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Geologic units in Lincoln county, Wyoming

Additional scientific data in this geographic area

Alluvium and Colluvium (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 11 % of this area

ALLUVIUM AND COLLUVIUM--Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.

Lithology: alluvium; colluvium

Stump Formation, Preuss Sandstone or Redbeds, and Twin Creek Limestone (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late) at surface, covers 8 % of this area

STUMP FORMATION, PREUSS SANDSTONE or REDBEDS, and TWIN CREEK LIMESTONE. STUMP FORMATION--Glauconitic siltstone, sandstone, and limestone. PREUSS SANDSTONE OR REDBEDS--Purple, maroon, and reddish-gray sandy siltstone and claystone; contains salt and gypsum in thick beds in some subsurface sections. TWIN CREEK LIMESTONE--Greenish-gray shaly limestone and limy siltstone. Includes Gypsum Spring Member.

Wasatch Formation (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 8 % of this area

WASATCH FORMATION -- in Thrust belt: Main body--Variegated red to gray, brown, and gray mudstone and sandstone; conglomeratic lenses; in southwest Wyoming--Drab to variegated claystone and siltstone, carbonaceous shale and coal, buff sandstone, arkose, and conglomerate. In northwestern part of Green River Basin is thick arkosic light-yellowish-tan sandstone intertonguing with pale-green to gray claystone and shale; in east Wyoming--Drab sandstone and drab to variegated claystone; numerous coal beds in lower part.

Green River and Wasatch Formations (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 7 % of this area

GREEN RIVER AND WASATCH FORMATIONS -- in Thrust Belt: GREEN RIVER FORMATION--Buff laminated marlstone and limestone, brown oil shale, and siltstone. Includes Angelo and Fossil Butte Members. WASATCH FORMATION--Variegated mudstone and sandstone. Includes Tunp and Bullpen Members, other tongues and unnamed members, and main body (variegated red to gray, brown, and gray mudstone and sandstone; conglomerate lenses); in southwest Wyoming -- GREEN RIVER FORMATION--Oil shale, light-colored tuffaceous marlstone, and sandstone. WASATCH FORMATION--Drab to variegated claystone and siltstone, carbonaceous shale and coal, buff sandstone, arkose, and conglomerate. In northwestern part of Green River Basin is thick arkosic light-yellowish-tan sandstone intertonguing with pale-green to gray claystone and shale.

Ankareh Formation, Thaynes Limestone, Woodside Shale, and Dinwoody Formation (Phanerozoic | Mesozoic | Triassic-Early Triassic-Middle(?) Triassic-Late) at surface, covers 6 % of this area

ANKAREH FORMATION, THAYNES LIMESTONE, WOODSIDE SHALE, AND DINWOODY FORMATION. ANKAREH FORMATION--Red and maroon shale and purple limestone. THAYNES LIMESTONE--Gray limestone and limy siltstone. WOODSIDE SHALE--Red siltstone and shale. DINWOODY FORMATION--Gray to olive-drab dolomitic siltstone.

Gannett Group (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 6 % of this area

GANNETT GROUP--Red sandy mudstone, sandstone, and chert-pebble conglomerate; thin limestone and dark-gray shale in upper part, more conglomeratic in lower part. Includes Smoot Formation (red mudstone and siltstone), Draney Limestone, Bechler Conglomerate, Peterson Limestone, and Ephraim Conglomerate. Upper Jurassic fossils have been reported from the Ephraim.

Green River Formation: Laney Member (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 6 % of this area

GREEN RIVER FORMATION Laney Member (age probably about 45 Ma)--Oil shale and marlstone.

Sage Junction, Quealy, Cokeville, THomas Fork, and Smiths Formations (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 3 % of this area

SAGE JUNCTION, QUEALY, COKEVILLE, THOMAS FORK, AND SMITHS FORMATIONS. SAGE JUNCTION FORMATION--Gray and tan siltstone and sandstone. QUEALY FORMATION--Variegated mudstone and tan sandstone. COKEVILLE FORMATION--Tan sandstone, claystone, limestone, bentonite, and coal. THOMAS FORK FORMATION--Variegated mudstone and gray sandstone. SMITHS FORMATION--Ferruginous black shale and tan to brown sandstone.

