Triassic of Southeastern and Adjacent Areas




Studies in southeastern Idaho, western Wyo11ting, and southwestern , revealing one of the thickest and most complete marine sequences of Lower faunal zones in the world


Douglas McKay, Secretary

GEOLOGICAL SURVEY W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price $1 (paper cover) CONTENTS

Page )lbstract------165 Introduction------~------165 I>inwoodyformation______167 VVestern VVyoming______168 Southeastern Idaho______169 Southwestern ~ontana______170 VVoodsideformation______170 Southeastern Idaho------~------170 VVestern VVyoming ______~------~------T- 171 Southwestern ~ontana______171 Northern ______·__ 171 Thaynesformation------~------171 Southeastern Idaho______172 Fort Hall Indian Reservation to Grays Range ______:______172 Eastern Lake to Sublette Ridge______17 3 Bear River Range______175 VVestern VVyoming ______:______17g

Southwestern ~ontana______177 Central 'Vasatchand Uinta ~ountains______177 Post-Thaynes Triassic------179 Central VVasatchand Uinta ~ountains______179 Southeastern Idaho______180 VVestern VVyoming______181 of central VVyoming______.181 Age and correlation of formations of Triassic age______182 Literature cited------188 Index------191

ILLUSTRATIONS [Plates 34-40 in pocket] Pan PLATE 34. Composite correlation diagram of formations of Triassic age in ~ontana, Idaho, VVyoming, and Utah. 35. Correlation of Dinwoody and VVoodside formations between Paris, Idaho, and the VVind River ~ountains, VVyo. 36. Correlation of Dinwoody and Woodside formations between Provo, Utah, and Henry, Idaho. 37. Correlation of formations of Triassic age in southwestern ~ontana. 38. Correlation of the Thaynes and overlying formations of Triassic age between Fort Hall, Idaho, and Swift Creek, Wyo. 39. Correlation of the Thaynes and overlying formations of Triassic age between the , Idaho, and Muddy Creek, Wyo. 40. Correlation of outcrop sections of the Thaynes formation in the central VVasatch and Uinta Mountains, Utah. 'FIGURE 18. Correlation chart of Triassic formations in Montana, Idaho, VVyoming, and Utah______166 19. Diagram showing northeastward overlap of Triassic formation on formations in Idaho and VVyoming___ 169 20. Correlation diagram of the units of the Thaynes formation between Fort Hall, Idaho, and ~ublette Ridge, VVyo. 174 , 21. Correlation of formations of Triassic age along the south flank of Uinta Mountains, Utah and Colo______178 m




ABSTRACT studies have demonstrated that this area contains one '.rhick marine strata of age occur in eastern of the thickest Lower Triassic marine sections in the Idaho and adjacent areas. The area covered in this report lies world and one of the most complete sequences of Lower along the eastern margin of an ancient miogeosycline. Basin­ Triassic faunal zones. Lower Triassic deposits around ward (west) the strata are thickest and consist of fossiliferous marine rocks with no . Toward the craton (east) the the world are generally thin and incomplete in respect strata thin and intertongue with red and . to the number of faunal zones present. Data on the The Dinwoody and Thaynes formations attain their thickest Idaho section will add much to our knowledge of North marine development in the region of the Fort Hall Indian Res­ American Triassic stratigraphy and ; but, ervation. To the east, north, and south of Fort Hall, the Din­ as is probably more important, they are proving to be woody formation intertongues with the red Woodside and Chug­ water formations; the T:Q.aynes formation tongues out eastward a key in the interpretation and correlation of worldwide into the Ankareh and Chugwater formations. The zone of in­ Lower Triassic faunal zones. tertonguing for the Dinwoody formation follows a line from The Early Triassic seaways that covered much of southwestern Montana along the Idaho- boundary and western were more widespread than turns sharply westward in northern Utah. East of this line those of Middle or time. The distribution red beds are predominant ; west of the line the red beds are absent or of minor thickness. A similar line for the of facies and thickness of Lower Triassic strata in Thaynes formation passes southward from the Idaho-Wyoming western North America follows a pattern similar that boundary through the 'Vasatch Mountains and does not turn of the late Paleozoic. Permian and Triassic strata of westward in northern "'Ctah as for the Dinwoody formation. N evacla, California, Oregon, and Washington are char­ New ammonite faunas of Gyronitan and Flemingitan age are acterized by the presence of volcanic rocks. These areas recorded from the Dinwoody formation. The Prohungarites zone, the youngest Scythian ammonite zone, is recognized in include the eugeosyncline ofKay (1951). Strata of the the upper part of the Thaynes formation. The post-Thaynes same age in eastern Nevada, Arizona, Utah, eastern Triassic rocks of this area are of continental origin and are • Idaho, western Wyoming, and southwestern Montana correlated with the and Chinle forma­ contain no Yolcanic rocks and belong to the miogeosyn­ tion of the Colorado Plateau. The marine miogeosynclinal helt cline of Kay ( 1951). The line marking the approxi­ was destroyed at the end of Early Triassic time. The eastern mate boundary of the·miogeosyncline and the more sta­ Nevada geanticline (Nolan 1943) probably extended northward into Idaho in the middle and late Triassic. ble platform area of the continent has been named the Wasatch line by Kay ( 1951), and it passes in an approx­ INTRODUCTION imate north-south direction through the area of south­ eastern Idaho and the adjacent regions discussed in this Throughout the world, data on stratigraphy and report. At the Wasatch line the Triassic strata begin paleontology of the upper Permian and Lower Triassic to thin, and the marine rocks with red beds intertongue are surprisingly incomplete when compared to higher eastward onto the platform area or the craton of Kay beds of the . Considering that one of the im­ (1951). portant era boundaries separates these hvo series, in1- Nolan ( 1943) described a late Paleozoic and early portant physical and paleobiological data should be Mesozoic geanticline in eastern Nevada. This geanti­ sought in upper Permian and Lower Triassic rocks. cline began to form in the Permian period and extended Although the presence of thick marine deposits of northward until by Late Triassic time it reached en­ Early Triassic age in southeastern Idaho has long been tirely across Nevada. It was at least .a partial barrier known, it is only recently that field and laboratory between the miogeosyncline and the eugeosyncline dur- 16fi 166 SHORTER CONTRIBUTIONS TO GENER~L GE6LOGY ing Early Triassic time. Nolan (1943) refers to the Shinarump conglomerate) was derived fro;m positive geosynclines on either side of the geanticline as the areas to the west (Mansfield, p. 190, 1927). In west­ western and eastern troughs. He noted the presence of ern Wyoming, Love (p. 100, 1948) suggests that there volcanic rocks in the strata of the western trough and was recurrent uplift in Late Triassic time in an area the absence of volcanic rocks in the strata of the eastern trending northwest along the western margin of the trough. Across north- and west-central Utah and Wind River Basin. northern Nevada and in the Lower Triassic formations In summary, the eastern Idaho Triassic area occu­ of southwestern Nevada and in the Inyo Mountains of pies a position along the eastern margin of an ancient east-central California, ammonites are found, like those miogeosyncline. The eastern Nevada geanticline in Lower Triassic formations in Idaho areas, indicat­ (Nolan, 1943) did not extend across Nevada, for the ing that the geanticline did not form a complete bar­ Early Triassic seaways did have open connections with rier to the sea across the northern half of Nevada in the eugeosynclinal belt. By time the Early Triassic time. seaway retreated from the miogeosynclinal belt and _the The miogeosynclinal seaway of Paleozoic and Early eastern Nevada geanticline extended farther north. Triassic time disappeared at the end of Early Triassic Upper Triassic rocks in eastern Nevada, northern Ari­ time. Later Triassic rocks in this area-Shinarump zona, Utah, western Colorado, and eastern Idaho con­ conglomerate and and their equiva­ sist of a lower conglomerate (for example Shinarump lents-are of continental origin. The eastern Nevada conglomerate) overlain by a red and geanticline probably extended across Nevada and north­ formation (for example Chinle formation) of conti- _ ward at this time. Middle and Upper Triassic marine nental origin. The conglomerate suggests uplift of rocks are confined to western Nevada, California, Ore­ areas south of the Colorado Plateau, in the Uncom­ gon, and Washington. There appears to have been up­ pahgre Mountains of Colorado and in central or western lift in the region south of the Colorado Plateau in Late Idaho. Whereas the source of the Lower Triassic sedi­ Triassic time, which accounts for the widespread de­ ments for the Idaho area, and .the miogeosyncline in velopment of the Shinarump conglomerate (McKee, general, was to the east, the Upper Triassic rocks had 1951). The Gartra grit member of the Ankareh for­ sources that were peripheral to the area of deposition, mation in the western Uinta Mountains and the Shina­ with some westerly derived materials. rump conglomerate in the eastern Uinta Mountains are A list and correlation of the Triassic formations in possibly derived from the Uncompahgre positive area southeastern Idaho and adjacent regions is given in in west-central Colorado (Thomas and Krueger, p. figure 18. The thickest and most complete marine de­ 1273, 1946). The Higham grit of eastern Idaho ( = velopment of Lower Triassic rocks in the miogeosyn-

NORTHEASTERN UTAH . SOUTHWESTERN MONTANA SOUTHEASTERN IDAHO WESTERN Uinta Mountains WYOMING Central Wasatch CENTRAL WYOMING Tendo7 Hogback West of Mountains Fort Hall Grays Range East of Weatern Eastern Mountain Mountain I Bear Lake

Wood shale Wood shale tongue tongue ~er StaDaker Chinle member member rorma11011 Papo Aile member Deadman Deadman limestone Aokareh Not formation exposed § Gartra grit Gartra grit Sblnarwnp Higham. grit Highamgrll :0 a member § member conglomerate .!! Unnamed red Timothy sandstone : ~ Timothy sandstone 1 siltstone and member ~ sandstone members }~ member ~ ~ ~-<.!!1------....__ MahOg&J17 ~ Portneuf _____.--- f------Portneuf limestone memb~ member limestone :.:::-:::_,_ member

Middle shale Lower black limestone formation~· ·~·formation Middle limestone Lower shale ~ ~--L---.r-~-e-sto-ne--~~----w---r-1~-.-.to-ne------~~

Woodside 1------1 Woodside Woodside Woodside formation formation formation Db..~ DinwOOdy Woodside formatioo formation formation Dinwoody formation Dinwoody D!nwoody Dlnw~ formation form«tion formatioD formation

FIGURE 18.-Correlation chart of the Triassic formations in Montana, Idaho, Wyoming, and Utah. TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 167 cline is in the Fort Hall Indian Reservation, Idaho. of the original Dinwoody. Thus, at the type locality To the east, north, and south, the Dinwoody and the Dinwoody as redefined is 90 feet thick and overlain Thaynes formations thin and intertongue with red beds by gray shales; elsewhere it is generally overlain by of the Chugwater, Woodside, and Ankareh formations red shales and siltstones. The Dinwoody formation (pl. 34). The contact of the Dinwoody formation with crops out throughout western Wyoming, southeastern the underlying appears to be Idaho, and southwestern Montana. It thickens greatly conformable in southeastern Idaho. However, in west­ to the west with the addition of beds both below and ern and central Wyoming and in the southern Wasatch above those found at the type locality. Mountains, Utah, unconformable relationships exist. In southeastern Idaho the Dinwoody formation is The following discussion of the various formations and 700 to 2,400 feet thick and includes beds both older and the text figures present a detailed picture of the facies younger than are found at the type locality in the Wind relationships of the Triassic rocks in the Middle Rocky River Mountains, Wyo. In southwestern Montana, Mountains. A complete paleontological study of the along the boundary area of Idaho and Wyoming, and Triassic faunas from the Middle Rocky Mountains is in northern Utah, the Dinwoody intertongues with the now in progress. Because this study will. require a few red Woodside formation. The Dinwoody formation in more , the present summary is merely a progress southeastern Idaho, and southwestern Montana, and report of the main stratigraphic and faunal data. Western Wyoming is bounded below by the Phosphoria Five field seasons were spent studying the Triassic formation of Permian age and above by the Woodside formations of Montana, Idaho, Wyoming, and Utah. or Thaynes formations. The limestone with M eeko­ Work during the 1949 and 1950 field seasons was done oeras is the member of the Thaynes formation. At under the auspices of the U.S. Geological Survey. The the type locality of theWoodside formation in the Park writer wishes to express appreciation to Mr. V. E. City Mining District, Utah, it consists of red sandstone McKelvey for his constant aid and encouragement in and shale. The formation is underlain by the Phos­ the 1949 and 1950 seasons. Messrs. J. B. Reeside, Jr., phoria formation, and the M eekooeras limestone of the W. W. Rubey, and A. E. Granger contributed to the Thaynes formation is above. The Dinwoody formation work through stimulating discussions and advice on in southeastern Idaho and the Woodside formation at Triassic formational nomenclature. Messrs. W. R. its type locality near Park City, Utah, have the same Lowell, W. B. Meyers, and G. C. Kennedy kindly gave stratigraphic boundaries at their top and bottom. The locality information on Triassic exposures in south­ top boundary of the Dinwoody and Woodside forma­ western Montana. The writer was ably assisted in the tions in these two areas is marked by a well-defined 1949 field season by Mr. A. M. Gutstadt and in the 1950 .ammonite zone and can be considered as the same season by Mr. N. F. Sohl. The Research Committee of horizon. the Q-raduate School at the University of Illinois aided The relationship of the Dinwoo4.y and Woodside for­ in defraying field expenses for the 1950 field season and mations to the Phosphoria formation is not completely in the preparation of the manuscript. Messrs. H. R. understood. The Phosphoria formation is generally Wanless, A. E. Granger, and H. D. Thomas allowed the considered to be early in age (Newell, use of their unpublished Triassic sections, for which the 1948)., although the distinctive guide , on which writer is grateful. the age determination has been based, generally were not collected from the uppermost part of the Phos­ DINWOODY FORMATION phoria formation. A complete summary of the various The Dinwoody formation was named and· defined by opinions on the age of the Phosphoria formation has Blackwelder (1918, p. 425-426) from outcrops in Din- . been given by McKelvey ( 1946) . At most exposures woody Canyon on the northeastern slope of the Wind there is lack of physical evidence of a hiatus between the River Mountains, near Dubois, Wyo. The limits of Phosphoria and Dinwoody or Woodside formations in the formation were defined by the Phosphoria forma­ the Middle Rocky, Mountains. The Woodside forma­ tion below and the bright red shales and siltstones of · tion is separated from the Permian by an angular un­ the Chugwater formation above. Because the color conformity in the southern Wasatch Mountains, Utah, boundary between the Dinwoody, as originally defined, and bevels across nearly 2,000 feet of Permian strata in and the red Chugwater was not a useful or natural a horizontal distance of about 10 mile5 (Baker and Wil­ boundary, Newell and Kummel (1942, p. 941) redefined liams; 1940) . Newell and Kummel ( 1942) demon­ the Dinwoody at the type locality to include only the strated an between the Phosphoria and dominantly silty strata between the Phosphoria and the Dinwoody formations in southwestern and central top of the resistant siltstone about halfway to the top Wyoming. They gave as evidence: (1) The marked 168 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY leaching of cherty beds at the top of the Phosphoria side thickens rapidly and only a small part of the formation, (2) marked northeastward overlap of the nonred Dinwoody formation is present in central Wyo­ lower Dinwoody strata by upper Dinwoody on the sur­ ming and none at all in the Wasatch and Uinta Moun­ face of the Phosphoria from southwestern to central tains, Utah. (See pl. 35.) The contact with the Wyoming, and ( 3) the discovery by Alfred Fischer that Phosphoria formation in southweste~n Montana and upper beds of the Phosphoria are locally truncated by southeastern Idaho is conformable. No physical evi­ basal beds of the Dinwoody formation. In the same dence of a hiatus has been recognized. In southwestern general area, Love (1939, 1948) also noted local evi­ and central Wyoming and the southern Wasatch Moun­ dence of unconformity at the boundary between the tains, Utah, there is evidence of an unconformity be­ Phosphoria and Dinwoody fonnations and reported tween the Dinwoody and Phosphoria formations. that the discordance is apparent only in regional studies. WESTERN WYOMING In southeastern Idaho in the uppermost Phosphoria In the Creek and Wind River Mountains the the shale is black and in some places phosphatic. The Dinwoody formation ranges in thickness from 40 to 120 upper shale member of the Phosphoria and the lower feet. The formation is about 120 feet thick at Green shale member of_the Dinwoody are seldom well ex­ River Lakes; 235 feet at Gros Ventre Canyon; 320 feet posed; but where they do crop out, the contact, which at Bear Gulch, Hoback Canyon, Hoback Mountains; does not suggest a hiatus, appears to be gradational. 370 feet at Phillips Pass, Teton Range; 430 feet near If the top of the Phosphoria is of the same age in south­ the junction of Martin Creek and River, Wyo­ eastern Idaho as in northern Utah, the Woodside and ming Range ; 440 feet along North Piney Creek, Wyo­ Dinwoody formations are probably the time equivalents ming Range; 735 feet at MacDougals Pass, Salt River of each other and intertongue at their margins. B€5- Range; 660 feet in Swift Creek Canyon, Salt River cause there are few fossils in the Woodside formation, Range; 575 feet at Turner Canyon, Sublette Ridge; 540 it will be necessary to rest heavily on the age of the up­ feet at Cokeville, Sublette Ridge (Newell and Kummel, per part of the Phosphoria formation to determine its 1942), and 180 feet along Muddy Creek, Lincoln exact time span. The Dinwoody formation in southwestern Montana County, Wyo. (H. D. Thomas, personal communica­ is similar to that in Idaho and intertongues with the tion). Woodside formation · to the east and north. Moritz Newell and Kummel (1942) recognized three major (1951), quoting Sloss, suggests that the basal beds of lithologic units in the Dinwoody formation that could the Dinwoody in southwestern Montana may be upper be traced over a wide area, and referred to them as the Permian. Moritz further adds: basal siltstone, the zone, and the Olaraia zone. The basal· siltstone unit is really a silty limestone and It is therefore suggested that these beds may represent the time in,terval that appears to be missing; thus, there may have will be called here the basal, silty limestone unit. This been a period of continuous sedimentation from upper Permian unit consists of buff to tan, silty limestone or calcareous to lower Triassic time; accounting for the klck of a recognizable siltstone and is present only along the most western part unconformity. of Wyoming in the Teton Range, the Wyoming Range, In the same area of southwestern Montana the writer the Salt River Range, and at Sublette Ridge. The unit has found lower Scythian amonites and Olaraia within is 50 to 175 feet thick, being thickest in the southern ex­ 5 feet of the Phosphoria formation. Throughout the posures. In the areas east of the Wyoming Range the Middle Rocky Mountains, fossils are not abundant in basal, silty limestone unit is absent and apparently is the lower part of the Dinwoody formation, but it is overlapped by the Lingula beds, which extend farther not uncommon to find poorly preserved specimens of toward the east. , Anodontophora and Olaraia, which are typi­ Overlying the basal si\ty limestone of the Dinwoody cal Early Triassic fossils. formation is the Lingula zone, a heterogeneous unit of In summary, the regional picture of the Dinwoody silty limestone, gray crystalline limestone, and ­ formation is as follows. Along an arcuate belt from buff to gray shales. The unit is distinguished by the southwestern Montana, the Idaho-Wyoming boundary, abundance of well-preserved specimens of Lingula; the and swinging westward in northern Utah, an inter­ Lingulas occur both above and below this zone but not tonguing sequence of nonred Dinwoody and red Wood­ as abundantly. The Lingula zone reaches a maximum side formations lies between the Permian Phosphoria observed thickness in the vicinity of Afton, Wyo., where formation and the Thaynes formation. West of this it ranges in thickness from about 250 to 350 feet. To­ arcuate belt the percentage of red Woodside rocks de­ ward the north and east, it thins progressively; and in creases rapidly, and east and south of it the red Wood- the Hoback, Gros Ventre, Owl Creek, and Wind River TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 169

