates. These, as shown in table 19, are all X fresh-water types and can be assigned only as Late Cretaceous. The highest beds of Lee's undifferentiated X X member of the Mesaverde formation are undated. X

1 Descriptions of localities follow. TABLE 19. Fossils found at various localities in the undiffer­ 13317. West side of Horse Canyon in SEJ4 sec. 28, T. 15 S., R. 14 E., Utah. Collected by D. J. Fisher, 1925. entiated member of the Mesaverde formation l Lot 6, unnumbered. Canyon of Horse Creek, Utah. "200 and 300 ft above base of Wasatch." Collected by O.-B. Richardson; identified by W. H. Dall, 1906. 13234. Green River, 36 miles above Green River, Utah, in sec. 16, T. 17 S., R. 17 E. U.S.G.S. Mesozoic loc. From gray limestone concretions in variegated shale. Collected by E. M. Spieker and J. B. Reeside, Jr., 1925. 13235. Same locality and collectors, but 312 ft higher, in gray limestone layer In shale. 4188 4191 4214 4486 13338. Soulier Mesa, north branch of Tuscher Wash, in NEW sec. 27, T. 19 S., R. 17 E., Utah. "265 ft above base of Wasatch." Collected by D. J. Fisher, X 1925. X cf. 17. priscus Meek and Hayden ______X X UNNAMED SANDSTONE X X The unnamed sandstone yielded no significant fos­ Valvatasp...... ^ ...... X X sils, and stratigraphic importance of the unconformity X qri X at its base is unknown. It rests on the Hunter Canyon X X X formation, whose age is also unknown. It resembles X X X the overlying "Wasatch" formation more than the X X Hunter Canyon. The suggestion is strong that it is X of Tertiary age, but it is here arbitrarily designated Tertiary (?). « Descriptions of localities follow. Collected in Colorado by W. T. Lee, 1907. 4188. Rapid Creek, 3 miles northeast of Palisade; about 1,000 ft below top of forma­ COLTON AND "WASATCH" FORMATIONS tion. 4191. -Itf miles northeast of Cameo; 800 ft below top of formation. 4214. 12 miles northeast of Delta; 600 ft below top of formation. In the area examined, little direct evidence of the 4486. Same locality as 4214; 300 ft below top of formation. age of the Colton and "Wasatch" formations has been found by the writers. Not far east of the eastern NORTH HORN AND FLAGSTAFF FORMATIONS end of the Book Cliffs, the beds that seem equivalent UNDIFFERENTIATED to those here called "Wasatch" have yielded verte­ In the Book Cliffs the North Horn and Flagstaff brates of late Paleocene and early Eocene age (Pat- formations undifferentiated yielded fossils from sev­ terson, 1934). Swain (1956) in discussing the ostra- eral beds of limestone, and the species contained in codes of the general region refers to "Colton ('Wa­ them are shown in table 20. The significance of this satch') formation" and his "Colton-Green River tran­ fauna, other than that it is strictly of nonmarine sition beds" to the Eocene. La Rocque (1956) refers origin and is probably Tertiary, is not now clear, as the Colton to the Eocene on the basis of the nonmarine the ranges hitherto assumed for some of the species mollusks. seem dubious. GREEN RIVER FORMATION La Rocque (1951, 1956) has expressed the opinion It is assumed here that the Green River strata of that the molluscan faunas of the typical North Horn the Book Cliffs are of Eocene age, though because of formation indicate a Cretaceous to Paleocene age and lateral gradations between the fluviatile facies here the molluscan faunas of the typical Flagstaff lime­ called "Wasatch" and the lacustrine facies here called stone indicate a Paleocene to Eocene age. Swain Green River, it is possible that differing parts of the (1956) has examined the ostracode faunas of parts Eocene may be included in the Green River at differ­ of the Book Cliffs and seems to agree in broad terms ent places. with La Rocque. It is not yet clear, however, what the stratigraphic relations are between the North NONMARINE FAUNAS IN THE SEQUENCE Horn and Flagstaff of the type areas and the expos­ As may be noted in several of the preceding faunal ures in the Book Cliffs. tables, certain assemblages of species of mollusks from GEOLOGICAL SURVEY PROFESSIONAL PAPER 332 PLATE 8

VIEWS IN HORSE CANYON AREA, CARBON COUNTY, UTAH . : . A. Castlegate sandstone cliff viewed from Bacon Gulch from a point southeast of center of sec. 29, T. 15 S., R. 15 E. B. Fault cutting Bluecastle sandstone member of Price River formation, Kpb, just north of southeast corner of sec. 28, T. 15 S., R. 14 E.; North Horn and Flagstaff formations undifferentiated, TKnhf, in middle slope; upper sandstone cliffs in lower part of Colton formation, Tc; distance from fault to skyline is about one-half a mile. C. Patmos Head (elev 9,849 ft) from point just north of E*4 corner sec. 34, T. 15 S., R. 14 E.; Colton formation, Tc, above, resting on North Horn and Flagstaff formations undifferentiated, TKnhf. D. Contact of North Horn and Flagstaff formations undifferentiated, TKnhf, on Bluecastle member, Kpb, of Price River formation; view north along cliff near southwest corner SE%SW& sec. 21, T. 15 S., R. 14 E. GEOLOGICAL SURVEY PROFESSIONAL PAPER 332 PLATE 9

A. SHEEP CANYON, TRIBUTARY TO HORSE CREEK, CARBON COUNTY, UTAH View looking into canyon N. 80° W. from N 1^ corner sec. 28, T. 15 S., R. 14 E. 1, Mancos shale; 2, lower sandstone member, Blackhawk formation; 3, middle shale member, Blackhawk formation; 4, middle sandstone member, Blackhawk formation; 5, Sunnyside coal zone; 6, upper shale member, Blackhawk formation; 7, Castlegate sandstone; 8, middle shale member, Price River formation; 9, Bluecastle sandstone member, Price River formation.

B. FORMATIONS IN HORSE CREEK CANYON, NEAR CENTER SEC. 4, T. 16 S., R. 14 E., EMERY COUNTY, UTAH Lower sandstone is Castlegate sandstone, Kc; shale slope is shale member, Price River formation, Kps; upper sandstone ledges are Bluecastle member, Kpb, Price River formation.

C. COLTON, NORTH HORN, AND FLAGSTAFF FORMATIONS, IN HORSE CREEK CANYON, CARBON COUNTY, UTAH Contact of Cotton formation, Tc, on North Horn and Flagstaff formations undifferentiated. TKnhf; view looking north from point west of center sec. 35, T. 15 S., R. 14 E. AGE AND CORRELATION OF THE FORMATIONS 37 the Mesaverde group are interpreted as having lived of rather late Cretaceous age the middle and later in a brackish-water environment, and others from parts of the Montana group and the immediately both the Mesaverde group and the higher zones are overlying beds. interpreted as having lived in fresh water. The Among the species interpreted as having lived in basis for these interpretations is the assumption that a fresh-water environment are all the species of the various types of life have had in the past the same Unionidae, the species of Spliaerium, Viviparus, Oam- habits that closely similar types of the present have. peloma, Tulotomops, Lioplacodes, Amnicola, Mesola- Supporting evidence is generally supplied by the nistes, Melania, Goniobasis, and Pliysa. The fresh­ associated fossils and by the characteristics of the water species include both long-ranging and more enclosing sediment. Land plants and vertebrates restricted forms. In the work here reported, few adapted for terrestrial life, for example, suggest a collections were made above the Cretaceous, and the terrestrial environment, as do also such features as discussion pertains almost wholly to the Cretaceous autochthonous coal beds and very lenticular or dis­ forms. Unio prisons Meek and Hayden, Sphaerium continuous bedding that is distributed through a planum Meek and Hayden, and Goniobasis? subtor- considerable thickness of sediment. tuosa (Meek and Hayden) have been reported from Commonly some mixture of faunal elements is the Judith River formation and from much later found. A dominantly brackish-water fauna may con­ zones. These species, as the brackish-water forms, tain a few species whose normal association is with do not seem to represent a very restricted interval marine species; or it may contain a few species whose within the Late Cretaceous, though GJ subtortuosa normal association is with fresh-water species. Simi­ is not known in the Laramie or Lance formations. larly, a dominantly fresh-water fauna may contain The highly sculptured unionids like Unio paraholme- a few species whose usual association is with brackish- sianus Yen and U. amarittensis Stanton, and the less water forms. It seems probably that this mixture is ornamented species like U. brachyopisthus White, U. in part mechanical, the result of natural accidents pseudoendliclii Yen, and U. brimhallensis Stanton, that bring shells together after the death of the together with the species of gastropods like Campe- organisms, though it may also be partly due to the loma amarittensis Stanton, are restricted to the higher capacity of some aquatic organisms to tolerate a con­ horizons represented by the Fruitland and Kirtland siderable range of salinity. In any event, the faunas formations, the , and the Lance as found do often contain some seemingly discordant formation. Tulotomops laevibasalis Yen is related elements. i to T. thompsoni (White), whose occurrences are in Among the species interpreted as having lived in the Laramie and Lance formations. The reptilian a brackish-water environment are Membranipora n. faunas of the Upper Cretaceous strata of the San sp., Ostrea glabra Meek and Hayden, Anomia gry- Juan Basin, specifically of the Fruitland, Kirtland, phorhynchus Meek, A. micronema Meek, Brachydon- McDermott, and Ojo Alamo formations, and of the tes laticostata White, B. regularis White, Corbicula North Horn formation of Utah are said to be dis­ cytherifor?nis (Meek and Hayden), Corbula subtri- tinctly older than that of the Lance formation (C. W. gonalis Meek and Hayden, O. perundata Meek and Gilmore, oral communications, 1939). There is, there­ Hayden, C. undifera Meek, Panope simulatrix Whit- fore, probability of a fairly long interval within the eaves, and P. n. sp. These brackish-water species very late Cretaceous during which these more re­ are mostly rather long ranging. Some of them have stricted fresh-water species lived, though it is much been reported from the Judith River formation of shorter than that of the brackish-water forms and the Montana, considered about equal in age to the type long-ranging fresh-water forms. Mesaverde group; some from the Mesaverde group At the western end of the Book Cliffs, the Black- of northwestern Colorado and southern Wyoming, hawk formation contains chiefly a brackish-water above which is the marine Lewis shale. Most of them fauna, with but a small admixture of fresh-water have been found in the Fruitland formation of the species. The overlying beds have yielded only fresh­ San Juan Basin of Colorado and New Mexico, above water species. the typical Lewis shale; and in the Laramie formation In the general vicinity of the Green River, the of the of eastern Colorado and the lower Blackhawk is still of brackish-water facies; and the part of the Lance formation of the Great Plains, Castlegate sandstone has yielded no fossils, but is above the Fox Hills sandstone. This fauna probably assumed to be nonmarine. The beds immediately represents an environment rather than a restricted above the Castlegate, however, representing the land­ interval of time, though all its occurrences are in beds ward part of the Buck tongue of the Mancos shale 508471 60 1 38 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO have yielded a small marine fauna. The beds next lar composition and structure and its flora, likewise above, constituting the Sego sandstone, carry a brack­ appears to be of fluviatile origin. ish-water fauna containing two fresh-water species. Immediately above it, in the lower part of the Neslen DAKOTA SANDSTONE formation, occurs a fresh-water fauna, and probably The Dakota sandstone as recognized in Utah and all the overlying beds are of fresh-water origin. Part the thicker equivalent in Colorado may differ some­ of the fresh-water beds of the Price River formation what in age. It appears that early in Late Cretaceous of the western Book Cliffs, then, pass eastward into time shallow marine waters advanced from the south marine and brackish-water beds. or east into western Colorado. The initial deposit In the vicinity of the canyon of Thompson Wash, was generally a pebble-bearing sand. The coastal most of the Blackhawk formation has given way to belt bordering the advancing waters for a while con­ marine shales, the Castlegate sandstone contains a tained swamp areas that favored the accumulation brackish-water fauna with one marine species, the Buck of carbonaceous materials, locally sufficient to form tongue is a well-defined marine unit, and the Sego sand­ mineable coals. The later deposits were muds and stone has a purely marine fauna. The overlying beds sands laid in marine waters and now forming com- have yielded only fresh-water species. The change from o paratively even and regular beds of rock. The shore­ nonmarine to marine beds has thus proceeded farther line apparently had not yet reached Utah, where at Thompson Wash. rather different materials were being deposited. There In the vicinity of the canyon of Westwater Wash, the lithologic heterogeneity of the formation suggests most of the Castlegate sandstone has passed into an origin in a flood-plain area, the conglomerate and marine shale, the Buck tongue is thicker, the Sego crossbedded sandstone perhaps forming in the main sandstone has a large and varied marine fauna, and channels of the streams, and the shale being deposited the lower part of the Neslen formation contains a away from the channels. Pond deposits were possibly brackish-water fauna. The overlying beds are appar­ formed locally. In early Mancos time the sea ex­ ently all fresh-water facies. tended far to the west, beyond the Wasatch Plateau. In the vicinity of Grand Junction, the lower part As the Cretaceous sea advanced into Utah, some of of the Sego sandstone has given way to marine shale, the sand, especially that in the upper part of the and the lower 200 feet of the Mount Garfield forma­ tion has become marine. The upper part of the Mount Dakota, may have been deposited under marine or Garfield and the overlying beds have yielded only at least brackish conditions. That the formation is fresh-water species. Farther southeast, in the Grand so widespread, though not everywhere preserved (the Mesa region, the marine part of the Mount Garfield Mancos and pre-Dakota formations are locally in of the Grand Junction region passes into marine contact), can be explained best by assuming a rela­ shale; much of the upper part acquires marine and tively flat pre-Dakota surface on which it was laid brackish-water f acies; and only the uppermost part, down. The nature of the lower contact supports this together with the overlying beds, is still of fresh­ assumption. The local presence in Utah of tree water f acies. trunks up to 2V$j feet in diameter, as well as other In general it may be said that in the Mesaverde plant fossils, is also in harmony with it. The group of the Book Cliffs region the fauna at a given Dakota strata may consist partly of reworked Morri- horizon changes in facies eastward from fresh-water son material, but it seems most likely that much of through brackish-water to marine and that the fresh­ the material came from the west. From Spieker's water fauna is restricted to progressively higher hori­ findings (1946, p. 150-152) in and near the western zons eastward. Neither the fresh-water nor the brack­ part of the Wasatch Plateau, it is clear that a high ish-water fauna changes materially in composition in area not very far to the west was yielding material the stratigraphic interval covered. during at least the earlier part of Late Cretaceous time. ORIGIN OF THE FORMATIONS LOWER CRETACEOUS UNITS MANGOS SHALE AND MESAVERDE GROUP By its lithologic character and its fossils, including Because of the large-scale interfingering of the dinosaur remains and fresh-water invertebrates, the upper part of the Mancos shale and the Mesaverde Cedar Mountain formation appears to be a fluviatile group, it is convenient here to consider these units deposit. The Burro Canyon formation, with its simi­ together. ORIGIN OF THE FORMATIONS 39

The Mancos shale of the Book Cliffs region is part waters were withdrawn somewhat toward the east, of a very extensive marine shale that does not lend permitting the widespread accumulation of sands. itself readily to division into lithologic units. By Following the deposition of the sand in middle means of the series of faunal zones given under the Carlile time, there came an apparently long period of heading, "Standard sequence of Cretaceous in the accumulation of finer material, the earlier part rep­ western interior region," it is possible to estimate resenting the time of the uppermost Carlile rocks the range in time of the formation at different places and the lower and middle parts of the Niobrara for­ and the relative positions of individual parts of the mation. Some sandstones are present, but they are formation in a time scale. For much of the Mancos usually muddy and inconspicuous. West of the Book epoch, the shoreline of the sea was west of the Book Cliffs ar6a, however, several tongues of resistant sand­ Cliffs region, but not very far west, for in central Utah stone are present, and in central Utah there is a thick a great thickness of very coarse material of Mancos conglomeratic series (Spieker, 1931, p. 18-20; 1946, age indicates proximity to land (Spieker, 1946, p. p. 128; Schoff, 1951, p. 624-62Y). The time interval 150-152). At different times and places the accumula­ is chiefly that of chalk formation in the Great Plains, tion of fine-grained material in parts of the great but the contemporary sedimentary rocks of the Book area of Mancos deposition gave way to the accumula­ Cliffs are not notably more calcareous than other tion of dominantly coarser material, ranging from silt parts of the Mancos here. Without appreciable break to sand. These bodies of coarser material are mostly fine sediment continued to accumulate through the thicker and coarser toward the west and extend as time interval represented by the Telegraph Creek and thinning sheets toward the east. Depending on the Eagle formations. These units have not generally direction in which erosion has cut into them and on been considered equivalent to the uppermost part of their lateral extent, many of them have been formally the Niobrara formation of the Great Plains, but it named as sandstone members of the Mancos shale now seems probable that they are. In the Wasatch or as tongues of some other formation. Plateau the Emery sandstone member of the Mancos In the Book Cliffs region the accumulation of fine­ shale, a near-shore deposit, was formed during this grained marine material began with the close of interval. In the Book Cliffs region the time interval Dakota deposition, perhaps somewhat earlier in of the Niobrara is represented by the main body of Colorado than in Utah, for the 60 to 90 feet of shale the Mancos shale. that are present in Colorado below the levels con­ The succeeding part of Late Cretaceous time is a taining Gryphea newberryi Stanton appear to be period of irregularly progressive restriction of the lacking in Utah. As Katich has noted (1956), area of marine deposition, though whether this was Oryphaea newberryi has not been found in the western effected by filling of the basin of deposition or by Book Cliffs, and there may have been a brief inter­ changes in relative level of land and sea is not clearly ruption of sedimentation near the beginning of Mancos determinable. Perhaps both processes played a part. time to account for its absence from that area. A The effect on the sediment of a given place, however, thin sequence follows that is undated, but may pos­ is that of successive replacement of marine muds first sibly represent the early Turonian interval, and the by marine sands, then by brackish-water sands and deposition of fine materials continued through the muds, then by fresh-water sands and muds. Coal time of the lower Carlile units, the middle Turonian may be associated with the first of the fresh-water epoch. deposits. The process of converting the region from Next f ollows a thin zone of sandy beds that extends one of marine to one of nonmarine deposition and of across the region and far beyond it over the western extension of sand eastward was not an even one, interior Cretaceous area. This zone contains the however; for though at times the sand was carried middle Carlile faunas (Prionocyclus macombi and far eastward, at times apparently the sea moved west­ P. wyomingensis zones), though the fauna of the ward and the deposition of fine materials in marine higher zone ranges somewhat upward into the over­ water temporarily extended much farther westward lying shale. Farther west and southwest a much than the eastward margins of the preceding non- thicker and purer unit of sandstone, at places con­ marine sands. Commonly the base of marine deposits taining coal beds and other apparently nonmarine is sharp, implying a rapid extension of the sea, rocks, has generally been considered the Ferron whereas the passage into nonmarine deposits is grada- sandstone member of the Mancos shale, and the tional, implying a slow withdrawal of the waters. In name has been applied by several authors to the thin general the succeeding sand bodies extended progres­ sandstone of the Book Cliffs. Apparently the sea sively farther eastward, and the successive areas of 40 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO fine sediment reached progressively shorter distances soon withdrew, though continuing to occupy the Book westward. The formation of coal beds apparently Cliffs area. At the end of middle Niobrara time, took place not far from the sea margin, for the coal erosion began in southwestern Utah; marine sands beds are in the Blackhawk formation in the west and were being deposited in the Wasatch Plateau area; in the higher formations toward the east, but seldom and fine sediment was reaching the Book Cliffs area. far above the highest marine beds. The record of a Somewhere between southwestern Utah and the retreating sea is shown with exceptional clearness in Wasatch Plateau was the shoreline of the Cretaceous these deposits. The landward materials (marine sea. As time passed, this sea gradually withdrew sand grading westward into brackish-water and fresh­ toward the east, and the nonmarine deposits of the water deposits) are the Mesaverde group. The sea­ Mesaverde group finally extended over the whole ward materials (chiefly marine shale) are the upper region. Then the fluviatile units, the Kaiparowits part of the Mancos shale. The youngest rocks of formation of the southwest, the lower part of the the Mesaverde group everywhere in the region are North Horn formation of the Wasatch Plateau, and of nonmarine origin, apparently fluviatile. an undetermined part of the sequence high in the Young (1955) has discussed in considerable detail Book Cliffs, possibly the Tuscher formation, closed this zone of intertonguing of marine and lagoonal- the Cretaceous. In the southwest the next higher littoral facies, naming 1 more such unit in Utah and formation is an unconformable unit much like the 3 more in Colorado than are recognized in this "Wasatch" formation of the Book Cliffs and unlike paper. He follows Spieker (1949, p. 61-65) in in­ the upper part of the North Horn formation of the terpreting dominantly continental deposits of for­ Wasatch Plateau, of Paleocene age. Nothing definitely mations in the west to pass eastward into lagoonal like the Flagstaff limestone of the Wasatch Plateau, deposits formed above littoral marine sands and Paleocene and Eocene, has been found, and it seems behind offshore bar sands that grade into marine likely that erosion was proceeding in southwestern Mancos shale to the east. The intricate intertonguing Utah during later North Horn and Flagstaff time. is interpreted to be the result of the deposition in a Because of uncertainty as to ages of the higher forma­ shallow basin in which there were long periods of tions, the sequence of events in the Book Cliffs is relative stability separated by sharp pulses of subsid­ still dubious. ence. Thick peat beds, formed during periods of In southwestern Utah (Gregory and Moore, 1931; quiet, are thought to have accumulated behind off­ Gregory, 1950) the Dakota sandstone resembles that shore bars, but little consideration is given to the of the Book Cliffs and is overlain by the marine differential compaction phenomena involved. Sharp , which is of later Greenhorn age in the subsidences preceded formation of the basal sand­ basal part and of Carlile age in the remainder. West­ stone tongues and lesser pulses preceded formation ward the Tropic passes into sandy nonmarine rocks of the offshore bars. A generalized cycle of four but northeastward may be equivalent to the part of units is recognized: basal marine shale, littoral ma­ the Mancos up to and including the sandy Ferron rine sandstone, lagoonal rocks, and coal. deposits. Above the Tropic lie the dominantly sandy Straight Cliffs and Wahweap sandstones, in part POST-MESAVEBDE FORMATIONS nonmarine and in part marine and of Niobrara age. The post-Mesaverde formations are all of nonmarine These pass westward into coarser nonmarine rocks, origin. Most of them, like the uppermost beds of but northeastward must be equivalent to the middle the Mesaverde group, have the characteristics usually part of the Mancos shale of the Wasatch Plateau and attributed to fluvial deposits, but the Green River the lower middle part of the Mancos shale of the formation is definitely lacustrine. eastern Book Cliffs. At the top of the Wahweap sand­ stone is a hiatus that appears to represent all the for­ REGIONAL RELATIONS mations of the Wasatch Plateau from the base of the It is of interest to consider briefly the relations of Emery sandstone member of the Mancos shale up to the Cretaceous formations of the Book Cliffs to those the base of the North Horn formation and the upper of the areas both southwest and southeast of the three-fifths of the Mancos shale and most, if not all, Book Cliffs. Plate 12 attempts to show these in a of the Mesaverde group of the eastern Book Cliffs. perspective diagram, though neither area can be con­ Upon the Wahweap sandstone rests the Kaiparowits nected directly with the Book Cliffs. formation, which contains a dinosaur fauna and is Thus it would seem that the Cretaceous sea reached like the lower part of the North Horn formation of southwestern Utah at least by early Mancos time, but the Wasatch Plateau. The top of the middle part of LOCAL SECTIONS 41 the Niobrara equivalent is the highest stratigraphic No. 5. Composite section in the Horse Canyon area, Carbon horizon that can be carried through the region and and Emery Counties, Utah [Thickness of individual units by C. E. Erdmann; correlation of Flagstaff limestone has been made the datum for the diagram. and North Horn formation undifferentiated unit by J. B. Reeside, Jr.] To the southeast of the Book Cliffs in southwestern "Wasatch" formation (part): Ftet Colorado (Reeside, 1924), the Dakota sandstone ap­ Upper sandstone unit, measured in SW}4 sec. 23, pears much like that of the Book Cliffs. It is over­ T. 15 S., R. 14 E. Thicknesses estimated: lain by the typical Mancos shale, which contains Top of Patmos Head, elev 9,851 ft. near the base beds of later Greenhorn age that include 237. Sandstone, gray-buff, massive; locally weathers brown; makes high vertical a calcareous unit with the latest Greenhorn fauna. cliff on southeast face of mountain. _ _ 250 Higher in the Mancos is a sandy unit with a Carlile 236. Slope, largely concealed, contains two fauna like that of the sandy beds of the lower part thin sandstone beds, each about 50 ft of the Mancos shale of the Book Cliffs area. Then thick. ___-._. 300 235. Sandstone, light-gray to buff, massive; follows a part of the Mancos of Niobrara age and a makes cliff on southwest face of moun­ higher part equivalent to that of the upper part of tain _____-_-____-_--__--______-_-- 200 the Mancos of the eastern Book Cliffs. In south­ 234. Shale, sandy_____...___.______50 western Colorado the typical Mesaverde group rests 233. Sandstone_------_-_----_-.__-----__ 100 conformably upon the Mancos shale and is probably 232. Shale, sandy__------_-______-_--__- 75 231. Sandstone.---.------.------100 equivalent to the lower beds of the Mesaverde group 230. Shale, sandy, and thin sandstone beds__ 175 of the Book Cliffs. In southwestern Colorado, how­ 229. Sandstone, gray-buff, arkosic, massive, ever, the next higher units are the marine Lewis shale medium-grained, soft, friable; feldspars and the overlying marine Pictured Cliffs sandstone, weathered; clastic muscovite; contains which have no counterparts in the Book Cliffs and tongues and lentils of red clay; bedding marked by clay galls; makes cliff _____ 50 must be represented by some part of the nonmarine sequence. The next higher beds in southwestern Thickness of unit, estimated.--.- 1, 300 Colorado, including the nonmarine Fruitland, Kirt- i i land, and McDermott formations, and the lower part Shale unit, measured on spur of Patmos Mountain in NW}4 sec. 26 and NE# sec. 27, T. 15 S., R. of the highly andesitic Animas formation, seem by 14 E.: their vertebrate and invertebrate faunas to be most 228. Mudstone, maroon, especially dark in nearly equivalent to the and upper 10 ft; parts of grayish red to the lower part of the North Horn formation. owing to white sand grains in red silt; evenly bedded; some groups of beds Thus we have in the rocks to the southeast of the harder and more resistant than others; Boole Cliffs in southwestern Colorado a record of a weathers into small angular platy marine invasion like that of the Mancos of the Book fragments that have sharp, rough Cliffs, followed by a temporary withdrawal of the edges ______-______-____---__-_--- 60 sea in the time of the typical Mesaverde and a second 227. Sandstone, grayish-buff, massive; cliff- making where thick; thickens and invasion in Lewis time that did not reach the Book thins, owing to irregularities on top of Cliffs nor the Wasatch Plateau. Following the underlying mudstone; probably fluvi­ second withdrawal of the sea, fluviatile deposition atile______-_.___ 0-20 prevailed, modified in McDermott and Animas times 226. Mudstone, maroon, like No. 228----... 15-20 225. Sandstone, grayish-buff, like No. 227; by an influx of volcanic detritus, partly of Cretaceous replaced by reddish shale where re­ age but extending into Paleocene time. The highest duced in thickness______-___ 0-20 beds are of Eocene age. 224. Mudstone, predominantly maroon; essen­ tially like No. 228...______100 223. Sandstone, gray-buff, medium-grained, LOCAL SECTIONS massive, evenly bedded; upper 10 ft The generalized descriptions and interpretations thin-bedded.-.____.___.____ 40 222. Mudstone, predominantly gray, sandy, given earlier are largely based on the local sections with minor amounts of maroon rock, some of which are presented in detail below. The which is in thin beds, one just below sections are numbered from west to east and the top_--__-__-___---____-_--_-___- 220 numbers agree with the locations shown on plates 1 Thickness of unit, estimated...-- 480 and 10. 42 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 5 Composite section in the Horse Canyon area, Carbon No. 5 Composite section in the Horse Canyon area, Carbon and Emery Counties, Utah Continued and Emery Counties, Utah Continued "Wasatch" formation Continued F"t North Horn and Flagstaff Continued Feet Lower sandstone unit; upper part estimated in Measured on spur, etc. Continued SEJ4 sec. 22, T. 15 S., R. 14 E.; lower part meas­ 196. Mudstone, dark-gray ______12-18 ured in E#SWtf sec. 3, T. 16 S., R. 14 E. 221. Sandstone, massive, cliff-making.------75 195. Limestone, gray, sandy, massive.______2 220. Shale, gray-green______--_- 25 194. Clay, greenish-gray______-______5 219. Sandstone, massive, cliff-making------30 193. Limestone, gray, dense, in layers l}_-2 218. Shale, dull, maroon..____--_____--____ 15 ft thick; weathers into splintery frag­ 217. Sandstone like No. 221__.-...-...--___ 30 ments______7 216. Shale, gray-green_._____..____--___. 40 192. Mudstone, gray, calcareous; makes slope_ 65 215. Sandstone, massive, cliff -making. ______75 214. Mudstone, reddish; some of it very 191. Limestone, gray, sandy______---___ 1}_ compact, platy, dull, maroon; mud- 190. Mudstone, gray___-_-____---_-__----_ 2 cracks. __....______-.__-_ 200 189. Sandstone, light-brownish-gray, mediujn- 213. Sandstone, massive, cliff -making. ______50 to fine-grained, calcareous, massive, 212. Shale, gray______-_.__. 40 ledge-making; the end of a lens that 211. Sandstone, massive, cliff-making. -_-_-. 50 thickens eastward in 600 ft to 30 ft. _ _ _ 7 210. Shale, gray______._____.___ 40 209. Sandstone, massive, cliff-making.------50 188. Mudstone, gray; makes slope.______6 208. Shale, gray______-_-----_--__-_--.--_ 40 187. Limestone, light-gray, brown-weathering, 207. Sandstone____...... __.__...._._ 50 sandy______^______!/-_ 206. Shale, gray______50 186. Mudstone, light-gray, calcareous; largely 205. Sandstone, tan, massive, cliff-making. __ 22 concealed in slope______-_____--__. 34 (Section below this point measured.) 185. Limestone, light-gray, brow^n-weathering, 204. Mudstone, light-gray-green, tan-weather­ ing; marly, with numerous mud pellets; sandy______-____-____------_ 1J_ sharply separated from bed above, 184. Mudstone, marly, light-gray; makes slope transitional below.______3 encrusted with layer of weathered soil 203. Shale and sandy shale, with a few sand­ about a foot thick..______27 stone layers 1 ft thick; predominantly 183. Limestone, light-gray, light-brownish- maroon, with a small amount of gray-weathering, sandy; in layers 6-10 variegated red and green rock._____ 65 in.thick..______1J_ 202. Sandstone, tan, massive, cliff-forming; 182. Mudstone, dull, maroon, weathering to lentils of clay-ironstone conglomerate purplish gray; probably variegated at base______50 201. Shale, light-gray-green-______22 with gray-green.______21 200. Sandstone, buff, fine-grained, massive, 181. Marl, with numerous nodules of gray cliff-making_ __-__-_-_____-_--_____ 25 limestone up to 3 in. in diameter; 199. Shale, light-gray-green----.-..-..------35 poorly exposed, but debris covers slope 198. Sandstone, buff- to brownish-gray, red­ below______2 dish-brown-weathering, fine- to me­ 180. Mudstone, dull, gray-green and drab____ 10 dium-grained, massive, cliff-forming, 179. Sandstone, light-gray, tan-weathering, crossbedded; some pellets of clay-iron­ stone; some subaqueous slump struc­ fine-grained, dense, massive, poorly tures. Locally underlain by 6-in. to sorted, with clusters of lumps of 1-ft layer of buff to salmon shale, coarser grained sand___-----_-_---__ 10 with thin stringers of sand and thin 178. Mud-pellet conglomerate; with unit 59 clay-pellet conglomerate in sand- _____ 46 makes a conspicuous ledge ______1 Thickness of unit, estimated. 1, 128 177. Shale, clayey, light- to dark-gray; less fissile and less well consolidated than Thickness of part of "Wasatch" shale beds below; weathers to a tough formation, estimated______2, 900 gumbo; largely concealed in slope _____ 30 176. Sandstone, light-gray, brownish-weather­ North Horn and Flagstaff formations undifferentiated: ing, fine-grained, dense..--______--_- 1 Measured on spur between North and South Forks of canyon of Horse Creek on west side NEJ4N W% 175. Sandstone, gray-green, chalky-gray- sec. 34, T. 15 S., R. 14 E.: weathering, fine-grained, dense; lo­ 197. Limestone, buff, dense, silty; lenticular cally calcareous; surface littered with mass in erosion channel at base of nodular pieces of dense dark-green overlying sandstone; maximum thick­ sandstone that weather reddish brown ness ______or show yellow-green stains ______3 LOCAL SECTIONS 43