Nugget Sandstone (Phanerozoic | Mesozoic | Triassic(?) Jurassic(?) ) at surface, covers 3 % of this area

NUGGET SANDSTONE--Thrust Belt: Buff to pink crossbedded well-sized and well-sorted quartz sandstone and quartzite; locally has oil and copper-silver-zinc mineralization. North Wyoming: Gray to dull-red, crossbedded quartz sandstone.

Lithology: sandstone

Hillard Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 3 % of this area

HILLIARD SHALE--Dark-gray to tan claystone, siltstone, and sandy shale.

Lithology: mudstone

Green River Formation: Wilkins Peak Member (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 3 % of this area

GREEN RIVER FORMATION Wilkins Peak Member (age about 49 Ma)--Green, brown, and gray tuffaceous sandstone, shale, and marlstone; contains evaporites in subsurface sections.

Madison Group and Darby Formation (TB, N) or Madison Group and Three Forks and Jefferson Formations (Y) (Phanerozoic | Paleozoic | Devonian-Late Carboniferous Mississippian-Early(?) Mississippian-Middle(?) Mississippian-Late) at surface, covers 3 % of this area

MADISON GROUP AND DARBY FORMATION (Thrust Belt, north Wyoming). MADISON GROUP--Group includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite). DARBY FORMATION--Yellow and greenish-gray shale and dolomitic siltstone underlain by fetid brown dolomite and limestone. MADISON GROUP AND THREE FORKS AND JEFFERSON FORMATIONS (Yellowstone). MADISON GROUP--Group includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite). THREE FORKS FORMATION--Pink, yellow, and green dolomitic siltstone and shale. JEFFERSON FORMATION--Massive siliceous dolomite.

Gravel, pediment, and fan deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 3 % of this area

GRAVEL, PEDIMENT, AND FAN DEPOSITS--Mostly locally derived clasts. Includes some glacial deposits along east flank of Wind River Range. Locally includes some Tertiary gravels.

Aspen Shale (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 2 % of this area

ASPEN SHALE--Light- to dark-gray siliceous tuffaceous shale and siltstone, thin bentonite beds, and quartzitic sandstone.

Bridger Formation (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 2 % of this area

BRIDGER FORMATION--Greenish-gray, olive-drab, and white tuffaceous sandstone and claystone; lenticular marlstone and conglomerate.

Wells and Amsden Formations (TB), or Casper Formation and Madison Limestone (N, S) (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Early Pennsylvanian-Middle(?) Pennsylvanian-Late(?) Permian) at surface, covers 2 % of this area

WELLS AND AMSDEN FORMATIONS (Thrust Belt). WELLS FORMATION--Gray limestone interbedded with yellow limy sandstone. AMSDEN FORMATION--Red and gray cherty limestone and shale, sandstone, and conglomerate. CASPER FORMATION AND MADISON LIMESTONE (north, south Wyoming). CASPER FORMATION--Gray, tan, and red thick-bedded sandstone underlain by interbedded sandstone and pink and gray limestone. May include some Devonian(?) sandstone along east flank of Laramie Mountains. MADISON LIMESTONE--Includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite).

Wasatch Formation (TB) (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 2 % of this area

WASATCH FORMATION Diamictite and sandstone--Diamictite grades laterally into other members of the formation.

Frontier Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 2 % of this area

FRONTIER FORMATION in thrust belt--White to brown sandstone and dark-gray shale; oyster coquina in upper part; coal and lignite in lower part; in north and south Wyoming--Gray sandstone and sandy shale.

Lithology: sandstone; shale; coal

Green River Formation: Fontenelle Tongue or Member [NONE ON MAP] (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 2 % of this area

WASATCH AND GREEN RIVER FORMATIONS: New Fork Tongue (dull-red and green mudstone, brown sandstone, and thin limestone beds, merging southward in T. 23 N. with other units) of Wasatch and Fontenelle Tongue or Member (oil shale, marlstone, limestone, and siltstone; occurs along Green and New Fork Rivers and on west side of Green River Basin from T. 33 N. south to and lensing out in T. 17 N.) of Green River.