Mountains, it rests directly on the Phosphoria forma­ Canyon; 2,443 feet at Bear Creek Reservoir Mountain, tion. Throughout its eastern ,__ area of outcrop, the near Henry; 2,000 feet in the Portneuf Quadrangle Lingula zone is commonly only 25 to 50 feet thick. (Mansfield, 1929); and 1,000 feet in the Fort Hall In­ The Olaraia zone, the uppermost unit of the Din~ dian Reservation (Mansfield, 1927). woody formation, is the most extensive of the three The lithologic units of the Dinwoody formation that units. It is characterized by tan calcareous siltstone, are recognized in western Wyoming by Newell and silty limestone, gray crystalline limestone, and a few Kummel cannot be readily traced into Idaho. The beds of shale. The calcareous siltstone and gray crys­ Lingula zone• and the Olaraia zones can be recognized talline limestone appear to grade into each other along in Montpelier Canyon and at Hot Springs. The lower­ the strike. This unit of the Dinwoody commonly 'con­ Inost part of the formation is mainly a shale sequence. tains abundant molds of of Olaraia and An- The basal, silty limestone unit of the Dinwoody, so persistent throughout extreme western Wyoming, is

West East not present. Along the eastern margin of Bear Lake Valley, the lower half of the Dinwoody consists of gray shale, silty in part, interbedded with thick beds of tan to olive-drab calcareous siltstone and gray, finely crys­ talline li1nestone. The upper half of the formation generally consists of massive beds of olive-buff to blue­ gray calcareous siltstone and gray limestone that grade into each other along the strike. The lower shaly por­ tion of the Dinwoody in this region is correlative with the basal, silty limestone and part of the Lingula zone of western Wymning. At both Montpelier Canyon and at Hot Springs, the Dinwoody is overlain by the red 300 Feet L-----' VERTICAL Woodside formation. 50 Miles L-----' HORIZONTAL West of Bear Lake in the Bear River Range the Din­

I woody formation is overlain by the Thaynes formation. I 0 A H 0 j oBIG PINEY OLANDER Only two small tongues of red shale are present, one HOTP:~~":,GS : W Y 0 M I N G - ---O'ftOKEVILLE 50 feet thick and approximately 300 feet above the BEAR LAK£ I ° KEMMERER I u T A H I L-_30 MILES Phosphoria formation and the other 20 feet thick and ·------about 125 feet above the lower red shale. These two INDEX MAP Mod1f1ed from Newell and Kummel {1942) red zones represent tongues of the red Woodside for­

FIGURE 19.-Diagram showing northeastward overlap of Triassic forma­ mation. The rmnainder of the Dinwoody in this area tions on Permian formations in Idaho and Wyoming. Modified from consists of an alternation of buff to gray calcareous Newell and Kummel (1942). siltstone and gray, finely crystalline limestone. Fossils odontophora. In the Salt River and Wyoming Ranges are present throughout the sequence, though they are the Olaraia zone is 200 to 300 feet thick; in the Wind generally poorly preserved. River Mountains this unit is as much as 100 feet thick. North of the Bear Lake Valley in the Aspen Range In the sotftheastern part of the Wind River Mountains, and in Dry Ridge, the Dinwoody formation is more as at Hidden Anticline, 12 miles southeast of Lander, than 2,000 feet thick. It is underlain by the Phosphoria Wyo., the beds of the Olaraia zone lie directly on the fonnation and overlain by the Thaynes formation. Phosphoria formation, and the lower units of the Din­ Less than 20 feet of 1naroon and chocolate shales in thin woody are missing, apparently because of nondeposi­ interbedded units are present 1,300 feet above the base tion (Newell and Kummel, 1942). The eastward over­ in the Dry Ridge section (pl. 36). At W oocl Canyon, lap of the Dinwoody is illustrated in figure 19 and Aspen Range, there is a 40-foot bed of chocolate and plate 35. maroon shale and siltstone in the Dinwoody, 250 feet SOUTHEASTERN IDAHO below its contact with the Thaynes. The sections at The Dinwoody formation is much thicker in south­ Dty Ridge and 'Vood Canyon display a twofold divi­ eastern Idaho than in Wyoming. It is 775 feet thick sion of the Dinwoody with a predominantly shale se­ at Hot Springs on the east side of Bear Lake, 1,240 quence in the lower half and a calcareous siltstone and feet or more in Paris Canyon in the Bear River Range, gray limestone sequence in the upper half. west of Bear Lake, Bear Lake Valley ; 719 feet in Mont­ The thickest section (2,443 feet) of the Dinwoody pelier Canyon; 2,24:4 feet in Dry Ridge, near Stewart formation known is at Bear Creek, Reservoir Mountain, 288901-54-2 170 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY near Henry, Idaho, where no red beds are prc:-.senr. Gardner and others, 1946) along Indian Creek, Madi­ (Newell and Kummel, 1942) . The lithologic sequence son County, Mont., appears to belong to the Dinwoody is similar to that at Wood Canyon and Dry Ridge, ex­ formation, judging from the published description. cept :for the presence of more shales in the upper part of The section here is 268 feet thick a:p.d is composed of the formation. In the Fort Hall Indian Reservation, the interbedded, calcareous siltstone and fine- to medium­ Dinwoody is composed of approximately 1,000 feet of grained sandstone with some interbedded, sandy lime­ shale, thin beds of limestone, and calcareous siltstone stone and shale. The upper part of the section is gyp­ (Mansfield, 1927). No red beds are present. It is sig­ siferous. At Devils Slide, Cinnabar Mountains, just nificant to note that this most western exposure is less north of Gardiner, Montana, where Newell and Kummel than half the thickness of the formation at Henry, (1942) measured, the Dinwoody formation is 62 feet Idaho, or Dry Ridge. thick. Here the Dinwoody consists mainly of olive­ green, silty shale with thin beds of gypsum; the upper SOUTHWESTERN MONTANA 10 feet is olive-green sandstone, siltstone, and a thin bed of limestone. The formation is overlain by red shale and The lithologic character of the Dinwoody formation sandstone of the Red Pea.k member of the Chugwater in southwestern Montana is similar to that in south­ formation. eastern Idaho (pl. 37). Most sections are incomplete, The Dinwoody formation at Trapper Creek and Dalys however; for the Dinwoody at many localities ·is over­ Spur is overlain disconformably by the Kootenai for­ lain uncomformably by the Lower Kootenai mation. At Greenstone Gulch it is overlain by the formation. The Dinwoody measures 639 feet in thick­ Woodside. At Hogback Mountain, Odell Canyon, and ness at Trapper Creek (Newell and Kummel, 1942) ; Creek, the Dinwoody is overlain by the Wood­ 703 feet at Greenstone Gulch northwest of Dillon, side formation. In Little Water Canyon the Dinwoody Mont.; 945 feet at Dalys Spur; 893 feet at Small Horn is overlain by the Thaynes formation. Canyon; 1,000 feet at Little Water Canyon; 483 feet at Blacktail Creek; 62 feet at Ciunabar Mountain (Newell WOODSIDE FORMATION and Kummel, 1942); and 268 feet at Indian Creek,· Madison County, (Gardner and others, 1946). Boutwell (1907) named the Woodside from Wood­ Sections of the Dinwoody formation measured thus side Gulch in the Park City mining district, northeast­ far have a general twofold division-a lower shale unit ern Utah. In the type area the formation consists of and an upper unit of interbedded calcareous siltstone, approximateli 1,000 feet of maroon and red, shaly silt­ silty limestone, and gray crystalline limestone with stone and is barren of fossils. It overlies the Phos­ some interbedded gray to buff shale. Moritz (1951) phoria formation and underlies the Thaynes formation. recognized the twofold division of the Dinwoody forma­ The Woodside formation extends over a wide area in tion in southwestern Montana and called them the northern Utah, western Wyoming, and southwestern "Shale member" and the "Limestone member" of the Montana; it tongues out westward in southeastern Dinwoody. formation. The lower shale unit is 200 to Idaho and southwestern Montana into the Dinwoody 300 feet thick in the more western exposures. Along formation. The regional relations o:f the Woodside the west fork of Blacktail Creek, the lower shale con­ formation with the Dinwoody formation has been dis­ tains a great amount of interbedded, gray crystalline cussed above in the chapter on the Dinwoody forma­ limestone. At Little Water Canyon, Small Horn Can­ tion. yon, Dalys Spur, Greenstone Gulch, and Trapper Creek, SOUTHEASTERN IDAHO the lower shale unit contains thin-bedded calcareous The Woodside formation in southeastern Idaho is siltstone and a few beds of gray limestone. In the well developed along the east side of Bear Lak~ Valley, upper unit of the Dinwoody formation at Dalys Spur, and at Hot Springs the Woodside is 800 feet thick, of Small Horn Canyon, and Little Water Canyon, there which about half is red shales and siltstone. (See pl. 36.) are some thin ilitercalated b~ds of red shale and silt­ The red beds are rather evenly distributed throughout stone. These are interpreted as the featheredge of the 800 feet of the formation. At Montpelier Canyon tongues· of the Woodside formation. The thick shale the W oodsid_e is about 390 feet thick, of which approxi­ at the top of the Dinwoody at Dalys Spur and at Small mately half is red beds; the nonred rocks are concen­ Horn Canyon is dark green and noncalcareous, quite trated more toward the middle of this section. The unlike other shale beds of the :formation. Dinwoody formation is probably the time equivalent of The section of Triassic ( ~) undifferentiated rocks the lower part of the Woodside in its type area (Newell" measured by T. A. Hendricks and H. D. Hadley (see and Kummel, 1942). The red beds above the Din- TR1ASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 171 woody in SDeer Creek ming Range, and Sublette Ridge, all in western Wyo­ west of Charleston and 150 feet at Spanish Fork near ming; the Woodside formation is made up almost en­ Thistle. tirely of red shales and siltstone. Thin nonred beds In the Uinta Mountains the Woodside ranges from are found at only a few localities in Sublette Ridge 500 to 800 feet in thickness (Thomas and Krueger, and the Salt River Range. In Sublette Ridge the 1946). Eastward along the Uinta Mountains the red Woodside is about 490 feet thick at Cokeville and 565 color gives way in places to tan, or olive-drab beds. In feet at Turner Canyon. In the Salt River Range th~ the eastern part of these mountains the red beds of the · Woodside is about 710 feet thick at Swift Creek Canyon Woodside grade downward into red beds contemporary m1d 670 feet at MacDougals Pass. In the Wyoming with those of the Park City (Thomas and Krueger, Range the Woodside is 695 feet thick at North Piney 1946) and are commonly included in the Moenkopi Creek and 680 feet at Martin Creek. Gardner ( 1944, formation. p. 8) records 1,130 feet of Woodside on a ridge between THAYNES FORMATION Palisade and Trail Creeks, near the notheast corner of the Irwin Quadrangle. In the Snake River Range The Thaynes formation was described by Boutwell along Red Creek the Woodside is about 470 feet· thick ( 1907) from outcrops in Thaynes Canyon, Park City (H. R. Wanless, personal communication). In Bear mining district, Utah. In the type region, the Thaynes Gulch, Hoback Canyon, Hoback Mountains, the Wood­ formation consists of 1,190 feet of limestone, calcare­ side is 645 feet thick; and in Gros Ventre Canyon, north ous sandstone, sandstone, shale, and, in the middle, a red west of Gros Ventre slide, the Woodside is 555 feet shale member. At the type locality, the Thaynes is thick. underlain by the Woodside formation and overlain by In central Wyoming the Dinwoody is overlain by red the Ankareh formation. The Thaynes formation is shales and siltstones belonging to the Red Peak mem­ found over a wide area in northern Utah, eastern Idaho, ber of the Chugwater formation. This member has the western Wyoming, and southwestern Montana. Along same lithologic character as the Woodside, but it is its southern, eastern, and northern margins it inter­ equivalent to only the upper half of the type Woodside. tongues with the red Ankareh formation or the Chug­ water formation. The thickest development of the SOUTHWESTERN MONTANA Thaynes is in the Fort Hall Indian Reservation. No Formations of Triassic age in southwestern Montana red beds are present in this section. The Thaynes in are generally overlain disconformably by formations of southeastern Idaho is diffierentiated into several litho­ the Ellis or by the Cretaceous Kootenai logic units, which can be traced over a wide area. In formation. Northwest of Dillon, at Greenstc;me Gulch, southwestern Montana, in most of western Wyoming, 165 feet of red Woodside is present. The Dinwoody and in northern Utah, the lithology of the Thaynes formation at Dalys Spur, Small Horn Canyon, and formation is more homogeneous. Little Water Canyon contain several thin, intercalated The base of the Thaynes formation throughout east­ red shale and siltstone beds that represent the feather­ ern Idaho is a prominent limestone bed containing an edges of tongues of the Woodside forma~ion. At Hog­ abundant ammonite fauna characterized by M eeko­ back Mountain, Snow crest Range, the Woodside is 610 ceras. This same fauna is found in the Wasatch Moun­ feet thick and is overlain by the Thaynes formation. tains, Utah, and in southwestern Montana. In western 172 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY Wyoming the limestone with M eekoceras is present in Portneuf li1nestone member of the Thaynes formation. the Salt River Range and Sublette Ridge. In the The Portneuf member contains numerous beds of cal­ Wyoming Range and Teton Range, the lower limestone careous sandstone and sandy limestone, and in Grays with M eekocera8 is not present and that horizon is oc­ Range it appears to grade into the Timothy sandstone cupied by red beds of the Woodside formation. The member. However, Mansfield ( 1927, p. 91) has re­ eastward thinning of the Thaynes formation in western ported limestone pebbles, possibly derived from the