No. 5 Composite section in the Horse Canyon area, Carbon No. 5 Composite section in the Horse Canyon area, Carbon and Emery Counties, Utah Continued. and Emery Counties, Utah Continued Erosional unconformity. Feet North Horn and Flagstaff Continued Ftet Measured on spur between North and South Forks Measured on spur, etc. Continued of Horse Canyon in SE#NW# sec. 34, T. 15 S., 153. Sandstone, reddish-brown, fine-grained; R. 14 K: thin, slabby layers in lower part, more 174. Shale, tan, drab, and dark-gray; frag­ massive above______.______2}_ ments of limestone concretions on 152. Shale, light-gray, sandy______3 surface ______.-----____ 12 151. Shale, dark-brown, sandy, fissile, carbo­ 173. Sandstone, light-gray, weathering slightly naceous. ______3 brownish or drab; fine- to medium- 150. Shale, light-gray, sandy, granular; grades grained, in 2- to 6-in. slabby layers; into underlying beds______4 locally massive _ .______--_----_ 172. Shale, light-gray to tan, sandy; makes Thickness of North Horn and slope ______-_---_-_---___-_- 24 Flagstaff formations undiffer- 171. Sandstone, slabby___-_- _ __ __ 2>_ entiated______570 170. Sandstone, gray, salt-and-pepper, brown­ ish-weathering, medium-grained, evenly Disconformity. bedded, with some crossbedding; base Price River formation: irregular .______-______-___---__-- 14 Upper sandstone unit, equivalent approximately to 169. Siltstone, drab, nonfissile; makes slope. _ 25 the Bluecastle sandstone member of the Neslen 168. Sandstone, gray, fine-grained, slabby ____ 2}_ formation, measured on spur between the canyon 167. Sandstone, medium-grained, evenly of Horse Creek and tributary from east near bedded, noncalcareous __-______---_ SW. cor. sec. 34, T. 15 S., R. 14 E. 166. Sandstone, gray, salt-and-pepper, con­ 149. Sandstone, gray-white to grayish-buff, taining lentil of gray, reddish-weather­ weathering tan and rose; cement cal­ ing limestone that is dense, sandy, and careous; beds 6-8 ft thick, except near about 10 ft long. With Nos. 168 top, where they are a foot thick; indis­ and 167 locally makes a cliff ______3 tinctly crossbedded. Upper 20 ft gray 165. Sandstone, gray, medium-grained, mas­ white, mottled with a little darker sive, soft, friable; makes slope______12 gray sand that weathers out, leaving 164. Shale, light-gray, sandy, largely con­ shallow pits. Predominantly medium cealed by talus; makes slope______21 grained, but with numerous irregular 163. Sandstone, gray, medium-grained, soft, lentils and stringers of coarse sugary shaly______. ______10 gray sand that contain a few pebbles of 162. Sandstone, gray, medium-grained, soft; gray chert and quartz up to one- thinly and evenly bedded. ______\ quarter of an inch in diameter; an 161. Shale, light-greenish-gray, with a 3-ft arkosic grit______70 layer of fissile brown carbonaceous 148. Shale, gray, sandy, poorly exposed.____ 5 shale 6 ft above base. ______25 . 147. Sandstone, gray to buff, medium-grained, 160. Shale, gray, fissile, slightly carbonaceous; massive, cliff-making ______25 upper 18 in. a drab shaly sandstone. __ 35 159. Siltstone, light-drab to greenish-gray, 146. Shale, gray; contains a few thin layers of granular; 2-ft layer of sandstone 5 ft brownish sandstone in upper part; below top; along strike a lentil of sand­ largely concealed in slope ______33 stone at base__-______--___-__ 45 145. Sandstone, yellow-gray to brown, soft, 158. Sandstone, light-gray at top and gray silty; contains clay ironstone concre­ below, medium-grained, soft, friable; tions ______4 base irregular ; probably a lens ______144. Shale, gray; largely concealed in slope.._ 26 157. Shale, light-brownish-gray, sandy. _____ 143. Sandstone, buff to brown (grayer toward 156. Sandstone, light-gray, salt-and-pepper, top and slightly mottled) medium- medium-grained, soft, friable; upper grained, hard, massive; cement prob­ 1 ft slabby ; contains a few concretions ably calcareous; beds 1-4 ft thick; of dense brown-weathering sandstone; cliff making.______40 about 20 percent of the sand consists of Possible disconformity. dark grains; remainder consists largely 142. Shale, gray; upper foot darker and more of kaolinized feldspar; quartz is a carbonaceous ______7 J>_ minor constituent; muscovite acces- 141. Sandstone, light-brown, dense, massive; thinly bedded at top; cliff-making.___ 7 155. Shale, light-gray to bluish-gray, with 140. Shale, gray, with 2-ft layer of siltstone dark-gray at top; sandy, slightly car­ in middle______7 bonaceous ; makes slope ______27 139. Sandstone, light-reddish-brown, medium- 154. Sandstone, light-gray, fine-grained, soft; grained, hard, dense______2 thin, slabby, irregular layers. ______138. Shale, gray; makes slope_____-______. 12 44 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 5 Composite section in the Horse Canyon area, Carbon No. 5 Composite section in the Horse Canyon area, Carbon and Emery Counties, Utah Continued and Emery Counties, Utah Continued Price River formation Continued Feet Price River formation Continued Feet 137. Sandstone, buff, fine-grained, shaly, soft, Lower shale unit, etc. Continued in 4-in. layers, makes slope.______7 117. Sandstone, buff, brown-weathering, 136. Sandstone, buff, medium-grained, soft, fine- to medium-grained, thinly and friable; upper half massive; lower half irregularly bedded; soft, friable, but in 6- to 12-in. layers.______6 grades up into harder thicker more 135. Shale, gray______6 massive layers______-_-_____-___-_ 10 134. Sandstone, light-gray, buff- to brown- 116. Shale, carbonaceous, dark-brown to weathering, soft, silty, friable, in beds black, thinly laminated; makes slope. _ 23}4 8-10 in. thick______!______5 115. Sandstone, brown, fine-grained; in thin 133. Shale, dark-gray, flaky______8 irregular layers interbedded with thin 132. Sandstone, gray-buff, medium-grained, layers of carbonaceous shale. ______1% hard, dense; makes ledge______2 114. Shale, gray and brown; contains a few 131. Sandstone, buff, fine-grained, silty, thinly thin layers of fine-grained brown sand­ laminated, dense, hard; makes massive stone ______4 ledge ______1 113. Sandstone, brown, fine-grained, in thin 130. Sandstone, gray, brown-weathering, me­ wavy layers interbedded with grayish dium-grained ______2 and brownish shale______-__-_- 18 129. Shale, gray, flaky______3}_ 112. Shale, dark-brown, carbonaceous. ______). 128. Sandstone, grayish-buff, brown-weather­ 111. Coal, bony______1 ing, massive, ledge-making; base ir- 110. Shale, black, fissile, with thin lentils of regular______2 bright coal______1 127. Shale, gray; upper part dark, carbona­ 109. Shale, dark-brown, carbonaceous.______1 ceous ______-___-___-_-_____-_-____ 7 (Nos. 112 to 109 make a black band on the cliff 126. Sandstone, brown, reddish-brown-weath­ face.) ering, fine-grained, dense; contains 108. Sandstone, brown, fine-grained; in thin carbonaceous debris; capped by 2- to irregular wavy layers interbedded with 4-in. layer of orange-brown clay iron­ thin layers of gray and brown shale. __ 11 stone ______2 107. Shale, carbonaceous, dark-brown, thinly 125. Shale, gray__--___---______5 laminated, with a few thin layers of 124. Sandstone, buff, brown-weathering, gray-weathering sandstone.______25 medium-grained, massive, ledge- 106. Sandstone, light-gray, weathering brown, making: thins northward to thickness medium-grained, in layers 4 to 10 of 1ft_--__------___.______. 6H inches thick; makes hard, thin, resist­ 123. Shale, gray, granular______11 ant ledge______2J_ 122. Sandstone, buff, weathering brown; upper 105. Shale, dark-brown, carbonaceous; foot thinly bedded______4 weathers light bluish gray.______3 121. Sandstone, buff, brown-weathering, 104. Sandstone, gray, in thin wavy layers medium-grained, shaly; in irregular interbedded with gray carbonaceous beds 1-4 in. thick; contains a few shale______14 stringers of orange-brown ironstone 103. Shale, dark-brown, carbonaceous, fissile.. 3 that are softer than the sandstone.___ 5 102. Sandstone, carbonaceous, shaly; weathers 120. Sandstone, buff, brown-weathering, bluish gray______2 medium-grained, massive, in layers 101. Sandstone, grayish-buff, fine-grained, 18-24 in. thick; contains a few stringers thin-bedded ______3 of orange-brown clay ironstone______9 100. Sandstone, in thinly laminated layers 6-10 in. thick interbedded with shale, Thickness of unit. 299 predominantly carbonaceous.______9 99. Sandstone, light-gray, fine-grained, in 6- Lower shale unit, measured on north wall of the in. layers______8 canyon of Horse Creek, 1,750 ft east and ^850 98. Sandstone, light-gray, fine-grained, in ft north of NW. cor. sec. 3, T. 16 S., R. 14 E. slightly wavy layers up to an inch 119. Shale, gray to dark-gray, carbonaceous; thick. ______3 fissile at base, becoming more granular 97. Shale, dark-brown, carbonaceous, thinly at top, where it weathers into rounded laminated ______3K 96. Sandstone, chocolate-brown, fine-grained, forms.. ______16 carbonaceous; top and bottom surfaces 118. Sandstone, brown, medium-grained, hard, wavy; resistant ledge.______2 dense, irregularly laminated, ledge- 95. Siltstone, carbonaceous, bluish-gray- making; contains numerous pellets of weathering, dense, compact; layers brown clay ironstone at top.______6-12 in. thick______5 LOCAL SECTIONS 45

No. 5 Composite section in the Horse Canyon area, Carbon No. 5 Composite section in the Horse Canyon area, Carbon and Emery Counties, Utah Continued and Emery Counties, Utah Continued Price River formation Continued Feet Blackhawk formation: Feet Lower shale unit, etc. Continued Upper shale member, measured on north wall of 94. Shale, brown to black, carbonaceous, Bacon Gulch, 2,700 ft south and 3,400 ft east of flaky.___.______----____-_____.. 1 NW. cor. sec. 29, T. 15 S., R. 14 E.: 93. Sandstone, light-gray, with bluish tone, 78. Sandstone, gray, carbonaceous, in layers fine-grained, slightly carbonaceous; 1-2 ft thick with partings of coaly shale 6 in massive single bed-______6 77. Shale, brown to black, carbonaceous, 92. Siltstone, chocolate-brown, bluish-gray- coaly. __ -_ .______6}_ weathering, carbonaceous, compact. _. 5 76. Sandstone, brown to buff, fine-grained, 91. Sandstone, light-gray, medium-grained, with contorted thin bedding, lenticular. 6}_ in 4- to 6-in. layers; a few rusty-brown 75. Shale, gray, sandy, with thin layers of ironstone layers interbedded with shale sandstone.______3J4 in layers 6-8 in. thick ______5 74. Sandstone, brown to buff, medium-grained, 90. Sandstone, chocolate-brown, bluish- in beds 6 in. thick; makes low ledge. . _ 3 weathering, fine-grained, carbona­ 73. Shale, purplish-brown to black, carbona­ ceous ______1 ceous, thinly laminated, fissile.______7 89. Shale, chocolate-brown, compact; grades 72. Sandstone, brown, fine-grained, in gnarly up into fissile carbonaceous shale.--.- 2 layers up to 4 in. thick parted by light- 88. Sandstone, chocolate-brown, bluish-gray- gray carbonaceous shale______5 weathering, dense, fine-grained, carbo­ 71. Shale, gray, sandy, carbonaceous; weathers naceous. ______1 into rounded forms.______3^_ 87. Shale, dark-brown, carbonaceous; 70. Shale, black, carbonaceous, fissile____. 11 weathers bluish gray, compact______2 69. Sandstone, brown, fine-grained, in beds 86. Sandstone, light-gray, fine-grained, dense, up to 10 in. thick with shaly partings. _ 4). with blebs and stringers of carbonaceous 68. Shale, dark-gray to black, carbonaceous, material; in layers 2-8 in. thick._____ 3 fissile______11 85. Shale, dark-brown to nearly black, car­ 67. Sandstone, gray, reddish-brown-weather­ bonaceous, flaky__-______\Yz ing, fine-grained, in slabby layers up to 84. Shale, chocolate-brown, lead-gray-weath­ 10 in. thick with shaly partings; cliff ering, compact--.------..--- 1}_ making ______-_-__--_-______-___ 7 83. Sandstone, light-gray, fine-grained; rock 66. Shale, gray, sandy, with 6-in. layer of nearly white, with small amount of brown-weathering sandstone in middle limonite stain; upper foot bluish with of bed...---____.___------8 shale; in slabby layers 2-12 in. thick; 65. Shale, dark-gray to black, carbonaceous, intricately crossbedded, with thin len­ fissile; somewhat coaly in middle part__ 20 tils of gray shale between the laminae; 64. Shale, gray, sandy, with 6-in. layers of crossbedding less in upper half. ______20}_ gray sandstone that weather brown.___ 8 82. Shale, gray, sandy, nonfissile. ______3 63. Shale, carbonaceous.______2 81. Sandstone, light-gray, fine-grained, in thin 62. Sandstone, gray, brown-weathering, fine­ slabby layers_____-_-_-___-_--___-__ 2)_ grained, massive, crossbedded; makes 80. Shale, light- to dark-gray, fissile, some­ low cliff; lower 5 ft soft, shaly. Shale what sandy______3}_ parting 2 ft thick 6 ft below top_._____ 18 61. Shale, dark-gray to black, carbonaceous.. 9}_ Thickness of unit. 234 60. Sandstone, gray, weathering light brown; upper 4 ft massive_____.__-____.___ 7 Thickness of Price River formation. 533 59. Shale, gray, sandy____-_.______..__ 3 58. Sandstone, brown, fine- to medium-grain­ Castlegate sandstone: ed, massive, thinly laminated, friable, Measured on north wall of canyon of Plorse Creek, soft..._-_-__------_-___- 7 near WM cor. sec. 3, T. 16 S., R. 14 E.: 57. Shale, gray, fissile.--_-_--__-______. 3 79. Sandstone, grayish-buff to light-gray, me­ 56. Coal, black, clean, bituminous.______4 dium-grained, massive, heavy-bedded, 55. Shale, chocolate-brown, carbonaceous, fis­ cliff-making; white and reworked at top, sile...... ______....__...... __ }_ 54. Siltstone, drab_____-___-______2 which is uniform and slightly wavy; 53. Shale, black, carbonaceous, papery ______1}_ weathers dark gray to brown; bone 52. Shale, gray, sandy, fissile, weathering into fragments in some massive layers; lower small chips___--_____-______-______6 part contains numerous pits up to three- 51. Sandstone and shale, interbedded; sand­ fourths of an inch from which ferrugi­ stone in 2-in. layers, nodules, and small nous concretions have weathered..__. 160 lentils; shale in layers 4-6 in. thick.__. 6}_ 508471 00 5 46 CRETACEOUS AND TERTIARY .FORMATIONS, UTAH AND COLORADO No. 5 Composite section in the Horse Canyon area, Carbon No. 5 Composite section in the Horse Canyon area, Carbon and Emery Counties, Utah Continued. and Emery Counties, Utah Continued Blackhawk formation Continued Feet Blackhawk formation Continued Feet Upper shale member Continued Lower sandstone member, measured 1,900 ft west 50. Sandstone, brown, fine-grained, soft, in and 1,300 ft north of SE. cor. sec. 4, T. 16 S., slabby layers up to 4 in. thick; makes R. 14 E. 5 27. Sandstone, gray-white, massive, sugary, Sunnyside coal bed: Ft. in. cliff-forming; evidently a reworked part 49. CoaL____-_____--____------_- 1 . 4 of underlying unit______-_-______20 48. Shale, chocolate-brown, carbo- 26. Sandstone, brown to buff, massive, sugary, cliff-f orming______65 47. Coal ______9 25. Siltstone, gray______18 46. Shale, gray, sandy, and thin gray 24. Sandstone, gray, tan-weathering, massive. 2 sandstone- ______3 3 23. Shale, sandy, with layers of thin-bedded 45. CoaL ______10 1 gray sandstone______2 22. Sandstone, tan, fine-grained; lower half 16 thin bedded-______1 21. Shale, gray___.______-_.______4}_ Thickness of member. ______170 20. Sandstone, orange-brown, fine-grained, ferruginous.______}_ Middle sandstone member, measured at mouth of 19. Shale, gray_____..______1 canyon of Horse Creek, in sec. 4, T. 16 S., R. 18. Sandstone, orange-brown, fine-grained, 14 E.: ferruginous.______1 44. Sandstone, light-gray to white, medium- 17. Shale, gray__-______-______8 grained, of sugary texture; top is 16. Sandstone, gray, medium-grained, mas­ 24 sive. ---____--______-_--______1 43. Sandstone, brown to gray ish-tan, medium- 15. Shale, gray, probably marine.______27 grained, massive, cliff-forming; base 14. Siltstone, gray, soft; contains several 8-in. 82 layers of sandstone._ __-______7 13. Sandstone, gray, weathering tan [to 106 grayish-tan, fine-grained, in beds 4r-. 12 in. thick with partings of soft gray Middle shale member measured 1,150 ft north siltstone; makes broken cliff.______7 and 800 ft west of S% cor. sec. 4, T. 16 S., R. 12. Siltstone, gray.______-__--_-___-__ 2 14 E. 11. Sandstone, gray, fine-grained, tan- 42. Shale, sandy, gray ______1 weathering, finely crossbedded. ______2 41. Sandstone, tan, fine-grained, compact.... 1 10. Siltstone, gray.______._--__-______-__ 7 40. Shale, sandy, gray ______% 9. Limestone, gray, sandy, hard, dense, thinly 39. Sandstone, tan, fine-grained, compact __ % and evenly laminated___------__._-__ 2 38. Shale, gray, fissile, in 6-in. layers inter- 8. Siltstone, gray.______2 bedded with 2-in. layers of grayish-tan 7. Limestone, gray, sandy.______% 14 6. Siltstone, gray, with a few thin lentils of 37. Sandstone, tan, fine-grained, dense, mas- finely laminated sandstone ______5 3 5. Limestone, gray, tan-weathering, sandy.. 1}_ 36. Shale, gray, fissile, in 6-in. layers sepa­ 4. Siltstone, light-gray, and fine-grained rated by layers of tan sandstone up to gray tan-weathering sandstone; in 4>_ alternating beds 2-3 in. thick.______5 35. Sandstone, tan, fine-grained, dense; mas- 3. Limestone, gray, reddish-brown-weather­ 2Yz ing, sandy ______% 34. Shale, blue-gray; somewhat sandy, grad­ 2. Siltstone, light-gray, nonfissile, with a ing toward top into alternation of 4-in. few layers of more sandy rock that layers of brownish shaly sandstone and weathers brown______6}_ shale. ______22 1. Sandstone, drab, yellow- to brown- 33. Shale, lead-gray, fissile; probably marine. 35 weathering, fine-grained.. ______\% 32. Limestone.. ______-_.--______% 31! Shale, lead-gray, fissile; probably marine. 1% Thickness of member. 200 30. Limestone, dull, gray, weathering brown. >. 29. Shale, lead-gray, fissile; probably marine. 11}. 28. Shale, brown, carbonaceous______3 Thickness of Blackhawk forma­ tion _--______-_---_---____ 578 Thickness of member. ______102 Mancos shale. LOCAL SECTIONS 47