Bighorn Dolomite, Gallatin Limestone, and Gros Ventre Formation (TB), Bighorn Dolomite, Snowy Range Formation, Pilgrim Limestone, Park Shale, Meagher Limestone, Wolsey Shale, and Flathead Sandstone (Y), Bighorn Dolomite, Gallatin Limestone, Gros Ventre Formation, and Flathead Sandstone (N), or Whitewood Dolomite, and WInnipeg and Deadwood Formations (NE) (Phanerozoic | Paleozoic | Cambrian-Middle Cambrian-Furongian(?) Ordovician-Early(?) Ordovician-Middle(?) Ordovician-Late) at surface, covers 2 % of this area

BIGHORN DOLOMITE, GALLATIN LIMESTONE, and GROS VENTRE FORMATION. BIGHORN DOLOMITE (Thrust Belt)--Gray massive cliff-forming siliceous dolomite and locally dolomitic limestone. GALLATIN LIMESTONE--Gray and tan limestone. GROS VENTRE FORMATION--Greenish-gray micaceous shale. BIGHORN DOLOMITE, SNOWY RANGE FORMATION, PILGRIM LIMESTONE, PARK SHALE, MEAGHER LIMESTONE, WOLSEY SHALE, AND FLATHEAD SANDSTONE (Yellowstone). BIGHORN DOLOMITE--Light-gray massive siliceous dolomite. SNOWY RANGE FORMATION (Gallatin Group)--Medium-gray limestone and underlying greenish-gray shale. PILGRIM LIMESTONE (Gallatin Group)--Blue-gray and yellow mottled hard limestone. PARK SHALE--Green micaceous soft shale. Upper part may be Late Cambrian. MEAGHER LIMESTONE--Blue-gray and yellow mottled hard limestone. WOLSEY SHALE--Green micaceous soft shale. FLATHEAD SANDSTONE--Dull-red quartzitic sandstone. BIGHORN DOLOMITE, GALLATIN LIMESTONE, GROS VENTRE FORMATION, AND FLATHEAD SANDSTONE (north Wyoming). BIGHORN DOLOMITE--Gray massive cliff-forming siliceous dolomite and locally dolomitic limestone. GALLATIN LIMESTONE--Blue-gray and yellow mottled hard dense limestone. GROS VENTRE FORMATION--Soft green micaceous shale (Upper and Middle Cambrian Park Shale Member), underlain by blue-gray and yellow mottled hard dense limestone (Middle Cambrian Death Canyon Limestone Member), and soft green micaceous shale (Middle Cambrian Wolsey Shale Member). FLATHEAD SANDSTONE--Dull-red quartzitic sandstone. WHITEWOOD DOLOMITE, AND WINNIPEG AND DEADWOOD FORMATIONS (northeast Wyoming). WHITEWOOD DOLOMITE--Buff massive fossiliferous dolomite. WINNIPEG FORMATION--Pink to yellow siltstone and shale. DEADWOOD FORMATION--Red and brown quartzitic sandstone.

Landslide deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 2 % of this area

LANDSLIDE DEPOSITS--Locally includes intermixed landslide and glacial deposits, talus, and rock-glacier deposits.

Fowkes Formation (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 2 % of this area

FOWKES FORMATION--Light-colored tuffaceous sandstone and siltstone, locally conglomeratic. Locally designated by some as Norwood Tuff.

Bear River Formation (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 2 % of this area

BEAR RIVER FORMATION--Black shale, fine-grained brown sandstone, thin limestone, and bentonite beds.

Glacial deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 1 % of this area

GLACIAL DEPOSITS--Till and outwash of sand, gravel, and boulders.

Lithology: glacial drift

Phosphoria, Wells, and Amsden Formations (TB), Phosphoria Formation and related rocks, Quadrant Sandstone, and Amsden Formation (Y), or Phosphoria Formation and related rocks, Tensleep Sandstone, and Amsden Formation (N) (Phanerozoic | Paleozoic | Carboniferous Mississippian-Late Pennsylvanian(?) Permian) at surface, covers 1 % of this area