Wyoming takes place by lateral change into the lith­ Thaynes, in the Timothy in Home Canyon near1Mont­ ology of the underlying "\Voodside formation and the pelier, Idaho. The Timothy sandstone member is un­ overlying Ankareh formation. The Thaynes forma­ conformably oYerlain by the Higham grit. tion completely disappears east of the Wyoming Range. The Thaynes is well developed in the area between In the Fort Douglas area of northern Utah, the Thaynes the Fort Hall Indian Reservation and Bear Lake. formation consists of a thick, normal marine succes­ "\Vithin this area of outcrop, sever~l distinct lithologic sion. Eastward along the Uinta Mountains, the members are traceable, and there are considerable Thaynes formation thins and passes rapidly into the changes of facies from the southeast to the north and red Ankareh and the Woodside formations. Thus, the northwest. The thickest section of the Thaynes was regional relationship of the Thaynes formation is very 1neasured in the Fort Hall Indian Reservation. The similar to that of the Dinwoody formation except that sa1ne sequence of facies present at Fort Hall can be the boundary area between the red facies and the marine traced eastward to Grays Range, south of Grays Lake. facies goes south from eastern Idaho through the In the area along the eastern side of Bear Lake Valley Wasatch Mountains, Utah, rather than westward in toward Sublette Ridge in western "\Vyoming, a quite northern Utah as for the Dinwoody formation. different sequence of facies is encountered. A third and The Thaynes is the most fossiliferous formation of unique facies deYelopment is found in the Bear River Triassic age in the Middle Rocky Mountains. Several Range west of Bear Lake. The Thaynes formation and distinct ammonite zones are recognized, which are pres­ the interrelation of facies as developed in southeastern ent only in the thicker geosynclinal sections. In the Idaho will be discussed in terms of exposures in these areas where the Thaynes thins and red beds intertongue, three areas. the ammonites are generally not present. Smith ( 1932) recognized three ammonite zones in the Thaynes for­ FORT HALL J;NDIAN RESERVATION TO GRAYS RANGE mation; these are in ascending order the J/eekocera8, , and Oolumbites zones. Mathews (1929) rle­ :Mansfield ( 1916) raised the Thaynes formation to scribed fron1 the Fort Douglas area of Utah, a fauna the rank of a group and subdivided it into three forma­ which is present just above theMeekocera8 zone that is tions, which in ascending order are the Ross Fork lime­ referred to the A nasibirites zone. This zone is also stone (called the Ross limestone in Mansfield's paper of present in southeastern Idaho. A new and highly im­ 1916), the Fort Hall formation, and the Portneuf lime­ portant zone, the Proh111ngarites zone, is present above stone. In the area between · Fort Hall and Grays the Oolumbite8 zone in the upper part of the Thaynes Range, these three divisions of the Thaynes are dis­ formation in the Bear River Range. tinctive. Eastward toward the Salt River Range and southward toward the Bear Lake Valley, the Ross Fork SOUTHEASTERN IDAHO and Fort Hall formations lose their identity, although the broad relationships of the various facies of Mans­ Mansfield ( 1927) defi1ied the limits of the Thaynes field's Ross Fork and Fort Hall formations with units formation in southeastern Idaho as including all the of the Thaynes recognized around Bear Lake have been strata between the base of the limestone, which contains established. The Portneuf limestone is a much more JJ eekocera8, and the Timothy sandstone. Most stratig­ distinctive unit, however, and parts of it can be traced raphers have followed this procedure. Because the from Fort Hall, Idaho, to Cumberland, Wyo. It is Timothy is lithologically related to the Thaynes forma­ thought best to retain the name Portneuf limestone for tion and appears to be gradational to the Thaynes, it a member of the Thaynes formation but not to use in is here considered as the uppermost member of the the present paper the names Ross Fork and Fort Hall, Thaynes formation. The Timothy sandstone member as those two units have a very limited distribution. typically consist of approximately 250 feet of yellow­ The Timothy sandstone is here considered to be the ish to grayish sandstone. It attains a maximum thick­ uppermost member of the Thaynes formation. ness of 800 feet in the Fort Hall Indian Reservation The Thaynes formation is about 5,525 feet thick at and thins rapidly eastward toward Wyoming. The Fort Hall and 3,550 feet along Sheep Creek, Grays Timothy sandstone 1nember is comformable on the Range. Seven major lithologic units are present in TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 173 both of these sections (pl. 38). In the Sheep Creek in these beds at Fort Hall, but a :few poorly preserved section there is a prominent tongue (Lanes tongue) of ammonites and pelecypods were :found at Sheep Creek. the red Ankareh formation in the upper part of the Preliminary examination of these very fragmentary Thaynes that pinches out westward toward Fort Hall, specimens indicate affinities with the ammonite :fauna of where there are no red beds in the Thaynes :formation. the upper part of the Thaynes :formation in the Bear The lithologic units :frmn bottom to top are as :follows : River Range area west of Bear Lake. (a) Lower limestone, (b) lower black limestone, (c) Sandstone and lim.estone.-This unit includes all the tan silty limestone, (d) upper black limestone, (e) beds placed in the Fort Hall :formation by Mansfield. sandstone and limestone, (:f) the Portneu:f limestone It is about 480 feet thick at Fort Hall and 475 feet rnember, and (g) the Timothy sandstone member. The along Sheep Creek. The sandstone and limestone unit lower limestone, lower black limestone, tan silty lime­ consists of gray limestone, cherty in part; tan to gray­ stone, and the upper black limestone units of the brown calcareous sandstone, and siltstone. The upper Thaynes :formation of Fort Hall and Grays Range com­ contact with the Portneu:f limestone member is grada­ prise the Ross Fork :fonnation of Mansfield and the tional and somewhat difficult to define in the field. The sandstone and li1nestone unit (e) is the Fort Hall :for­ unit is more. brownish than the Portneu:f member and mation of Mansfield. is not generally massively bedded like the overlying Lower lin~estone.-The lower limestone unit of the Portneuf member. Thaynes formation is present throughout southeastern Portneuf limestone 1nember.-The most conspicuous Idaho, southwestern Montana, extreme southwestern unit of the Thaynes formation in the area between Fort Wyoming, and in the Wasatch Mountains, Utah. It is Hall and Grays Range is the Portneu:f limestone mem­ a gray crystalline limestone with a large ammonite ber. At Fort Hall it is 1,730 :feet thick and qomposed :fauna of the M eekoceras zone. The lower limestone is dominantly of 1nassive, gray, finely crystalline lime­ 187 feet thick at Fort Hall and 100 :feet at Sheep Creek. stone containing abundant chert nodules. The lime­ At Sheep Creek this limestone unit contains several silty stone is silty and sandy in part, and the member in­ beds and some shale in its lower part. cludes some beds of calcareous siltstone and sandstone. Lower black lhnestone.-Overlying the lower M eeko­ Along Sheep Creek the Portneu:f limestone member of ceras-bearing limestone is a thick unit of limestone, the Thaynes is 1,170 :feet thick and consists of massive, calcareous siltstone, and shale, generally dark gray to gray, cherty limestone; it is sandy in part and contains black. The strata are thin and contain some zones of some thin interbedded units of calcareous sandstone. nodular and lenticular black limestone. At Fort Hall The limestone generally contains myriads of poorly this unit is 680 feet thick and poorly exposed; at Sheep silicified :fossils. At this locality the Portneu:f contains Creek, however, where the unit is 600 :feet thick, the a 440-:foot redbed tongue of the Ankareh :formation, here exposures are good. Poorly preserved ammonites were named the Lanes tongue. This tongue of the Ankareh is found near the base of the unit at both localities and at named after Lanes Creek, of which Sheep Creek is a scattered horizons throughout the unit. At Sheep tributary. The best exposures of this tongue are :found Creek a :fragment of a 0 olumbites sp. was :found 250 at the south end of Grays Range, a mile west of the :feet :from the top of the unit. junction of Lanes Creek and Sheep Creek. No redbeds Tan silty lim.estone.-This lithologic unit consists of are present in the Portneuf limestone member at Fort gray and gray-brown, silty limestone and calcareous siltstone that weathers tan and generally slahby. Fos­ Hall. sils are very poorly preserved and are not abundant. Timothy sandstone mmnber.-The Timothy sand­ Along Sheep Creek, where the unit is 655 :feet thick, stone member of the Thaynes formation is named :from very fine exposures occur; at Fort Hall the unit is 785 Timothy Creek in the Freedom quadrangle and was :feet thick and poorly exposed. The lithology of this originally given :formational rank by Mansfield (1920) ; unit is very characteristic of formations of Triassic age it typically consists of approximately 250 :feet of yel­ in tne Middle Rocky Mountains. lowish to grayish sandstone and is generally no~ well Upper black li1nestone.-In the Fort Hall area the exposed. In the Fort Hall Indian Reservation the Tim­ tan silty limestone beds are overlain by 865 :feet of a othy is about 800 :feet thick. The contact with the un­ homogeneous unit composed of silty, black to blue-black derlying Portneu:f limestone member is conformable. limestone, alternating with irregular-bedded, · silty, There are several sandstone beds similar to those of the· gray-black limestone. Along Sheep Creek this unit Timothy in the upper part of the Portneu:f limestone­ consists of 295 :feet of gray-brown to black calcareous member in the Grays Range. No :fossils have been siltstone, shale, and limestone. No :fossils were observed :found in the Timothy sandstone member. 174 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY ® ® @

Timothy sandstone

the Ankareh formation

Upper calcareous siltstone

Middle shale

c Middle limestone 0 -c Lower shale E...... E

en (1) c >- 0 .._..s::::. Vertical scale (!)Fort Hall

Sheep [email protected] WYOMING

0 A H 0

~SprinQ Canyon ------~:_~~r~ Bear Lak~-, u T A H I 0 50 Miles


FIGURE 20.-Correlation diagram of the units of the Thaynes formation between Fort Hall, Idaho, and Sublette Ridge, Wyo.

EASTERN BEAR LAKE TO SUBLETTE RIDGE Lower Limestone.-The basal unit of the Thaynes Between eastern Bear Lake and Sublette Ridge, formation is a grayish-blue to gray, massive limestone, eight lithologic units are recognized within the boun­ which weathers gray and contains abundant cephalo­ daries of the Thaynes formation (Kummel, 1943, pods of the M eekooeras fauna. Throughout southeast­ 1950) . These units, from bottom to top, are the lower ern Idaho the limestone is a prominent stratigraphic limestone, the lower shale, the middle limestone, the marker ranging from 50 to 100 feet in thickness. In middle shale, the upper: calcareous siltstone of the the Bear Lake Valley region and in Sublette Ridge, the Thaynes, the Lanes tongue of the Ankareh formation, M.eekooeras-bearing limestone contains very little clas­ the upper part of the Portneuf limestone member of the tic material. To the northeast of the Bear Lake Valley Thaynes, and the Timothy sandstone member of the region, as at Swift Canyon and at MacDougals J?ass, Thaynes formation (pl. 39). Complete sections of the Wyo., the lower limestone includes buff shale and silt­ Thaynes were measured at Hot Springs, at the north­ east corner of Bear Lake, where it is 2,440 feet thick; stone beds. The quantity of fine clastics intercalated at Spring Canyon, in Sublette Ridge, where it is 2,560 within the limestone increases to the northeast and east feet, and at Cokeville, Sublette Ridge, where it is 1,575 o·f Bear Lake. feet. The relationships of the lithologic units recog­ At every locality studied, the M eekooeras fauna is nized in the Thaynes in"the areas between Fort Hall confined to a 5 to 15 foot zone within the whole lower and Grays Range and between Bear Lake and Sublette limestone unit. The remainder of the unit contains no Ridge are illustrated in figure 20. , but it does contain pelecypods and lingu- TRIASSIC STRATIGRAPHY OF SOUTHEASTERN. IDAHO AND ADJACENT AREAS 175 las. The bed with. the cephalopods generally is in the Valley area, and for the time being it is placed in the upper third of the lower limestone (Kummel, 1943). upper calcareous siltstone unit. Lower shale.-The lower shale unit of the Thaynes Lanes tongue of the .A.nkareh formation.-The red formation is seldom well exposed. It is generally rep­ shales and siltstones of the Lanes tongue of the Ankareh resented by a covered interval between the underlying formation are 508 feet thick at Hot Springs, 745 massive beds of the lower limestone and the overlying feet at Spring Canyon, Sublette Ridge, and 200 feet middle limestone. In Spring Canyon, Sublette Ridge, at Cokeville Canyon. In the Spring Canyon section 287 feet of well-exposed dark-gray, silty limestone is there are several thin, white sandstone beds and a con­ assigned to this unit. At Cokeville the unit is 107 feet spicuous 31-foot bed of white, calcareous sandstone, 145 thick and at Hot Springs 229 feet. Fossils are rela- feet above the upper calcareous siltstone unit. West of . tively scarce, but flattened impressions of cephalopods Bear Lake the upper part of the Thaynes formation, are occasionally found. which will be discussed separately, contains no red beds. Middle limestone.-In the Hot Springs, Montpelier Portneuf limestone member.-At Hot Springs this Canyon, and Sublette Ridge areas, the first massive member of the Thaynes formation consists of 67 feet of scarp above the lower limestone consists of 90 to 400 feet massive, gray to blue, crystalline limestone that is of massive, gray, finely crystalline lill).estone containing cavernous in the lower part and contains a few interstratified silty beds. The middle limestone and pelecypods. The upper 5 feet is massive dark­ is 90 feet thick at Cokeville, Wyo.; 290 feet at Spring gray siltstone that weathers to a greenish buff and con­ Canyon, Sublette Ridge; 230 feet at Hot Springs and tains some chert bands. In Spring Canyon, Sublette 385 feet in the Montpelier Canyon, where the limestone Ridge, it is 12.5 feet of unfossiliferous olive-gray, mas­ is very silty. This unit contains bra.chiopods and pelec­ sive limestone and olive-buff calcareous siltstone. l'he ypods, but in this area no ammonoids have been found. same thickness and lithology is fo~nd in Cokeville Middle shale.-Througl)out the Bear Lake Valley ·canyon, Sublette Ridge. and Sublette Ridge areas, a black shale and shaly lime­ Timothy sandstone 1nember.-In Home Canyon stone unit, containing fossiliferous black limestone con­ about 6 miles east of Montpelier, the Timothy contains cretions, overlies the middle limestone. Cephalopods conglomeratic layers with limestone pebbles possibly are the most abundant fossils present; the ammonites derived from the Thaynes (Mansfield, 1927, p. 91). At belong to the Oolumbites zone of Smith (1932). The Hot Springs along Indian Creek, the Timothy is com­ middle shale ranges from 80 to 130 feet in thickness in posed of 125 feet of red siltstone, shale, and sandstone. Paris Canyon, Bear River Range; Montpelier Canyon; Here it has more of the appearance of the typical lower and at Hot Springs, Idaho. In Sublette Ridge this unit part o:f the Ankareh formation of northern Utah. In measures about 105 feet in Spring Canyon and only Spring Canyon and at Cokeville, in Sublette Ridge, the 50 feet at Cokeville. The fauna of the middle shale Timothy is missing, and Higham grit lies on the upper consists of cephalopods, pelecypods, and fragmentary part of Portneuf limestone, Thaynes formation. bones. The concretions contain abundant well-pre­ served specimens; in fact, many concretions are co­ BEAR RIVER RANGE quinoid. The enclosing shale also contains the flattened The top of the 3,500 feet of Thaynes west of Bear impressions of cephalopods and pelecypods. Upper cawareous siltstone.-This homogeneous unit Lake in Paris Canyon area of the Bear River Range of silty limestone overlying the middle shale is one of (pl. 29) is unexposed. The lower limestone with the thickest and most conspicuous units of the Thaynes Meekoceras, middle shale with Oolwmbites, and upper formation in this area of southeastern Idaho. The unit calcareous silt~tone in Hot Springs-Sublette Ridge are as a whole is buff and thin to massively bedded and recognizable here. Above the upper calcareous silt­ forms long talus slopes of blocky, silty, buff limestone stone, however, there is 1,500 feet of non-red lime­ and calcareous siltstone. Fossils are not common. The stone and shale unlike the beds above the middle shale unit is about 1,000 feet thick in the area between Hot in the Hot Springs-Sublette Ridge area.. The top Springs and Sublette Ridge. of this sequence is buried under deposits of Cenozoic In Sublette Ridge approximately 60 to 200 feet of age, but the beds are at least partially equivalent to nodular, black, silty limestone immediately overlies the the Lanes tongue of the Ankareh formation east of middle shale. Lithologically, these beds appear to be Bear Lake and to the upper black limestone, sandstone more closely allied to the underlying black shales than and limestone, and the Portneuf limestone member of to the overlying gray, silty . The nodular the Thaynes formation in the area between Fort Hall limestone facies has not been found in the Bear Lake and Grays Range. These upper. beds of the Thaynes 176 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY for1nation in the Paris Canyon area were discovered bedded. The upper 350 feet of this unit is poorly ex­ and differentiated by V. E. McKelvey of the U. S. Geo­ posed, and only isolated pieces of limestone were found. logical Survey in the course of geologic mapping in 1943. The only fossils found throughout the exposed portion The lower limestone of the Thaynes is 116 feet thick were pelecypods. and lithologically identical with the exposures of this The ammonoids present in the lower half of this unit east of Bear Lake. The lower shale and middle 1,500-foot sequence are particularly diagnostic because limestone units of the Hot Springs area are not readily of the presence of Proh111ngarites, a ceratite previously distinguishable. On the west bluff of Bear River, 2.25 only known from Timor and possibly the Himalayas. miles west of Georgetown, Idaho, the lower part of the Spath (1934) named his highest division of the Scyth­ lower shale is well exposed and consists of black shale ian after this genus. The writer has previously re­ containing black limestone concretions and lenses, ferred this ceratite to Aratoceras (Kummel, 1950) . which are very fossiliferous. The ammonites present are similar to those from Fort Douglas, Utah, described WESTERN WYOMING by Mathews (1929) and belong to the Anasibirites zone The Thaynes formation exposed in Sublette Ridge is of the Scythian series (Spath, 1934). Between the identical in character and lithologic units with that lower limestone and the middle shale with 0 olu1nbites recognized around Bear Lake Valley, Idaho. South­ in the Paris Canyon area is 1,000 feet of gray to black east of Sublette Ridge, along Muddy Creek, just west limestone, nodular in part. The lower 300 feet of this of Cumberland, the Thaynes consists of 1,165 feet of sequence is not exposed and is probably shaly. The limestone, mostly silty and sandy, interbedded with fine­ overlying 320 feet is dark-gray to gray-buff, fissile, thin­ grained sandstone (H. D. Thomas, personal communi­ beaded limestone containing impressions of cephalo­ cation). This section is overlain by about 285 feet of pods. The overlying beds are gray to black limestone,. red shale and sandstone, which is the Lanes tongue of nodular in part, containing cephalopods belonging to the Ankareh formation. Overlying the Lanes tongue the Tlrolites fauna of Smith (1932). The upper 35 is a 3-foot bed of dense, finely crystalline, gray lime­ feet of this unit is gray, finely crystalline limestone stone, which is thought to be a tongue of the upper containing myriads of Pugnoides triassi(fUIS. None of part of the Portneuf limestone member of the Thaynes this sequence, except possibly the upper 35 feet, is lith­ formation (pl. 39). The lithology of the Thaynes sec­ ologically similar to the middle limestone unit that is tion at Muddy Creek is more homogeneous in character so well developed east of Bear Lake. The middle lime­ than the Thaynes in southeastern Idaho and in Sub­ stone unit appears to tongue out westward, as it does lette Ridge. northward toward Sheep Creek, into the lower black North of Sublette Ridge in Swift Creek Canyon, limestone of that section. The middle shale is 130 feet Salt River Range, the Thaynes formation is about 1,385 thick and identical with the exposures east of Bear feet thick (pl. 38). The lower two-thirds of the sec­ Lake. The upper calcareous siltstone is similar to that tion consists of alternating beds of gray, massive lime­ unit as exposed at Hot Springs. stone and calcareous siltstone. The gray limestone beds Overlying the upper calcareous siltstone unit is 1,500 form massive vertical walls in the canyon, and the cal­ feet of beds that are completely unlike any other beds careous siltstone beds form the depressions between in the upper part of the Thaynes formation known else­ these walls. The upper third of the formation is cal­ where in southeastern Idaho. Only part of this unit is careous siltstone with which a few thin gray, finely well enough exposed tQ permit detailed study and meas­ crystalline limestones are interbedded. The Thaynes urement. The sequence does not seem to be compli­ formation is overlain by 775 feet of red beds of the cated by faults or folds, and the thicknesses seem correct. Ankareh formation. The M eekoceras fauna occurs in The lowest 400 feet consists of gray, shaly limestone, the basal limestone unit 135 feet above the Woodside in the lower part grading to olive-gray and gray­ formation. The upper part of the Portneuf limestone brown shales containing several thin limestone beds in member of the Thaynes formation at Sheep Creek, the upper part. These lower beds contain abundant Grays Range, Idaho, tongues out eastward toward the cephalopods and pelecypods. This lower unit is over­ Salt River Range. The Thaynes formation at Swift lain by 450 feet of gray, argillaceous limestone, part of Creek is equivalent to the beds extending from the which is nodular and fossiliferous. The uppermost lower part of the Portneuf limestone member to the part, 650 feet, consists of gray, massive, finely crystal­ lower limestone with M eekoceras at Sheep Creek. The line limestone, which is silty in part. Approximately numerous lithologic units recognized in the Thaynes 1'60 feet above the base of this upper unit is a 25-foot in Idaho cannot be distinguished in this part of west­ bed of white, mottled sandstone., medium to massively ern Wyoming. In the Wyoming Range near the head- TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 177