No. 8. Section in the NE^ sec. 14, T. 17 S., R. 14 E., 4 miles No. 6. Section in the NEy± sec. 14, T. 17 S., R. 14 E., 4 miles east of Grassy Dome east of Grassy Dome Continued Castlegate sandstone: Feet Gradational contact. Feet. 15. Sandstone, massive; buff- to light-brown cliff Man cos shale: maker; locally somewhat friable and cross- 2. Shale, gray; not examined in detail; makes bedded.. .._--..-..__..._-._._____ 181 up basal part of cliffs and a wide flat expanse to west. Baculites sp. undet. Conformable contact. and a fish scale found 500 ft below top. Blackhawk formation: Niobrara fauna (13319) in a 6-in. gray- Upper member: brown coarse-grained limestone 3,200 ft 14. Shale, with minor coal and sandstone; shale below top. Thickness measured by plane- medium gray in main, though parts are table traverse to lower contact in sec. 3, black, carbonaceous and red, sandy; upper T. 17 S., R. 13 E.______-.______- 4, 120 7 ft carries much limy silty, nodular- Conformable contact. weathering mudstone; thin impure sandy Dakota sandstone: layers are especially common in lower part; 1. Conglomerate and other rock. Not exam­ coal mainly in upper 15 ft.___..____-__« 71 ined in detail. Makes a pronounced dip Middle sandstone member: slope. Edwin Kirk identified one of the 13. Sandstone, medium-brown, thin-bedded, pebbles as Madison limestone carrying platy, friable.__-______-_____-_-_-_. 5 Schuchertella chemungensis (Conrad)? 12. Sandstone, faint-buff, massive, crossbedded, ledge-maker, light-gray, weathering faint No. 7. Section taken on north side of the upper end of Price River buff, friable...._._..._--___-..._-----> 37 canyon, 8% miles east of Woodside, Utah 11. Coal (Sunnyside), with minor shale and [Measured by D. J. Fisher] sandstone ___.______--_____---___-- 23 Price River formation (lower part only): Feet 10. Sandstone, very light-gray ("white")--- 27 23. Shale, gray____.______25± 9. Sandstone, buff-brown, massive; cliff____, 42 22. Sandstone, buff- medium-fine-grained, thin- bedded, friable; with numerous Ostrea Thickness middle sandstone member. 134 glabra, Meek and Hayden, at top___._- 7 21. Mudstone, medium-gray, silty, limy ______2 Middle shale member: 20. Sandstone, buff, medium-fine-grained, friable 8. Mudstone and sandstone in alternating thin-bedded; with minor shale ______24 bands; marks gradation between lower and 19. Mudstone, like No. 21; 2 in. of coal at top. _ 1 higher beds; mudstone (40 percent) is 18. Sandstone and shale; in about equal amounts medium gray, limy, silty, nodular weath­ in lower part, but largely sandstone above; ering; sandstone (60 percent) is buff brown sandstone, buff, shale, medium gray, in and there is more of it in upper part.-.-. 72 places carrying carbonized wood; this 7. Shale, mostly concealed medium-gray slope; unit, or at least its lower more shaly part, lower part carbonaceous, black to rich is correlated with the Buck tongue of brown -______----___-_-___-__-__. 66 Mancos shale--___-_____---_____-__--_ 84

Thickness middle shale member. _ _ _ _ 138 Part of Price River formation_.__. 143±

Lower sandstone member: Castlegate sandstone: 6. Sandstone, light-buff, coarse-grained, mas­ 17. Sandstone, buff, massive; cliff maker; firm, sive, crossbedded, friable; locally carries weathering blocky______120± a 6-ft shaly layer______^...... 20 Contact conformable. * 5. Sandstone, like No. 3, 75 percent; shale, like Blackhawk formation: No. 4, (25 percent); sandstone more Upper member: conspicuous in upper part; a local channel 16. Shale, locally carbonaceous to coaly.------2 unconformity is present at top ______111 15. Sandstone, buff, friable, round-weathering 4. Shale medium-dark-gray, gritty, calcareous, surfaces_-_--_---__-_---______-___- 10 gypsiferous, with much carbonized wood. 10 14. Shale, medium-gray, with minor thin sand­ 3. Sandstone, medium-gray, fine-grained, thin- stone layers; 8 ft above base is a 4}_-ft bedded, crossbedded, very hard, cal­ coal zone_____-______--_- 26 careous cement; rich in carbonized wood 13. Sandstone, buff, well-rounded and medium- fragments; some fucoidal markings. ____. 10 grained; carries much carbonized wood___ 12 12. Shale, coal, and a little sandstone.______11 11. Shale, like No. 14______._____._-____-- 30 Thickness lower sandstone mem- 10. Coal and siltstone.______2 ber______. 151 9. Shale, like No. 14____._-______-.---_- 9

Total Blackhawk formation______343 Thickness upper member._-____-_--.___--_---- 102 48 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 7. Section taken on north side of the upper end of Price No. 8. Section taken along the west side of the Beckwith Plateau River canyon, SYz miles' east of Woodside, Utah Continued in the NEV± sec. 80, T. 19 S., R. 15 E., 4y2 miles northeast of Desert, Utah Continued Blackhawk formation Continued Feet Feet Middle sandstone member: Castlegate sandstone: 8. Sandstone; lower part buff; upper part gray­ 18. Sandstone, very light gray, medium-buff- ish white_____.______24 brown-weathering, massive, cliff-maker; 7. Coal (Sunnyside), sandstone, and shale___ 22 in part quartzite, with grains one two- 6. Sandstone, like No. 8------.------41 hundredths of an inch through; locally 5. Shale, medium-light-gray (thins along out­ friable and coarser grained (one-fiftieth crop) ______12 of an inch); in places beautifully cross- 4. Sandstone, buff--______--_-_--_--__-___ 59 bedded, resembling the Navajo sand­ stone of the San Rafael Swell; upper Thickness middle sandstone member. __ 158 part somewhat shaly at a few places; some beds carry what may be small clay Middle shale member: galls. ______85 3. Shale and sandstone; lower part dominantly medium-light-gray shale forming a slope; Contact conformable and indefinite. upper part is about 60 percent of cross- Blackhawk formation: bedded, buff-brown sandstone in medium Upper member: (near top) to thin beds.______158 17. Coal__------__-_---_____---_-_-.____ 16. Mudstone, medium-gray, silty, limy_____ Lower sandstone member: 15. Coal__~~~_- ______--_--_.____ 2. Sandstone, forming a pronounced cliff; sepa­ 14. Sandstone, like No. 18, with minor shale rated into three distinct ledges; upper one and a coal lens___-____.______71 is massive sandstone, gray white near top, 13. Coal___. ______. __-____._. 3 but with a 2-ft brown sandstone at top; 12. Sandstone, with minor shale_-----______10 middle ledge is thinner bedded, slightly 11. Coal...... ______3 shaly; lower one is more shaly, and in lower 10. Shale, medium-gray, gypsiferous; minor part consists of alternating shale and sand­ thin sandstone layers. ______48 stone beds, each about 6 in. thick______270 Thickness upper member_____ 141 Total Blackhawk formation ______688 Middle sandstone member: Gradational contact 9. Sandstone, massive, indistinctly cross- Mancos shale: bedded, friable; upper half has grains 1. Shale, bluish-medium-gray, somewhat sandy about Koo of an inch in diameter; rest is in upper part. finer (%so of an inch); top 10 feet is gray- No. 8. Section taken along the west side of the Beckwith Plateau white, rest is buff.______42 in the NE^i sec. SO, T. 19 S., R. 15 E., 4Y2 miles northeast of 8. Coal (Sunnyside) in two seams, split by Desert, Utah sandstone ______6 [All beds except Dakota measured by planetable traverse. In part the descriptions 7. Sandstone, buff, fine-grained (J_6o of an are taken from studies made in sec. 8, T. 20 S., R. 15 E. By D. J. Fisher] inch), cliff-maker; lower three-fourths Price River formation (lower part only): " Feet contains about one-fourth of shale in 23. Sandstone (Bluecastle sandstone member), alternating beds with sandstone______196 buff; ledge-making unit, forms the dip- slope surface capping the Beckwith Thickness middle sandstone mem­ Plateau.______125 ber. ______244 22. Sandstone, massive, with thin zones of carbonaceous shaly material at top and Middle shale member: near middle. ______90± 6. Shale, medium-gray, fissile, soft, powdery, 21. Shale, with minor sandstone, forming gypsiferous______103 slope; upper third carries much carbon­ aceous material; a thin coal /one in lower Lower sandstone member: part.______260± 5. Sandstone, forming an unbroken, non- 20. Sandstone, like No. 18 in all essential scalable cliff; upper 25 ft is gray white respects, except it lacks the friable and weathers to rounded surfaces; 50 ft coarser grained material; may represent lower part of Sego sandstone______50± following is massive and light medium 19. Shale, medium- to light-gray, soft, fissile, gray to buff and weathers into huge gypsiferous; locally carbonaceous, prob­ blocks; remainder contains more or less ably is Buck tongue of Mancos shale_ 50 ± shale interbedded with the sandstone.__ 208

Part of Price River formation_ 575 ± Total Blackhawk formation. 696 LOCAL SECTIONS 49

No. 8. Section taken along the west side of the Beckwith Plateau #o. 9. Section measured 8 miles north of Qreen River, in the in the NE% sec. 80, T. 19 S., R. 15 E., 4y2 miles northeast SWy± sec. 6, T. 20 S., R. 16 #. Continued of Desert, Utah Continued Blackhawk formation Continued Feet Gradational contact. Feet Upper member Continued Mancos shale: 15. Shale, medium-gray, silty, and carbona­ Section measured between sees. 12 and 17, T. 19 ceous, black fissile shale______3% S., R. 14 E. 14. Sandstone, massive to shaly, crossbedded. __ 6 4. Shale, bluish-medium-gray; makes up lower 13. Shale, like No. 15, but with seamlets of part of cliffs and a flat nearly 4 miles fibrous gypsum.______2$ wide; not measured in detail; 825 ft 12. Coal, gypsiferous______1 above base is a 7-ft buff sandstone bed 11. Shale, carbonaceous, fissile ______1% that makes a minor hogback 1 mile east of that made by the Dakota..______3, 875 Thickness upper member.______135

Conformable contact. Middle sandstone member: Dakota sandstone: 10. Sandstone, medium- to light-buff-brown . Section measured in NE# sec. 17, T. 19 S., R. (except gray-white at top); massive, 14 E.: cliff-forming; lower part of sandstone is 3. Sandstone, very light gray, fairly friable, 99 percent of quartz in fairly well-rounded quartzose, calcareous cement; 3- to 6-in. grains averaging Yi&o of an inch in diam­ beds; grains about Jfos of &n inch, fairly eter; no coal or shale at Sunny side hori­ well rounded; poorly preserved Haly- zon; 11 ft below top in a slightly shaly menites and other fossils abundant; forms zone get a 10-in. thin-bedded cross- top of a dip slope.______4 bedded medium-dark-gray sandstone layer 2. Sandstone, shaly, laminated; mostly con­ that contains abundant brackish-water cealed ______-_-----_-_-_- 12/2 fossils (13327)....______65± 1. Sandstone, very light-gray, crossbedded; 9. Sandstone, carrying about 40 percent of minor ledge______shale; gypsiferous; generally forms a slope ______50 ± Total Dakota sandstone. 17 8. Sandstone, carrying minor shale; forms a cliff at most places.______95±

Thickness middle sandstone member. 210± 2Vo. 9. Section measured 8 miles north of Green River, in the sec. 6, T. 20 S., R. 16 E. Middle shale member: 7. Shale, medium-gray, with minor sandstone; [Nos. 22 and 23 measured 1 mile to the west by alidade] slope-former. ______152 Price River formation (lower part only) : Feet 23. Sandstone, buff; ledge-making unit (Blue- Lower sandstone member: castle sandstone member) capping Beck­ (Note: This section was taken near the east­ with Plateau; massive, blocky, with ward limit of this member, which gives way to minor shaly beds_--__-___-___------117 Mancos shale near here. Two miles south of 22." Shale and sandstone, not examined. Lower here the top massive sandstone of this member is part includes equivalents of Sego sand­ 95 ft thick.) stone and Buck tongue of Mancos shale. 378 6. Sandstone, medium-buff-brown to light-gray (near top), ledge-making, somewhat friable Part of Price River formation.._____ 495 with calcareous cement; upper surface weathers into rounded forms which locally Castlegate sandstone: make small depressions containing water; over 95 percent consists of fairly well- 21. Sandstone, not examined in detail._.______86 rounded colorless quartz grains about Xeo of an inch in diameter; also carries grains of Contact conformable. feldspar and of dark minerals______20 Blackhawk formation: 5. Sandstone (60 percent) and shale, medium- Upper member: gray, in alternating layers an inch or two in 20. Shale and sandstone (50 percent), inter- thickness; sandstone is crossbedded, light bedded....______17}_ buff brown to medium gray, platy; other­ 19. Sandstone, massive, cliff-forming, like No. 21_ 68 wise like No. 6, though very slightly coarser 18. Shale and sandstone (50 percent), inter- grained; near top of shale occur lenticular bedded--.____-___--______.___------17/2 beds up to 3-6 in. thick carrying a salty 17. Sandstone, massive, ledge-making.______15J4 and bitter tasting powdery white mineral. 51 16. Coal..____--_--_---_-_-_--__------1J.' 4. Shale, limy in upper portion; slope.______47db 50 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 9. Section measured, 8 miles north of Green River, in the No. 10. Section measured from a point near Elgin, Utah, up SW-y* sec. 6 T. 20.S., R. 16 E. Continued canyon of Tuscher Wash Continued Blackhawk formation Continued Feet North Horn and Flagstaff Continued Feet Lower sandstone member Continued pie from the base is friable, pale 3. Sandstone, ledge-making, fairly firm to semi- brownish, with grains }io-/4oo of an friable, massive, crossbedded to very thin- inch in diameter, with a calcareous . bedded, in part platy; weathers medium cement, and though largely of poorly gray to medium buff brown; rather fine rounded quartz, contains some feld­ grains (}_oo-^5o in.), subangular to slightly spar and about 10 percent of dark rounded; largely quartz, but with small minerals occurring in limonite- amounts of altered feldspar______25 stained clusters or nests; higher up, 2. Shale, limy; would ordinarily be put with No. lenses of conglomerate are present; a 1, but traced to west this unit gives way to sample shows about 10 percent of sandstone ______74 ± angular pebbles up to one-half of an inch in diameter mostly of red, black, Thickness lower sandstone mem- and white chert and of, black basalt in ber______217 a matrix of sandstone as just de­ scribed, but slightly coarser, which Total Blackhawk formation_.______.714± also contains small masses of pale greenish clayey material; limestone Gradational contact. (5 percent) of medium to very light- Mancos shale: gray to pale-brownish colors with a 1. Shale, forms slope about 75 ft high, underlain semilithographic texture; a 4-ft lime­ by limy shale capped by one or more thin stone bed 110 ft below top carries beds of fine-grained buff-weathering sand- a few specimens of the fresh-water . stone forming cliff about 100 ft high; Physa pleromatis White 13338- 375 underlain by slope-forming shale. Contact relations not clear. No. 10. Section measured from a point near Elgin, Utah, up Tuscher formation: canyon of Tuscher Wash 36. Sandstone, with minor conglomerate; [Lower 3,090 ft of Mancos measured by planetable; Nos. 10-22 inclusive taken by H. F. massive, crossbedded, weathers into Moses in the SE# sec. 13, T. 20 S., R. 16 E.; Nos. 23-33 inclusive measured in sees. rounded domelike forms; sandstone 8 and 9, T. 20 .S., R. 17 E.; higher part of section taken in sees. 27 and 34, T. 19 S., is gray white and friable, with a little R. 17 E. by D. J. Fisher] calcareous cement; grains largely of " Wasatch" formation (lower part only): feet slightly rounded frosted quartz, about 39. Sandstone; upper and lower parts are YIOO of an inch in diameter; less than massive cliff makers and weather red 1 percent is of black grains, not brown; a hand sample from near the limonite-stained; among the grains is base is pale gray brown, has extremely a fine white powder; 25 ft below top fine rather angular grains )ioo-^oo of is a 1-ft bed of conglomerate similar an inch in diameter, is firmly ce­ to that of No. 37, but more than 50 mented by calcareous material; percent of pebbles, which show some though largely of quartz, some grains rounding; higher in the section iso­ are of dark minerals, so that the rock lated pebbles up to three-fourths of has a light-colored peppery appear­ an inch in size are found here and ance; central part is crossbedded, there _____-______-_-__-_-__-___ 110 somewhat shaly, brick red______135 35. Sandstone, massive, crossbedded, mak­ 38. Shale and sandstone (20-30 percent); ing cliff unscalable at most places; shale mostly brick red; sandstone sample from lower part is composed weathers red brown and forms three of slightly rounded grains (about 1/75 massive ledges, each 50 ft or more of an inch) which are cemented by thick. ______350 calcite, though the rock is quite friable; while mostly of quartz, there "Wasatch" formation, part meas- is present 10-15 percent of only 485 slightly decomposed feldspar (faintly limonite stained), and 1-2 percent of North Horn and Flagstaff formations undifferentiated: black grains; though fresh surface is 37. Shale, sandstone, conglomerate, and nearly gray white, cliffs are stained limestone; shale (75 percent) is red-­ buff to rich brown______-______160 dish in upper and lower parts, but medium gray in central part; sand- Total Tuscher formation.______270 : ", . . stone (20 percent) is variable; a sam- LOCAL SECTIONS 51 No. 10. Section measured from a point near Elgin, Utah, up No. 10. Section measured from a point near Elgin, Utah, up canyon of Tusclier Wash -Continued canyon of Tuscher Wasli Continued Contact apparently conformable, but beds are so Feet Sego sandstone Continued Feet irregular that an erosional unconformity may be 26. Shale, like No. 32, but somewhat sandy. : 35 present. 25. Sandstone, like No. 27; fossils similar to Farrer formation (this member as given probably those in No. 27 5 ft below top (lot also includes upper 65-70 ft of Neslen formation): 45 34. Shale and sandstone; generally forms a slope, but locally cliff-making where Total Sego sandstone 140 protected by Tuscher strata and properly bolstered by sandstone beds. Buck tongue of Mancos shale: Shale is medium gray, with a distinct 24. Shale, like Mancos. 100 olive-green tinge; makes up 85 per­ cent of upper part and 70 percent of Castlegate sandstone: lower part. Much of it is not lami­ 23. Sandstone, massive, cliff-forming; upper nated, and so may more properly be part weathers light gray and forms a called mudstcne; in part is somewhat pronounced dip-slope surface dotted silty; carries a few limestone layers with cedars and having a few water up to a foot in thickness; these vary holes and sand dunes on it______120 from sandy and white to lithographic and greenish gray; in part they are nodular and limonite stained; poorly Contact conformable. preserved leaf impressions found in Blackhawk formation: limestone 525 and 545 ft below top. Upper member: Sandstone occurs in ledge-making 22. Siltstone and shale in alternating layers; massive crossbedded layers, in units siltstone brown, incoherent except for up to 50 or 60 ft thick; in part friable, a 3-ft light-gray layer 10 ft above but largely very firmly cemented; base; shale gray, in part coaly; abun­ varies from medium gray (greenish dant carbonized wood______26 tinge) like the shale to dirty buff 21. Sandstone and siltstone; gray to gray- owing to limonite staining and 10-15 brown siltstone grading upward into percent dark grains; weathers light sandstone that is coarse grained at buff to rich brown; medium-fine to top of unit; cliff forming, with poorly fairly coarse-grained; clay pellets or preserved pelecypods and with frag­ galls up to an inch through are com­ ments of carbonized wood______68 mon in certain layers; these are 20. Siltstone, mudstone, and shale; slope-, lozenge shaped and weather out forming; poorly exposed unit; car­ readily giving exposed surfaces with a bonized wood___-______-______._ 86 pitted appearance.______725 Thickness upper member. 180 Neslen formation: 33. Sandstone, buff, massive, ledge-maker. Middle sandstone member: This is the Bluecastle sandstone mem­ 19. Sandstone, brown (gray white near top), ber that caps the undissected part of massive, with grains up to }£o of an the Beckwith Plateau______-__ 55 inch in diameter.______17 32. Shale, medium-gray (slightly bluish), 18. Sandstone, shale, and siltstone; lower weathering drab______110 part consists of alternating 2- to 4- 31. Sandstone, buff, ledge-making; car­ in. layers of gray-brown to muddy- bonaceous zone in lower part ______50 brown coarse-grained sandstone and 30. Mudstone, medium-gray, silty; alter­ coaly shale, with 1 ft of coaly shale nates with buff-weathering sandstone; near middle; upper part of alternating abundant fresh-water fossils in lower layers of buff platy siltstone and buff 10 ft (lots 13334 and 13335) _____ 30 silty shale, with carbonized wood; 29. Shale, velvety, black, bone, and coal lower part carries Anomia micronema (Palisade coal zone?)____.______2 Meek and Ostrea sp. undet. (13333). 18 28. Mudstone, medium-gray, silty. ______3 17. Sandstone, massive, crossbedded, cliff- forming; grains fairly well rounded,, Total Neslen formation. 250 mostly quartz but some dark minerals Sego sandstone: and feldspar, ranging from fine in 27. Sandstone, shaly, thin-bedded, buff- lower part to coarse at top; light buff weathering, friable; 10 ft below top to (at top) gray white with rounded marine and brackish-water fossils of weathering surfaces; minor lenses of late Montana age (13336)..___.-. 60 sandy shale______52 52 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 10. Section measured from a point near Elgin, Utah, up No. 10. Section measured from a point near Elgin, Utah, up canyon of Tuscher Wash Continued canyon of Tuscher Wash Continued Blackhawk formation Continued Feet Dakota sandstone Continued Feet Middle sandstone member Continued stone is gray white; conglomerate is 16. Siltstone, dirty-gray-brown, medium- very heterogeneous, with pebbles up bedded, incoherent, with carbonized to several inches in diameter; pebbles wood ______58 mostly of gray chert, but also of chert 15. Sandstone, siltstone, and shale; weak of other colors, black basalt, purple, bluff-forming unit of ash-gray shale gray, and brown quartzite, epidote(?)- with interbedded buff siltstone and stained masses, hard dense limonite, fine-grained sandstone, the latter graphic granite, pink granite, dense more important in upper part_____ 45 gray limestone, dark-gray porphyritic aphanite; some pebbles (not lime­ Thickness middle sandstone stone) well rounded; matrix sand­ member______190 stone, friable to quartzitic, sandy shale, and limestone; fossil tree Total Blackhawk formation. 370 trunks, up to several feet long a.nd 2}£ ft in diameter______6-12 Contact gradational. 6. Sandstone, dense, quartzitic, limonite- Mancos shale: stained, crossbedded..______% 14. Shale, gray to black, slope-forming, 5. Shale, gray, sandy in 1- to 3-in. beds___ 2-3 probably carrying minor buff siltstone 4. Conglomerate, as just described______1-3 layers______52 3. Sandstone, fine-grained, quartzitic, in 13. Shale, light-yellowish-gray to gray- layers and lenses 2-4 in. thick inter- black; upper third carries a dozen 1- bedded with sandy shale ______0-2 to 6-in. sandy layers that give rise to 2. Shale; laterally gives way to conglomer­ a weak bluff; lower 20 ft has 3 lime­ ate. ______.___._____ 2-4 stone beds }i to 1 ft thick; these are 1. Conglomerate as described for No. 7 dense textured and brecciated, with grading laterally and vertically into cracks filled by calcite, and weather sandstone, white to yellowish (rests on to yellow, orange, or bright red. _ . __ 295 variegated limy shales of Morrison 12. Shale, mostly ash-gray, with carbonized age).______1 4-6 wood; nodular layers in upper part; top consists of lenses of red and yellow Total Dakota sandstone______15)^-31 clay _-_-__-_------_-_----_------6 11. Shale, dull, gray to bluish-gray, with No. 11. Section taken in canyon of Coal Creek, Utah carbonized wood and coaly streaks and nodules and lenses of crystalline [Nos. 1-22 inclusive measured by H. F. Moses, remainder by D. J. Fisher] limestone. Fauna of Montana age Tuscher formation (lower part only): Feet (lot 13332)______.______%-2 55. Sandstone, friable, crossbedded; largely 10. Shale, gray-black, dense, weathering quartz, but a little feldspar and dark fissile; fish scales and cracks carrying minerals ______42+ gypsum needles; top consists of ash- 54. Sandstone, shaly, and shale; medium-gray, gray shale rich in fragments of fossil weathering light gray, but dirty-brown at wood and leaves.______6 top; plant remains.______20 9. Shale, with minor limy and sandy layers; 53. Sandstone, light-buff, medium-gray-weather­ not examined in detail. Sandy zone ing, massive, crossbedded, cliff-making; in lower part. Niobrara fossils found very feldspathic______24 at 1,400 and 1,900 ft above base (lo­ 52. Shale and sandstone; fairly fat dark-gray calities 13328, 13330-31)______3, 090± clay shale layers weathering light gray; unit probably carries interbedded sand­ Total Mancos shale______3, 450 ± stones ______20 51. Sandstone, light-buff, massive, crossbedded, Conformable contact. ledge-making, friable; mostly quartz, but Dakota sandstone: some feldspar (partly kaolinized and li- 8. Limestone, pale-brownish-gray, very monite-stained) and a little dark mineral fine-textured__,______o-K matter. ______13 7. Conglomerate, sandstone, and shale; 50. Shale and sandstone, like No. 52______25 extremely variable lithologically both 49. Sandstone, like No. 51----_-----__------22 parallel to and across the bedding; shale is light gray to gray black, Tuscher formation, part measured. __ 166 + sandy, with carbonized wood; sand- LOCAL SECTIONS 53 No. 11. Section taken in canyon of Coal Creek, Utah Continued No. 11. Section taken in canyon of Coal Creek, Utah Continued Contact apparently conformable. Feet Neslen formation Continued Feet Farrer formation: 33. Shale, like No. 35. 12 48. Shale, medium-light-gray, with distinct 32. Sandstone, like No. 34; 3- to 4-ft shaly zone greenish cast; carries interbedded sand­ about 20 ft above base; locally carries a stones, largely concealed by slump boul­ few clay pellets; upper part has birdshot- ders and wash.-__---__._-______160 like masses that are white, giving the rock 47. Sandstone, minor light-buff ledge of coarse­ a pimpled appearance; this is probably grained, incoherent material; laterally the Bluecastle sandstone member, which merges with underlying sandstone-__-.-_ 5 caps the undissected part of the Beckwith 46. Sandstone with minor shale forming a talus Plateau-_-____-______. __.__..._ 53 slope here, a cliff there; sandstone is thin 31. Shale, like No. 35------.-----...... _. 32 bedded, buff brown______21 30. Sandstone, crossbedded, friable, with shaly 45. Sandstone, medium-gray to buff to medium- lenses in the lower part; only locally a brown, medium-grained highly cross- prominent ledge maker; up to one-fifth of bedded, friable______23 the lower part is locally of clay pellets up 44. Shale with minor sandstone, largely con­ to 3 in. thick; sandstone is 95 percent of cealed by talus; shale is greenish gray and fairly well-rounded 1/100-inch grains of carries layers and lenses of sandstone; quartz, with minor feldspar (partly kao­ 150-175 ft above base is a friable nodular buff sandstone which locally forms a ledge. 275 linized) and dark minerals---______29 43. Sandstone, buff to dark-brown, fine-grained, 29. Shale, with minor sandstone; quite variable; crossbedded; rather firm; 90 percent of shale medium-gray, silty, locally really a quartz, but with 8 percent of limonite- mudstone, to fissile, black, carbonaceous stained kaolinized feldspar and minor and coaly______.__ 13 dark minerals....------______-_--_ 21 28. Sandstone, light-gray to light-buff, cross- 42. Shale, like No. 48.-..------13 bedded, friable, very fine-grained quartz. 4 41. Sandstone, massive, ledge-making, like No. 27. Shale, mostly medium-gray; weathers 43 in all respects; calcareous cement; car­ lighter, but some nearly black carbona­ ries claj' pellets or galls which weather out ceous layers; fat to silty, with one thin readily, leaving a pitted surface.___-_--_ 41 sandstone layer; carries irregular thin 40. Shale, like No. 48-.------22 layers of sandy clay ironstone______. 28 39. Sandstone, with a little shale in the lower 26. Sandstone, like No. 28 except upper and part; makes a broken slope; sandstone is lower parts are shaly ______4 medium grained (#5 of an inch), buff to 25. Shale and mudstone; mostly the latter; medium dark brown; while largely quartz, medium gray in the upper part; black dark minerals are abundant (20 percent); carbonaceous shale in lower part, with in lower part are clay pellets as in No. 41. 85 four thin coal layers-______13 38. Shale, with minor sandstone, like No. 48; fresh shale has nodular shaped masses; a 24. Shale and sandstone, like above two units __ 6% few shale layers up to 1 ft thick are dark 23. Coal and shale (Farrer mine; probably gray, gypsiferous, and carry abundant Chesterfield seam)______5Ji fragments of carbonized wood______72 22. Shale with sandstone; shale medium gray in 37. Sandstone, crossbedded; forms a pronounced main but partly black, carbonaceous, lens, which laterally gives way to shale especially near top; lower part carries like No. 38 within about 100 ft_-...__ 30 about one-half fine-grained sandstone weathering thin, platy.______58 Total Farrer formation______768 21. Sandstone; forms a bench; medium to heavy N eslen formation: bedded, gray to very light buff; upper 36. Sandstone, light-gray to buff to medium- part weathers into rounded masses and brown, friable, ledge-making unit; mostly carries a few ironstone concretions up to 4 of slightly rounded colorless quartz grains in. thick; a sample of the sandstone shows Ms-Moo of an inch in diameter, but carries it to be made mainly of fine to very fine a little dark material and partly kaolinized somewhat rounded quartz grains with feldspar.______25 perhaps 5 percent of slightly limonite- 35. Shale, with minor sandstone, largely con­ stained kaolinized feldspar, weakly ce­ cealed; shale is medium dark gray weather­ mented by calcite; lower 10 ft carries ing light gray, clayey, gypsiferous.__--._ 21 some interbedded sandy shale______34 34. Sandstone, massive, crossbedded; makes a 20. Shale, with minor limestone like No. 19 in minor ledge; almost entirely of well- central part; lower part greenish-gray rounded medium-fine grains of colorless gypsiferous shale; upper part similar, but quartz, loosely cemented by calcite; in part carbonaceous; central shales weathers buff to medium brown_____-_-_ 12 yellowish, clayey. ______23 54 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 11. Section taken in canyon of Coal Creek, Utah Continued No. 11. Section taken in canyon of Coal Creek, Utah -Continued