waters of Middle Piney Creek the Thaynes formation ~fountain near the Notch Ranger Station. Thin in­ is approximately 1,000 feet thick and lithologically sim­ complete sections are also present in Odell-Canyon, Cen­ ilar to the section at Swift Creek. The 11! eekoceras tennial Range, and along Fossil Creek in the Gravelly fauna is not present at the base of the formation. In Range. The most striking character of the Thaynes in fact, no cephalopods were found in the Thaynes for­ southwestern Montana is the predominance of calcare­ mation in this area. No unfaulted section was found ous sandstone (pl. 37). where detailed measurements of the formation could be In Little-Water Canyon 680 feet of the Thaynes for­ made. mation is overlain unconformably by sandstones of the H. R. Wanless (personal communication) measured . The lower 109 feet of this sectim~ consists 1,157 feet of the Thaynes formation in the Snake River of gray, finely crystalline limestone interbedded with Range at Wolf Creek and at Red Pass. The section is silty and sandy limestone. Approximately 90 feet similar to that at Swift Creek and at Middle Piney above the base of the Thaynes are ammonites belonging Creek. The formation consists entirely of an alternat­ to the llfeekoceras fauna. This lower li1nestone of the ing sequence of limestone, calcareous siltstone, and Thaynes formation is overlain by 218 feet of grayish­ sandstone. No cephalopods have been found in the white to tan calcareous, fine-grained sandstone. The Thaynes formation in this locality. ,The Thaynes for­ upper 355 feet consists of an alternating sequence of mation is 645 feet thick at the drainage divide between gray, finely crystalline limestone, with numerous chert the headwaters of Buck Creek and Adan1s Creek, about nodules in parts, and calcareous sandstone and siltstone. a mile northwest of Ramshorn Peak, Hoback Range. Ammonites are present only in the lower part of this The lower 118 feet consists of sandy and silty, gray section. Pelecypods, brachiopods, and columnals of limestone with a 3-foot red shale in the middle. This Pentacrinus are sparse throughout the section. Moritz is overlain by 243 feet of red shale and siltstone which ( 1951) recognized the threefold lithologic divisions of . is a westward tongue of the Chugwater formation. The the Thaynes formation in this part of soutlnvestern upper 283 feet consists of gray sandstone, limestone, and Montana and named them the '"Lower limestone mem­ siltstone. The Thaynes formation here is overlain by ber;· the "Sandstone member," and the "Upper lime­ approximately 700 feet of red shale and siltstone of stone member." Fossil evidence is not yet available to the Ankareh formation (H. R. Wanless, personal com­ correlate these units of the Thaynes with those rec­ munication) . ognized in southeastern Idaho. Near the northeast corner of the Irwin Quadrangle, At Hogback Mountain in the Snowcrest Range, 610 the Thaynes formation is 1,000 feet thick (Gardner, feet of Thaynes formation is unconformably overlain 1944) . The formation consists of a gray limestone and by the l(ootenai formation. Here the Thaynes forma­ calcareous sandstone, 80 feet thick at the base, overlain tion is almost entirely fine to medium grained, gray to by 295 feet of red shale and sandstone and a few gray buff, calcareous sandstone; but it contains several thin sandy limestone beds, and finally 625 feet of sandy, gray beds of gray limestone, sandy li1nestone, and shale. limestone and calcareous sandstone. In the Gros Ventre Two red sandstone beds and several that are n1ottled Canyon the interval of 400 feet between the Woodside red are present in the section. Pelecypods are the only formation and the is mostly ~ed shale eonunon fossils in this 610-foot section. Along Odell and siltstone (Newell and Kummel, 1942) . There are, Creek, Centennial Range, 145 feet of silty limestone with however, at the base and near the middle of this red numerous chert nodules in the upper part is assigned to sequence, thin beds of gray limestone and shale that the Thaynes. appear to be tongues of the Thaynes formation extend­ ing eastward into the Chugwater formation. CENTRAL WASATCH AND UINTA MOUNTAINS The Thaynes formation is well developed in the Fort SOUTHWESTERN MONTANA Douglas ~iilitary Reservation in Salt Lake City, Utah. Pre-Jurassic erosion in southwestern Montana has Eastward along the Uinta :Mountains and southward to­ rmnoved much of the formations of Triassic age so that ward Provo, Utah, the Thaynes intertongues with the most sections are incomplete and unconformably over­ Ankareh fonnation and ultimately disappears com­ lain by the Jurassic Ellis group or the Cretaceous pletely. At Fort Douglas the Thaynes is about 1,930 . Few thick sections of the Thaynes feet thick and consists of gray limestone, shale, and cal­ formation and no Ankareh fonnation appear to be careous sandstone (A .. E. Granger, personal communica­ present in this area. Rather well-exposed but incom­ tion) . In the Park City mining district, the type plete sections of the Thaynes formation were measured locality of the Thaynes, it consists of 1,190 feet of lime­ at Little Water Canyon, west of Dell, and in Hogback stone, calcareous sandstone, sandstone, shale and a mid- 288901--54-3 178 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY CD @ ® Vertical scale @ 1500' Stonoker member Chinle formation

Gartra grit Shinarump conglomerate member

1000' .J:: ~ c .X c: Mahogany ~ member



Bear--1 Lake I Thaynes I formation I y I w 0 M N G I l : oEvanston I Fort Douglas L------~---

0 @Weber River l Park [email protected] Whiterocks ! COLO Canyon® 0Vernal 6 1 OHeber @) ®Lake Fork @ Duchesne Split 8 1 Woodside U T River A H Mountain 1 @ I Skull g formation 0 50 Miles 0 Duchesne Creek INDEX MAP

Modified from Thomas and Kru eger(l946, plate 36)