Neslen formation Continued Feet Conformable contact. Feet 19. Limestone, dark- to light-gray (weathering Blackhawk formation: light yellow-brown), dense, medium- Upper member: bedded______4 6. Shale, light-gray to black, carbonaceous, 18. Sandstone, medium-coarse-grained, light- coaly ______15 brown, weathering dark-brown.______2 5. Sandstone, tan through buff to very light- gray, massive crossbedded, thick-bedded 17. Shale; upper 6-8 ft dark gray, carbonaceous; in upper part grading downward into rest slightly greenish gray to yellow gray medium-bedded sandstone with inter- to light buff..._____.._..____.__ 29 bedded lenses of sandy shale at the base; cliff maker.______74 Total Neslen formation. 408 4. Shale with minor sandstone layers; more sand layers in upper part______93 Sego sandstone: 16. Sandstone, yellowish-white to light-brown, Thickness upper member______182 medium-fine-grained, thin- to medium- bedded, crossbedded; minor ledge maker; Middle sandstone member: poorly preserved pelecypods 6 ft below 3. Sandstone, light-buff to gray-white (upper top.------.------.---.----. 24 part) massive, crossbedded; cliff maker; 15. Sandstone and shale; slope-forming unit with minor interbedded thin platy sand­ poorly exposed, but a few 1- to 2-ft layers stone; sample from the lower part is com­ of thin-beddea, dark- to light brown fine­ posed mainly of very fine rounded quartz grained sandstone crop out.______67 grains weakly cemented by calcite and with a little lightly limonite-stained felds­ 14. Sandstone, gray-brown (except upper third, which is gray-white), fine-grained; thin- par. ______84 to thick-bedded ledge-making unit; locally 2. Shale and sandstone, like overlying and underlying units, and marking a grada­ somewhat shaly______24 tion between the two; more sandy in upper Total Sego sandstone.______115 part; forms a weak cliff at most places. _ _ _ 56

Buck tongue of Man cos shale: Thickness middle sandstone member. 140 13. Shale, with thin layers of sandstone, more Total Blackhawk formation ______322 important in upper part; shale brown to gray, sandy, locally coaly; sandstone platy, Gradational contact. shaly, fine grained, yellow brown..______138 Mancos shale: 1. Shale, limy to clayey, with a few thin layers Castlegate sandstone: of limestone and of sandstone; shale dark, 12. Sandstone, yellow-brown (weathering deep slightly bluish gray, weathering drab, brown), massive crossbedded, dense, gypsiferous______220 + No. 12. Section taken on the west side of canyon of Saleratus Wash, 11. Sandstone, white to brown, medium-grained, mainly in the southwestern part of T. 20 S., R. 19 E., Utah medium-bedded; locally shaly ______11 [Measured by D. J. Fisher] 10. Shale, gray, brown, and black, in part coaly_ 2}_ "Wasatch" formation (lower part only): . Feet 9. Sandstone, like No. 11, but fine grained____ 1 66. Sandstone and shale (25 percent), varie­ 8. Shale, like No. 10; plant remnants; changes gated; sandstone, which is in part pebbly, rapidly laterally to fine-grained yellowish forms massive cliff-making units 50-100 ft clayey sandstone; varies in thickness from thick. Total thickness not measured. 0 to 8 ft.; in places the two higher units 65. Conglomerate, massive, firm; ledge-making are also absent; thickness where section unit; consists of about 60 percent sand measured ______4% matrix, made up mostly of slightly rounded 7. Sandstone, massive, crossbedded; makes a medium-sized quartz grains, but with cliff; this or No. 11 or 12 caps the pro­ about 5 percent each of feldspar and dark nounced Castlegate dip-slope bench; color minerals, in a calcareous cement; carries deep buff to yellow gray; gray white in many poorly to well rounded pebbles up to upper part; a sample from the lower part 3 in. in diameter, but averaging about 1 is mainly of fine to very fine slightly in.; locally has lenses of crossbedded sand­ rounded colorless quartz grains with about stone; pebbles composed of black basalt, 5 percent of lightly limonite-stained felds­ chert of several colors (black, light gray, par, cemented loosely by calcite______106 jasper red, green), silicified limestone, white and lilac quartzite, lilac felsite, Total Castlegate sandstone_-_____._ 130 white vein quartz, limonite, leucophyre, and probably reddish syenite or granite. _ _ 26 LOCAL SECTIONS 55 No. 12. Section taken on west side of canyon of Saleratus Wash, No. 12. Section taken on west side of canyon of Saleratus Wash, mainly in the soutlvwestern part of T. 20 8., R. 19 E., Utah mainly in the soutlvwestern part of T. 20 S., R. 19 E., Utah Continued Continued "Wasatch" formation Continued Feet Farrer formation Continued Feet 64. Shale, gray...----.-...______....______12 40. Shale and sandstone, like No. 44.______10 63. Sandstone, very light-gray, crossbedded, 39. Sandstone, like No. 33_____._-_---_._..__ 10 friable; mostly of medium-coarse grains of 38. Shale, like No. 46-----_--_------__---- 10 glassy quartz with perhaps 10 percent 37. Sandstone, like No. 33.__.______-_ 41 kaolinized feldspar and 5 percent dark 36. Shale and sandstone slope; shale like No. 46; minerals in a calcareous cement______- 17 sandstone, light gray, coarse, with dark 62. Shales, clayey; yellow, pale brick red. ______55 minerals, in a bed 36 ft above base.____- 57 61. Sandstone, like No. 63, but weathers almost 35. Sandstone, like No. 33; with carapace of a white and in rounded forms-______-- 25 1-ft fresh-water turtle near base______46 34. Shale, sandstone, and minor limestone; "Wasatch" formation, part measured- 135 probably about equal amounts of shale and sandstone, but the unit is a talus-covered Contact relations apparently conformable, but not well slope; 10 ft above base is a 1-ft bed of exposed. greenish-gray lithographic limestone__'.__ 72 Tuscher formation: 33. Sandstone, very massive, well crossbedded, 60. Shale, with minor sandstone; shale buff to makes buff-brown cliff; subangular to well- gray_.__------_---_---_-_---_--_- 30 rounded fine grains, mostly of frosted 59. Sandstone, buff -weathering. ______10 quartz but with 10 percent of limonite- 58. Shale, like No. 60...______54 stained feldspar and a little dark mineral 57. Sandstone, like No. 49; weathers to rounded matter; carries clay pellets or galls and a forms. _--_-----____-___-_-_.______._ 26 few small pebbles; friable, with calcite for 56. Shale, sandy___.______-_.___--___ 36 cement _____-_---______-____-_-______56 55. Sandstone, like No. 49, except near middle 32. Shale and sandstone; upper part about 40 carries 20 ft of shale and shaly sandstone. _ 81 percent sandstone, with less below; sand­ 54. Shale and sandstone.______35 stone interbedded with shale; 1 sandstone 53. Sandstone, like No. 49_--.-_.______-_--_ 48 layer is a 10-ft ledge maker, but the rest are 52. Shale.-----.------.------.------12 thinner; upper 50 ft generally forms a 51. Sandstone, like No. 49----_-_--___------12 weak, shaly cliff, appearing greenish- 50. Shale, with minor sandstone layers.______54 medium-gray, owing to the shale. ______84 49. Sandstone; rich brown where cliff forming, 31. Sandstone, buff-brown weathering, friable, owing to limonite stain; where it weathers crossbedded; massive ledge, with a 1- to 2- to somewhat rounded surfaces it is fairly ft shaly parting near the middle; calcare­ light gray; its texture at first glance is pe­ ous cement_------_----__-___------_- 34 culiar, resembling a somewhat felty aggre­ 30. Sandstone and shale (40 percent) slope; gate; made mainly of fine-grained glassy lithology like two underlying units---... 32 quartz mottled with 5 percent of slightly 29. Sandstone, buff-brown weathering, friable, limonite-stained feldspar and dark min­ crossbedded; massive ledge maker; mostly erals, loosely cemented___-__-______- 38 of fine to very fine grains of frosty quartz 48. Shale and sandstone making a slope. ______36 with some feldspar, dark minerals, and 47. Satidstone, friable, crossbedded; weathers mica; calcareous cement.___.-_--___.__ 16 into rather light-gray rounded masses; 28. Shale, greenish-tinged medium-gray.______51 largely of medium-fine glassy quartz grains with about 3 percent each of feld­ Total Farrer formation_____--__.__ 641 spar and dark minerals, with a little calcite cement; locally forms a cliff, stained rich Neslen formation: brown _---__-_--.______--- 85 27. Sandstone; weathers fairly light-gray..___. 29 26. Shale, with minor buff-brown sandstone in Total Tuscher formation______557 upper part; shale medium gray to buff brown ______-___-___.__--__--___-_- 73 Contact apparently conformable, but not clearly exposed. 25. Sandstone; minor ledge; weathers light gray Farrer formation: to buff brown__-___-______-______9 46. Shale or mudstone; poorly exposed since it is 24. Shale with two minor coal zones 8 and 24 ft clayey and forms a slope; where it can be above base.__---_-______--___-______81 seen it consists of greenish-medium-gray 23. Sandstone, buff, massive to thin-bedded, mudstone, noncalcareous, but slightly crossbedded______3K silty--._----_-___------_------_---- 28 22. Shale, with 2 ft of coal (Chesterfield zone).. 9 45. Sandstone, ledge, like No. 33.----_------_ 28 21. Sandstone, 'buff, thin-bedded; minor ledge 44. Shale and sands tone; makes a slope___-_---_ 27 capped by an 8-in. massive gray layer.___ 4 43. Sandstone, minor cliff, like No. 33_ ___------24 20. Shale, in part carbonaceous, with a 1-ft coal 42. Shale, like No. 46..___..__...___._ 5 bed 61 ft above the base; carries minor 41. Sandstone, like No. 33------__------10 interbedded sandstone.______79 56 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 12. Section taken on west side of canyon of Saleratus Wash, No. 12. Section taken on ^vest side of canyon of Saleratus Wash, mainly in the southwestern part of T. 20 8., R. 19 E., Utah mainly in the southwestern part of T. 20 S., R. 19 E., Utah Continued Continued Neslen formation Continued Feet Blackhawk formation Continued Feet 19. Sandstone, buff-brown; very minor ledge. __ 3}£ Upper member Continued 18. Shale, buff to light-gray, with two carbo­ 4. Sandstone, buff (gray to white at top), fine naceous zones____-_-______------__- 35 to very fine-grained, crossbedded; thin bedded and shaly in lower part to massive 17. Sandstone, buff, crossbedded______1 in upper third; friable______-----_-_.-- Ill 16. Shale with minor sandstone, largely con­ 3. Shale, medium-gray; mostly concealed by cealed; carbonaceous zone in upper part _ 29 wash; about______100 15. Sandstone, buff-brown, very limy: contains abundant shells of Ostrea glabra Meek and Thickness upper member__.______. 230 Hayden______-______-_--____-_-_ 2 14. Shale (presumably); concealed by slope Middle sandstone member: wash______12 2. Sandstone, shaly; weak cliff-maker; gives way to Mancos shale a short distance to the east; Total Neslen formation._____-__-__ 370 110

Sego sandstone: Total Blackhawk formation ______340 13. Sandstone, buff, crossbedded______24 12. Sandstone, shaly, with some shale, carbona­ Contact gradational. ceous in upper part; gypsiferous; sandstone Mancos shale: shows drying cracks.______58 1. Shale, medium-dark-gray weathering drab, with some sandy layers in upper part; 490 11. Sandstone, light-gray, fine-grained, massive, ft below top is a minor sandstone that caps crossbedded, conspicuous; variable thick­ little buttes near Saleratus Wash; 565 feet ness ______7± below top is a 20-ft sandstone layer that 10. Shale, with some sandstone (like No. 9)___- 38 makes a small hogback northwest of Floy. 9. Sandstone, light-buff to buff-brown, massive, crossbedded, ledge-making; largely of very No. IS. Section taken in canyon of Crescent Wash to the top of fine frosty quartz grains; some of it limo- Crescent Butle, sec. 84, T. 20 S., R. 19 E., Utah nite stained, cemented loosely by calcite; [Nos. 50-83 by J. B. Eby; Nos. 22-49 by R. M. Leggette; Nos. 6-8 by K. K. Landes;. Nos. 1-4 by James Gilluly and C. H. Dane along Salt Creek about 6 miles south carries fucoids.______15 of Highway 50] 8. Sandstone, with shaly material in central Farrer formation, in part: Feet part; buff, crossbedded, thin-bedded; 84. Sandstone, massive; reddish-brown cliff- locally a minor ledge-maker______40 maker; caps Crescent Butte___ --_____ 128 83. Shale___---_____-_--_.-_--____.___-__ 20± Total Sego sandstone._-__-_____-_- 182± 82. Sandstone_____--__-_-_-.____-______10i 81. Shale...---.-______15± Buck tongue of Mancos shale: 80. Sandstone______20± 7. Shale, gritty; dark gray weathering light 79. Shale__---_-______12 medium gray; lower 60 ft concealed.---- 163 78. Sandstone__------__-----_-___-_-_-___ 6 77. Shale--_--_-__.-_..-.-______...... _ 8 Castlegate sandstone: 76. Sandstone------_--___---__-... 20 6. Sandstone, mostly light-buff, but may be 75. Shale and sandstone, thin-bedded. ______12 stained rich brown on cliff faces; carries 74. Shale______85 zones of gray-white sandstone, which as a 73. Sandstone...... ______4 rule cannot be traced far; massive, cross- 72. Shale_------_----_------_---._--_. 85 bedded; a white sample is friable, nearly 71. Sandstone....-__-_-----__._._--______10 all fine to very fine quartz grains moder­ 70. Shale...--.--.______70 ately well rounded; a brownish sample 69. Sandstone, massive, brown; ledge maker; shows fine to very fine angular quartz with clay shale, gray, in an 8-ft bed 6 grains, with 10 percent of brown grains, ft below top and in a 2-ft bed 6 ft above probably of limonite-stained quartz______132 base.---_-_-__-_---_-_____-_-.-____ 32

Conformable contact. Farrer formation, part measured __ 537 ± Blackhawk formation: Upper member: Neslen formation (top may be somewhat below top of 5. Sandstone, shaly, with some carbonaceous No. .68): material; poorly exposed, but in places 68. Shale.__.______40 carries medium-gray slightly silty mud- 67. Coal____._..._---__.---_-._._ stone, and gray-brown coaly mudstone 66. Shale-______30 with plant fragments and specks of resin. _ 19 65. LOCAL SECTIONS 57

No. IS. Section taken in canyon of Crescent Wash to the top of No. IS. Section taken in canyon of Crescent Wash to the top of Orescent Butto, sec. SJ,, T. 20 8., R. 19 E. Utah Continued Crescent Butte, sec. 84, T. 20 S., R. 19 E. Utah Continued! Neslen formation Continued Feet Sego sandstone: Feet 64. Shale..-..---._-_--.------._-- 40 21. Sandstone like No. 18; rather shaly in 63. Sandstone.----.------8 lower part; carries fucoids; locally re­ 62. Shale------..------.---.- 32 sembles the light-gray sandstone of 61. Coal....-----.----.------1 No. 17______21 60. Clay__------_--.-______-_... 2 20. Sandstone, like No. 17; but less pro­ 59. Coal___------___------_-_---- 1 nounced cliff maker; lower part light 58. Shale---.-----.-.------20 gray, with rounded surfaces; upper part 57. Sandstone.-.----.------5 buff brown, blocky; poorly preserved 56. Shale-.--..___------______--_ 10 Ostrea zone locally present at top______55. Sandstone..-----____------_--- 15 19. Shale, sandy, medium-gray in all proba­ 54. Coal ------% bility, but mostly concealed; carries 53. Shale..-----.--_...--_-._-_____._ 4 thin beds of sandstone.______-__-__ 48 52. Sandstone_._._.-_------__-----__ 20 18. Sandstone, friable, crossbedded, in part 51. Clay, with thin beds of coal..______6 shaly; medium-thick-bedded and light- 50. Shale, sandy, with thin-bedded sandstone gray to thin-bedded and buff-brown; layers.. _ _._-_____.______--_-____ 45 slightly platy near top______49 49. Shale and thin-bedded sandstone (25 per­ 17. Sandstone, massive; ledge maker; upper cent) ; shale brown to gray, carbonaceous part buff brown, blocky, with clay pel­ near base______25 lets; lower part mostly light gray, with 48. Coal____.--______% rounded surfaces.______16 47. Sandstone and shale, carbonaceous (20 percent) in upper part; sandstone thin Total Sego sandstone___--_--_--_ 140 bedded ----__---_---_-______-._ 11}. 46. Coal and bone__------_---_-_ 1% Buck tongue of Mancos shale: 45. Shale, deep-brown, carbonaceous.______1 16. Shale and sandstone (40 percent); shale 44. Sandstone, thin-bedded.______8 like No. 15, but appears buff at most 43. Shale, brown______.______1 places owing to slope wash; sandstone, 42. Bone.....______--_.---. % buff, crossbedded and in thin beds 41. Shale, brown.______2 separated by shale______.__-____-___ 68 40. Sandstone and shale (10 percent); sand­ 15. Shale, lower part concealed by wash; shale stone thin bedded, partly concealed; is medium to dark gray, gypsiferous; shale, carbonaceous, mainly in lower resembles Mancos, and carries thin part....._------____-__--_- 12^ brown-weathering limy layers.______113 39. Coal and bone (Chesterfield zone).___.__- 2 38. Sandstone, massive to medium-bedded. 9 Total Buck tongue..___._.__.... 181 37. Sandstone, gray to buff, thin-bedded. _ _ __ 6 36. Shale, brown to black ______6 Castlegate sandstone: 35. Sandstone, buff, thin-bedded...-______- 2^ 14. Sandstone, light-buff to light-gray, mas­ 34. Coal and bone (Ballard horizon) ______1% sive, crossbedded, friable; locally con­ 33. Shale, brown to black, carbonaceous _ _ _ 1 Ys tains shaly material (in part carbona­ 32. Shale, sandy, gray to buff.__-_-----__-_ 1}_ ceous or even coaly) near top; elsewhere 31. Sandstone, thin-bedded; shaly near base._ 4 upper part is pebbly, glauconitic, with 30. Shale, gray; black near top-__-_-__-___-_ 3 fossils (carapace of a fresh-water trio- 29. Sandstone, thin-bedded, gray to buff; nychid turtle; teeth and bones of the shaly in upper part-_-_-_--______10 marine shark Lamna sp.; and possibly 28. Shale, brown; somewhat sandy near top__ 19 worm borings). This member is a cliff- 27. Sandstone, thin-bedded, buff.______7 forming unit, and its top or upper part 26. Shale, brown to black, very carbonaceous causes a pronounced dip-slope bench. __ 75 near top-----.--.------6>_ 25. Sandstone, thin-bedded, gray to buff, _ _ _ _ 13 24. Coal, with minor carbonaceous shale (Pali­ Conformable contact. sades coal zone)_____-_-_-_---_---___ 6% Blackhawk formation: 23. Shale, black to brown, carbonaceous; Upper member: somewhat sandy near middle.______22 13. Shale, buff to medium-gray____.______5 22. Sandstone, thin-bedded, shaly, medium 12. Coal and bone_------_------4 gray__.-_-__--_------__------35 11. Shale, like No. 13____._ . . . 30 10. Shale, carbonaceous, with coaly streaks__ 2)_ Total Neslen formation. 501 9. Coal, dirty.___-.___-____-____. 3 8. Sandstone, massive, very light-gray______- 34 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 13. Section taken in canyon of Crescent Wash to the top of No. 14. Section in canyon of Thompson Wash, Utah Continued Crescent Butte, sec. 84, T. 20 S., R. 19 E. Utah Continued Tuscher formation Continued Feet Blackhawk formation Continued Feet 69. Sandstone, coarse-grained, friable, mas­ Upper member Continued sive; very irregularly bedded cliff maker; 7. Sandstone, massive, buff; with No. 8 con­ weathers to a cream or buff-cream; stitutes a cliff-forming unit______36 weathered surfaces are more rounded 6. Sandstone, thin-bedded, buflL______100 and of lighter color than is true of lower sandstones-___-_____-___--____ 80 Total Blackhawk formation. ______214% 68. 'Sandstone, very coarse-grained, thin- bedded, friable, buff-weathering. ______30 Gradational contact. Mancos shale: Total Tuscher formation. 406 ± 5. Shale, bluish-gray; thin sandstone beds in upper part; sandy zone about 350 ft Farrer formation: above base------4, 050± 67. Shale, gray to green; and very coarse­ Dakota sandstone: grained friable brown to greenish-brown 4. Sandstone with conglomerate at base; sand­ sandstone of lighter tone than beds stone white and light gray, carbonaceous, lower in the section______110 and heavily limonite stained; pebbles in 66. Sandstone, brown to green, coarse-grained, conglomerate are of black chert; forms a friable, massive cliff maker.______36 strong ledge.______9 65. Sandstone and shale, like No. 53.______45 3. Shale and sandstone; upper part gray shale 64. Sandstone, like No. 66.----______- 60 with sandstone lenses up to 6 in. thick, 63. Sandstone and shale, like No. 53, but sand­ carrying plant fragments; lower 15 ft stone somewhat coarser and greener. __ 130 mostly of 6-in. sandstone layers inter- 62. Sandstone, like No. 66-_--_-_---_.--___ 50 bedded with shale; Halymenites common, 61. Shale, light-gray; and brown sandstone as are plant fragments but no carbon. _ _. 51 that is fine grained and thin-bedded to 2. Conglomerate, crossbedded, with pebbles coarse grained and massive._-_-__-___ 135 up to three-fourths of an inch in diameter 60. Sandstone and shale, much like No. 53; of white, gray, yellow, and black chert-- 10 sandstone is finer grained and browner, but some greenish-gray sandstone is Total Dakota sandstone. 70 present; forms point of a long spur____ 62 59. Sandstone, like No. 57____-___------15 Morrison formation, uppermost part: 58. Shale with some sandstone, like No. 53_ 57 1. Clay, light-gray; greenish gray near top; 57. Sandstone, buff, medium-grained, massive, carries marly layers, limestone nodules, weathers to greenish-gray; with clay and some lenses of grit-__-__--.-____ 68 galls.. _-______-.-__-___-_-_-_---_-_ 40 56. Sandstone, massive layers like No. 52; 10-20 ft above base are fresh-water fos­ sils of probable Fruitland age (Tuloto- No. 14- Section in canyon of Thompson Wash, Utah mops thompsoni White; Unio cf. U. baueri Stanton, and Unio holmesianus [1-18 measured by J. H. Hengst; 19-45 by R. M. Leggette; 46-79 by E. M. Spieker and J. B. Reeside, Jr.] White)______-_ 60 55. Shale, like No. 53; along outcrop this unit "Wasatch" formation: Feet carries massive sandstone layers_____ 100 79. Varicolored beds not examined in detail. 54. Sandstone, like No. 52, massive to thin- Tuscher formation: bedded, very irregular, crossbedded, 78. Sandstones, like No. 69, with minor inter­ with clay galls..-______-_____-_---_ 14 vening shaly beds; not examined in 53. Shale and sandstone; shale in greenish- detail.-.___-__-_---_----__...__ 200± gray layers about 10 ft thick is inter- 77. Conglomeratic sandstone; matrix like No. bedded with sandstone in beds 2-5 ft 69; pebbles up to 6 by 2 in., mainly thick.______56 quartzite and chert (black, pink, white, 52. Sandstone, green to brown to gray (coated gray, and yellow), some igneous rock__ 20 red) medium-grained, massive; carries 76. Sandstone, like No. 69__-____--_-_._.__ 30 lenses of clay galls, and resembles the 75. Sandstone, gray, like No. 71___-_-___-__ 3 sandstones of the ''Wasatch''______30 74. Shale, gray______5 51. Sandstone and shale; latter in layers 4-5 ft 73. Sandstone, brown-buff, crossbedded, thick; sandstone is buff, blocky; lime­ coarse-grained, with ferruginous nod­ stone layer of unknown thickness near ules. ___-_------__.___-____...... 30 base.______95 72. Shale, gray, granular______--___-____ 2 71. Sandstone, gray-white, calcareous.______2 Total Farrer formation_____._ 1, 095 70. Shale, green-gray, granular_-______4 LOCAL SECTIONS 59