FIGURE 21.-Correlation of formations of Triassic age along the south flank of Uinta Mountains, Utah and Co~o. Modified from Thomas · and Krueger, 1946, fig. 5. cUe red shale unit (Boutwell, 1907). The lower 375 feet with the middle red unit of the section at Park City and of the Ankareh formation of Boutwell contains inter­ represents a westward-extending tongue of the Ankareh calated beds of gray sandstone and grayish-blue lime­ formation. Along the Duchesne River~ north of stone. These nonred strata are eastward-extending Hanna, Utah, the Thaynes is 270 feet thick and ;qpears tongues of the Thaynes in the Ankareh formation (fig. to be correlative with the lower nonred unit of the 21 and pl. 40.). Thaynes at Weber River. The section at Duchesne Along the Weber River, in the western Uinta Moun­ River likewise contains a 110-foot red shale and cal­ tains, the Thaynes formation is approximately 750 feet careous sandstone unit near the top. Along the east thick and has a 190-foot red shale and sandstone unit side of Lake Fork, in Duchesne County, Ub.h, the just above the middle. Above and below this red unit, Thaynes is represented by 118 feet of calcareous silt­ the Thaynes consists of gray limestone, sandy limestone, stone and sandstone. In 'Vhiterocks Canyon the and calcareous siltstone. The red unit is correlated Thaynes consists of 12 feet of white sandy limestone TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 17Y (Thmnas and Krueger, 1946). The Thaynes disap­ in the region around Proyo, Utah. A. E. Granger pears completely between Whiterocks Canymi and (personal communication) followed the same procedure Vernal, Utah (Thomas and Krueger, 1946). Through­ in mapping the area just east of Salt Lake City. out the Uinta Mountains the Thaynes contains numer­ For southeastern Idaho and adjacent parts of Utah ous poorly preserved pelecypods; cephalopods are and vVyoming, Gale and Richards (1910) used the extremely rare. name Ankareh for red shales lying between the Thaynes At the mouth of Diamond Fork, southeast of Provo, and the restricted Nugget formation of Veatch. Utah, the Thaynes formation is composed of 1,350 feet Schultz (1914) used the name Ankareh for red shale of gray limestone, which is generally sandy and cherty and sandstone lying between the Thaynes and theN ug­ in part; sandstone; and shale. Numerous red beds get formations in Lincoln County, Wyo. This usage is are intercalated. The whole section represents an still followed in western Wyoming (W. W. Rubey, per­ intertonguing facies of the Thaynes and Ankareh sonal communication) . formations. In southeastern Idaho the thickest sequence of pm;t­ POST-THAYNES TRIASSIC Thaynes Triassic rocks is found in the Fort Hall Indian Reservation. Mansfield ( 1927) recognized the follow­ A variable sequence of beds that are generally red ing formations: Timothy sandstone, Higham grit, lies between the top of the Thaynes formation and the Deadman limestone, and Wood shale. These units thin base of the Nugget sandstone throughout western 'Vyo­ and tongue out eastward toward Wyoming. ming, southeastern Idaho, and northern Utah. Bout­ As now used the name Ankareh formation is applied well ( 1907) called these beds, in the Park City dis­ to different parts of the post-Thaynes sequence in the trict, the Ankareh formation. Although they are still Middle Roc.ky Mountains. In western Wyoming it is so defined in western vVyoming, they have since been applied to all the strata between the Thaynes forma­ subdivided and named differently in other areas. tion and the Nugget sandstone. In Utah it. is applied There has been a great deal of confusion in nomencla­ only to the beds from the Thaynes to the Gartra grit. ture and correlation of these formations. In Idaho the name Ankareh was abandoned by Mans­ In the original definition of the Ankareh, Boutwell field. However, the Gartra grit is probably equivalent (107, p. 453) stated that only part of this formation oc­ to the Higham grit, and the Higham grjt is present in curs in the Park City district and that the uppermost western Wyoming in the Ankareh formation. To part was marked by a prominent, massive, white sand­ simplify· and clarify the nomenclature of these post­ stone member. Boutwell (1912) later restricted the Thaynes Triassic rocks, the Ankareh formation as orig­ Ankareh and included the upper 500 feet of white sand­ inally defined by Boutwell to include all the strata stone with some intercalated reddish shale in Veatch's between the Thaynes and Nugget formations is here a p­ Nugget formation as redefined by Gale and Richards plied in northern Utah and western ·1Vymning, and (1910). A similar ptocedure was followed by Mathews all the various formations that have been proposed for (1931) and Boutwell (1933) for the central Wasatch parts of this sequence reduced to 1nember rank. In Mountains. These authors thus considered the An­ the eastern Uinta Mountains, the Colorado Plateau kareh to include the red strata frmn the top of the nomenclature is used following Kinney and Rominger Thaynes to a prominent "basal conglmnerate," ( Gartra (1947). In southeastern Idaho, the Timothy sands:one grit of Thomas and Krueger, 1946) which is associated is now considered to be the uppermost 1nember of the with red shales they thought to be part of the Nugget. Thaynes formation. The Higham grit and Deadman Thomas and Krueger ( 1946) reviewed in detail the limestone are ranked as independent formations, and literature on these post-Thaynes Triassic rocks for the the Wood shale is considered a westward extencLng central 1V asatch and Uinta ~1ountains. They proposed tongue of the reel Ankareh formation as used in a threefold division of this interval into the Ankareh vVymning. This plan should lead to 1nore consiste11cy formation, Gartra grit, and Stanaker formation. Wil­ and understanding of this stratigraphic interval. E~1ch liams (1945) proposed using the Idaho terminolgy, of the main areas of outcrop and the units present will Ankareh for1nation, Higham grit, and Wood shale for be discussed briefly. the formations in the central Wasatch Mountains and western Uinta Mountains, and the Colorado Plateau CENTRAL WASATCH MOUNTAINS AND UINTA tern1inology, Red Wash formation, Shinarump con­ MOUNTAINS glomerate, and Chinle formation, for those in the east­ ern Uinta Mountains. The red bed sequence between the Thaynes and the Baker (1947) included in the Ankareh all the red Nugget formations in the central Wasatch and Uinta strata between the Thaynes and the Nugget formations .Mountains is divisible into three distinct units. There 180 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY is ( 1) a lower red shale and sandstone, ( 2) a n1iddle advantage in using the name Red Wash formation coarse white to pink, conglomeratic sandstone, and ( 3) ( =Moenkopi) proposed by Williams ( 1945). The an upper red shale and sandstone. Thomas and Krue­ Moenkopi formation is equivalent to the interval of the ger (1946) proposed restricting the name Ankareh to Woodside, Thaynes, and Mahogany member of the the lower red shale and sandstone ; they called the con­ Ankareh formation in the western Uinta Mountains glomeratic sandstone and the overlying red beds the and Wasatch Mountains. The Shinarump conglom­ Stanaker formation and named the conglomeratic sand­ erate correlates with the Gartra grit member of the stone the Gartra grit member of the Stanaker fonna­ Ankareh formation, and the Chinle formation with the tion. Williams ( 1945) proposed using Ankareh forma­ Stanaker member of the Ankareh formation in the tion, Higham grit, and Wood shale in the central ~western Uinta and Wasatch Mountains. Wasatch and western Uinta Mountains. It does not The Gartra grit member is a poorly sorted, coarse­ seem advisable, however, to use the Idaho terminology grained, feldspathic quartz grit. It ranges in thickness for this series of beds. from 26 to 93 feet and lies unconformably on the. 1\fa­ Extending the name Ankareh to include the beds be­ hogany member of the Ankareh formation (Thomas tween the Thaynes and the Nugget formations as orig­ and Krueger, 1946). The Stanaker member consists inally defined by Boutwell necessitates reducing the new of varicolored shale and sandstone between the Gartra names proposed by Thomas and I\:rueger to member grit member and the Nugget sandstone. The thickness rank. Thus, there would be the Stanaker member and of the Stanaker in northern Utah ranges from 120 to Gartra grit member of the Ankareh formation. The 400 feet (Thomas and Krueger, 1946). unit referred to the Ankareh, as restricted by Thomas In the vicinity of Provo, Utah, Baker (1947) meas­ and Krueger (1946) .and Williams (1945), will have to ured 1,485 feet of the Ankareh in Scott Draw west of receive a new name since the name Ankareh cannot be Charleston, Utah, and 1,530 feet along Diamond Fork used both for the formation and for one of its members. near Thistle, Utah. The Ankareh formation at both The Mahogany member of the Ankareh formation is localities is divisible into a lower red shale and sand­ proposed for the red shale and sandstone beds be­ stone unit and an upper unit of variegated, red shale tween the top of the Thaynes and the base of the Gartra with interbedded red and purplish-red, fine-grained to grit in the central Wasatch and Uinta Mountains. The conglomeratic sandstone. At Scott Draw, Baker re­ member is named after the Mahogany Hills, north of cords a 35-foot conglomeratic bed at the base of the Weber River, T. 1 S., R. 6 E., Summit County, Utah, upper 1nember. This is probably equivalent to the where the Thaynes and Ankareh formations are well Gartra grit member of the Ankareh formation. The developed. The Mahogany member of the Ankareh Gartra grit member does not appear to be distinguish­ formation also intertongues with the Thaynes forma­ able at Diamond Fork. tion. In the Fort Douglas Military Reservation, Salt Lake SOUTHEASTERN IDAHO City, the Mahogany member is 850 feet thick, the Gartra grit member 60 feet, and the Stanaker member Mansfield ( 1927) recognized the following sequence 390 feet (A. E. Granger, personal communication). of beds between the Thaynes and Nugget formations : Between Park City and the Duchesne River, the Ma­ Wood shale hogany member of the Ankareh formation thickens Deadman limestone greatly as the Thaynes formation tongues out eastward Higham grit (fig. 21). Between the Duchesne River and Whiterocks Timothy sandstone. Canyon of the Uinta Mountains, the Mahogany member These units are each distinct lithologically and are thins and is only 555 feet at Whiterocks Canyon. Be­ equivalent to the Ankareh formation of the Wasatch yond the point where the tongue of the Thaynes wedges and Uinta Mountains and of western Wyoming. In tllis out, the red beds of the Woodside formation and the report the Timothy sandstone is considered to be the Mahogany member of the Ankareh cannot be separated. uppermost mmnber of the Thaynes formation. The Thomas and Krueger ( 1946) believe this sequence is Timothy sandstone member is lithologically related to entirely Woodside. and in part gradational with the Portneuf limestone However, in the eastern Uinta Mountains where the member of the Thaynes formation. The Higham grit Thaynes fonnation is absent, the Triassic nomencla­ unconformably overlies the Timothy sandstone member. ture of the Colorado Plateau, namely the Moenkopi, The Higham grit and Deadman limestone are recog­ Shinarump, and Chinle formations, is applicable nized as independent formations, but the Wood shale (Kinney and Rominger, 1947). There is no apparent is considered a westward extending tongue of the An- TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 181 kareh formation comparable with the Lanes tongue At Swift Creek in the Salt River Range, the Ankareh of the Ankareh formation. formation is 775 feet thick. It contains a massive 10- The Higham grit consists of coarse conglon1eratic, foot bed of light-tan sandstone 215 feet above the white, pink, and purple quartz sandstone. This forma­ Thaynes formation that may be correlative with part or tion was named by Mansfield (1916) from Higham all of the Timothy sandstone member of the Thaynes Peak in the northeastern part of the Fort Hall Indian formation of Idaho. At the headwaters of Middle Reservation, where it is about 500 feet thick. In the Piney Creek in the Wyoming Range, the Ankareh is Freedom quadrangle it measures about 200 feet. The composed of 850 feet of red sandstone and some red Higham is 135 feet thick at Hot Springs, 55 feet at shale beds. Spring Canyon, and 105 feet at Cokeville, Sublette In the Snake River Range, H. R. Wanless (personal Ridge, Wyo. The Higham lies unconformably on the communication) measured 359 feet of beds between the Timothy sandstone member or, where this member is Thaynes formation and the Nugget sandstone. The not present, on the Thaynes fonnation. The Higham lower 258 feet is red shale and sandstone, and the upper probably correlates with the Gartra grit and Shinarmnp 111 feet is red and purple shale and siltstone with which conglomerate of northern Utah. numerous thin beds of gray, red, and purple limestone The Deadman limestone has its type locality in the are intercalated. This 111-foot member Wanless ten­ Fort Hall Indian Reservation, where it is 150 feet thick. tatively correlates with the Deadman limestone, but it It consists of white, pinkish, or green, dense, massive, is possible that the intercalated beds of limestone may nodular limestone. In its type area it lies directly on represent the featheredge of the Thaynes formation the Higham grit; southward around Montp~lier the tonguing eastward into the Ankareh. At any event the Deadman limestone appears to lie in the midst of red whole sequence should be considered the Ankareh for­ shales (Mansfield, 1927, p. 95). The Deadman limestone mation. In the Hoback Mountains there is approxi­ was not recognized at Spring Canyon, Sublette Ridge, mately 700 feet of red shale and sandstone with a 4-foot or at Hot Springs. At Cokeville a 10-foot limestone bed of limestone near the middle that is referable to the bed resting on the Higham grit may belong to the Dead­ Ankareh formation (Wanless, personal communica­ man limestone. tion). The underlying Thaynes formation contains a Red shales and siltstones that are generally poorly ex­ prominent red tongue of the Ankareh formation. Near posed lie between the Deadman limestone and the the northeast corner of the Irwin Quadrangle, the Jurassic Nugget sandstone. Mansfield (1916) named Ankareh is 550 feet thick (Gardner, 1944). these beds the Wood shale in the Fort Hall Indian Reservation, where they range from 200 to 250 feet CHUGWATEn FORMATION OF CENTRAL WYOMING in thickness. This unit is considered to be a westward Throughout the Wind River Mountains, post-Din­ extending tongue of the Ankareh formation and is here woody Triassic rocks are all red sandstones and silt­ called theWood shale tongue of the Ankareh formation. stones except for one thin limestone member; they are The Wood shale tongue is approximately 250 feet thick all placed in the Chugwater formation. There are three·. in Spring Canyon, 40 feet at Cokeville, and 400 feet at members of the Chugwater that are distinctive enough Hot Springs. to be useful in regional work (Love, 1948). These are WESTERN WYOMING the Red Peak, Alcova li1nestone, and Popo Agie mem­ Throughout western Wyoming the red bed sequence bers. The Red Peak consists of 800 to 1,000 feet of between the Thaynes formation and Nugget sandstone red siltstone, shale, and silty sandstone overlying the is called the Ankareh formation. The Higham grit Dinwoody formation and underlying the Alcova lime­ is discontinuous and does not constitute a mappable unit stone member. Newell and Kun~mel (1942) demon­ (W. W. Rubey, personal communication); where pres­ strated that at least the lower part of the Red Peak ent it is considered a member of the Ankareh. The grades into the Woodside formation of the southeastern Ankareh formation at Muddy Creek, in Lincoln Idaho. In the area west of Paris~ Idaho, and around County, is about 650 feet thick (H. D. Thomas, personal Henry, Idaho, the rocks of equivalent age are entirely communication). The formation contains a· 3-foot bed gray and buff limestone, shale, and siltstone of marine of gray limestone in the middle of the section that is origin. The red beds of the Red Peak intertongue with correlated with the upper part of the Portneuf lime­ these nonred marine deposits. stone member of the Thaynes formation of southeastern The Alcova limestone member consists of approxi­ Idaho. If this correlation is correct, the underlying mately 15 feet of gray to slightly pinkish, hard, finely red beds are part of the Lanes tongue of the Ankareh crystalline, thin-bedded limestone. The limestone is formation. present throughout the Wind River Basin and is th~ 182 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY only limestone in the Chugwater formation in this sen ted. The known faunas are· cosmopolitan and sur­ area (Love, 1948). The Alcova member is probably prisingly homogeneous. Much less is known of Lower equivalent to some part of the Thaynes formation of Triassic faunas than those of the Middle and Upper southeastern Idaho. Love (1948, p. 99) states, "* * * Triassic. This is also true for the upper Permian the Alcova limestone is somewhat younger ithan at faunas. One of the principal reasons for this is the lack least the major part of the lower Triassic Thaynes of well-developed late Permian and Early Triassic formation." marine deposits. The late Permian ammonoid, Oyclo­ ',I'he youngest member of the Chugwater formation lobus, is·found only in the Salt Range, Pakistan; in the is the Popo Agie. It consists of " * * * 100 to 200 Himalayas, India; Madagascar; Timor; and in East feet of ocher-colored, oolitic, siliceous, dolomitic clay­ Greenland. Other young Permian deposits, such as the stone; limestone pellet conglomerate; purple and red Bellerophonkalk of the and the beds at Djulfa shale; and red silty sandstone'' (Love, 1948, p. 99). in Armenia, contain rather sparse and poorly under­ In the northwestern part of the Wind River Basin the stood faunas. Earliest Scythian rocks, characterized Alcova limestone member is missing, but there is a se­ by the presence of the ammonite OtoOO'l'as, are only quence of gray, oil-saturated sandstone called by Love known in the Himalayas and in East Greenland. In ( 1939) the Crow Mountain member of the Chugwater the Ussuri Bay region near Vladivostock, early Scyth­ formation which is equivalent to sandstone that both ian deposits occur, but Otoceras is not present. Younger underlies and overlies the Alcova member in other parts Scythian rocks are of more widespread occurrence. of the Wind River Basin (Love, 1948). In the Wind Zoning of the Lower Triassic has been done mostly River Basin there is generally a series of red siltstones on the basis of ammonites as in the remainder of the and sandstones between the Alcova and the Popo Agie Mesozoic. However, there are some pelecypods, es­ members. This post-Alcova-pre-Popo Agie unit is simi­ pecially Olaraia, which are important. The establish­ lar in lithology to the Red Peak member but has not re­ ment of a chronology of Lower Triassic ammonite zones ceived a separate name. Around Green River Lakes has been attempted by numerous Triassic students. J. the post-Alcova consists of 240 feet of maroon sand­ P. Smith was the leading American student, and he stone over lain by 85 feet of typical Popo Agie rocks very ably summarized his views in his last monograph (Richmond, 1945). (1932). In Europe there were numerous individuals Fossils are very scarce in the Chugwater formation, who tackled this problem, in which names of W aagen, and exact dating and correlation with the marine se­ Mojsisovics, Diener, Arthaber, Frech, and Noetling are quence in Idaho is uncertain. The only fossil recorded important. Smith (1932) was the last of the above from the Red Peak member is a poorly preserved group of authors to summarize his views on Lower "Monotis" sp. identified by J. B. Reeside. The Alcova Triassic faunal zones. Smith established five faunal limestone member has yielded a few marine inverte­ zones, into which he placed all the important Lower brates and a marine , but none of these fossils Triassic faunas known to him. His faunal chronology, are diagnostic. The Alcova member is probably cor­ relative with some portion of the upper part of the starting with the oldest, is as follows: Otoceras, (}eno­ Thaynes formation. The Popo Agie member has d~CU'8, Meekoceras, Tirolites, Oolwmbites. yielded some phytosaurian remains, poorly preserved The latest review of Triassic ammonoids and faunal plants, and a few pelecypods. The age of the Popo chronology is by Spath ( 1934, 1951). He propos~d six Agie member has been considered to be Upper Triassic faunal divisions, each of which contains one or more by some investigators and Middle Triassic by others ammonite zones. Spath's subdivisions are as follows: (Love, 1948). The Popo Agie member may be cor­ Prohungaritan relative with all or part of the post-Thaynes Triassic Upper . Lower { Flemi~gitan Eo-Triassic OColu~tabitan Eo-Triassic Gyromtan beds of Idaho and the Stanaker and Gartra grit mem­ { wen1 n · Otoceratan bers of the Ankareh- formation in the central Wasatch and Uinta Mountains of Utah. The Gyronitan is equivalent to the Genod~cus zone of Smith (1932), the Flemingitan and Owenitan to the AGE AND CORRELATION OF TRIASSIC FORMATIONS M eekoceras zone of Smith, and the Columbitan includes Lower Triassic faunas throughout the world are not the Tirolites and 0 olumbites zones of Smith. Spath varied and consist mainly of pelecypods and ammonites. demonstrated in a convincing manner that Smith had Whole phyla, such as the , , failed to appreciate the incompleteness and limited time , coelenterates, and are practically un­ span of his own faunas; likewise, that many of Smith's known; brachiopods and gaStropods are sparsely repre- zones (for example Oolumbites) included heterochron- TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 183 ous faunas. At the same time Spath pleads caution and 0. (Discophiceras) subkyokticum Spath stresses the incompleteness of our knowledge of Lower 0. (Metophiceras) su.bdemissum Spath Triassic faunas. The Prohungaritan division was estab­ The species listed above are present in the Ophiceras lished tentatively due to lack of sufficient data and beds (of Otoceratan age) of East Greenland. As most faunas. It is a worthy testament to Spath's genius that students of early Triassic ceratites are aware, specific new faunas in the upper Thaynes substantiate clearly his identification is extremely difficult, especially so when original theory on this upper Scythian faunal division. only a few poorly preserved specimens are available. The Lower Triassic strata in Idaho comprise one of Whereas the above identifications of lower Dinwoody the thickest marine sections known in the world. .Like­ ammonites can only be considered tentative on a specific wise, the succession of amonite zones is more complete level, the generic assignments appear to be correct. than in most of the classic Scythian localities in Eur­ Newell and Kummel ( 1942) list the following species asia. The great thickness of marine deposits .and the from the "Lingula" unit of the Dinwoody formation: numerous faunas present make the Lower Triassic of Discophiceras subkyokticum Spath Idaho one of the very important sections in the world. Metophiceras subdemissum Spath Monographic treatment of the Lower Triassic faunas M entzelia sp.? from the Middle Rocky Mountains is now in progress. Spirijerina mans{ieldi Girty Pleurophorus? bergeri Girty The following discussion of faunal zones is confined Lingula borealis Bittner mainly to the ammonite zones, partly because they are Myalina putiatinensis Kiparisova the most significant for interregional correlation and M. spath-i Newell and Kummel because data on the pelecypods and brachiopods are not Olaraia stachei Bittner yet assembled. These data, however, will not alter the Faunas of Otoceratan age are very limited in dis­ correlations established by the ammoni~es. The Din­ tribution, and large ammonite faunas of this age are woody and Thaynes formations contain ammonite known only from the Himalayas, East Greenland, and faunas belonging to all six of the faunal divisions estab­ the Ussuri district of eastern Siberia. Spath (1935) lished by Spath. The Dinwoody formation contains has demonstrated the close faunal affinities between ammonite zones of the Otoceratan, Gyronitan, and these three areas. To these three areas we must now Flemingitan divisions. The Thaynes formation con­ add the lower Dinwoody fauna as pointed out by Newell tains ammonite zones of the Owenitan, Columbitan and and Kummel (1942). The lower Dinwoody fauna in­ Prohungaritan divisions. The Otoceratan and Gyroni­ dicates an upper Otoceratan age, though the ceratite tan age of part of the Dinwoody formation was estab­ Otoceras, which characterizes the lowest Scythian am­ lished by Newell and Kummel ( 1942). New ammonite monite zone in the Himalayas and East Greenland, has faunas of Gyronitan and Flemingitan age from the Din­ not been found in the Middle Rocky Mountains. _woody formation are listed below. Smith (1932) There are other areas inNorth America where faunas monographed the ammonite faunas from the Meeko­ of Otoceratan age have been reported, but the evi­ ceras, Tirolites, and 0 olu.mbites zones of the Thaynes dence is not conclusive. Muller and Ferguson ( 1939) formation. Mathews (1929) has described the A.na­ record Olaraia clarai, 0. stachei, and 0. aurita from sibirites fauna (upper Owenitan) from Fort Douglas, the lower part of the formation in south­ Utah; this fauna is now also known from Idaho. An western Nevada; where they tentatively place this ammonite fauna of Prohungaritan age is present in the fauna in the Otoceras zone. These species of Olaraia upper Thaynes in the Paris Canyon area of Idaho. are good index fossils of the Sythian, but they do range No large faunas of ammonites have as yet been found above the 0 toceras zone. Three similar species of in the Dinwoody formation; however, three small Olaraia ( 0. stachei, 0. clarai occidentalis, and 0. faunas of a dozen or less individual specimens and rep­ tnulleri) have been recorded from the "Olaraia" unit resenting three distinct zones have been found. The of the Dinwoody formation in southeastern Idaho and lower shale unit of the Dinwoody formation in Mon­ western Wyoming at a horizon younger than the tana and the silty limestone and "Linqula" unit of the Otoceras zone (Newell and Kummel, 1942). However, Dinwoody in southeastern Idaho and western Wyo­ overlying the Olaraia zone in southwestern Nevada, a ming have yielded a few, generally poorly preserved, Proptychites fauna occurs which is Gyronitan in age ammonites. ·From these beds the following species are (Muller and Ferguson, 1939). In the Candelaria recognized : formation the beds with Olaraia could be either Oto­ ceratan or Gyronitan in age. Ophiceras cf. greenlandicum Spath 0. (Lytophiceras) cf. 0. commune Spath Warren ( 1945) records Olaraia stachei from a bed 0. (Glyptophiceras) nielseni Spath at or near the base of the Sulphur Mountain member of 184 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

the Spray River formation in . A black 1nag­ marls of the Salt Range of Pakistan. Both of these nesiun1 li1nestone bed containing many flattened am­ species are Flemingitan in age. The K oninckites as:;o­ monites is in sections closely associated with the sec­ ciated with the above species compares most closely tion containing Olara: 8tache-i. Whereas the state of with K. timorense in general shape and involution, but preservation of these ammonites prohibits specific there are discrepancies in their sutures. The genus identification, Warren believes they include the fol­ K oninckites range through the Gyronitan and Flein­ lowing genera: Ophiceras, Proptychites, and Otoceras. ingitan. On the basis of specimens available, the up­ This is a very important discovery, and it is unfortunate per half of the Dinwoody formation contains faunas of that more positive identifications cannot be made. Gyronitan and Flemingitan ages. The material is too Otoceras and Ophiceras are Otoceratan in age, and all scanty and poorly preserved to allow definite identifi­ previous records of P,roptychites place it in the Gyro­ cation as to particular zones at the present time. The nitan, definitely younger than either Otoceras or Gyronitan age of at least part of the Dinwoody forma­ Ophiceras. This fauna is probably lower scythian, but tion was recognized by Newell and Kummel ( 1942). its exact age will remain open to question until better They recorded no am1nonites but did list, among others, n1aterial is found. the following species: Myalina spathi Newell and Kum­ In the valley of the Liard River, British Colun1bia, mel, Olaraia stachei Bittner, and Anadotophora fas­ Kindle ( 1944) discovered Olaraia cf. 0. stachei in the saen.r5is Wissmann. The upper Dinwoody pelecypod Grayling formation. As McLearn (1945) has pointed faunas are very similar to those of the Ussuri district out, Olaraia stachei ranges through the Otoceratan described by Kiparisova (1938), the East Greenland and Gyronitan ages in East Greenland. However, the faunas described by Spath ( 1930, 1935), and to the presence of Olaraia stache,i in British Columbia, faunas of the Seis member of the in Alberta, Idaho, and Nevada alford at least tentative the Alps. means of correlation. It likewise suggests that the In southwestern Nevada, Muller and Ferguson ( 1939) Lower Triassic geosynclines extended from Nevada and recognize a Proptychites fauna overlying their Oland,a Idaho northward to the Arctic . An open sea­ fauna in the lower Candelaria formation. Their way in this position would pennit migration of faunas Proptychites fauna contains: between East Greenland and Idaho and the U ssuri dis­ Hedenstroemia (Olypites) cf. H. (0.) evolvens Waagen trict of eastern Siberia. 31 eekocet·as cf. M. lilangense Krafft The limestone-siltstone beds inunediately overlying Meekocet·as cf. M. tenttistriat'll!m Krafft the lower shale unit of the Dinwoody formation in Pt·optychites cf. P. ammonoides Waagen southwestern Montana have yielded two new ammonite ProptychUes cf. P. trilObatus Waagen Grypocems cf. G. brahmanicum (Griesbach) faunas. In Frying Pan Gulch, Beaverhead County, Gt·ypolepis? sp. southwestern Montana, a small amn1onite fauna was According to Spath ( 1934) M eekoceras lilangeTJSe found in a gray, crystalline limestone approximately 60 Krafft belongs in Prionolobus, and M eekoceras tenuis­ feet above the lower shale unit of the Dinwoody forma­ triatum is a transitional form between K ingite8 and tion. This fauna contained several specimens referred Proptychites. M eekoceras lilangense, M eekoceras ten­ to Prionolobus n. sp. cf. P. atavus ('Vaagen) and one uistriatum, and Grypoceras brahtnanicum have been specimen referred to Koninckites cf. K. t1"111ncatus previously known only from the so-called "Meekoceras" Spath. In the same section approximately 70 feet above beds of the Himalayas. Pr,optychites ammonoides, the bed with Prionolobus, the following ammonites Proptychites trilobatus, and H edenstroemia ( Olypites) occur : K ymatites n. sp. cf. K. radio sum ( W aagen), evolven.rs are known only from the Ceratite marls of the K oninckites n. sp. cf. K. tirnorense (Wanner), and Salt Range. Muller and Ferguson assigned their P'rop­ Xenodiscoides cf. X. involutus (Frech). At Dalys tychites fauna to the Gyronitan division of Spath. It Spur, 13 miles south of Dillon, Montana, approximately is correlative with the horizon of Prinolobus n. sp. cf 100 feet above the lower shale unit of the Dinwoody P. atavus, Konincktites cf. K. trwncatus, and Gyronites formation, one small ammonite, Gyronites cf. G. cf. G. frequens of the Dinwoody formation in south­ frequens W aagen,, has been found. western Montana. , No other faunal zones above the Prionolobus atavus and K oninckites truncatus occur Proptychites fauna have been found in the Candelaria in the Lower Ceratite limestone of the Salt Range, as formation in southwestern Nevada. does Gyronites frequens. These forms are Gyronitan The Thaynes formation contains five ammonite in age. K ymatites radiosum occurs in the lower part faunas which from bottom to top belong to the Meek­ of the Ceratite sandstone of the Salt Range and X eno­ oceras;, Anasibirites, Tirolites, Oolumbites, and Pro­ discoides involutus occurs in the underlying Ceratite hungarites zones. All except the latter of these zones TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 185 were recognized by J.P. Smith (1932). The most wide­ compressus Smith spread and fossiliferous ammonite zone in the Middle pertenuis Smith Juveniles dienet·i (Hyatt and Smith) Rocky Mountains is the M eekoceras fauna of the lower kraffti Smith limestone unit of the Thaynes formation. The JJ;J eek­ sanctorum Smith oceras fauna has been reported from several localities septentrionalis Smith in Nevada and in California ; also from the Moenkopi thermarum (Smith) formation in southern Utah. The last monograph by "Prenk-ites-" dept·esstts Smith J. P. Smith (1932) was largely a description and dis­ The Meekoceras fauna has a very wide distribution. cussion of the M eekoceras fauna. In the past twenty It is well developed in Timor and the Himalayas. years there have been important additions and revisions Warren ( 1945) records Flemingites? ·and Olwraia in the of Lower Triassic ammonites. The griesbachi Bittner MO feet above the base of the Sul­ following faunal list of species in the JJ,f eekocera.s phur Mountain member of the Spray River formation fauna of Idaho is primarily that of J. P. Smith; but in Alberta. Kindle correlates this horizon with the the list has been revised and each species placed in its Jfeekocera.s beds in Idaho. Petkovic and Mihajlovic proper taxonomic position. The generic names enclosed ( 1935) identified M eekoceras gracilitatis White, M eeko­ in quotation marks are those used by Smith that do not ceras ( K oninckites) vetustus W aagen, H ede,nJStroemia appear to be correct but are still uncertain. hyatti Smith, and PseuAlosageceras multilobatum "Lecanites" knechU Hyatt and Smith N oetling from the W erfen beds in Yugoslavia. They "Xenodiscus" cordillet·amts Smith place these forms in the M eekoceras zone and correlate gilberti Smith them with the M eekocera.rs zone of Idaho. intermontamM Smith The lower shale unit of the Thaynes formation, which tarpeyi Smith overlies the lower limestone with M eekoceras, contains toulai Smith waageni (Hyatt and Smith) ammonites characteristic of the Anasibirites zone. whiteanus (Waagen) This fauna from Fort Douglas, Utah, was first de­ Dieneroceras dieneri (Hyatt and Smith) scribed by Mathews (1929). Smith (1932) considered Wyomingites aplanatus (White) the A nasibirites zone to be merely a subzone of his arnoldi (Hyatt and Smith) illeekoceras zone; however, recent work by Spath (1934) FlemingUes aspenensis Smith -. bannockensis Smith and ~lcLearn ( 1945) on faunas of this zone strengthen russelli Hyatt and Smith its position as an independent zone. rttsselli Hyatt and Smith var. gracilis Smith The Anasibirites fauna frmn Fort Douglas, Utah, Ruflemingites cirratus (White) described by Mathe,vs is rather poor in diversity of Jlf eekoceras arthaberi Smith genera but appears to contain numerous species. Both cristatum Smith gracilitatus White Smith (1932) and Spath (1934) combined 1nany of sylvanum Smith ~Ia thews' species ; likewise, the original generic assign­ bridgesi (Smith) ments of 1nany of the species have been changed. Ma­ S1tbmeekoceras mushbachanum (White) thews' faunal list is given below; no attempt is made mushbacha.mtm (White) var. corrugatum (Smith) evansi (Smith) in this list to correct or modify the original species, patelliforme (Smith) but the generic names are brought up to date. The bonnevillense (Smith) status of many of Mathew's species will be discussed Svalbardiceras? haydeni (Smith) in a later paleontological paper on this fauna. pea lei (Smith) Pseuda-spidites mttthianmn (Kraft) Pseudosageceras interrnontanum Hyatt and Smith Ana-hedenstroemia hyatti (Smith) Cot·dUlerites comprcss1ts Mathews kossmati (Hyatt and Smith) Xenoceltites matheri (Mathews) Olypites tenuis Hyatt and Smith hannai (Mathews) "Dalmatites" richardsi Smith douglasensis (Mathews) Aspenites acutus Hyatt and Smith Meekocems davisi Mathews hertleini Mathews obtusus Smith A.nasibirites kingianns (Waagen) Pseudosagecems sp. ( =Aspenites laevis Smith) saUsburyi Mathews multilobatum Noetling madisoni Mathews Lanceolites compactus Hyatt and Smith johannseni Mathews Jlletussuria occidentalis (Smith) whitei Mathews waageni (Hyatt and Smith) blackwelderi Mathews Oordillerites angulatus Hyatt and Smith fisheri Mathews Pat·anannites aspenensis Hyatt and Smith emmonsi Mathews columbianus Smith welleri Mathews 186 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY powelli Mathews Hyatt and Smith ( 1905) record Anasibirites noetlingi whit{ieldi Mathews from the M eekoceras zone of the Inyo Range, Inyo crickmayi Mathews · veranus Mathews County, Calif.; however, it is unfortunate that neither ketchumi Mathews of these authors published stratigraphic sections re­ pe1-rini Mathews cording the exact occurrence of their forms. McLearn weaveri Mathews ( 1945) described a small fauna that belongs to the wardi Mathews Anasibirites zone from the Toad formation on the Liard pseudoibex Mathews River, British Columbia. This fauna contains species mcclintocki Mathews bifurcat·us Mathews of "Prionites," W asatchites, AnfliWasatchites, and alternatus Mathews Xenoceltites. Even though the genus Anasibirites is romeri Mathews absent, the other genera afford close correlation with dieneri Mathews the Idaho and Utah faunas of the Anasibirites zone. .. clarki Mathews Outside of North America the Anasibirites fauna has bretzi Mathews vanbuskirki Mathews been recorded from the Upper Ceratite limestone of the rollini Mathews Salt Range, and in Timor, and Spitzbergen. The edsoni Mathews '( M eekoceras" fauna from Shikoku, Japan, described by bassleri Mathews Yehara (1928) probably belongs to the Anasibirites guyi Mathews zone. Spath ( 1934) does not consider the various gibsoni Mathews hyatti Mathews Anasibirites beds of different localities to be contem­ mojsisovicsi Mathews poraneous and states "that a number of additional hori­ H emiprionites typus ( Waagen) zons may eventually be recognized in the Owenitan and americanus (Mathews) Columbitan ages." He further adds that the beds with walcotti (Mathews) W asatchites and Gurleyites in Spitzbergen are probably utahiensis (Mathews) shumardi (Mathews) a little younger than the Anasibirites beds of Utah. slocomi (Mathews) In Paris Canyon, west of Bear Lake, in a gray lime­ ornatus (Mathews) stone bed below the middle shale with 0 olu;mbites and butleri (Mathews) approximat~ 800 feet above the lower limestone with varians (Mathews) M eekoceras occurs a small fauna of amonites and pele­ resseri (Mathews) "Kashmirites" subarmatus Diener cypods that belong to the Tirolites zone. Smith ( 1932) Wasatchites wasatchensis (Mathews) considered the fauna to have distinct. Mediterranean thornei (Mathews) affinities, and he records the following species from this gilberti (Mathews) bed: seerleyi (Mathews) perrini Mathews Dalmatites attenuatus Smith meeki Mathews Tirolites harti Smith magnus Mathews knighti Smith quadratus Mathews pealei Smith Gurleyites sm4thi Mathews sp. indet. chamberlini Mathews sp. indet. milled Mathews Pseudomonotis idahoensis White boutwelli Mathews pealei White Pugnoides triassicus Girty There are impressions of ammonites in all outcrops of Pentacrinue (Isocrinus) smithi Clark and Twitchell the lower shale unit of the Thaynes formation in Idaho. Mathews ( 1931) records Tirolites pacificus from a Only one locality in Idaho is known with a well-pre­ light-gray fossiliferous limestone 280 feet above the served fauna in these beds. West of Georgetown, Idaho, uppermost fossiliferous bed containing the Anasibirites the lower part of the lower shale unit has yielded a fauna in the Fort Douglas area, Utah. The single large, well-preserved fauna, which is almost the same as that at Fort Douglas, Utah. This unit contains nu­ locality in Idaho and another in Utah are the only merous species of H emiprionites, Gurleyites, Anasibi­ two localities known for this fauna in North America. rites, W asatchites, and Anawasatchites. Species of The middle shale unit of the Thaynes formation Hemiprionites are far more abundant and diversified in which overlies the limestones with Tirolites in the Bear the Georgetown fauna than at Fort Douglas, where Lake Valley region, contains a unique ammonite fauna Anasibirites is the principal element of the fauna. referred to the 0 olJumbites zone. This is the only area The Anasibirites fauna has not been recognized as in the world where this zone has been recorded al­ yet in the Candelaria formation of southwestern Utah. though Mathews ( 1931) does record 0 olwmbites TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 187 parisianus from the Thaynes formation in the Fort P. crasseplwatus are known only from the upper Scy­ Douglas area. No other Scythian ammonite faunas thian beds of Timor. Svalbardieeras, Keyserlingite8 strictly contemporaneous with the 0 ol!urmbites fauna of subrobutus, Ozek:anm.oskites, and Olenikites are known Idaho are known. The 0 olumbites fauna of the Bear only from upper Scythian beds of the Olenek river Lake Valley area has been described by Smith (1932), region of northern Siberia and in Spitzbergen. .~.lf eta­ and he recognized the following species ; the generic hedenstroemia, I sculitoides, and Epiceltites are known names enclosed in quotation marks are those used. by from upper Scythian beds in Albania· and the Island of Smith that do not appear to be correct but are still un­ Chios, off the coast of . certain. When Spath (1934) proposed the Prohungaritan age "Ophiceras'' jacksoni Hyatt and Smith as the upper division of the Scythian, he emphasized "Ophiceras" spencei Hyatt and Smith the incompleteness of our knowledge of the uppermost "Meekoceras" curticostatum Smith beds of the Scythian. He recognized the close affinities "Meekocera8" micromphalus Smith of the Subcol!umbites fauna of Albania with the Al­ "Meekoce·ras" pilatum Hyatt and' Smith banites fauna of Timor. However, there was little to "Meekooerat:J" sanctorum Smith H ellenites idahoense (Smith) correlate them with the "Hungarites" middlemissi beds Tirolites cf. T. iUyricus Mojsisovics of Kashmir or the faunas of the Olenek region in Pseudosageceras multilobatum Noetling Siberia or Spitzbergen. Likewise Spath was prompted "Oeztites" apostolicus Smith to propose a new age for the uppermost Scythian based "Oeltites" planovoZvis Smith upon the obvious differences between the lowest "Oeltites" ursensis Smith "* * * Oolumbites oonsanguineus Smith and the highest Scythian faunas so far Zigatus Smith known * * *." m!inimus Smith Renz and Renz ( 1948) have recently published an iiil­ ornatus Smith portant monograph on an upper Scythian ammonite parisianus Hyatt and Smith fauna from the Greek Island of Chios that on this Smith recognized the Oolwmbites fauna only in Paris problem. The fauna of Chios substantiates the close Canyon, but the writer has found fossiliferous ex­ relationship between the Subcol!umbites fauna of Al­ posures of the middle shale unit in several places in bania with the Albanites fauna of Timor. Neither of southeastern Idaho. The collections now being studied these faunas have much in common with Arctic or contain many more genera and species than recorded by Himalayan faunas mentioned above. The Prohun­ Smith. garites fauna of Idaho is an important link in correlat­ The upper 1,500 feet of the Thaynes formation in the ing these Tethyian faunas with the Boreal faunas of Paris Canyon area, west of Bear Lake, contain Lower Triassic ammonoids younger than any previously re­ Siberia and Spitzbergen. The Idaho Prohttvngarites ported from North America. The ammonoids are most fauna occurs about 1,000 feet above the 0 olumbites zone. abundant in the upper part of the lower half of this The association of these Boreal and Tethyian elements· 1,500-foot sequence, and no ammonoids have been found in this zone strongly verifies Spath's arguments for the in the upper half of this sequence. establishment of a Prohungaritan age. Spath ( 1934) This ammonoid fauna is at present being studied and included the Spitzbergen, Olenek, Kashmir, _Albanian, the following forms are recognized in the collections : and Timor faunas in his Prohungaritan age but was Prohungarites n. sp. cf. P. sim·iUs Spath uncertain as to their correct zoning. This Idaho fauna Proh1mgarites n. sp. cf. P. crasseplicatus (Welter) clearly demonstrates the age relationships of these Svalbardiceras sp. Tethyian and Boreal faunas, but more detailed paleon­ M etahedenstroemia n. sp. Keyserlingites n. sp. cf. K. subrobttStus (Mojsisovics) tologic work is needed to establish the proper zonal I sculitoides n. sp. relationships. Epiceltites n. sp. cf. E. genti Arthaber A fauna of Prohungaritan age from the south U ssuri Ozekanawskitest sp. coastal region of Siberia near Vladivostock has been Stacheites sp. Olenikites t sp. reported by Kiparisova (1945). No description of the Prohungarites, Keyserlfngites, and lsculitoides are fauna has appeared as yet but Kiparisova's faunal list the most common genera present. 0 zekanowskites and (1945, p. 439) includes the following ammonite gen­ Olenikites are based on only a few poorly preserved era : Subcolwmbites, Prosphingites, M egaphyllites, specimens in which no sutures are preserved; however, Paranannites, and Pseudosageceras. Interpretation of the general appearance of the conch strongly suggests this fauna must wait until more information is avail­ these generic assignments. Proh'ltngarites similis and able. 188 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