No. 14- Section in canyon of Thompson Wash, Utah Continued No.14. Section 'in canyon of Thompson Wash, Utah Continued Neslen formation: Feet Sego sandstone Continued Feet 50. Shale, like No. 46..------_---.---.--- 5 14-. Sandstone, buff, fine-grained, limonite- 49. Shale, black, carbonaceous._---_--._--- 3 stained, crossbedded; weathers into thin 48. Shale (probably), and sandstone; mostly plates, has limonite nodules.....______30 concealed, but carries layers of platy brown ferruginous sandstone..______75 Total Sego sandstone___.____._ 200 47. Sandstone, gray, medium-fine-grained; blotched with brown___._._._._.___ 20 Buck tongue of Mancos shale: 46. Shale, gray, sandy__-._.______.__ 22 13. Shale and sandstone, in alternating beds, 45. Sandstone, buff, medium-fine-grained, with more shale in lower part and more thin-bedded._------_------__-.-- 15 sandstone above; this unit is a gradation 44. Shale, gray to brown. ______1 zone between the Buck and Sego; sand­ 43. Bone...... ------_------_---- 2 stone is fine grained, crossbedded, 42. Sandstone, thin-bedded (below) with car­ limonite-stained. ______26). bonaceous shale; partly concealed-____ 6% 12. Sandstone; buff, fine-grained, massive, 41. Shale, black, carbonaceous..._____..__. 1 crossbedded; ledge maker..______4 4.0. Coal and bone.____.__-_____._-_.__--- 2 11. Shale, with minor thin lenses and layers 39. Shale, brownish-gray.__.__.____.____._ 1 of sandstone; shale is gray and gyp- 38. Sandstone, thin-bedded; largely con­ siferous and carries fragments of carbon­ cealed ____----_-_---_-_.--_-_------5 ized wood; lower part concealed____. 172 37. Sandstone, medium-bedded...______1% 36. Shale, carbonaceous. _----__--_------1 Total Buck tongue-.-....___._ 203 35. Coal (Chesterfield zone)______4 34. Shale, brownish, carbonaceous.______2 Castlegate sandstone: 33. Sandstone, thin-bedded, shaly.______6 10. Sandstone, buff, weathering reddish brown ; 32. Sandstone; massive, buff, ledge-forming._ 18 massive, crossbedded; ledge maker. ... 40 31. Coal, bone, and carbonaceous shale (Bal- 9. Sandstone, with minor shale, nodular lard zone)-----_-__------_--- 3% weathering; sandstone is a thin-bedded 30. Shale, carbonaceous, and a little coal_.__ 6^ reddish-brown fine-grained cliff maker.. 14 29. Sandstone, medium-bedded_.-_-______1 8. Sandstone; buff, weathering reddish brown ; 28. Shale, brown______---__..-_ 18 massive, crossbedded; cliff maker; 27. Shale, carbonaceous...... --.------1 weathered surface shows white areas 26. Shale, brown to black, somewhat sandy. _ 12 the size of birdshot..______30 25. Shale and sandstone, thin-bedded; sand­ stone in upper part; unit concealed in Total Castlegate sandstone. ------84 middle; shale (gray to brown and car­ bonaceous in lower part)______25 Conformable contact. 24. Sandstone and shale (25 percent); brown Blackhawk formation: shale in lower part; thin-bedded shaly Upper member: sandstone above.______40 7. Shale and sandstone, very thin-bedded, 23. Coal (Palisade)--.------.------5 intercalated- ______2)_ 22. Shale----.------.------.-.----- 3). 6. Bone and coal-_--_-____---_-___-_---_ 1% 21. Coal and shale, carbonaceous-----..---- l}_ 20. Shale, carbonaceous, brown to black___-_ 4 5. Shale...------_--..-...._------1% 19. Sandstone, buff, thin-bedded; concealed 4. Sandstone and shale; sandstone is light near middle---_--____--__-_--_--__- 23 buff, crossbedded; shale, which is in small part carbonaceous, constitutes Total Neslen formation. 335 about one-third of the unit___.__-___. 20 3. Sandstone, light-gray, fine-grained, car­ Sego sandstone: bonaceous; weathers buff_____.___._ K 18. Sandstone, massive, crossbedded, gray- 2. Sandstone; buff to reddish-brown, medium- white, coarse-grained ______75 grained, massive, crossbedded; cliff 17. Sandstone, weathering to thin sheets and maker ______95 with rounded surfaces ______25 16. Sandstone, with a little shale in thin beds; Total Blackhawk formation. -... 121 sandstone crossbedded and weathers to Gradational contact. rounded forms; somewhat limonite Mancos shale: stained __-__-_--_-_____.__--______- 10 1. Shale, bluish-gray, limy, gypsiferous; thin 15. Sandstone, buff, fine-grained, massive, beds of fine-grained sandstone in upper ledge-forming. ______60 part. 60 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 15. Section measured on the north side of the Nash Wash No. 15. Section measured, on the north side of the Nash Wash reentrant, in sees. 35 and 25, T. 19 S., R. 21 E., northwest of reentrant, in sees. 35 and 25, T. 19 S., R. 21 E., northwest of Cisco, Utah Cisco, Utah Continued fDakota and Morrlson strata measured by C. H. Dane south of Cisco on the road Feet to Castleton, remainder by D. J. Fisher] Contact apparently conformable, but not well exposed and the lithology of the units changes rapidly "Wasatch" formation (in part): Feet laterally. 80. Sandstone and shale (25 percent); sand­ Farrer formation: stone in massive ledges and cliffs; locally 70. Shale and sandstone; thin greenish sand­ stained red by wash; higher sandstone stone beds in greenish-tinged clay shale beds are light gray and weather to beds._ _-_--_.---_-______-______49 rounded surfaces; lower sandstone beds 69. Sandstone, lithologically like No. 53; are buff brown, blocky; interbedded lower part is somber and blocky; the with purplish-brick-red sandy shales upper part is light gray, rounded._____ 11 (to top of exposure here). (See pi. 6C.) _ 825 68. Shale and sandstone in equal amounts; like Nos. 52 and 53______29 79. Conglomerate, like No. 65 in stratigraphic 67. Sandstone, like No. 55______...-._..__ 11 section 12; massive, dark-brown ledge- 66. Shale, like No. 54, with some medium- to maker; lower two-thirds is 15 percent thin-bedded sandstone___-____---__-_ 16 sandstone and 85 percent conglomerate 65. Sandstone, like No. 55.____-_____--._._ 11 (50 percent pebbles); upper one-third is 64. Shale, like No. 54__-______-.____ 12 95 percent coarse friable quartzose cross- 63. Sandstone, like No. 55---_--__--_-_____ 4 bedded sandstone; on next point to 62. Shale, like No. 54.______39 southeast this unit is 75 ft thick; on 61. Sandstone, like No. 53, with one next point to west it is absent, and its shaly parting.______54 position is occupied by red shale. (See 60. Shale, like No. 54-_-._.______6 pi. 4A and 6C.)_----______40 59. Sandstone, like No. 53; carries one thin shale bed___-_____-_-_-___-______48 'Wasatch" formation, part meas­ 58. Shale, like No. 54; with at least 2 sand­ ured______- 865 stone beds about 5 ft thick, and prob­ ably contains other thinner sandstone Contact discomformable, gently undulating; conglom­ beds______96 erate rests on shale at point of section, but elsewhere 57. Sandstone, resembling No. 53; a pro­ it lies on sandstone, apparently No. 77. nounced ledge maker______19 Tuscher formation: 56. Shale, like No. 54___.______9 55. Sandstone, minor ledge, like No. 53____ 4 78. Shale, medium-gray with greenish tinge __ 22 54. Shale, like No. 52; largely talus covered. _ _ 26 77; Sandstone; massive crossbedded ledge; 53. Sandstone, forms a buff-brown, semiblocky mostly of very fine colorless quartz ledge, beautifully crossbedded; compos­ grains with 2 percent white feldspar ed of friably cemented, fine grains, and a few dark mineral grains loosely about 75 percent frosty, subangular cemented to a friable mass; weathers quartz with most of the rest of slightly to beautiful white rounded surfaces__ 51 limonite-stained angular feldspar, but 2-3 percent dark grains; fresh surface 76. Shale, like No. 78...___.______16 shows a somewhat f elty texture ______14 75. Sandstone, buff-brown, friable, medium- 52. Shale, light-gray, with faint but distinct bedded______6 greenish tinge______12 74. Shale and sandstone, like No. 70.____ 20 Total Farrer formation. 470 73. Sandstone, white, saccharoidal; medium- fine frosted quartz grains with 10 per­ Neslen formation: cent feldspar and 2 percent dark grains; 51. Sandstone, light-gray to buff, massive___. 8 friable; weathers to rounded surf aces __ 26 50. Shale, medium-gray to brown___-___._ 19 72. Shale, like No. 78.....___------26 49. Sandstone, buff-gray, medium- to thick- bedded, crossbedded-__-_ _.____-__-__ 28 71. Sandstone, with minor shaly beds in upper 48. Shale, brown to gray, in part sandy; 2-in. half; sandstone of medium fine angular coal seam 6 ft above base.______16 grains of frosted quartz with 5 percent 47. Sandstone, buff; lower 10 ft thin-bedded buff-yellow feldspar and a very few dark to thick-bedded; upper 3-4 ft medium grains; sugary texture, friable; weathers bedded; remainder forms a semimassive to very light gray rounded surfaces..-- 100 ledge. __-_-__-_--_____._--_____._ 37 46. Shale, brown______._____.______.. 2 Total Tuscher formation. 267 45. Coal ____--___---___-----__---.---_ % 44. Shale, gray to buff, sandy_--_____-_.__- 12 LOCAL SECTIONS 61 No. 15. Section measured on the north side of the Nash Wash No. 15. Section measured on the north side of the Nash WasJi reentrant, in sees. 35 and 25, T..19 S., R. 21 E., northwest of reentrant, in sees. 85 and 25, T. 19 S., R. 21 E., northwest of Cisco, Utah Continued Cisco, Utah Continued Neslen formation Continued Feet Buck tongue of Mancos shale: Feet 43. Coal______-__-___--_---______} 19. Shale, largely concealed by slope wash; 42. Shale, brown..__.._..______.__.______12 some shaly thin-bedded sandstone layers 41. Coal, bony.--_---_------_-- J probably present in upper part____._ 188 40. Shale, gray and brown_.______14 39. Coal, bony, (Chesterfield horizon) ______} Castlegate sandstone: 38. Shale, gray...______---____--_.__-___ 6 18. Sandstone, buff-brown to buff-gray, me­ 37. Concealed (shale or shuly sandstone) 3 dium- to thick-bedded, crossbedded; 98 36. Sandstone, buff to light-gray, massive, percent of fairly well-rounded fine glassy crossbedded, forms ledge; mostly of fine quartz grains; some slightly kaolinized, Avell-rounded clear but limonite-stained limonite-stained white to flesh-colored quartz grains with 10 percent white feld­ feldspar, and a few dark grains; carries spar and a few dark grains; more or less marine invertebrates (13685)______22 friable and concretionary.... ______21 17. Sandstone, largely concealed; apparently 35. Bone, bony coal, and carbonaceous shale like No. 15______-______"_ 38 (Ballard coal zone)______4 16. Sandstone; generally a medium- to thick- 34. Sandstone, buff-gray, medium- to thick- bedded ledge maker..______26 bedded; forms ledge.______7 15. Sandstone, slightly shaly, thin-bedded, 33. Concealed (in main); some medium- to buff-gray, friable; generally a slope._ _ _ _ 6 light-gray thin-bedded slightly shaly 14. Sandstone, like No. 12______1 sandstone in upper part and some gray shale in lower part; 5 in. of bony coal Total Castlegate sandstone. 93 2 ft above base..._-_.__---_____-___ 17 32. Sandstone, buff, crossbedded; ledge maker; Conformable contact. lower 12 ft medium bedded with a 6-in. Blackhawk formation: limy layer; rest is massive, though medi­ Upper member: um bedded at top-__---_____------33 13. Sandstone and shale, lower part concealed; 31. Shale, medium-gray, and 20 percent buff probably largely of thin-bedded buff- thin-bedded sandstone; 2 in. of bony gray friable slightly shaly sandstone. ... 50 coal locally present at top.______29 12. Sandstone, buff-brown, massive, cross- 30. Sandstone and shale (40 percent), medium- bedded ; forms ledge______gray; sandstone buff4 medium- to thin- bedded______-_--____-_-- 12 Total Blackhawk formation ______51 29. Shale, carbonaceous___----_------1 28. Coal, bony, with bone and carbonaceous Conformable contact. shale (Palisades zone).______6 Mancos shale: 27. Shale, carbonaceous.------2 11. Shale, blue-gray; forms the wash-covered 26. Bone and bony coal-______13. lower slope of Book Cliffs and broad flat 25. Shale, gray; largely carbonaceous; 2 in. to south; about 875 ft below top is a bone 1 ft above base______-_---_-_ sandy zone, carrying two prominent sandstone beds; total thickness about. . _ 3, 450 Neslen formation. 295 Dakota sandstone: Sego sandstone: 10. Sandstone, white, sugar-textured, cross- 24. Sandstone, massive, although locally cen­ bedded______..____._-___.... 13 tral part is thin-bedded, shaly; generally 9. Shale, light-gray, sandy__---___-_------17 makes a cliff; upper part composed 8. Sandstone, white______-_--____--__---- 7 mainly of very fine frosted quartz grains 7. Shale, gray, sandy______18 with some 5 percent of kaolinized feld­ 6. Sandstone, white___-__-__-__--______- 6 spar ______53 5. Shale, gray and greenish-gray, limy______18 23. Sandstone, somewhat shaly, like No. 21.__ 63 4. Sandstone, white, fine-grained, quartzitic, 22. Sandstone, buff to gray, massive; ledge with biotite flakes.______8 maker ______12 3. Shale, gray and green, limy______23 21. Sandstone, shaly, thin-bedded, buff with 2. Conglomerate, limestone pebbles._-----_ 4 some gray shale; slope maker at most 1. Conglomerate, quartzitic, with subangular places. ______-_-___---___-____- 29 pebbles up to 4 in. in diameter of crystal­ 20. Sandstone, buff-gray, medium-bedded, line quartz; orange, brown, white, drab, locally thin-bedded. ______15 red, and black.______12

Total Sego sandstone______172 Total Dakota sandstone. 126 62 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 15. Section measured on the north side of the Nash Wash No. 16. Section up the canyon of a northern tributary to Cotton- reentrant, in sees. 35 and 25, T. 19 S., R. 21 E., northwest of wood Creek, north of Cisco in sees. 8 and 17, T. 19 S., R. 23 E., Cisco, Utah 'Continued Utah Continued

Irregular wavy surface (unconformity?) Feet Farrer formation Continued Feet Morrison formation (part): 45. Sandstone, buff; minor ledge maker.__ 6 Clay, variegated with subangular pebbles of 44. Shale, as in No. 52; locally sandy; few quartz, all colors, and sizes up to 2 in.______17 medium-thin sandstone beds in up­ per part__------_--______._-_-_. 33 No. 16. Section up the canyon of a northern tributary to Cottonwood 43. Sandstone, buff to light-brown; minor Creek, north of Cisco in sees. 8 and 17, T. 19 S., R. 28 E., Utah ledge ___.-__.___.-______14 [Measured by D. J. Fisher] 42. Shale, medium-light-gray; with a little Tuscher formation: Feet sandstone______13 56. Sandstone and shale; sandstone like No. 41. Sandstone, friable, medium- to thin- 55; forms massive ledges 20-100 ft bedded; varies from slope maker to high; interbedded with about equal ledge maker; some beds are light amounts of shale and thin-bedded olive, but most are buff.______24 shaly sandstone that weathers into 40. Shale as in No. 44______10 slopes; not examined in detail_____ 600-900 39^. Sandstone, light-buff, thin-bedded; slope 55. Sandstone, massive cliff maker; lower maker (generally)______9 part is friable, light brown, blocky; 38. Shale, somewhat sandy, more or less upper part is very light gray, with concealed slope; shale in part brown rounded surfaces; samples from lower with fragments of carbonized wood.. 18 part are light to medium light gray on 37. Sandstone, ledge maker, generally som­ a fresh surface and are composed ber brown and blocky but locally mainly of fine to very fine, only buff gray with rounded, weathered slightly rounded grains of frosted, surfaces; crossbedded; largely of fine coated quartz with 2-4 percent white to very fine grains of quartz, but car­ feldspar and 1-2 percent dark grains. 86 ries 10 percent limonite-stained feld­ spar. ______6 Total Tuscher formation. 800 ± Total Farrer formation. 419 Contact approximately conformable, but ill exposed. Neslen formation: Farrer formation: 36. Shale, with minor sandstones; in small 54. Shale and sandstone (one-third); like No. part concealed; shale is medium light 52, but some of the sandstone is me­ gray to brown.______19 dium thick bedded... ______72 35. Sandstone, buff, medium- to thin- 53. Sandstone; forms massive ledge contain­ bedded, shaly_-__-_.___..--_..__ 12 ing minor shaly partings varying 34. Shale, medium-gray; locally carries greatly laterally; resembles No. 51; minor sandstones; 4-in. coal lens 20 medium light gray locally stained ft above base.______30 brown; rounded weathering surfaces; 33. Sandstone, gray to buff to brown, mas­ fragmentary plant remains ______22 sive; cliff maker______54 52. Shale and sandstone (20 percent); shale 32. Sandstone, shaly, gray; locally forms a is greenish-tinged medium gray; sand­ single cliff with overlying and under­ stone is dirty buff, thin bedded, lying units._ ___-_---___-__----_-. 4 platy. __-__-_-----_---___.___ 34 31. Sandstone, thin-to medium-bedded. __ 31 51. Sandstone, massive, crossbedded, buff- 30. Shale; sandy in lower part___-_____. 49 brown to light-gray; ledge maker; 29. Coal, carbonaceous shale, and bone__._ 2 mostly of angular, medium-sized 28. Shale, buff-gray; sandy in upper part; grains of frosted quartz, but carries limy in lower part_-__-_-_-_-___--_ 23 10 percent of white feldspar, partly 27. Sandstone, buff; lower part massive limonite-stained; contains petrified and crossbedded; upper part medium log 1 ft in diameter_-.____.._____ 19 bedded__ _ _----______. 7 50. Sandstone and shale; shale as in No. 26. Bone, coal, and shale, brown (Chester­ 52; sandstone like No. 51; locally field coal zone)____-----_-__-_-____ 4 gives way to all sandstone, in which 25. Shale, brown to gray_____-___--__.__ 1) case Nos. 51-47 inclusive form a 24. Sandstone, buff-brown, medium-bedded. 3 single cliff-making unit 93 ft thick. __ 27 23. Shale, gray and brown, carbonaceous; 49. Sandstone, like No. 51------21 5 in. of bone 1 ft above base.------. 7} 48. Shale, as in No. 52___._----______-_. 7 22. Sandstone, like No. 24__---.______7 47. Sandstone, like No. 51_-_--_--_._-_-_ 19 21. Sandstone, buff, medium-bedded to 46. Shale and sandstone (30 percent); shale thin-bedded, shaly ______18 as in No. 52; sandstone is medium 20. Shale, sandy, with 8 in. of bony coal in bedded.______.-_.__ __ 65 middle.______6 LOCAL SECTIONS 63

No. 16. Section up the canyon of a northern tributary to Cotton­ No. 17. Section measured in and near canyon of Westwater Wash, wool Creek, north of Cisco in sees. S and 17, T. 19 8., R. 23 E., Utah .Utah Continued [Nos. 1-37 taken at Dry Canyon in sees. 5,7, and 8, T. 18 S., R. 24 E., by D. J. Fisher; Feet Nos. 38-56 by E. M. Spieker and J. B. Reeside, Jr., on the east side of canyon of Neslen formation Continued Westwater Wash] 19. Sandstone, like No. 21... ______22 18. Coal, slightly bony ______1 "Wasatch" formation, not examined in detail. 17. Shale, brown to gray, with some thin- Tuscher formation: Feet bedded buff sandstone ______24 55. Sandstone, with minor shale; like Nos. 16. Sandstone, buff to brown massive. _.__ 4 48-54; conglomeratic at top (like No. 77 15. Shale and 40 percent sandstone; like of section 14); not examined in detail.... 250± No. 17__-_____---_---___----_ . 36 54. Sandstone, like No. 50, though possibly 14. Coal, carbonaceous shale, and bone browner; causes several irregular benches (Palisade zone)-.-. ------and contains many ferruginous bands.... 56 13. Shale, brown.... _------_---- 4}_ 53. Sandstone, like No. 50, but softer...... 45 12. Sandstone, buff, thin- to medium-bed- 52. Sandstone, like No. 50______80 6 51. Shale...... _--..--.._--._--_...... 30 11. Shale, brown, weathering gray; upper 50. Sandstone, massive, coarse-grained, more part limy ______17>. reddish than No. 48; forms rounded out­ 10. Sandstone, buff, thin-bedded, shaly_ crop; carries partings of blue shale._____ 70 49. Sandstone and shale, slope-forming unit...- 25 Total N eslen formation ______413 48. Sandstone, gray, massive, crossbedded, coarse-grained; has an angular outcro __. 35 Sego sandstone: 9. Sandstone; massive cliff-maker; lower 11 ft is buff brown; upper 19 ft is very Total Tuscher formation.______600± light gray, crossbedded, friable; com­ posed of poorly rounded fine grains of Farrer formation: frosted and coated quartz with 1 per­ 47. Sandstone, like No. 44, with two layers of cent of somewhat limonite-stained gray shale; slope-forming unit.______63 white feldspar and a trace of dark 46. Sandstone, like No. 44, making 7 ledges 40, minerals.______------______- 30 25, 100, 45, 70, 42, and 28 ft thick_____ 350 8. Shale and sandstone, like No. 6.______67 45. Sandstone, much like No. 44, with a hard 7. Sandstone, buff, medium-bedded, forms ferruginous concretion layer at top____-- 60 ledge. __.-.______------_- 3 44. Sandstone, light-buff, friable; some harder 6. Shale and 30 percent sandstone; shale layers weathering dark-brown; forms slope like Mancos; sandstone, shaly, thin to capped by ledge.______70 medium bedded-_----_-----_____-_- 48 43. Sandstone; lower part brown buff; upper part 5. Sandstone, buff, crossbedded; forms gray green; weathers dark brown; very ledge; in beds mainly between 1 and 6 hard and calcareous; forms bench ______27 in. thick, with some shale.______23 42. Sandstone, friable, greenish-gray weathering brown or buff; in part with clay galls; Total Sego sandstone. 171 forms long slopes.______40 41. Sandstone, brown; clay galls near top__-___ 30 Buck tongue of Mancos shale: 40. Sandstone; ledge maker; shale at base.-.-- 32 4. Shale, sandy in upper part; carries a few 39. Sandstone, buff; ledge maker; like No. 38; lenses of fine-textured, buff weathering top ledge carries poorly preserved fossil limestone______267 plantS-_-___----.-----_------_---___- 45 38. Sandstone, buff, friable, medium-grained, Castlegate sandstone: irregularly bedded; forms ledge.---...-. 22 3. Sandstone; very massive resistant layer capping a pronounced dip slope; cross- Total Farrer formation ______739 bedded, fine grained; weathers light gray to buff to brown; varies notably Neslen member: in thickness.__.._--____-_____-___-- 2. Sandstone and 40 percent shale in alter­ 37. Shale, gray; a very small part is carbona­ nating beds; sandstone crossbedded, ceous; carries a minor amount of thin- fine grained, medium gray and weath­ bedded sandstone and a 2-ft lens of ers buff; in beds 1-8 in. thick; limy greenish-buff-gray fine-textured limestone. 59 lenses present in upper part; fucoids.. 52 36. Sandstone, buff to gray thin-bedded._____ 2% 35. Shale, gray, in large part carbonaceous; 3 Total Castlegate sandstone. 56 ft above base is 6 in. of bone.______33}_ Conformable contact. 34. Sandstone, gray to buff, thin-bedded-_____ 10 Mancos shale: 33. Shale, brown to gray---_-______--_____ 6}_ 1. Shale, gray; upper part limy, silty with 32. Sandstone, buff, medium-bedded, cross- some very thin siltstone beds. bedded .-__---_--_---._.__.._._____ 5% 64 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 17. Section measured in and near canyon of Westwater No. 17. Section measured in and near canyon of Westwater Wash, Utah Continued Wash, Utah Continued)

Neslen member Continued Feet Sego sandstone Continued Feet 31. Shale, brown to gray; carries three thin 5. Sandstone, massive______-_-_-___ 66 layers of bone______16 4. Sandstone, buff-gray, thin-bedded; partly 30. Sandstone, buff, massive; locally highly concealed ______44 crossbedded; ledge maker; upper part medium bedded; basal part contains a Top Sego sandstone.______212 little intercalated carbonaceous shale; carries poorly preserved fossil plant frag­ Buck tongue of Mancos shale: ments, carbonized wood, worm borings, 3. Shale, gray; largely concealed by wash; and fragments of fossil bones..-___---.,- 21/2 carries a few lenses of limestone and limy 29. Bone, coal, and carbonaceous shale (Carbo- sandstone.______338 nera? coal zone)______9 28. Shale, medium- to dark-gray, limy, locally Castlegate sandstone: sandy; partly carbonaceous.______11 2. Siltstone, buff, crossbedded; in beds 2-8 in. 27. Sandstone, buff, medium- to thin-bedded, thick separated by gray shale (20 percent); crossbedded ___.______28 upper 2-4 ft consists of very fine-grained 26. Bone (Chesterfieldhorizon)______buff to brown crossbedded massive sand­ 25. Sandstone, medium-bedded to massive; stone forming narrow dip-slope bench; lower forms ledge; buff in lower part; light gray beds carry a few limestone lenses______72 near top______17 24. Shale, medium-gray; upper 3-4 ft very Gradational contact. sandy______23 Mancos shale: 23. Sandstone, buff, medium to thin bedded, in 1. Shale, gray; upper part largely concealed by small part shaly______36 debris. 22. Bone, carbonaceous shale, and coal______21. Sandstone, buff to gray; shaly in lower part.. 15 20. Sandstone, buff to light-gray, massive, cross- No. 18. Stratigraphic section from the top of the Mancos shale bedded , forms ledge______2 to base of Green River formation near West Salt Creek, Colo. 19. Shale and sandstone, variable; shale, (From top of Mancos shale to top of Sego sandstone by C. E. Erdmann, near Carbo- medium-gray to brown, carbonaceous; sand­ nera, Colo.; section from top of Sego sandstone to top of highest Carbonera coal by stone, thin-bedded, buff to gray; locally carries G. B. Richardson (1909, p. 34-35), near Carbonera, Colo., from top of highest Carbo­ 6-in. bone layer 15 ft below top_.______21 nera coal to base of Green River formation by C. E. Erdmann. This latter section begins at NE. cor. SWH sec. 18, T. 7 S., R. 103 W.( and ends in sec. 4, T. 7 S., 18. Sandstone, buff to gray, thin- to medium- R. 103 WJ bedded; lower part limy and shaly. ______11 Tertiary 17. Bone______-__---__--_--_--_._____ Green River formation: Feet 16. Sandstone, limy and shaly, buff to gray____ 6 Douglas Creek member: 15. Shale, carbonaceous, with a little bone and 124. Sandstone, buff, limy; bears an abun­ coal (Palisadeszone)______6 dance of ostracodes and algal struc­ 14. Sandstone, massive and light gray to thin- tures, interbedded with gray-green bedded and buff yellow; upper 6 ft shaly._ 15 lacustrine shales, which predominate-. 50 13. Bone.______12. Shale, medium-gray______3J_ "Wasatch" formation: 11. Sandstone, gray, buff, and brown, medium- 123. Shale, clay, sandy, dark, greenish, tough. to thin-bedded, crossbedded; upper part Breaks into cleavage pieces one-fourth varies from firm to shaly sandstone._____ 15 of an inch in diameter. ______10 10. Shale, carbonaceous, black to brown, with a 122. Shale, clay, variegated red and gray____ 20 little bone______2/2 121. Slope, concealed. Probably underlain by 9. Sandstone, buff to gray, medium- to thin- gray clay shale______30 bedded ; locally shaly in upper part. ______6 120. Shale, clay, variegated greenish-gray and red; hackly cleavage flakes %-% in. in Total Neslen formation ______386 diameter.______35 119. Shale, clay, brick-red, dull. ___ ._..__.. 20 Sego sandstone: 118. Shale, cl&y, gray____-_-__--_------_ 25 8. Sandstone, buff to light-gray, thin-bedded to 117. Sandstone, gray, fine-grained, micaceous massive, crossbedded______30 with some black minerals; thin-bedded, 7. Sandstone, buff to brown, massive; forms minor ledge______8 %-\ in. Some slabs covered with limo- 6. Sandstone, shaly, thin-bedded; forms slope; nite pseudomorphs after pyrite. Ferru­ brackish-water and marine invertebrate ginous concretions present. Irregular fossils in limy layers 38 ft above base bedding causes apparent unconformity (13687)______64 with bed below.______4 LOCAL SECTIONS 65 No. 18. Stratigraphic section from the top of the Mancos shale No. 18. Stratigraphic section from the top of the Mancos shale to oase of Green River formation near West Salt Creek, to oase of Green River formation near West Salt Creek, Colo. Continued Colo. Continued "Wasatch" formation Continued Feet Unnamed sandstone Continued Feet 116. Conglomerate, limestone pebble; pebbles 104. Shale, clay, sandy, gray. A few thin 1-in. Ji-1 in. diameter (average one-fourth of layers of platy sandstone 30 ft above an inch), well rounded. Matrix is gray base. Slope surface washed over with fine-grained sandstone of sugary texture; sand from above___---______estimated composition: quartz, 60-70 103. Shale, clay, gray, with slight greenish cast percent; limy material, as cement (?), toward top; marked by splotches of yel­ 30 percent; dark minerals, mica, jasper low ferruginous sand %-l in. in diameter; cleavage fragments small, irregular and 115. Shale, clay, soft gray-green and olive___- 45 friable; 45 ft above base is 3-ft ledge of 114. Shale, clay, light gray-green.. ______47 buff arkosic sandstone, with pronounced 113. Shale, clay, green, dull; cleaves into platy pimply concretionary structure on weath­ pieces y&-}i in. in diameter._____-.____ 15 ered surfaces; 20 ft above base is a 2-ft 112. Shale, clay, drab-green to gray. Contains ledge of massive brown fine-grained ar­ few pebbles __ ..._.__..______20 kosic sandstone___-______48 111. Shale, clay, light-green______15 102. Sandstone, massive, 10- to 15-ft beds, 110. Shale, clay, slate-colored. __-----_------_ 25 brown to buff; lower 20 ft is lighter than [Note: The 145 ft of soft shale above upper part; medium-sized poorly rounded makes a slope that is in large part covered grains average 0.01-0.02 in. in diameter; with red soil wash from above.] arkosic; friable, crossbedded. Estimated 109. Shale, clay, soft, yellow-brown and green composition: quartz, 60 percent; weath­ variegated. There is no sharp line of di­ ered feldspar, 30 percent; dark minerals, vision between any of these beds______25 10 percent; a few flakes of muscovite. Pronounced pimply, concretionary sur­ Total "Wasatch" formation.______340 face on weathered faces, the small gray Tcrtiary(T) pimples about one-eighth of an inch in Unnamed sandstone: diameter and standing out as bleached 108. Sandstone, gray, medium-grained, impure, spots against the brown background.___ 60 arkosic______13 101. Brush-covered slope. Probably formed on 107. Sandstone, gray, medium-grained, impure, thin sandstone beds alternating with arkosic. Contains lenses of clay, and shale layers______27 chert pebble conglomerate like those be­ 100. Shale, clay, sandy, gray. Passes east­ low, ranging from 3 in. to 1 ft in thick­ ward into conglomeratic sandstone ness .------__----_------_--- 7 that is gray buff slightly mottled with 106. Shale, clay, gray-green to black. Cleaves white, massive, coarse grained, arkosic, into small hackly fragments (%-% in.). soft, and friable. Ferruginous concre­ Makes slope. Beds generally concealed. 27 tions %-!% in. in diameter. Pimply 105. Sandstone, gray, becoming lighter toward concretions on weathered surfaces. top; much of unit is splotched with light Estimated composition: quartz, 60 greenish yellow; massive, beds 5-10 ft percent; weathered feldspar, 30 per­ thick; crossbedded, false bedding surfaces cent; dark minerals, 10 percent; small dip 0°-20°; medium grained; average di­ amount of clastic mica. Upper 3 ft is ameter 0.01 in.; arkosic. Estimated thin bedded and platy.______18 composition: quartz, 65 percent; weath­ 99. Sandstone and mud-ball conglomerate, ered feldspar, 20 percent; dark minerals, sandstone predominating; conglomerate some probably hornblende, 15 percent. tends to overlie sandstone; both facies Small pimply, concretionary structures change laterally rapidly into shale_ __ 0-2 on weathered surfaces, finer and more 98. Shale, clay, sandy, soft, gray-brown.__._ 11 numerous, and with the same relation to 97. Sandstone, brown to buff, hard, medium- the bleached spots as in the rocks below. grained, arkosic. Two feet thick where At 31J-6 ft above base is a zone section was taken. Grades east into 3- of very hard, compact, oblate, spheroidal to 4-ft massive bed of brown sandstone fine-grained sandstone concretions, the at 50 ft; to west into mud-ball conglom­ fresh surfaces of which show many small erate of underlying bed.______1-4 flashing points. Estimated composition 96. Shale, clay, sandy, gray-brown, soft; of concretions: quartz, 60 percent1; unde- breaks into cleavage fragments, %-% in. composed feldspar, 25 percent; dark long. Grades upward into fine-cleaving minerals, 15 percent (small fragments of . yellow shale, and laterally (50 ft to hornblende, larger brownish fragments of west) into hard mud-ball conglomerate. 10 chert; and a few red and green grains of 95. Sandstone, brown, soft; gray on weathered jasper or chert)______70 surf aces.....______2 66 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 18. Stratigraphic section from the top of the Mancos shale No. 18. StratigrapJiic section from the top of the Mancos shale to base of Green River formation near West Salt Creek, to base of Green River formation near West Salt Creek, Colo. Continued Colo. Continued Unnamed sandstone Continued Feet Hunter Canyon formation Continued Feet 94. Conglomerate, mud-ball; matrix light 87. Sandstone, massive, cliff-forming; grayish brown to gray, with mottled red and brown on weathered surfaces; gray (salt- yellow spots (clay balls); some carbo­ and-pepper) on fresh surfaces; medium naceous matter present; rock compact to coarse grained, diameter of grains and hard. Clay balls make up 20 per­ averaging 0.01-0.03 in.; arkosic; beds cent of mass, diameter %-l in.; a few 1-6 ft thick. Estimated composition: well-rounded chert and quartz pebbles, quartz, 70 percent; feldspar, 15 per­ Ys~% in. in diameter and numerous fer­ cent; dark minerals, 15 percent. Pimply ruginous concretions. Casts of unios concretions on weathered surfaces very abundant, especially at top, occurring numerous and larger than those rocks in all positions and at all angles with below, maximum diameter being 0.01 respect to horizontal; external casts of in.; roughly outline false bedding lam­ shells generally deformed______inae, which slope at angles of 15°-20° 93. Sandstone, brown, slightly streaked with between the true beds. Some ferrugi­ gray, medium-grained. Estimated com­ nous concretions scattered irregularly __ 40 position: quartz, stained by iron oxide, 86. Shale, clay, gray-purple; gray towards top; 70 percent; chert, 20 percent; weathered largely concealed. ______23 feldspar, 10 percent-______85. Sandstone, gray-buff, medium-fine-grained, massive, arkosic. Small pimply concre­ 92. Shale, clay, gray, concealed______tions on surface__-_-_----__------r _- 13 91. Sandstone, buff to brown, massive, soft, 84. Shale, clay, gray. Concealed______28 fine-grained. Estimated composition: 83. Sandstone, massive; weathered surface quartz, 80 percent; feldspar, often con­ brown to buff, with numerous small cealed, 10 percent; dark minerals, 10 pimply concretions in relief; fresh sur­ percent-______20 face light gray (salt-and-pepper) ; medi­ um fine grained averaging 0.01 in. in 90. Conglomerate, chert pebble, massive, diameter; arkosic. Estimated com­ coarse, compact, strong; mottled gray, position: quartz, 65 percent; feldspar, yellow, and black; cement yellow fine­ 20 percent; dark minerals, 15 percent. grained ferruginous sandstone. Varies False bedding laminae dip as much as considerably from place to place; at one 10 locality it was a medium-coarse-grained 82. Shale, sandy, gray, fine-grained. ___-__._ 12 sandstone. Estimated composition: 81. Sandstone, buff, massive. Pimply concre­ quartz, 70 percent; chert, 30 percent. tions on weathered surfaces ______10 Pebbles all well rounded, from % to 1% 80. Shale, clay, gray, with some carbonaceous in.; a very few 6-in. quartzite cobbles. material; contains thin interbedded gray General composition: chert predomi­ sandstone beds. Largely concealed on nant, black, blue, gray, green, white and slope ______15 banded; quartz common; clay or shale, 79. Sandstone, brown to buff, medium- common; white limestone, rare; jasper, grained, massive, crossbedded, arkosic; one example______contains large ferruginous concretions. Small pimply concretions on weathered Total unnamed sandstone- 380 surfaces.. _ _-_-_-______-_-______33 78. Shale, clay, interbedded with thin sand­ Unconformity. stone beds; some carbonaceous material. Upper Cretaceous Mesaverde group Largely concealed on slope ______60 77. Sandstone, massive, brown to buff; medi­ Hunter Canyon formation: um-grained, 0.01 to 0.02 in. in diameter; 89. Sandstone, brown, massive, medium- to arkosic. Some low-angle false bedding. coarse-grained. Estimated composi­ Pimply concretions on weathered sur- tion: quartz, subangular grains stained 50 brownish-yellow, 80-90 percent; small 76. Sandstone, brown to buff, medium-grained, amount of chert and coaly matter pres­ arkosic. Largely concealed. ______10 ent. Small (Ys-y* in.) white pimply con­ 75. Sandstone, brown to buff, medium- cretionary structures on weathered sur­ grained, massive, with some false bed­ faces. _-_----_.______ding. Small pimply concretions on weathered surfaces. ___-_---___-_____ 14 88. Shale, clay, gray. Largely concealed on slope. Thin ledge of sandstone 24 ft Total Hunter Canyon formation __ 367 above base.______44 LOCAL SECTIONS 67

No. 18. Stratigraphic section from the top of the Mancos shale Z\To. 18. Stratigraphic section from the top of the Mancos shale to base of Green River formation near West Salt Creek, to base of Green River formation near West Salt Creek, Colo. Continued Colo. Continued Mount Garfield formation: Feet Mount Garfield formation Continued Feet 74. Shale in slope; largely concealed and prob­ 62. Sandstone, buff, medium- to fine-grained, ably interbedded with thin-bedded sand­ arkosic, massive, locally crossbedded. stone ____--__-______------___-.._-- 25 Shaly partings and thin-bedded sandy 73. Sandstone, buff, fine-grained, massive layers occur between heavier beds. A but thinly laminated; dark grains con­ 5-ft shale lens occurs near middle. spicuous .._-_-_-_____-----_--.____- 13 More iron oxide and fewer dark min­ 72. Shale, gray; interbedded with thin-bedded erals in bed below. Mud lumps (1-2 sandstone beds. Largely concealed on in.) near base. Changes laterally from slope _ __.._____-_____---_----._____ 8 very massive to thin-bedded sandstone. 46 71. Sandstone, buff, thin-bedded (1-2 in.), 61. Shale, carbonaceous, gray. Thin band fine-grained, arkosic, micaceous.______5 (3-4 in.) of coaly material occurs 1 ft 70. Sandstone, buff, medium-grained (0.2 in. 6 in. from base, and contains a 1-in. average diameter), massive, arkosic. layer of shaly sandstone. Seamed with Grains all well rounded. False bedding irregular secondary veins of gypsum___ 4%-7 marked by small pimply concretions on 60. Sandstone, buff, massive; dark minerals weathered surfaces. True beds 2 in. to concentrated in bunches______6 1 ft thick. Estimated composition: 59. Shale, gray, clay.______9). quartz, 70 percent; feldspar, 15 percent; 58. Sandstone, buff, arkosic, platy and thin- dark minerals, 15 percent; some mica; bedded___---_-----._----_--._____ 2 less iron oxide than in beds below, only 57. Sandstone, buff, arkosic, massive. Four a few ferruginous concretions present. _ 9 feet from base is 2-ft 3-in. zone of cal­ 69. Shale, clay, gray, containing thin lenses careous sandstone containing some car­ of sandstone. Largely concealed on bonaceous matter. ______10 slope.--__------_------_----- 51 56. Shale, clay, gray. Two sandstone layers 68. Sandstone, yellow-buff, medium- to fine­ (2-3 ft) occur at 10 and 20 ft above grained, arkosic, massive, soft, with base, and from 20-35 ft above base is a fluviatile crossbedding. Brown wea­ bed of gray carbonaceous clay shale__ 44 thered surfaces covered with small 55. Sandstone, gray-buff, medium-fine-grained pimply concretions_____--___-______- 12 arkosic, massive. Estimated composi­ 67. Shale, clay, containing thin lenses of sand­ tion: quartz, 50 percent; feldspar, 35 stone; slightly carbonaceous. Largely percent; dark minerals (hornblende?), concealed on slope_____--____.____- 100 15 percent_.____.______._..___ 5 66. Sandstone, buff, medium-grained (0.01 in. 54. Shale, gray, clay, slightly carbonaceous. in diameter), massive, arkosic, cross- Makes slope and weathers to gray- bedded; contains ferruginous concre­ brown soil______.______8 tions___.____-___----_------_---- 12 53. Sandstone, massive (beds 2-3 ft thick, 65. Shale, clay, purplish-gray; interbedded with thin clay partings), medium- with thin irregular buff sandstone beds; grained (0.01 in. in diameter), arkosic.. 10 often several layers finger together to 52. Shale, gray, clay______32 form a single massive bed; slightly 51. Sandstone, buff to brown, arkosic, mas­ carbonaceous. Generally concealed on sive (beds 3-6 ft); contains some clastic slope _____--_---__--_------______-- 46 mica. Grain slightly coarser than in 64. Sandstone, buff, very fine-grained (aver­ beds below, and rock is more ferrugi­ aging diameter 0.003-0.004 in.), mas­ nous, with nodules of iron carbonate sive. Basal bed is 15 ft thick; asym­ along bedding and base..___._.._____ 18 metric current and ripple markings; 50. Shale, gray, clay.______10 crossbedding, some much contorted, 49. Sandstone, buff to brown, medium-fine­ probably owing to subaqueous slump­ grained, arkosic, micaceous, ferrugi­ ing. Ferruginous concretions (1 in.) on nous, massive; some crossbedding..... 9J-. bedding surfaces. Estimated composi­ tion: quartz, 60 percent; weathered 48. Shale, gray, clay.______10 feldspar, 30 percent; dark minerals, 10 47. Sandstone, brown to buff, massive. Like percent..._-_-_-__----__-_-_____--_ 50 those above and below, only more 63. Shale, clay, gray, largely concealed on crossbedded ____-_-_____------_____ 13 slope.. ___.....__..______.._..- 20 46. Shale, gray, clay.______2 68 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 18. Strdtigraphic section from the top of the Mancos shale No. 18. Strdtigraphic section from the top of the Mancos shale to base of Green River formation near West Salt Creek, to base of Green River formation near West Salt Creek, Colo. Continued Co lo. Continued'

Mount Garfield formation Continued Feet Mount Garfield formation Continued Feet 45. Sandstone ; brown to buff on weathered sur­ 24. Shale, carbon aceous ______2 faces; light buff on fresh surfaces; 23. Shale, dark, sandy_---_-_- 10 medium fine grained; massive; contains 22. Sandstone, buff __.____-__ 5 carbonaceous matter and small carbo­ 21. Shale, carbonaceous __ __-. 15 nate nodules scattered indiscriminately; 20. Sandstone, buff ______2 crumpled crossbedding near top. Esti­ 19. Shale, drab______-__-_- 3 mated composition : quartz, stained with 18. Sandstone, buff ______7 limonite, 50 percent; weathered feldspar, 17. Shale, carbon aceous_____- 18 30 percent; hornblende, 20 percent. _ 13 16. Sandstone, buff __-_____-_ 7 44. Shale, gray, clay______7 15. Shale, drab__--_-_----__- 3 43. Sandstone, fine-grained, arkosic, thin- 14. Sandstone, buff ______10 bedded- ______4 13. Shale, carbonaceous ______2 42. Shale, gray, clay, slightly carbonaceous.- 10 12. Sandstone, buff ______25 41. Sandstone, light-brown, fine-grained, 11. Shale, carbonaceous. _____ 3 slightly ferruginous, arkosic, thin- 10. Sandstone, shaly______5 bedded; contains casts of plant stems 9. Shale, carbonaceous ______5 and mud balls. ______4% 8. Sandstone, buff ______10 40. Shale, clay, carbonaceous. ______3 7. Shale, drab.----.--.----- 15 39. Shale, chocolate-gray, clay; contains some 6. Sandstone, shaly ______10 carbonaceous matter______25 5. Palisade coal zone: 38. Sandstone, buff (with thin white streaks), fine-grained, arkosic; massive (with Shale, carbonaceous. . 2 some thin-bedded layers) . At the hori­ Sandstone, shaly. _._- 20 zon near Carbonera, Richardson collected Shale, carbonaceous. . 3 Unio sp., Vivipara sp., Goniobasis sp., Coal... ..___-_-__-._ and Tulotomops thompsoni... ______Shale, carbonaceous _ _ 37. Shale, clay, carbonaceous, locally sandy. Coal ______A 10-in. bed of ferruginous sandstone Shale, carbonaceous. _ occurs 12 ft above base------39% Sandstone, buff, shaly. 36. Sandstone, buff, fine-grained, arkosic, Shale, carbonaceous. _ thin-bedded (4-6 in.) ______5 35. Sandstone, buff, fine-grained, arkosic, Shale, carbonaceous massive (2 ft beds) ______--_-- 5 34. Shale, clay, ferruginous ______4% Total Mount Garfield formation._ 1, 047 33. Sandstone, buff, fine-grained, arkosic, massive (in 3 beds with thin shaly part­ Sego sandstone: ings) __ ___-_____---______-_____-- 15 Upper unit: 32. Sandstone, buff, somewhat clayey, medi­ 4. Sandstone, gray, white, thin-bedded, with um-grained, arkosic, thin-bedded- ___ 2 partings of sandy shale______10 31. Sandstone, buff, medium-grained, arkosic, 3. Sandstone, brown to buff, massive; some massive. ______8 crossbedding present. Small oval fer- 30. Shale, carbonaceous, platy and thin-bed­ fuginous concretions are conspicuous__ 55 ded; a few seams of bony coal and min­ 2. Anchor Mine tongue of Mancos shale: eral charcoal; less carbonaceous and Sandstone, brown to light-buff, thin- more sandy toward top______3% bedded (1-4 in.), irregularly bedded. Part­ 29. Carbonera coal group (Richardson's sec­ ings between sandstone beds are drab tion down to top of Sego sandstone) : shale. Films of carbonaceous matter con­ Coal ______3J_ spicuous; mud pellets plentiful. Shaly Shale, carbonaceous..-.------2 character so typical along front of cliffs Sandstone, buff ______10 is largely lost.______67 3% Lower unit: Shale, carbonaceous. _____-__-____- 3 Sandstone, buff ______8 1. Sandstone, massive, buff to brown______60 Coal and bone______2 28. Sandstone, buff, thin -bedded, and shale. 35 Total Sego sandstone and Anchor 27. Sandstone, buff ______5 Mine tongue______.__ 192 26. Sandstone, buff, thin-bedded, and shale. _ 20 25. Cameo coal horizon (?). Coal______2 Mancos shale. LOCAL SECTIONS 69