In Spring Canyon, Sublette Ridge, a piece of lime­ Gardner, L. S., 1944, Phosphate deposits of the Teton Basin stone float was found 150 feet below the top of the up­ area, Idaho and Wyoming: U. S. Geol. Survey Bull. 944-A, per calcareous siltstone unit, containing a well-pre­ p. 1-36. Gardner, L. S., Hendricks, T. A., Hadley, H. D., and Rogers, Jr., served ammonite assigned to Stacheites. The specimen C. P., 1946, Stratigraphic ·sections of upper Paleozoic and is similar to species of Stacheites described by Renz Mesozoic rocks in south-central Montana: Montana Bur. and Renz (19±8) from the Island of Chios. This sug­ Mines and Geology Mem. 24, p. 1-100. gests that the upper part of the upper calcareous silt­ Hazzard, J. S., 1937, Lower Triassic rocks in San Bernardino stone unit in Sublette Ridge is equivalent to at least part · County, California: Geol. Soc. America Proc. 1936, p. 329. Hyatt, A., and Smith, J. P., 1905, The Triassic genera of the ammonitiferous beds of the upper part of the of America: U. S. Geol. Survey, Prof. Paper 40, p. 1-394. Thaynes formation west of Bear Lake. Kay, Marshall, 1951, North American Geosynclines: Geol. Soc. Hazzard ( 1937) records Stephanites sp. and Sub­ America Memoir 48, p. 1-143. colurmbites sp., among other fossils, from LOwer Trias­ Kindle, E. D., 1944, Geological reconnaissance along Fort Nel­ sic rocks in the Providence Range, San Bernardino son, Liard, and Beaver Rivers, northeastern British Co­ lumbia and southeastern Ukon : Geol. Survey Paper County, Calif. S~tbcolurmbites is present in the upper 44-16, p. 1-19. Scythian faunas of Albania and the Island of Chios. Kinney, D. M., and Rominger, J. F., 1947, Geology of the White­ If the identifications are correct these strata are cor­ rocks River-Ashley Creek Area, Uintah County, Utah: U. S. relative with the upper part of the Thaynes formation, Geol. Survey Oil and Gas Investigation Series, Prelim. of southeastern Idaho. Map. no. 82. Kiparisova, L., 1938, The Lower Triassic pelecypoda of the Us­ The writer has no new data on the age of the post­ suriland: Acad. Sci. U. R. S. S., Inst. Geol. Travaux tome Thaynes Triassic formations of the Middle Rocky 7, p. 197-311. Mountains. These formations, which have yielded no --- 1945, A contribution to the stratigraphy- of the lower diagnostic_fossils, have been considered to be either Mid­ Triassic of the south -Ussuri coastal region (Primorie) : dle or Late Triassic in age by various authors. The Acad. sci. U. R. S. S., C. R. (Dokl.), v. 49, no. 6, p. 438-441. Kummel, B., 1943, The Thaynes formation, Bear Lake Valley, Higham grit, Deadman limestone, and the Wood shale Idaho: Am. Jour. Sci., v. 241, p. 316-332. tongue of the Ankareh formation in southeastern Idaho, ---1950, Triassic Stratigraphy of the area around the Green the Popo Agie member of the Chugwater formation in River Basin, Wyoming: Wyo. Geol. Assoc. Guidebook, western vVyoming, and the Gartra grit and Stanaker Southwest Wyoming, p. 28-36. members of the Ank'areh formation in the central Love, J. D., 1939, Geology along the southern margin of the Absaroka Range, Wyo.: Geol. Soc. America Spec. Paper, Wasatch and western Uinta Mountains have been corre­ no. 20, p. 1-134. lated with the Shinarump and Chinle formations of the --- 1948, Mesozoic stratigraphy of the Wind River Basin, Colorado Plateau and considered Late Triassic in age central Wyoming: Wyo. Geol. Assoc. Guidebook, Wind (see Williams, 1945; and Thomas and Krueger, 1946). River Basin, p. 96-111. Stokes (1950) suggests that the Shinarump conglomer­ Mansfield, G. R., 1916, Subdivisions of the and Nugget sandstone, Mesozoic, in the Fort Hall Indian ate is a pediment deposit of Middle Triassic age. Reservation, Idaho: 'Vashington Acad. Sci., Jour., v. 6, p. 31-42. LITERATURE CITED --- 1920, Triassic and Jurassic formations in the south­ Baker, A. A., and ·williams, J. Steele, 1940, Permian in parts eastern Idaho and neighboring regions: Am. Jour. Sci., v. 50, of Rocky Mountains and Colorado Plateau regions: Am. p. 53-64. Assoc. Geologist Bull., v. 24, p. 617-635. --- 1927, Geography, geology and mineral resources of part Baker, A. A., and others, 1947, Stratigraphy of the Wasatch of southeastern Idaho: U. S. Geol. Survey, Prof. Pap.er Mountains in the vicinity of Provo, Utah: U. S. Geol. Sur­ 152, p. 1-409. vey Oil and Gas Inv. Prelim. chart no. 30. --- 1929, Geography, geology, and mineral resources of the Blackwelder, E., 1918, New geological formations in western Portneuf Quadrangle, Idaho: U. S. Geol. Survey Bull. 803, Wyoming: Washington Acad. Sci., Jour., v. 8, p. 417-426. p. 1-110. Boutwell, J. M., 1907, Stratigraphy and structure of the Park Mathews, A. A. L., 1929, The Lower Triassic cephalopod fauna City mining district, Utah: Jour. Geology, v. 15, p. 434-458. of the Fort Douglas area, .Utah: Walker Museum Memoir, --- 1912, Geology and ore deposits of the Park City dis­ v. 1, no. 1, p. 1-46. trict, Utah: U. S. Geol. Survey, Prof. Paper 77, p. 1-231. ---1931, Mesozoic stratigraphy of the central Wasatch Moun­ Boutwell, J. M., and others 1933, The Salt Lake Region: Six­ tains: Oberlin College Lab. Bull., n. ser. 1, p. 1-50. teenth Internat. Geol. Cong. United States, Guidebook 17. McKee, Edwin D., 1951, Sedimentary basins of Arizona and ad­ Fidlar, M. M., 1950, Baxter Basin Gas Fields, Sweetwater joining areas: Geol. Soc. America Bull., v. 62, p. 4'n-506. County, Wyoming: Wyo. Geol. Assoc. Guidebook South­ McKelvey, V. E., 1946, Stratigraphy of the Phosphatic shale west Wyoming, p. 109-110. member of the Phosphoria formation in western Wyoming, Gale, H. S., and Richards, R. W., 1910, Preliminary Report southeastern Idaho, and northern Utah: Unpublished doc­ on the phosphate deposits in southeastern Idaho and ad­ toral thesis, University of Wisconsin. jacent parts of Wyoming and Utah: U. S. Geol. Survey ---1931 Mesozoic stratigraphy of the central Wasatch Bull. 430, p, 457-535. l\Iountains: Oberlin College Lab. Bull., n. ser. 1, p. 1-50. TRIASSIC STRATIGRAPHY OF SOUTHEASTERN IDAHO AND ADJACENT AREAS 189

McLearn, F. H., 1945, The Lower Triassic of Liard River, Brit­ Schultz, A. R., 1914, Geology and geography of a portion of Lin­ ish Columbia: Canada Geol. Survey Paper 45-28, p.1-6; and coln County, Wyoming: U. S. Geol. Survey Bull. 543, p. appendix, p.1-2, pls.1-3. 1-141. Moritz. C. A., 1951, Triassic and Jurassic stratigraphy of south­ Smith, J.P., 1932, Lower Triassic Ammonoids of North America, western Montana: Am. Assoc. Petrol Geol. Bull., v. 35, p. U. S. Geol. Survey Prof. Paper 167, p. 1-199. 1781-1814. Spath, L. F., 1930. The Eo-Triassic fauna of East Muller, S. W., and Ferguson, H. G., 1939, Mesozoic stratigraphy Greenland: Meddelelser om Grs-inland, Band 83, p. 1-90. of the Hawthorne and Tonopah Quadrangles, Nevada: Geol. Soc. America Bull., v. 50, p. 1573-1624. ---1935, Additions to the Eo-Triassic invertebrate fauna Newell, N. D., 1948 Key Permian section, Confusion Range, of East Greenland: Meddelelser om Grs-inland, band 98, western Utah: Geol. Soc. America Bull., v. 59, p. 1053-1058. p. 1-115. Newell, N. D., and Kummel, B., 1942, Lower Eo-Triassic stra­ ---1951, Catalogue of the fossil Cephalopoda in the British tigraphy, western Wyoming and southeast Idaho : Geol. Soc. Museum (Natural History): Part 4, The of the America Bull., v. 53, p. 937-995. Trias, (I ) , p. 1-521, 1934 ; (II) p. 1-228, London. Nolan, T. B., 1!)43, 'l'he Basin and Range Province in Utah, Stokes, W. M., 1950, Pediment concept applied to Shinarump and. Nevada, and California: U. S. Geol. Survey, Prof. Paper similar conglomerates: Geol. Soc. America Bull. v. 61, 197-D, p. 141-196. p. 91-98. Petkovic, K. V., and Mihajlovic, D., 1935, La faune des cephalo­ Thomas, H. D., and Krueger, l\1. L., 1946, Late Paleozoic and podes trouvee dans le Trias Inferieur en Montenegro early Mesozoic stratigraphy· of Uinta Mountains, Utah: (Yougoslavie) ses caracteristiques et son importance, Ann. Am. Assoc. Petrol. Geol. Bull., v. 30, p. 1255-1293. geol. Penins. Balkan., tome 12, p. 253-269. Warren, P. S., 1945, Triassic faunas in the : Renz, Carl, and Renz, Otto, 1948, Eine untertriadische Am­ Amer. Jour. Sci., v. 243, p. 480-491. monitenfauna von der griechischen Insel Chios: Schweizer. palaeont. Abh., Band 66, p. 1-98. Williams, J. Stewart, 1945, Nomenclature of Triassic rocks in Richmond, G. M., 1945, Geology and oil possibilities at the north­ northeastern Utah: Am. Jour. Sci., v. 243, p. 473-479. west end of the Wind River Mountains, Sublette County, Yehara, Shingo, 1928, The Lower Triassic cephalopod and bi­ Wyoming: U. S. Geol. Survey Oil :md Gas Inv. Series, valve fauna of Shikoku: Japanese Jour. Geol. and Geog., Prelim. Map no. 31. v. 5, p. 135--172.


A B Page Page Abstract______165 bannockensis, Flemingites ______'- ______185 Acknowledgements______167 bassleri, Anasibirites______186 acutus, Aspenite8- ______------______~ ______185 Bear River Range, Thaynes formation ______175,176 Alcova limestone member, Chugwater formation _____ ------181-182 Thaynes formation, Anasibirites zone __ ------176 aUernatus, Anasibirites______186 bergeri, Pleurophorus ______------______----~ ______------183 american us, Hemiprionites __ ~ ___ ------______186 bifurcatus, Anasibirites. ______------______------__ 186 ammonoidea, Proptychitts ______184 blackwelderi, Anasibirites ______------______185 Anadotophora fassaensis ______· 184 bonnevillense, Submeekoceras .. ______------______185 Anahedenstroemia hyattL______185 borealis, Lingula______183 kossmatL ------______185 boutwelli, Gurleyites ______------______186 Anasibirites______183 brahmanicum, Grypoceras. ______------______184 alternatus ______------______18n bretzi, Anasibirites ______------____ ------______186 basslerL- ______--- _-- ______186 bridgesi, Meekoceras ______------______------______185 bifurcatus______186 butleri, Hemiprionites ______------____ .. ______------______186 blacku·elderL ______185 bretzL __ ------_-- ____ -- __ -______186 c

clarki. ____ ---- ___ -~ __ -_-- _____ --_- _____ -______186 Celtites, apostolicus __ ___ .. _--- .... ______-~ ___ --- _____ --- ______181 crickmayL- --- _--- ___ --- ___ --- _--- ______: ______186 planovolis ______.. ______187 dienerL ___ ------___ - __ ------______186 ursensis ______------______187 edsoni______--- ___ -______-__ ---- _.______186 Central Wasatch and Uinta Mountains. post Thaynes Triassic-----~------179-180 emmonsL _---- ______-_-- ______185 Thaynes formation ______177-179 fisheri_ ____ ------_------_- --- ______185 chamberlin£, Gurleyites ____ .. ____ -- ______-_- ______186 gibsonL------______------______186 Chinle formation .. ______.. _.. ______.. 166, 180 guyL------______186 Chugwater formation ______.. ______---______167 hyattL _------_- _--- _--- ___ -_- -- ______186 central Wyoming ______181-182 186 ketchumL------__ -- _-- --- ___ -_- ______-- ______Red Peak member------171 kingianus .. ------_--- -- _- ____ -- _- ______185 cirratus, Eujlemingttes______185 lohannsenL- -- _--- ___ -_- ___ - ___ --- ______-- ______185 clarai, ______.. ______183 madisont __ ------_------_-- _---- ______185 occidentalis, Claraia ___ .. ______183 mcclintocki_ ___ _--- ___ -_- ___ - ______--- ______186 Claraia. ------______.. ______168, 182 mojsiso.vicsi-- --- ___ -_- _____ - ___ -______186 aurita ______.. ___ .. __ .. -----______183 perrini_ ____ ------__ ------__ ---- ______186 claraL ------______.. ____ .. ______183 powellL------_------______186 occidentalis______183 pseudoibex _____ ------______186 mulleri______" ______183 rnllinL------_- _--- -- ______186 stacheL ______183, 184 romerL ------______186 Claraia zone, Dinwoody formation, western Wyoming ______168,169 salisburyi_- --- ___ ------_----- ______---- ______185 clarki, Anasibirites. ______186 vanbuskirkL------__ ------______-~ ______186 Clypites tenuis ______---- ______--- _--- ______185 veranus------______186 (Clypites) evolvens, Hedenstroemia ______------184 wardi_ ___ ------______186 columbian us, Paranannites ______.. ______--- 185 weaveri __ .. ------___ -.. -- .. -- .... ------_____ ------______186 Columbites ______------.. ______---- 176, 182, 183 v~llerL -----.------______185 consangttineus ______.. ______.. ______~- ______187 whitei_ __ .. _------·---- ______185 ligatus __------______.. ______.. _.. ______187 whitfieuJi ______------___ --- ______186 minimus ______------____ ------.. ______------187 Anasibirites zone, Thaynes formation______172 ornatus_ ------__ ------___ ------______--- __ --- ______187 Thaynes formation, Bear River Range ______------176 parisian us. ____ ------__ ------______187 angulatus, Cordillerites ______------____ --- ______182 sp., in lower black limestone, Thaynes formation, southeastern Idaho __ _ _ 173 Ankareh formation, Gartra grit member______180 Columbites zone ______------_____ ------__ - __ ---_--- 175 Idaho, southeastern_------______173 Thaynes formation ______------~------172 Lanes tongue, eastern Bear lake to Sublette Ridge______175 commune, Ophiceras (Lytophiceras) ______--- _------______183 Idaho, southeastern _____ --- ______---~--______174 compactus, Lanceolitea _____ ----- ______------______185 Wyoming, western_------______176 compressus, Cordillerite8------~- ______-- __ -- __ ___ 185 Mahogany member______180 Paranannites ______" _____ ------______--- __ 185 Stanaker member---- ______------_--- ______,______180 consanguineus, Columbites ___ ------___ ------______------___ --- ___ --- __ _ 187 Anodontophora ______-- ______168, 169 cordilleran us, Xenodiscus------______-----_------_---- _ 185 aplanatus, Wyomingites ______.______185 Cordillerites angulahts------______----- __ ------______185 apostolicus, Celtites ____ ---- ______-______187 compressus ______------______--- ______------___ __ 185 Aroctoceras_ ------_- _- ______-- __ -_-. ______176 corrugatum, Submeekocerfls mu.shbachanum______185 185 arnoll'i, lVyomingites ______.. ______crasseplicatua, Prohungarit~B------_----- ______------___ ------187 arthiberi, Meekoceras_- ---- ______185 crickmaui, Anasibirites ______---- _____ --- ______------186 aspenensis, Flemin,ites______185 cristatum, Meekoceras ______.______------185 Paranannite8______185 curticostatum, Meekoceraa ______------187 Aspenites acutus ______T ______185 Cuclolobus ______.. _- _____ -- ___ ----- ____ -- ______------182 laevis ______--- _-- ______--- ______185 Czekanowskites sp ______.. __ .. ______-- ______------187 obtusus ______-- ______185 atavus, Prionolobus ___ -- .. - ______: ______184 D attenuatus, Dalmatites ______. ______186 Dalmatites attenuatus .. ______------.. __ .. ------___ ------186 aurita, Claraia______183 richardsi ______-·-- ______------185 191 192 INDEX

Page Page davisi, Meekoceras______185 Hemiprionites americanus ______------____ ----- ____ -- 186 Deadman limestone ______180, 181 butlerL __ ------______186 depressus, Prenkites______185 ornatus ______------___ ------~---- 186 dieneri, Anasibirites ______186 resseri______186 Dieneroceras ______185 shu mardi. ______---- ______------186 Juvenites ______185 slocomL ______-__ . ______-___ -_- _- _--- ___ ------_------186 Dieneroceras dienerL ______185 typus ______186 Dinwoody formation, Claraia zone in western Wyoming ______168,169 utahensis ______------_____ ----- ___ ------___ ------186 defined______167 t1arians ______------186 "limestone member" of in southwestern Montana_------170 walcotti ______-_-- ______---- __ ------_------186 Lingula zone in western Wyoming ______168,169 hertleini, l.Ieekoceras ______--- ______------185 redefined ______------______167 Higham grit______------______- 166, 180, 181 regional outline oL __ ------______168 hyatti, Anahedenstroemia ______--- _____ ------___ - 185 "shale member" of in southwestern Montana______170 Anasibirites ______------___ ------______------186 thicknesses, in ·southeastern Idaho ______169-170 in southwestern Montana __ ------170 in western Wyoming______168 Idaho, southeastern, Dinwoody formation thickness ______169-170 Discophiceras subkyokticum______183 Lanes tongue ______-______--- __ -- 173, 174 (Discophiceras) subkyokticum, Ophiceras ______183 post-Thaynes Triassic ______--- ______---- ___ 18Q-181 douglasensis, XenoceUites ______------_.______185 Ross Fork formation ______--_____ 173 E Thaynes formation ______------172-176 defined ______----______172 Early Triassic seaways______165 lithologic units______173 Eastern Bear Lake to Sublette Ridge, Ankareh formation, Lanes tongue______175 lower black limestone ______--- ___ - 173 Thaynes formation, lower limestone unit______174 limestone ______------_____ 173 lower shale unit_ __ ---.------______175 Portneuf limestone member ______------173 middle shale unit______175 Timothy sandstone ______173. 174 Timothy sandstone member ______------175 upper black limestone ______-______------.-- ____ - 173 upper calcareous siltstone unit______175 Woodside formation ______-______------______--- ___ 17Q-17l edsoni, Anasibirihs______186 idahoens~, Hellenites ______---- __ -_------__ ------187 Ellis group ___ ------______171, 177 idahoensis, Pseudomonotis ______-______------18!1 emmonsi, Anasibirites_ ------______185 illyricus, Tirolites ______---- ___ ------______c __ ------187 Eo-Triassic, upper and lower ______------______182 intermontanum, Pseudosageceras ______-__ -____ ------_------___ --- 185 Epiceltites genti______187 intermontanus, Xenodiscus ______-_-- _____ ------_------_--- -- 185 Erosion, pre-Jurassic in southwestern Montana______177 involutus, Xenodiscoir'es_: ______------___ ------184 Euflemingites cirratus _____ -______185 Isculitoides n. sp ______------187 evansi, Submeekoceras ______185 (Socrinus) smithi, Pentacrinue. ______--- ____ ------186 evolvens, Hendenstroemia ( Clypites) ______184 J F jacksoni, Ophiceras ______--- ____ -----. _------187