No. SO. Slratigraphic section from the base of the top of Mancos No. 20. Stratigraphic section from the base of the top of Man- shale to the Green River formation in canyon of Salt Wash, cos shale to the Green River formation in canyon of Salt Colo. Wash, Colo. Continued [Section begins In sees. 7 and 8, T. 7 S., R. 101 W., and extends to NE. corner sec. 12. Feet T. 8 8., R. 102 W. From Cameo coal downward, section was measured In sec. 30, Unnamed sandstone Continued T. 8 S., R. 101 W. From top of Mancos to top of sandy member of "Wasatch" 98. Sandstone, coarse-grained, conglom­ measurements by hand leveling; from base of "Wasatch" to base of Green River eratic; carries stringers and layers of formation measurements by aneroid barometer. Measured by C. E. Erdmannj chert pebbles. Some crossbedding of Tertiary torrential type; false laminae dip Green River formation: E. 10° ±__-_____--_--.___.... 20 Douglas Creek member: Feet 97. Conglomerate______117. Clay shale, greenish-gray______10+ 96. Conglomerate and conglomeratic sand­ 116. Limestone, gray-white, sandy; some stone; lower layer has matrix of layers thinly laminated, others cry­ coarse-grained gray sand, in which stalline; contains a few ostracodes___ 10 are embedded smooth, well-rounded "Wasatch" formation: pebbles of black, gray, yellow, and 115. Shale, clay, light-gray______55 reddish chert, not exceeding 2 in. in 114. Shale, clay, varigated red, dull, brick- diameter; also flattened pebbles of red and gray. Thickness of beds white limestone, lumps of gray and ranges from 5 to 30 ft.______380 dull green clay, lenses of coarse­ 113. Sandstone, gray-buff, soft and friable, grained brown sandstone; grades up­ like No. 106___--__--___-_-__--.-_ 18 ward into a sandstone whose chan­ 112. Clay, gray, washed over with dull red. _ 10 neled top carries lenses of brown 111. Limestone, gray, fresh-water; weathers conglomeratic sandstone.______brown. Coiled gastropops and Unio fragments common______1 Total unnamed sandstone. 156 110. Shale, clay, brick-red, dull______30 109. Shale, clay, drab-gray; some red._____ 30 Unconformity. 108. Shale, clay, brick-red, dull______30 Upper Cretaceous Mesaverde group 107. Shale, clay, drab-gray, washed over by Hunter Canyon formation: dull brick-red_--___-_-_---____-__- 40 95. Sandstone; weathered surface cream tan; fresh surface light gray, coarse grained Total "Wasatch" formation. ___ 594 (0.02 in.), massive, cliff-forming; con­ torted crossbedding; thin layer clay- Tertiary (?) ball conglomerate at top, some balls Unnamed sandstone: being 4 in. long, 2 in. thick. Esti­ 106. Sandstone, coarse-grained, thin-bedded; mated composition: quartz, 50 percent; pockets of clay-pellet conglomerate feldspar, 30 percent; dark minerals, totaling 3 ft in thickness, containing 30 percent______15 pebbles of limestone. Casts of Unio 94. Shale, gray-purplish; carbonaceous; top shells abundant.______6 channeled. ______1± 105. Sandstone, gray-buff; fresh surface tan; 93. Sandstone, buff, soft______5 soft and friable, medium grained; 92. Sandstone, gray, thinly bedded; some weathers into rounded forms; makes shale ______25 cliff. Estimated composition: quartz, 91. Sandstone, gray-drab, thinly bedded 65 percent; weathered feldspar, 20 (one-fourth of an inch), platy, shaly; percent; dark minerals, 15 percent.__ 15 grades up into sandy, platy gray shale, 104. Shale, clay, gray, dull, gray-green with with films of carbonaceous matter on a few purplish-gray bands; some dull bedding surfaces_____-__------____- 20 maroon clay__-______-______-_ % 25 90. Sandstone, gray, coarse-grained, soft__ 10 103. Shale, clay, purplish with red streaks. _ 2 89. Sandstone, gray-tan, soft, friable, mas­ 102jShale, clay, light-gray with greenish sive, cliff-forming; grain diameter aver­ tinge. _.______23 ages 0.01 in. Estimated composition: lOl.^Shale, clay, gray-green to field-gray; quartz, 75 percent; feldspar, 18-20 dull; contains a few thin layers of percent; dark minerals, 0-8 percent, platy sandstone_____--__-______35 usually gathered in clusters. Small 100. Sandstone, gray, coarse-grained; grades concretionary forms weather into relief on exposed faces, maximum diameter downward into bed below ______20 0.08 in.; distribution averages 60-75 99. Sandstone, gray-brown; contains pockets per square inch of surface; appear of conglomerate, with limestone peb­ white (light gray) on freshly broken bles more numerous than in beds surfaces, giving rock a mottled ap­ below; ferruginous concretions com- pearance, probably owing to local mon______6 cementation by silica.______18 608471 60 6 70 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO No. 20. Stratigraphic section from the base of the top of Man- No. 20. Stratigraphic section from the base of the top of Man- cos shale to the Green River formation in canyon of Salt cos shale to the Green River formation in canyon of Salt Wash, Colo. Continued Wash, Colo. Continued Hunter Canyon formation Continued Feet Hunter Canyon formation Continued Feet 88._Shale; weathered surface clayey; gray at 78. Slope, covered; probably thin-bedded top; dull green to olive-drab near sandstone and shale.______15 base______44 77. Sandstone, gray-buff, coarse-grained, 87. Coal, platy black lignite 6 in. thick, massive. ______10 underlain by 6-in. carbonaceous shale. 1 76. Sandstone, thin-bedded, platy, inter­ 86. Shale, clay, green to olive-drab, dull____ 25 calated with gray, shale; makes slope; 85. Sandstone, massive, cliff-forming; "as a mostly concealed.______whole gray buff with some buff and red 75. Sandstone, massive, cliff-forming; weath­ browns, fresh surfaces grayish; upper ered surfaces buff to reddish brown; few feet are thinly bedded (6-8 in.) fresh surfaces gray (salt-and-pepper); and irregular, contain pockets of crossbedding conspicuous, torrential . coarse-grained brown to greenish-drab type common; upper part weathers sand, which exhibit stem impressions, into mushroom forms. Some layers and rounded lumps of chocolate-brown thickly speckled with small spherical to black carbonaceous clay; remainder ferruginous concretions (Ys-% in.), is coarse grained (diameter averaging which may or may not conform with 0.02 in.); rock soft and friable; much bedding. Locally the partings between loose sand on outcrops. Estimated the layers are more coarsely grained composition: quartz, grains subangular and contain numerous flattened mud- and dull, 70 percent; feldspar, grains pellets whose maximum dimensions broken along cleavages, dull white to are 3 in. long, % in. thick; these partings tan, 20 percent; dark minerals (horn­ are very irregular; included beds blende?) irregularly distributed, some thicken and thin and sometimes pass cleavage fragments, 5-10 percent; a into a pocket filled with coarse sand few grains of a red jasper like material. and lumps of clay; carbonaceous matter Joint blocks on vertical cliff assume and plant stems common on bedding rounded forms on weathering. Ver­ surfaces. Across the gulch to the tical cliff on north wall of head of north, this sandstone is broken by a second west tributary to Salt Wash shale parting about 30 ft thick whose above Buniger ranch shows an erosional top is about 20 ft below top of this unconformity near middle of unit. 58 unit.______115 84. Shale, drab to dark-gray; contains some 74. Shale, gray, sandy______25 beds of thin sandstone and sandy 73. Sandstone, buff to yellow, medium- shale; weathers to slope with clayey grained, impure, arkosic, cliff-forming; surface______81 contains some mud pellets______83. Sandstone, weathered surface gray buff 72. Shale, gray, sandy______with some browns and reds; fresh 71. Sandstone, buff to yellow-brown, me­ surface brownish gray; medium to dium-grained, thinly laminated, soft coarse grained, soft and friable, arkosic. and friable, locally crossbedded, mas­ Lower 10 ft concealed; joint blocks in sive, cliff-forming; small concretions upper 35-ft cliff weather into rounded (by cementation) arranged parallel to forms; solution cavities also present_ 50 bedding; less massive at top______82. Shale, gray, with some soft thin-bedded 70. Shale, sandy, dull; color when fresh, lead sandstone; makes slope.______55 gray with slight brownish tone; weath­ 81. Sandstone, gray, arkosic, massive. Like ers into thin irregular flakes; bedding No. 80______56 very thin at top; locally contains thin 80. Shale, gray; makes slope; mostly covered, 20 lenses of sandstone.______55 79. Sandstone, gray, arkosic, massive; makes 69. Sandstone, buff to brown, massive, cliff- ledge, and weathers into rounded mush­ forming- ______21 room forms______20 68. Shale, sandy; ranges from light to dark [Note: In general the sandstone beds gray; in thin irregular beds breaking above and including bed No. 79 appear into thin-edged hackly pieces- ______30 67. Sandstone, buff to brown, soft and fri­ to be somewhat lighter in color than those able, massive, cliff-forming, weathering below. The difference seems to be due into rounded forms______chiefly to the lack of red browns, yellows, 66. Sandstone, gray, irregularly bedded, and their combinations form the weath­ platy; lenses out into buff sandstone ered surfaces.] along outcrop__.______LOCAL SECTIONS 71 No. 20. Btratigraphic section from the base of the top of Man- No. 20. Stratigraphic section from the base of the top of Man- oos shale to the Green River formation in canyon of Salt cos shale to the Green River formation in canyon of Salt Wash, Colo. Continued Wash, Colo. Continued

Hunter Canyon formation Continued Feet Mount Garfield formation: Feet 65. Sandstone, massive, cliff-forming; weath­ 60. Shale, clay, gray; thin-bedded clayey ered surface as a whole light yellow sandstone in lower 5 ft______27 brown, in detail shows many shades of 59. Sandstone, gray-buff, medium-grained, dark red brown, orange, and yellow; arkosic; thinner bedded at top; makes medium to coarse grained; thick massive ledge______10 bedded; thinly laminated; many irregu­ 58. Shale, clay, gray______15 larities in bedding. Large oval con­ 57. Sandstone, brown, massive.______2 cretionary masses of fine- to medium- 56. Shale, clay, gray.______10 grained hard and dense gray sand­ 55. Sandstone, in thin beds (1 in to 1 ft); the stone in pockets on bedding surfaces; hard massive layers are separated by larger ones may be 8 ft long and 3 ft the softer-______11 thick; weathers dark brown. A few 54. Calcareous concretionary layer, gray to lenses of soft gray sand fill shallow buff, hard, dense, with conchoidal channels on bedding surfaces.______52 fractures.______1 64. Sandstone and sandy clay with lumpy 53. Shale, clay, gray.______1 forms; dull; bluish gray with greenish 52. Sandstone, light-brown, medium-grained, cast; some lead gray; in irregular and arkosic; a massive thinly laminated alternating beds; sandstone breaks ledge; some false bedding; current with hackly fracture.______10-15 marks.______3>_ 63. Sandstone, massive, cliff-forming, coarse­ 51. Shale, clay, gray.______44}£ grained; pinkish buff at base on weath­ 50. Shale, clay, gray; contains thin lenses of ered surfaces; some orange and yellow; brownish sandstone that show current irregular, thinly laminated false bed­ markings on bedding surfaces. Nearby ding. Ferruginous concretions (by a 5-ft lens of thin-bedded sandstone cementation) up to 1^ in. diameter on caps this unit-_-_____-_-_--____--_- 40 bedding surfaces. Small pimply con­ 49. Sandstone, brownish-buff, medium- cretionary forms on weathered sur­ grained, thin-bedded______2 faces___-_____--______--.- 21 48. Shale, clay, gray______25 62. Shale, sandy, clayey; weathered surfaces 47. Sandstone, buff, medium-grained (maxi­ dull, lead gray and greenish gray; mum diameter 0.01± in.), massive, weathers into rounded, lumpy forms; impure, arkosic, soft; thickness of beds locally contains thin lenses of sandstone ranges from 6 in. to 6 ft; weathers into and calcareous, concretionary mate­ rounded forms, and makes broken rial... ______...____----.__ 7 cliff; estimated composition: quartz, 61. Sandstone, massive, cliff-forming; weath­ 75 percent; feldspar, 20 percent; others, ered surfaces gray buff to brownish red; 5 percent__-______-__-__---- 33 top noticeably gray; some yellow tones 46. Shale, clay, gray______-______-___- 20 at base; fresh surfaces gray (salt-and- 45. Sandstone, buff, thin and platy; grades pepper); bedding heavy at base, less rapidly into massive ledge______7 so toward top; individual beds thinly 44. Shale, clay, gray______15 laminated, weathering into rounded 43. Sandstone, light-brown, medium-grained, forms; fluviatile crossbedding; pockety arkosic, crossbedded______2% structures; coarse subangular grains, 42. Shale, clay, gray, with a few thin sand­ averaging 0.02 in. in diameter. Esti­ stone lenses in lower half.______55 mated composition: quartz, 80 per­ 41. Sandstone, gray, medium-grained, very cent; feldspar, 12 percent; dark min­ thin-bedded (one-fourth of an inch), erals, 8 percent. Flattened mud pel­ platy and irregular.______1% lets up to three-fourths of an inch in 40. Calcareous concretionary layer, gray to diameter. Small pimply concretionary buff, hard and dense with conchoidal forms on some weathered surfaces. In f racture______% places along base, is 6-in. layer grading 39. Shale, clay, carbonaceous, dark gray____ 2 up into coarse-grained brown sand­ 38. Sandstone, light-brown, fine- to medium- stone, containing numerous mud lumps and irregularly shaped hard grained, massive, thinly laminated; limonitic concretions______18 contains clastic mica; some carbona­ ceous material on bedding surfaces; Total Hunter Canyon formation. 1, 012 current marks-__--__-___-__--____- 2% 37. Shale, clay.______6H 72 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 20. Stratigraphic section from the base of the top of Man- No. 20. Stratigraphic section from the base of the top .of Man- cos shale to the Green River formation in canyon of Salt cos shale to the Green River formation in canyon of Salt Wash, Colo. Continued Wash, Colo. Continued Mount Garfield formation Continued Feet Mount Garfield formation Continued Feet 36. Shale, clay, gray; near middle of bed that below, much of it sandy, or con­ there is layer of coaly, chocolate-brown taining thin lenses of sandstone. carbonaceous clay shale containing Massive sandstone at base______300 some woody and vegetable material; 18. Palisade coal zone: local burning at this horizon extends Shale, highly carbonaceous, black and into the heavier burned area to the east. 15 chocolate, with a few thin sandstone 35. Sandstone, gray, medium-grained, cross- partings------_____ 6% bedded.. ______Shale, with sandstone nodules_. _ _ _ _ 1% 34. Shale, clay, gray, slightly sandy, locally Shale, clay, gray; sandy at top______4% carbonaceous; weathers into angular Sandstone---_--_-_-__-______._____ % granules and making slope ______48 Shale, carbonaceous, chocolate; con­ 33. Sandstone, massive, cliff-making; tains seams of charcoal-_-_____._ 4% weathers buff; fresh color gray (salt- Shale, clay, light-gray_____..__.___ \% and-pepper) with slight brownish tone; Sandstone, shaly.______V/3 medium grained (average diameter Shale, gray, with sandstone nodules at 0.01 in.) ; thinly laminated, with fluvia- top______5y2 tile crossbedding. Upper 5 ft thin Bone...______-. % bedded (8 in.). Estimated composi­ Coal___ _--__---.---______IJ/g tion: quartz, 20 percent; light-gray Clay, white______% weathered feldspar, 52 percent; weath­ Coal.______.. iy6 ered brown grains, probably feldspar, Shale, carbonaceous, chocolate_._____ 1 20 percent; dark minerals, 8 percent. Sandstone, gray______%-% Small mud lumps rare. ______15 Shale, carbonaceous, chocolate______3% 32. Shale, clay, dark-gray; weathers pur­ plish gray; carbonaceous, somewhat Total Mount Garfield formation- 1, 002 sandy; contains a few thin, platy, brown sandstone beds near middle. ___ 25% Sego sandstone: 31. Sandstone, brown, slightly burned, thin- Upper sandstone member: bedded; contains mud lumps. A few 17. Sandstone, brown, medium-grained, thin- hundred feet to the east the burning bedded. Makes cliff______20 extends upward about 75 ft ______5 Anchor Mine tongue of Mancos shale: 30. Sandstone beds, burned dull brick red _ 2 16. Shale, chocolate, highly carbonaceous___ % 29. Shale, clay, gray, with layer of platy 15. Shale, light-chocolate, carbonaceous.___ 5 brown sandstone at middle ______20 14. Sandstone, light-gray______-__-______1 28. Clinker of burned sandstone and shale__ 145 13. Shale, chocolate, carbonaceous.______5% 27. Sandstone, bluish-gray to red, partly 12. Concretionary layer, calcareous and fer­ burned, fine-grained, dense, clayey; ruginous ______1 grades upward into clinker-covered 11. Shale, carbonaceous, chocolate color____ 11 slope. Top taken at approximate base 10- Sandstone lens, gray, massive-______3%-10 of upper bench. Cameo coal, now 9. Shale, gray to brown, carbonaceous, burned out______10 mineral charcoal. ______2% 26. Lower bench of Cameo coal bed, partly 8. Clay, with sandstone nodules at top____ 3 burned, very sooty, with hard bony 7. Anchor coal: Bone.____------_------______25. Sandstone and shale in thin, platy, 2/2 irregular alternating layers ____--__-_ Shale, carbonaceous, chocolate color. _ 24. Shale, sandy, light-ash-gray, platy...--- Bone. -___------__ ------% 23. Sandstone, brown, thin and platy______22. Shale, carbonaceous, gray, platy _ ___-._ 6. Shale, carbonaceous, chocolate; weathers 21. Shale, carbonaceous, black, platy______- gray. Hard and dense, highly jointed. 20. Sandstone, gray-white, quartzose, slightly Grades laterally into sandy layer_____ 5 carbonaceous, usually massive, but may 5. Shale, highly carbonaceous, laminated, have gray shale parting near mid die __ 20 chocolate ; plant remains ______1 19. Sandstone and shale in alternating beds; 4. Shale, carbonaceous; seams of mineral sandstone usually light gray (salt-and- charcoal-. ______-_____--__---_____ pepper) to buff, medium grained; shale 3. Shale, carbonaceous, light-chocolate; clayey, frequently carbonaceous, like weathers gray_--______---_-__.____ LOCAL SECTIONS 73 No. 20. Stratigraphic section from the base of the top of Man- No. 21. Type section of Hunter Canyon formation in Hunter 008 shale to the Oreen River formation in canyon of Salt Canyon, in sees. 20, 29, and 32, T. 8 S., R. 100 W. Colorado Wash, Oolo. Continued Continued Sego sandstone Continued Feet Cretaceous Continued Feet Lower sandstone member: Hunter Canyon formation Continued 2. Sandstone, light-gray, fine-grained; mas­ bedding well developed. Lower 10 ft sive beds with thin shaly partings.___ 25 composed of medium-grained gray-buff 1. Sandstone, light-gray, thin irregular beds. 15 quartz-feldspar sand with an admixture of ferruginous minerals; characterized Total Sego sandstone and Anchor by small mud pellets, and also contains Mine tongue------113 many small spherical ferruginous con­ cretions, whose maximum diameter is Man cos shale. about 2 in. Near top are lenses or channels of varying shapes filled with No. 21. Type section of Hunter Canyon formation in Huntet a coarser grayer sand.______40 Canyon, in sees. 20, 29, and S2, T. 8 S., R. 100 W., Colorado 17. Shale, sandy, lead-gray, with layer of [Measured by O. E. Erdmann] black carbonaceous shale containing Tertiary (?): fragments of mineral charcoal on top__ 6 Unnamed sandstone. 16. Sandstone, thin-bedded, gray. These beds Unconformity. strike N. 45° W. and dip 5° NE., beds Cretaceous: immediately below strike N. 75° W. Hunter Canyon formation: peet and dip 3° N. This discordance is 28. Shale, gray, sandy, soft, containing thin probably local and due to large scale beds (1-2 ft) of sandstone, which be­ crossbedding______3 come thicker toward base.__.---_--__ 143 15. Sandstone, gray to buff, massive, composed 27. Sandstone, massive, medium-grained, gray 10+ of impure quartz-feldspar sand. Some 26. Shale, gray, sandy, platy, but irregularly clastic mica over 0.02 in. in diameter. bedded, slightly calcareous. Bedding At base average size grain is about 0.01 surfaces show current markings. Con­ in. Bedding uniform in general, though tains thin lenticular beds of sand, which there is local crossbedding. Basal part have same general character.______28 contains large irregular fragments of 25. Sandstone, gray-white, medium-grained, poorly laminated sandy shale.______34 massive. Bedding fairly uniform, but 14. Shale, sandy, gray; carbonaceous at top. locally is cut by thin lenses of a more Lenses out rapidly-______-_-___-_ 2 brownish sandstone_.__------__ 26 13. Sandstone, thin-bedded, and sandy shale, < 24. Sandstone (similar to bed next above) and intercalated. The rapid interchange lead-gray shale containing thinner lenses of sandstone and shale is characteristic. of sandstone, in alternating beds which Toward the base the beds of sandstone vary in thickness from 25 to 40 ft. Just . become thinner and more regular._____ 93 below highest sandstone bed, shale is 12. Sandstone, light gray, massive, cliff-form­ dull and greenish-gray and contains a ing, impure, feldspathic. Near middle thin layer of chocolate-brown to black is thin layer of finely laminated dark- carbonaceous shale and about 4 in. of brown carbonaceous sandstone, with coal_.______--__._-_-____---_--_-- 144 thin lenses of normal sandstone. Base 23. Sandstone, gray (salt-and-pepper), me­ is intricately crossbedded_.__.____-_ 17 dium-grained, cliff-forming, massive. ._ 46 11. Shale, lead-gray, thin, platy, carbonaceous. 22. Shale, clay, gray.______-_---_--_-____ 10 Contains woody remains and thin lenses 21. Sandstone, gray (salt-and-pepper), coarse­ of sandstone. Passes downward into grained______15 thin-bedded sandstone_____-______9-11 20. Shale, clay, gray. Contains thin beds 10. Shale, clay, gray__.______15 (1-3 ft.) of coarse-grained gray sand­ stone. About 120 ft. above base is a 9. Sandstone, gray, coarse-grained, crossbed­ massive cliff-forming bed of medium- ded, thin-bedded 11 in. at top. Shows grained gray (salt-and-pepper) sand­ a few thin limy layers______15 stone, 20-25 ft thick, which lenses out 8. Shale, sandy, gray; contains many small rapidly. Just below the sandstone bed irregular channels filled with a medium shale is somewhat carbonaceous, but impure feldspathic sand, which is seamed most is typically gray____-___----____ 235 with thin films of carbonaceous mate­ 19. Sandstone in thin beds (maximum 2 ft) rial. ______15 interbedded with thin, platy sandy 7. Sandstone, buff, coarse-grained, massive, shale__ _ 30 cliff-forming. Contains thin layers of 18. Sandstone, massive. Upper 30 ft lighter gray-green and crimson shale. Weath­ in color and slightly coarser-grained ers into rounded forms, smooth pedes­ than lower part, thinly laminated; cross- tals, and turrets______30 74 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 21. Type section of Hunter Canyon formation in Hunter No. 22. Stratigraphic section from top of Mancos shale up­ Canyon, in sees. 20, 29, and 32, T. 8 S., R. 100 W. Colorado ward to crest of Book Cliffs at Book Cliff mine, SWty sec. 8, Continued T. 10 S., R. 99 W., Colorado Continued Cretaceous Continued Feei Upper Cretaceous Continued Feet Hunter Canyon formation Continued Hunter Canyon formation Continued 6. Shale, sandy, gray to gray-black. Nodu­ 59. Alternating series of sandstone and shale; lar structure. Contains ferruginous sandstone making up about 70 percent concretions.______30 of unit. Sandstone massive, cliff form­ 5. Sandstone, coarse-grained, gray with rusty ing, becoming more so toward top where specks; weathers brownish black. Beds sandstone is 40 feet thick; buff on 12-16 in. thick, each uniformly cross- weathered surfaces; light gray (salt- bedded, tangential type, dipping north _ 30 and-pepper) on fresh surfaces, medium 4. Shale, grayish to black; contains numerous grained, feldspathic; some thin layers thin irregular and lenticular layers of of reddish carbonaceous sandstone and medium-grained grayish sandstone. shaly sandstone with white or greenish Some are finer grained, dense, calcar­ spots. Gray clay shale more abundant eous- ______35 at base where sandstone is thinner 3. Sandstone, gray, medium- to coarse­ bedded. All beds are lenticular and grained, specked with black and brown; vary considerably in thickness along weathered surfaces black to brown. strike.______._.______----_--- 437 Contains thin layers and lenses of green­ ish-gray sandy shale.______25 Total Hunter Canyon formation, 2. Shale, gray to greenish-gray; contains thin part measured.----.__------600 lenticular gray sandstone which weath­ ers brown. Just above base, 6-8 ft of Mount Garfield formation: greenish-gray shale is parted by a thin 58. Non-coal-bearing rocks ("barren meas­ lens of crimson clay shale ______40 ures"): An alternating series. Sandstone, 1. Sandstone, gray to buff, medium-grained; sandy shale, and clay shale, with 2 thin in massive lenticular beds 30-50 ft thick, layers of brown carbonaceous shale near separated by partings of gray to gray- the middle and 1 near the top. Five green sandy shale 2-6 ft thick. Some principal beds of sandstone form massive of these shale beds contain plant re­ ledges. They are about equally spaced, mains. Crossbedding is .rare in basal and lowest is at the base of the unit. part but common in upper third, where Relatively thin-bedded in detail, layers beds are less massive and are most intri­ being separated by thinner softer beds cately interbedded with the shale in or by shaly partings. Some cross- channels, lenses, and pockets. In many bedding. Weathered surfaces reddish parts, isolated lumps of shaly material brown and have many solution pockets. appear to be enclosed in sandstone. Fresh surfaces gray to buff. Medium- Lateral irregularity of beds very marked. grained throughout; grains are chiefly Weathered surfaces of crossbedded quartz, but some weathered feldspar and parts are alveolated. Base of strata of some ferromagnesian minerals are pres­ probably post-Laramie age is placed ent. A few layers of arkosic sand at base of this sandstone______300 present. Shale beds predominantly ; gray and contain varying amounts of Total Hunter Canyon formation. 1, 427 sand and carbonaceous material, but only three beds contain much carbo­ Mount Garfield formation: naceous material. Many shale beds have a sharply defined base where they No. 22. Stratigraphic section from top of Mancos shale upward to rest upon sandstone but grade upward crest of Book Cliffs at Book Cliff mine, SW% sec. 8, T. 10 S., into overlying sandstone.____-----__- 410 R. 99 W., Colorado. 57. Coal-bearing rocks ("coal measures"): Shale, purplish-gray carbonaceous _._ &/ [Upper 1,000 ft measured by aneroid barometer; lower beds measured by hand Sandstone, sandy shale, and gray shale. _ 12 leveling. Measured by C. E. Erdmann] Shale, carbonaceous, with thin seam of Upper Cretaceous Mesaverde group: bony coal 4 in. below top.------28 Hunter Canyon formation (part): Sandstone, medium-grained, massive, 60. Sandstones, light-gray to buff, thick- ledge-forming. Weathered surface buff; bedded, massive, cliff-forming; lenticu­ fresh surface gray. Small spherical lar, pinching and swelling along out­ ferruginous concretions. Some carbo­ crop; make up 85 percent of unit; in­ naceous material. Crossbedding, in tercalated light-gray shale constitutes beds 2-4 ft thick, separated by thinner remaining 15 percent__---_-______163 layers ______-----_-----.----- 15 LOCAL SECTIONS 75 No. 22. Stratigraphic section from top of Mancos shale up­ No. 22. StratigrapMc section from top of Mancos shale up­ ward to crest of Book Cliffs at Book Cliff mine, SWy^ sec. 8, ward, to crest of Book Cliffs at Book Cliff mine, SW% sec. 8, T. 10 8., R. 99 W., Colorado Continued T. 10 8., R. 99 W., Colorado Continued