Juveniles dieneri. ______--- ______------______J ____ -- 185 fassaensis, Anadotophora __ _------______184 kraf/ti. ______--~ --- ___ ------___ ------185 Faunal divisions of Triassic formations______182 sanctor·um ______-______---- ___ ------185 ji.sheri, A"',asibirites ______------______185 Flemingites aspenensis______185 septentrionalis ______---- _____ ------185 bannockensis______185 thermarum ______--- ___ ------185 russelli_ ____ -- _____ ------___ -______185 K gracilis ______-_---______185 Kashmirites subarmatus ______- __ -______-__ - ____ ------___ ------____ - 186 Fort Hall Indian Reservation to Grays Range, Thaynes formation ______172-173 ketchumi, Anasibirites ______-__ -______------__ ----- __ ------__ ------_----- 186 jrequens, Gyronites.------· ______184 Keyserlingites subrobustus. ______-- ______---- ______- 187 kingianus, Anasibirites ______--- ____ - __ --- ___ ----- ______------______------185 G knechti, Lecanitts ___ ------_____ ------184 Gartra grit member, Ankareh formation ______166,180 knighti, Tirolites ___ ------186 Geanticline ___ -- ______165 Koninckites timorense ______-______--- ______--- ____ ------_____ - 184 Genodiscus______182 truncatus ______--- ____ ------__ ------184 genti, Epiceltites______187 Kootenai formation ______- __ --- ___ ----- _____ --~----- _____ --- 170, 171, 177 gibsoni, Anasibirites ______·--______186 kossmati, Anahedenstroemia ___ --- ____ ------__ -- __ -- ______------____ ----- _____ - 185 gilberti, Wasatchites. _------______186 kraf!ti, Juvenites ______----- ____ ------___ ------____ ------_____ - 185 Xenodiscus ______-- ______185 Kymatites radiosum ______--- ______-- ______------______184 (Glyptophiceras) nielseni, Ophictras______183 L gracilis, Fltmingites russelli ______185 gracilitatus, Meekoceras______185 laevis, Aspenites ______------185 greenlandicum, Ophiceras______183 Lanceolites compactus ______----- __ ------__ ------____ ------_____ ------_---- 185 Grypoceras brahmanicum______184 Lanes tongue, .(\.nkareh formation, eastern Bear Lake to Sublette Ridge______175 Gurleyites boutwellL______186 Ankareh formation, southeastern Idaho_ ------~------173,174 Wyoming, western ______.______176 chamberlini. ____ ------______186 milleri ___ ---- ______186 Lecanites knechti ____ ------_------___ ------___ -- 184 smithL ______------______186 ligatus, Columbites ______------______------___ __ 187 lilangense, J.feekoceras ______-- ______184 guyi, Anasibirites ___ ------______186 Gyronites jrequens______184 Limestone, lower, Thaynes formation, eastern Bear l-ake to Sublette Ridge__ 174 lower black, Thaynes formation, southeastern Idaho______173 H middle, Thaynes formation, eastern Bear Lake to Sublette Ridge______175 tan silty, Thaynes formation, southeastern Idaho______173 hannai, Xenoceltites______185 upper black:, Thaynes formation, southeastern Idaho______173 harti, Tirolites ------______186 "Limestone member," Dinwoody formation, southwestern Montana______170 haydeni, Svalbartliceras ______.______185 Lingula ______c _ _ _ _ _ 183 Hedenstroemia ( Clypites) evolvens______184 borealis______183 Hellenites idahoense______187 Lingula zone Dinwoody formation in western 'Vyoming ______168,169 INDEX 193

Page Page lohannseni, A.nasibirites ______185 Orthoceras sp ______-- ___ --- __ ---- __ ----______186 Lower shale unit, Thaynes formation, eastern Bear Lake to Sublette Ridge __ _ 175 Otoceras ______---- ______182, 184 (Lytophiceras), Ophiceras, commune ______183 Overlap of Triassic on Permian formations, Idaho and Wyoming- __ ---- _____ fig. 19

M p madisoni, A.nasibirites ______------185 Paranannites aspenensis ______------__ ---- 185 magnus, lVasatr,/lites_ ------______· 186 columbianus ______------185 Mahogany member, Ankareh formation______180 compressus ______-- ___ - __ ------185 mansjieldi, Spiriferina______183 pertenuis. ______------__ ---- 185 matheri, XenoceUites ______185 parisianus, Columbites ______-_____ --- _----- _------187 mcclintocki, A.nasibirites______186 patelliforme, Submeekoceras ______----- __ ------185 meeki, lVasatchites ______186 pealei, Pseudomonotis ______---_~- ______-___ ------__ ------186 Meekoceras ______----- ______174, 176, 182, 183 Svalbardiceras ______--- ___ -_____ ---- _--- ___ ------185 arthabesi______-______185 Tirolites ______------_--- 186 bridgesL ______185 Pentacrinue (Isocrinus) smithL ______--- __ ------186 cristatum ______--- ______------______185 Pentacrinus ______-~ ___ ------177 wrticostatum______187 perrini, A.nasibirites ______-- ____ ---_--- -- _------186 davisi ______-______185 Wasatchites ______--- ___ ------186 gracilitatus ______. ______185 pertenuis, Paranannites _____ ~ _____ -- ____ -____ ------185 hertleini______--- ___ ---- ______------______185 Phosphoria formation. ____ ---_-----_------167 lilangense ______-- ______184 pilatum, Meekoceras __------______------187 micromphalus. ____ --- ____ -- ______- ______187 planovolvis, CeUites ______--- __ ------187 pilatum ______-- ______-~- ______187 Pleurophorus bergerL _ ------183 sanctorum ______--- ______187 Popo Agie member, Chugwater formation ______181,182 sylvanum_. ______--- ___ --- ______185 Portneuf limestone member, Thaynes formation______172 tenuistriatum. ______--- ____ --- ______. ______184 Thaynes formation, southeastern Idaho ______173,174 167 Meekoceras limestone_------_------___ -______Post-Thaynes Triassic ______---- ___ ---_------179 Meekoceras wne. ___ --- --·· ------____ ---- ______172 central Wasatch and Uinta Mountains ______179-180 Thaynes formation_------______172 southeastern Idaho ______------______------18Q-181 lower limestone in southeastern Idaho_------__ . 173 powelli, A.nasibirites ______-_____ --- __ --- ___ ------186 Mentzelia sp ___ ------_------______183 Pre-Jurassic erosion, southwestern Montana ___ -- ____ ------177 Metaheden.~troemia n. sp __ ------______187 Prenkites depressus ______------__ --- __ -_____ ------185 Metophiuras subdemissum __------______18~ Prohungarites ______-_____ ---- __ -~------176 (Metophiceras) subdemissum, Ophiceras______183 Prohungarites zone, Thaynes formation______172 Metussuria occidentalis______185 Proptvchites _____ ------_------183,184 waageni. ______------______-______185 ammonoides ______----_----- _------~ ------184 micromphalus, 1\feekocerae __ _--- ____ ---- ____ -- ____ --- ___ - ______187 trilobatus ______-- ____ -- ____ ------_-- _------184 milleri, Gurleyites_ ------______--- ______186 Pseudaspidites muthianum __-- ___ -- ____ --- ___ --- _- _------185 minimus, Columbites______187 pseudoibex, Anasibirites _-- ___ -- _--- ____ ------186 Montana, southwestern, "Limestone member" of Dinwoody formation in____ .170 Pseudomonotis idahoensis ______----_--- _____ ------186 pre-Jurassic erosion in ___ ------______-______177 pealei ______------______------__ ------186 "Shale member" of Dinwoody formation in______170 Pseudosageceras intermontanum_ ------185 Thaynes formation.______177 multilobatum ______--- ______---- ____ - __ ------185, 187 Woodside formation, thickness.______171 sp______185 Dinwoody formation, thickness ______-----______170 Pngnoides triassicus ______--- ___ ------176, 186 Miogeosyncline ______-- ______165 putiatinensis, lvfyalina. ______--- _----- __ ------183 seaway ______------____ ------166 Moenkopi formation______180 Q mojsisovicsi, A.nasibirites______-- ______--- ______186 ~ifonotis sp ______------______--- ______--- _____ -______182 qnadrafus, fVasatchites ______-- ___ ------___ ------186 mui'leri, Claraia______183 multilobatum, Pseudosageceras ______185, 187 R mushbachanum, Su.bmeekoceras .. ______185 corrugatum, Submeekoceras______185 Red Peak member, Chugwater formation ______171,181 muthianum, Pseudaspidites______185 Red Wash formation ___ ------180 J\,fyalina putiatinensis______183 resseri, Hemiprionites ______------_------186 .~pathi. ______183, 184 richard8i, Dalmatites ______------___ ------185 rollini, Anasibirites ______------___ ------186 romeri, Anasibirifes ______------186 Ross Fork formation, southeastern Idaho______173 Nautilus sp______1S6 rztsselli, Flemingites ______------_------185 niel.~eni, Ophiceras (Glyptophiceras)______183 gracilis, Flemingites _____ ------185 ::-.lugget formation ______179, 180 8 0 salisburyi, Anasibirites ______--- ___ ------185 obtusus, Aspenites_ ____ -~-- ______18.5 sanctorum, Ju~>enites ______-_____ --- _-- _- ___ ------185 occidental is, Claraia clarai ______183 1\feekrceras ______------_____ ------187- ~ifetussuria ______--- _------185 Sandstone and limestone, Thaynes formation, southeastern Idaho------_----- 173 Olenikites sp ______187 Seaway, Early Triassic ______------______------165 Ophiceras ______--- ______184 miog-eosynclinal ______------166 (Discophiceras) subkyokticum ______183 seerleyi, Wasatchensis ______--- ____ ------___ . ------"------186 (Glyptophiceras) nielsenL ______183 sepfentrionalis, Juveniles ______----_-_--- ___ ---_------.- 185 greenlandicum ______183 "Shale member" of Dinwoody formation, southwestern Montana____ ------170 jacksoni ______- __ ------______187 Shinarump conglomerate ___ --- __ --- __ ---- ___ --- ___ ------166, 180 (Lytophiceras) commnne ______183 shumarc'i, HemipriO'Y/,ites ____ - ____ --- -· ----_------186 (J.fetophicera~) subdemissum. ______183 slocomi, Hemiprionites______-- _____ -___ --- _------186 SJ9enceL _____ ------______-- ______187 smithi, Gurleyites ______----_--- __ ------186 ornatus, Col·umbites ______-______1R7 Pentacrintte (Isocrinus) ______------186 Hemiprionites. ______-- __ ------___ _------______-- ______1\6 spathi, ~Myalina ______------183, 184 194 INDEX

Page Page 1pencei, Ophiceras ______------_------______------__ 187 toulai, Xenodi&cus.~------______185 Bpiriferina man&jieZdL------__ ------183 Triassic formations_------______------______182, ISS Spray formation.------______184 correlation charts of------figs. 18,21 stachei, Claraia------______183, 184 tria.&icus, Pugnoidu __------____ 176, 186- Stacheitell sp_------______------187 trilobatus, Proptychite&. __ ------_------___ ------__ 184 Stanaker member, Ankareh formation______180 truncatus, Koninckites ______.______184 nt.barmatus, Kashmirites ______------______186 typus, Hemiprionitu ______------______186· 1ubdemissum, Metophicera. ______------_------__ __ 183 Ophiceras (Metophiceras) ------______------_____ ------______183 u &ubkyokticum, Di&cophiceras.------183 Uinta and central Wasatch Mountains, post-Thaynes Triassic ______179-18(). Ophicera. (Discophiceras)- __ ----- __ c _____ ------______183 Submeekoceras bonneviUenae. _------______------______185 Thaynes formation in __ .------~------______177-179> Uncompahgre positive area __ ------______------______166 evanaL ____ ------_- _- ______185 Upper black limestone, Thaynes formation, southeastern Idaho______173. mushbachanum ____ ------______------______185 Upper calcareous siltstone unit, Thaynes formation, eastern Bear Lake to corrugatum.- _------_____ ------______185 patelliforme. ------______185 Sublette Ridge ___ ------______------_ 175- Svalbardiceras haydenL ____ ------______------185 ursensis, CeUite& __------__ ------______187 Utah, northern, woodside formation thickness______171 pealeL. _------_- _- ______185 utahenais, Hemiprionites _____ ------______186- sp.------______187 111lcanum, Meekoceras ___ ------______-----~--- 185 v T vanbuskirki, Anasibirites______186· varian&, Hemiprionites_ -.- ______------_------______186 Tan silty limestone, Thaynes formation, southeastern Idaho______173 veranus, Anasibirites ______186· tarpeyi, Xenodiscus_------____ ------______185 tenuis, Clypites_------______185 w tenui&traitum, Meekoceras.- --··------__ ------______184 waageni, Metussuria______185 Thaynes formation.------______171-179 Anasibirites zone ______------______------172, 176 Xenodiscus ___ ------______------______------______185 Bear River Range_-.------______175-186 walcotti, Hemiprionites_ ------______------______------____ 186 Anasibiritea zone ______------______176 wardi, Anaaibirites ______------______------__ __ 186 central Wasatch and Uinta Mountains ______177-179 Wasatch line ____ --- ___ ------______------______------____ 165 Columbites zone ______------_____ ------172 waaatchensis, Wa&atchitu ______------______------______186 defined ____ ------_--______171 Wa&atchtte& gilberti______------_------______------______186- southeastern Idaho_------_____ ------__ 172 magnus .. ___ ------_------__ ------______------______186 eastern Bear Lake to Sublette Ridge area ______173-175 meeki______------______186- 186· lithologic units aL.--_- _- _- _-----_------______174-175 perrinL ______-______quadratus ______~______186- lower limestone unit_ __ ------____ ------______------_ 174 &eerleyi_ ____ ------_- _--- _- -- _- _- ______186- lower shale unit. __ ------______175 thorneL. ______186- middle limestone unit._------______175 Timothy sandstone member------175 wasatchensis------_------______------186· upper calcareous siltstone unit------175 weaveri, Anasibirites ______------_____ ------______------____ 186· Fort Hall Indian Reservation to Grays Range ______172-173 welleri, Anasibirite&_ ------_------______------185 Idaho, southeastern ______------______172-176 whiteanus, Xenodiscus. __ ------___ ------_------18& whitei, Anasibirite& ______------______185. lower black limestone------_____ ------__ 173 lower limestone ______------_------__ 173 whitfeldi, Ana&ibirite&. __ ------186 Portneuf limestone member------173, 174 Wood shale------______------______180, 181 Woodside formation ______------______17o-171 lithologic units.------______173 sandstone and limestone unit------173 defined. ___ ------_____ 17()- tan silty limestone ___ ------______173 featheredge tongues of ___ ----_------___ ------170, 17:J. Idaho, southeastern _____ ---______11o-111 Timothy sandstone member------173,174 upper black limestone_------173 Wyoming, central, Chugwater formation_------181-182' Meekoceras zone ___ ------_------__ 172 western, Dinwoody formation, thickness------168- Montana, southwestern. ___ ------____ ------__ 177 Thaynes formation_------·------176-177 Portneuf limestone member ____ ------172 Woodside formation, thickness------171 Wyomingite& aplanatu~---- ______185 Prohungaritts zone ______------172 Timothy sandstone member ____ ------172 arnoldL ___ ------_____ ------185- Tirolites zone ___ ------172 X Wyoming, western.------______176-177 thermarum, Juvenites ___ ------185 XenoceUite& dougla&ensi& .. ______185- hannai______thornei, Wasatchites. ______------_------~- __ ------186 185- matherL ______-----______---______Timothy sandstone ------172,180 185 eastern Bear Lake to Sublette Ridge______175 Xenodi&coide& involutUB---- ______184 southeastern Idaho_------173, 174 Xenodi&cus cordilleranu& ______185· gilberti. ______Tirolites_- _------176, 182, 183 185 intermontanu& ______~ ______harti_- ______- ~ _------__ ---_- _- _----- _- _------______186 185- iUgricus ______-- ____ - --~ ______187 tarpevL __ ------~------185 knightL. ______---_------_------_--- __ --______186 toulaL __--- ______-----______185- pealeL. ______------_- _-- ____ -______186 waageni ______------______----______185 wldteanus ______7lrolites zone, Thaynes, formation.------172 181lo 0