Upper Cretaceous Continued Feet Rollins sandstone member Continued Feet Mount Garfield formation Continued brown, locally stained red or purplish by 56. Shale, clay, gray_____. ______wash from Cameo clinker. Coarse 55. Shale, carbonaceous, with some bony coal. grained and sugary in texture; 80-90 54. Shale, gray. Limy concretions at base, percent quartz and 10-20 percent dark and large channel sandstone lenses to­ minerals. Bedding thickest toward top. ward top.______.___ \\y-i Crossbedding present throughout. 53. Shale, carbonaceous, with bony coal in Locally, at both top and bottom, are middle..-.------_ _. ______7}_ thin bands and lenses of purplish- 52. Sandstone, light-gray, fine-grained; mas­ brown carbonaceous shale containing sive at base; thinner bedded and softer fragments of carbonized wood and mud at top. _._..______--_---.-- 9>£ pellets. Upper part may also contain 51. Shale, carbonaceous--__.____-___---___ 6% semispherical concretions of white sand­ 50. Coal, bony,. ______iy2 stone 10-30 inches in diameter. As­ 49. Shale, carbonaceous. _____-_-_____--___ H sociated with them are numerous casts 48. Sandstone, buff, thin-bedded, medium- of Halymenites major...... 71 grained, soft. Grades up into light-gray 26. Slope, strata concealed. Probably shale or sandy shale _ --_.______--___ 12 soft thin-bedded sandstone ______--- 14 47. Shale, brown, carbonaceous.-... ------25. Sandstone, medium-grained, crossbedded, 46. Coal, bony, ______massive, thin-bedded near base. ______10)4 45. Shale, brown, carbonaceous.--.------.-- 24. Shale, gray, interbedded with soft thin- 44. CoaL. --.___._____.._....____----___- bedded sandstone.______44 43. Shale, brown, carbonaceous______---_-- % 23. Sandstone, light-reddish-brown, thin-bed­ 42. Coal, bony,. _ ._ _ _.______1>_ ded, flaggy. Plant remains______.-- 3 41. Shale, carbonaceous, purplish- and choco­ 22. Shale, gray, carbonaceous. Some thin- late-brown. Contains some gray shale bedded brown sandstone near base. _ - - 30 and thin lenses of sandstone. ______21. Coal, subbituminous_-_-_.______--- 1 40. Concretionary layer, calcareous; red brown 20. Sandstone, grading up into purplish-gray on weathered surface; bluish gray on carbonaceous sandstone.-.-----..---- 2% fresh surface. Hard, dense, conchoidal 19. Shale, purplish gray, carbonaceous. fracture. Rests unevenly on shale sur­ Grades into bed above.___..______--- 8>_ face below ______2-3 18. Sandstone, micaceous. Grades upward 39. Shale, clay, gray.. ____.__-____-_-_-__- 13 into thin-bedded purplish-gray sandy 38. Sandstone, medium-grained, massive; red­ carbonaceous shale._-______--- 3% dish brown on weathered surface; lighter 17. Sandstone; upper part cream colored; on fresh surface. Contact with under­ lower part buff; gray-white on fresh lying shale uneven ______4 surfaces. Thin bedded, somewhat ir­ 37. Shale, purplish-brown, carbonaceous. regular. Crossbedding in upper part, Sandy lenses at top__-____-__-_---__- 14 which is separated from lower part by 36. Sandstone, brown, medium-grained; in false bedding surface. Medium-grained, thin irregular beds; crossbedded on sugary texture. Solution pits, rounded small scale. __------_------forms on weathered surface...______33 Cameo coal zone: 16. Sandstone, purplish-brown, dull, carbo­ 35. Coal, bony, with a few thin layers of car­ naceous, in thin, irregular, gnarly beds, bonaceous shale.. ______-_-_--__---. with some calcareous concretions near 34. Shale, carbonaceous, with carbonaceous base. Thin lenses and stringers of gray sandstone at top_ __.______---__._ crossbedded sandstone appear near top, 33. Coal, bony, with few thin seams of good and finally lenses of channel sandstones coal. ______predominate. Lenses are Yz in. to 3 ft 32. Shale, carbonaceous. __.______-----_.-. 8 thick, width in proportion ______29 31. Coal, bony. ______3% 15. Sandstone, medium-grained massive, ar- 30. Shale, dark-brown to black, carbonaceous. 1/4 kosic, cliff-making; buff to tan on weath­ 29. Coal, bony _ _. ______.__._._ 4% ered surfaces, which have a corroded 28. Shale, purplish-gray, carbon aceous...... appearance. Evenly bedded, but a Rollins sandstone member: crossbedded layer appears 14 ft above 27. Sandstone, massive, cliff-forming. Fresh base. Numerous irregular ferruginous surfaces grayish white to white; weath­ concretions at top. Grades into over­ ered surfaces light yellow gray and lying bed---_____-______-_-__-___--_ 33 76 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

No. 22. Stratiffraphic section from top of Mancos shale up­ Baker, A. A., 1946, Geology of the Green River Desert-Cataract ward to crest of Book Cliffs at Book Cliff mine, SW/^ sec. 8, Canyon region, Emery, Wayne, and Garfield Counties, T. 10 8., R. 99 W., Colorado Continued Utah: U.S. Geol. Survey Bull. 951 [1947]. Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., 1936, Cor­ Rollins sandstone member Continued Feet relation of the Jurassic formations of parts of Utah, 14. Sandstone, gray on fresh surfaces, in beds Arizona, New Mexico, and Colorado: U.S. Geol. Survey ranging from 10 in. to 5 ft in thickness, Prof. Paper 183, 66 p. with shaly parting 5± in. thick. Much Beckwith, E. G., 1855, Report of explorations for the Pacific of shale is carbonaceous. Sandstone Railroad on the line of the forty-first parallel of north laminae may be a quarter of an inch latitude: U.S. Pacific R. R. Expl., 33d Cong., 2d sess., thick or more; shale laminae much Senate Doc. 78, pt. 2, p. 1-66. thinner. All layers swell and pinch Brown, R. W., 1950, Cretaceous plants from southwestern along outcrop. Topmost bed consists Colorado: U.S. Geol. Survey Prof. Paper 221-D, p. 45-66. of intertongued sandstone and shale, Campbell, M. R., 1922, Guidebook of the , locally channeled and filled by sands of Part E, The Denver and Rio Grande Western Route: overlying bed--__--__--___-----__--- 34 U.S. Geol. Survey Bull. 707, 266 p. 13. Shale, sandy; grades into bed above. ____ 9 12. Shale, carbonaceous, purplish. Con­ Carter, W. D., 1956, The Burro Canyon-Dakota contact in the tains sandy lenses, which become Mt. Peale no. 1 quadrangle, western Colorado and eastern thicker and more numerous near top__- 16 Utah: Intermountain Assoc. Petroleum Geologists, 7th Palisade coal zone: ' Ann. Field Conf. Guidebook, p. 113-115, 1 fig. 11. Coal, subbituminous------2}4 Cater, F. W., Jr., 1955, Gateway, Colorado: U.S. Geol. Survey 10. Shale, chocolate-brown, carbonaceous..-- 4 Quad. Map GQ55. 9. Coal--.------.---- 1% Clark, F. R., 1914, Coal near Thompson, Grand County, Utah: 8. Shale, gray. Limy lens near bottom___. 14 U.S. Geol. Survey Bull. 541-J, p. 453^77. 7. Sandstone, gray, weathering tan, medium- 1928, Economic geology of the Castlegate, Wellington, grained, soft, friable, crossbedded; thin; and Sunnyside quadrangles, Carbon County, Utah: U.S. irregularly bedded with shale, becom­ Geol. Survey Bull. 793, 165 p. ing more massive toward top ______13 Cobban, W. A., and Reeside, J. B., Jr., 1952, Correlation of the 6. Shale, light-gray, flaky______3^ : Cretaceous formations of the western interior of the 5. Coal, subbituminous-___-_------__-_- 1}6 : United States: Geol. Soc. America Bull., v. 63, no. 10, 4. Shale, yellow-brown, sandy, carbonaceous, p. 1011-1044. platy. Plant remains. Locally nodu­ Cross, Whitman, 1899a, Telluride quadrangle, Colo.: U.S. lar. Becomes less sandy and more car­ Geol. Survey Geol. Atlas, Folio 57. bonaceous toward top______22 1899b, La Plata quadrangle, Colo.: U.S. Geol. Survey 3. Coal, subbituminous------J^ Geol. Atlas, Folio 60. 2. Shale, dark-brown to black, carbonaceous. Dane, C. H., 1935, Geology of the Salt Valley anticline and Contains carbonized vegetal remains, adjacent areas, Grand County, Utah: U. S. Geol. Survey resin, peppered with many small white Bull. 863, 184 p. [1936]. grains of quartz sand._____-_---.____ % Dane, C. H., Pierce, W. G., and Reeside, J. B., Jr., 1937, The stratigraphy of the Upper Cretaceous rocks north of the Total Mount Garfield formation __ 1,053 Arkansas River in eastern Colorado: U.S. Geol. Survey Prof. Paper 186-K, p. 207-232. Sego sandstone: .Dutton, C. E., 1880, Report on the geology of the high plateaus 1. Sandstone, massive in general appearance, of Utah: U. S. Geog. and Geol. Survey Rocky Mtn. Region but thin-bedded on closer examination; Rept. some crossbedding developed on mod­ Eldridge, G. H., 1901, The and bituminous rock de­ erate scale; whitish gray with a buff posits of the United States: U. S. Geol. Survey 22d Ann. tone, medium grained, of sugary texture, Rept., pt. 1, p. 209-452. soft, friable. Largely quartz ; gray tone Emery, W. B., 1918, The Green River Desert section, Utah: given by ferromagnesian minerals; some Am. Jour. Sci., 4th ser., v. 46, p. 551-577. Emmons, S. F., 1894, Guidebook for the geological excursion red jaspery grains. Upper half cor­ of the International Geological Congress (1891) to the roded into small holes and niches. A ; Rocky Mountains: Wiley and Sons. few small ferruginous concretions near Erdmann, C. E., 1934, The Book Cliffs coal field in Garfield and 31 Mesa Counties, Colo.: U.S. Geol. Survey Bull. 851, 150 p. [1935]. Mancos shale. .Fenneman, N. M., and Gale, H. 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H., 1877, Geological report on the San Juan dis­ 1877, Report on the geographical and geological survey trict: U.S. Geol. and Geog. Survey Terr., 9th Ann. Rept. of the Rocky Mountain region. for 1875, pi. 35. 1879, Report on the lands of the arid region of the Johnson, V. H., 1948, Geology of the Paonia coal field, Delta United States, with a more detailed account of the lands and Gunnison Counties, Colo.: U.S. Geol. Survey Coal Inv., of Utah: 45th Gong., 2d sess., H. Doc. 73, 2d. ed. unnumbered map. Reeside, J. B., Jr., 1923, Notes on the geology of Green River 1956, Cross-section of Upper Cretaceous rocks showing Valley between Green River, Wyo., and Green River, relationship of coal deposits to stratigraphic units and Utah: U.S. Geol. Survey Prof. Paper 132-C, p. 35-50. correlation between southern Castle Valley and west- 1924, Upper Cretaceous and Tertiary formations of the central Colorado: Intermountain Assoc. Petroleum Geolo­ western part of the San Juan Basin, Colo. and N. Mex.: gists, 7th Ann. Field Conf. Guidebook, p. 124, 1 pi. U.S. Geol. Survey Prof. Paper 134, 117 p. Katich, P. J., 1951, Recent evidence for Lower Cretaceous de­ 1927, An AcantJwceras rhotomagense fauna in the Cre­ posits in Colorado Plateau: Am. Assoc. Petroleum Geolo­ taceous of the western interior: Washington Acad. Sci. gists Bull., v. 35, p. 2093-2094. Jour., v. 17, p. 453-454. 78 CRETACEOUS AND TERTIARY FORMATIONS, UTAH AND COLORADO

Reeside, J. B., Jr., 1957* Nonmarine pelecypod (Nippononaia Spieker, E. M., and Reeside, J. B., Jr., 1925, Cretaceous and asinaria) from Lower Cretaceous of Colorado: Jour. Paleon­ Tertiary formations of the Wasatch Plateau, Utah: Geol. tology, v. 81, no. 3, 651-653, 1 fig. Soc. America Bull., v. 36, no. 3, p. 435^54. Richardson, G. B., 1907, The Book Cliffs coal field between 1926, Upper Cretaceous shoreline in Utah: Idem, v. 37, Grand River, Colo., and Sunnyside, Utah: U.S. Geol. Sur­ no. 3, p. 429-438. vey Bull. 316, p. 302-320. Stokes, W. L., 1944, Morrison formation and related deposits in 1909, Reconnaissance of the Book Cliffs coal field, be­ and adjacent to the Colorado Plateau: Geol. Soc. America tween Grand River, Colo., and Sunnyside, Utah: U.S. Bull., v. 55, p. 951-992. Geol. Survey Bull. 371, 54 p., 10 pis. 1952, Lower Cretaceous in Colorado Plateau: Am. Assoc. Sanborn, A. F., Hill, J. D., and Arnold, D. E., 1956, Correlation chart east central Utah: Intermountain Assoc. Petroleum Petroleum Geologists Bull., v. 36, p. 1766-1776. Geologists, 7th Ann. Field Con. Guidebook, p. 12. Stokes, W. L., Peterson, J. A., and Picard, M. D., 1955, Correla­ Schiel, James, 1855, Geological report on the country explored tion of Mesozoic formations of Utah: Am. Assoc. Petroleum under the 38th and 41st parallels of north latitude in Geologists Bull., v. 39, p. 2003-2019, 4 figs. 1853-1854: U.S. Pacific R. R. Expl., 33d Cong., 2d Sess., Stokes, W. L., and Phoenix, D. A., 1948, Geology of the Egnar- S. Doc. 78, pt. 2, p. 96-107. Gypsum Valley area, San Miguel and Montrose Counties, Schoff, S. L., 1951, Geology of the Cedar Hills, Utah: Geol. .Colorado: U.S. Geol. Survey Oil and Gas Inv. Prelim. Soc. America Bull., v. 62, p. 619-646. 'Map 93. Sears, J. D., 1925, Geology and oil and gas prospects of part of Stose, G. W., 1932, Geologic map of the United States: U.S. Moffat County, Colo., and southern Sweetwater County, Geol. Survey. Wyo.: U.S. Geol. Survey Bull. 751-G, p. 269-319. Swain, F. M., 1956, Early Tertiary ostracode zones of Uinta 1936, Geology and fuel resources of the southern part Basin: Intermountain Assoc. Petroleum Geologists, 7th of the San Juan Basin, New Mexico, part 1, the coal field from Gallup eastward toward Mount Taylor, with a Ann. Field Conf. Guidebook, p. 125-139, 1 fig., 3 pis, measured section of pre-Dakota (?) rocks near Navajo Taff, J. A., 1906, Book Cliffs coal field, Utah, west of Green Church: U.S. Geol. Survey Bull. 860-A, p. 1-17. River: U.S. Geol. Survey Bull. 285-F, p. 289-302. Sears, J. D., Hunt, C. B., and Hendricks, T. A., 1941, Trans- Tester, A. C., 1952, Additional facts concerning the age and gressive and regressive Cretaceous deposits in southern origin of the type section of the Dakota stage [abs]: Geol. San Juan Basin, N. Mex.: U.S. Geol. Survey Prof. Paper Soc. America Bull., v. 63, p. 1386. 193-F, p. 110-121. Winchester, D. E., 1923, Oil shale of the Rocky Mountain Spieker, E. M., 1931, The Wasatch Plateau coal field, Utah: region: U.S. Geol. Survey Bull. 729, 240 p. U.S. Geol. Survey Bull. 819, 210 p., 33 pis. Woodruff, E. G., 1912, The coal resources of Gunnison Valley, 1946, Late Mesozoic and Early Cenozoic history of cen­ Mesa and Delta Counties, Colo.: U.S. Geol. Survey Bull. tral Utah: U. S. Geol. Survey Prof. Paper 205-D., p. 471-H, p. 565-573. 117-161, pis. 18-25, 8 figs. Yen, Teng-Chien, 1954, Nonmarine mollusks of Late Cretaceous 1949, Sedimentary facies and associated diastrophism in the Upper Cretaceous of central and eastern Utah: Geol. age from Wyoming, Utah, and Colorado: U.S. Geol. Sur­ Soc. America Mem. 39, p. 55-81. vey Prof. Paper 254-B, pt. 2, p. 59-64. 1956, Mountain-building chronology and nature of geo­ Young, R. G., 1955, Sedimentary facies and intertonguing in logic time scale: Am. Assoc. Petroleum Geologists Bull., the Upper Cretaceous of the Book Cliffs, Utah-Colorado: v. 40, p. 1769-1815. Geol. Soc. America Bull., v. 66, p. 177-202. INDEX

A Page Page Page Aberdeen member, Blackhawk forma­ Cedar Mountain formation_ _ 7, 24, 38 Fox Hills sandstone, fauna______23, 37 tions ______10, 11 Cisco, Utah, Farrer formation__ 33 Fruitland formation, faunas_____ 6-7, 37 Acknowledgments 2-4 section near__ 62-63 Age and correlation of formations_ 22-36 Coal beds, Blackhawk formation_ 10, 40 Anchor Mine tongue, Mancos shale 10, Dakota sandstone 25 Gannett, Henry, quoted ____ 5 15-16 Mount Garfleld formation_____ 19-20 Grand Junction, Sego sandstone_____ 38 Animas formation, correlation of___ 41 Neslen formation 17 Grassy Dome, section at______47 Coal Creek, Utah, Farrer formation.- 18 Grassy member of Young______11 B section at___ 52-54 Gray Canyon, Green River, Castle­ Bear River formation, fauna_ _ 23 Colton formation______20-21, 36 gate sandstone ______14 Beckwith, E. G., quoted__ 4 Corcoran member of Young_ ___ 11 Green River, Castlegate sandstone_ 14 Beckwith Plateau, Blaclchawk forma­ Correlation and age of formations 22-36 section north of______49-50 tion ______12 Cottonwood Creek, section at__ 62-63 Tuscher formation______18 section at_ _ _ __ 48-49 Cozzette member of Young ____ 11 Wasatch formation______22 Belle Fourche shale, faunal zone__ 23 Crescent Butte, Castlegate sandstone- 15 Green River formation____ 21, 22, 36, 40 Bibliography ______76-78 Crescent Wash, Castlegate sandstone- 31 section of, Salt Wash ______69 Bitter Creek, Castlegate sandstone_ 14 section at___ 56-58 Greenhorn limestone, correlation and Blackhawk formation 10, 11-13, 14, 31, 37 Cretaceous and Tertiary systems 20-21 faunal zones______23 formations above ______13-20 Cretaceous system (see also una\er Gregory member, Pierre shale, faunal sections of, Bacon Gulch_____ 45-46 specific formation correlation ______23,32 Bcckwith Plateau__ __ 48 names) _____ 6,7-20 Gunnison Butte, Blackhawk forma­ Coal Creek-______54 lower, age and correlation of 24 tion______12 Crescent Wash-______57-58 origin of______- 38 Castlegate sandstone______14 Grassy Dome______47 nomenclature of _ 6 7 Green River, north of___ 49-50 standard sequence 22-24 H Nash Wash reentrant____ 61 Hell Creek formation, fauna _____ 23 Price River canyon_____ 47 48 Horse Creek canyon area, Blackhawk Saleratus Wash _ 56 Dakota sandstone__ 6, 7-8, 24-26, 38 formation__ _ 12, 45-46 Thompson Wash______59 sections of, Beckwith Plateau 49 Colton formation ______21,42 Tuscher Wash______51-52 Crescent Wash 58 North Horn and Flagstaff forma­ Blue Hill shale member, Carlile shale, Grassy Dome ___ 47 tions______21,42 correlation of_ __ 27 Nash Wash reentrant 61 Price River formation__ 14, 20, 43-45 Bluecastle sandstone member, Price Tuscher Wash 52 section at______41-46 River formation__ 11,14,18 Desert member of Young 11 Hunter Canyon, Anchor Mine tongue, Book Cliff mine, section at_____ 74-76 Douglas Creek member, Green River Mancos shale______16 Bowlo shale member, Mcsaverde for­ formation __ 22 section in : __ 73-74 mation___ 10, 19-20, 34-35 Draney limestone 23 'Sego sandstone______15 Brown, R. W., quoted______25 Dutton, C. E., quoted 5 Wasatch formation______22 Brown Cliffs, Wasatch formation__ 22 E Hunter Canyon formation_ 10,18, 20,36 Buck tongue, Muncos shale_ _ 10, Eagle formation, equivalents of 29, 23 sections of, Book Cliff mine___ 74 13, 15, 32, 37 Hunter Canyon _ _ 73-74 Coal Creek______54 East Salt Creek, Anchor Mine tongue, Mancos shale______16 Salt Wash ______69-71 sections of, Coal Creek- 54 West Salt Creek______66 Cottonwood Creek_ 63 Scgo sandstone 15 Crescent Wash 57 Elgin, Utah, section near 50-52 Nash Wash reentrant _ 61 101k Butte member, Pierre shale 23 Introduction 1-4 Saleratus Wash___ _ 56 Erdmann, C. E., quoted 19 Thompson Wash__ 59 F Tuscher Wash _____ 51 Judith River formation, fauna __ 23, 37 Wcstwater Wash__ _ 64 Fairport chalky shale member, Car­ lile shale, equivalents Buckhorn conglomerate member, Ce­ K dar Mountain forma­ of____ -____- 26 tion ______7 Farrer formation__ 11, 17-18, 33-34 Kaiparowlts formation______40 Burro Canyon formation 7, 24, 38 non-coal-bearing member 10,13 Kenilworth member of Young ___ 11 sections of, Coal Creek 53 Klrtland shale______6-7, 37 Cottonwood Creek 62 Caineo coal zone, section at Book Crescent Wash _ __ 56 Cliff mine______75 Nash Wash reentrant 60 Saleratus Wash 55 Lance formation, fauna______37 Cameo member of Young 11 Laramle formation______6-7, 37 Carlile shale______23, 27 Thompson Wash 58 Westwater Wash 63 Lewis shale_ _ _. 6-7, 37 Castlegate sandstone member, Price Location of the area______2 River formation 10, Fieldwork ____ . 2-4 Flagstaff limestone (see also North 14-15, 31, 37 M sections of, Beckwith Plateau 48 Horn and Flagstaff for­ Coal Creek______54 mations)__ 17, 20-21, 36, 40 McDermott formation______6-7, 37 Cottonwood Creek_____ 63 sections of, Horse Creek 42 Mancos shale (See also Buck tongue)- 6-7, Crescent Wash ______57 Tuscher Wash 50 8-9, 10, 13, 15-16, 26-31, 32, Nash Wash reentrant __ 6,1 Formations (see also under specific 37, 38-40. Price River Canyon_____ 47 names) _ _ 5-6 sections of, Beckwith Plateau_ 49 'Saleratus Wash______56 Fossils (see also "Age and correla­ Crescent Wash______57 Thompson Wash______59 tion of the forma­ Grassy Dome______47 Tuscher Wash ___ 51 tions") 8, Nash Wash reentrant-__ 61 Westwater Wash _ __ 64 13, 19, 20, 21, 22, 39, 40 Tuscher Wash _ ____ 51-52 79 80 INDEX

Page Page Page Mesaverde group (see also under Price River formation (see also Cas- Tertiary formations______6 s p e cifio formational tlegate sandstone) 10, Thompson Canyon sandstone bed, names) ______6-7, 11, 13, 14, 31-32, 38, 54 Neslen formation_____ 17 9-11, 31-36, 38-40 sections of, Beckwith Plateau_ 48 Thompson Wash, Blackhawk forma­ Mobiidge member, Pierre shale, Horse Creek-______43-45 tion______faunal zone_ __ 23 Price River canyon____ 47 section at ______Morrison formation, sections of, Tropic shale______Crescent Wash____ 58 R Tuscher Wash Canyon, Colton forma­ Nash Wash reentrant 62 Reeside, J. B., Jr., quoted______13,14 tion ______Mount Garfleld formation 10, Regional relations _ _ 40-41 Farrer formation______13,19-20, 34-35, 38 Roan Cliffs, Wasatch formation__ 22 section in ______sections of, Book Cliff mine__ 74-75 Rollins sandstone member, Mesa­ Tuscher formation 11, 18-19, 20, 21, Salt Wash______71-72 verde formation. 10, 19, 34-35 sections of, Coal Creek______West Salt Creek______67-68 section of Book Cliff mine___ 75-76 Cottonwood Creek______Mowry shale 23 Ruby formation of Lee______21 Nash Wash reentrant______N Saleratus Wash______Thompson Wash______Nash Wash reentrant, Blackhawk Saleratus Wash, Blackhawk forma­ Tuscher Wash______formation ____ 12 tion ______12 Westwater Wash ______section in ______60-63 Farrer formation _ 33 Wasatch formation _ 22 section at______54-56 U Neslen Canyon, 'Sego sandstone_ 15 Wasatch formation 22 Neslen formation 11,17, 33 Salt Valley anticline______5 Unnamed sandstone of Tertiary icoal-bearing member 10,13 Salt Wash, section at______69-73 age :. _ 22, 36 sections of, Coal Creek______,53-54 Schiel, James, quoted______4 sections of, Salt Wash_____ 69 Cottonwood Creek--_____ 62-63 Sections, stratigraphic ___ 41-76 West Salt Creek______65-66 Crescent Wash__ _ 56-57 Sego sandstone member, Price River Nash Wash reentrant.__ 60-61 formation_ ____ 10, Saleratus Wash 55-56 11, 13, 15-16, 33, 38 Thompson Wash__ __ 59 sections of, Book Cliff mine_ 76 Virgin Creek member, Pierre shale, Tuscher Wash______51 Coal Creek______54 faunal zone ______23 Westwater Wash______63-64 Cottonwood Creek 63 Newcastle sandstone, faunal zone__ 23 Crescent Wash______57 W Niobrara formation 23 Nash Wash reentrant 61 Wahweap sandstone______40 Nomenclature of Cretaceous forma­ 'Saleratus Wash______56 Wasatch formation_____ 20-21, 22, 36, 40 tions ______6-7 Salt Wash______72-73 Non-coal-bearing member, Price River Thompson Wash 59 sections of, Horse Canyon____ 41-42 formation.______10 Tuscher Wash ___ 51 Nash Wash reentrant __ 60 Nonmarine faunas in Cretaceous West ;Salt Creek______68 Saleratus Wash _ _ 54-55 rocks______36-38 Westwater Wash 64 Salt Wash______69 North Horn formation 13, Sego sandstone and Tertiary forma­ Thompson Wash_ ____ 58 18, 20-21, 32, 36, 37, 40 tions, units between__ 16-20 Tuscher Wash______50 sections of, Horse Creek 42 Skull Creek shale, faunal zone____ 23 West Salt Creek______64-65 Tuscher Wash______50 Soldier Creek, Colton formation __ 21 Wasatch Plateau, North Horn for­ North Horn and Flagstaff forma­ mation______32 0 tions ______21 Price River formation_ ___ 14 Ohio Creek conglomerate 22 Spanish Fork, Provo River, Castle- West Salt Creek, Castlegate sand­ Ojo Alamo sandstone, fauna_ _ 6-7, 37 gate sandstone-_____ 14 stone ______14 Origin of the formations 38-40 Price River formation______14 section near _ __ _ 64-68 Spieker, B. M., quoted _ _ 14 Wasatch formation______22 Spring Canyon member, of Young 10,11 Westwater Wash, Castlegate sand­ Palisade coal zone, section at Book Star Point sandstone ____ 10 stone______14, 38 Cliff mine______76 Storrs tongue, of Young ____ 10,11 section at ______63-64 Panther tongue of Young, Star Point Straight Cliffs sandstone 40 Sego sandstone______15 sandstone__ ___ 10,11 Stratigraphic sections. _ 41-76 Whitmore Creek, Colton formation_ 21 Paonia shale member, Mesa Verde Sulphur Canyon sandstone bed, Nes­ North Horn and Flagstaff forma­ formation__ 10, 19-20, 34-35 len formation______17 tions______21 Patmos Mountain, section at _ 41 Sunnyside, Castlegate sandstone- 14 Willow Creek, Colton formation__ 21 Peterson limestone, faunal zones in 23 Wasatch formation_____;___ 22 North Horn and Flagstaff forma­ Pictured Cliffs sandstone 6-7 Sunnyside coal seam ____ 12 tions ______21 Pierre shale_ 23,32 Sunnyside member, of Young 11 Woodside, Utah, section near____ 47-48 Plateau Valley beds 21 Previous work in the region 4-5 T Price River canyon, Price River for­ Telegraph Creek formation, correla­ mation ____ 14 tion ______29 Yampa River, Cretaceous nomencla­ section at______47-48 Tertiary and Cretaceous systems 20-21 ture in valley of____ o