PHOSPHORIA, WELLS, AND AMSDEN FORMATIONS (Thrust Belt). PHOSPHORIA FORMATION--Upper part is dark- to light-gray chert and shale with black shale and phosphorite at top; lower part is black shale, phosphorite, and cherty dolomite. WELLS FORMATION--Gray limestone interbedded with yellow limy sandstone. AMSDEN FORMATION--Red and gray cherty limestone and shale, sandstone, and conglomerate. PHOSPHORIA FORMATION AND RELATED ROCKS, QUADRANT SANDSTONE, AND AMSDEN FORMATION (Yellowstone). PHOSPHORIA FORMATION AND RELATED ROCKS--Brown sandstone and dolomite, cherty phosphatic and glauconitic dolomite, phosphatic sandstone and dolomite, and greenish-gray to black shale. Intertonguing equivalent is Shedhorn Sandstone. QUADRANT SANDSTONE--Light-gray sandstone. AMSDEN FORMATION--Red and green dolomitic shale, siltstone, and sandstone. PHOSPHORIA FORMATION AND RELATED ROCKS, TENSLEEP SANDSTONE, AND AMSDEN FORMATION (north Wyoming). PHOSPHORIA FORMATION AND RELATED ROCKS--Brown sandstone and dolomite, cherty phosphatic and glauconitic dolomite, phosphatic sandstone and dolomite, and greenish-gray to black shale. Intertonguing equivalents of parts of Phosphoria are Park City Formation (primarlily cherty dolomite, limestone, and phosphatic gray shale) and Shedhorn Sandstone. TENSLEEP SANDSTONE--White to gray sandstone containing thin limestone and dolomite beds. Permian fossils have been found in the topmost beds of the Tensleep at some localities in Washakie Range, Owl Creek Mountains, and southern Bighorn Mountains. AMSDEN FORMATION--Red and green shale and dolomite; at base is brown sandstone.

Evanston Formation (Phanerozoic | Mesozoic Cenozoic | Cretaceous-Late Tertiary | Paleocene) at surface, covers 1 % of this area

EVANSTON FORMATION--Gray siltstone, sparse red sandstone, and lignite beds.

Lithology: siltstone; sandstone; coal

Nugget Sandstone, Ankareh Formation, Thaynes Limestone, Woodside Shale, and Dinwoody Formation (TB), or Nugget Sandstone and Chugwater and Dinwoody Formations (N) (Phanerozoic | Mesozoic | Triassic-Early Triassic-Middle(?) Triassic-Late(?) Triassic(?) Jurassic(?)) at surface, covers 1 % of this area

NUGGET SANDSTONE, ANKAREH FORMATION, THAYNES LIMESTONE, WOODSIDE SHALE, and DINWOODY FORMATION (Thrust Belt). NUGGET SANDSTONE--Buff to pink crossbedded well-sized and well-sorted quartz sandstone and quartzite; locally has oil and copper-silver-zinc mineralization. ANKAREH FORMATION--Red and maroon shale and purple limestone. THAYNES LIMESTONE--Gray limestone and limy siltstone. WOODSIDE SHALE--Red siltstone and shale. DINWOODY FORMATION--Gray to olive-drab dolomitic siltstone. NUGGET SANDSTONE AND CHUGWATER AND DINWOODY FORMATIONS (north Wyoming). NUGGET SANDSTONE--Gray to dull-red, crossbedded quartz sandstone. CHUGWATER FORMATION--Red siltstone and shale. Alcova Limestone Member in upper middle part in north Wyoming. Thin gypsum partings near base in north and northeast Wyoming. DINWOODY FORMATION--Olive-drab hard dolomitic thin-bedded siltstone.

Teewinot Formation (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers 1 % of this area

TEEWINOT FORMATION (AGE ABOUT 9 Ma)--White lacustrine clay, tuff, and limestone. In thrust belt includes conglomerate.

Blind Bull Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.9 % of this area

BLIND BULL FORMATION--Gray to tan conglomeratic sandstone, siltstone, claystone, coal, and bentonite.

Phosphoria Formation (Phanerozoic | Paleozoic | Permian) at surface, covers 0.9 % of this area

PHOSPHORIA FORMATION AND RELATED ROCKS--Thrust Belt: Upper part is dark- to light-gray chert and shale with black shale and phosphorite at top; lower part is black shale, phosphorite, and cherty dolomite; north Wyoming: Brown sandstone and dolomite, cherty phosphatic and glauconitic dolomite, phosphatic sandstone and dolomite, and greenish-gray to black shale. Intertonguing equivalents of parts of Phosphoria are Park City Formation (primarily cherty dolomite, limestone, and phosphatic gray shale) and Shedhorn Sandstone.

Terrace gravel (Phanerozoic | Cenozoic | Tertiary Quaternary | Pliocene Pleistocene) at surface, covers 0.8 % of this area

TERRACE GRAVEL (PLEISTOCENE AND/OR PLIOCENE)--Partly consolidated gravel above and flanking some major streams.

Lithology: gravel

Adaville Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.7 % of this area

ADAVILLE FORMATION--Gray sandstone, siltstone, and carbonaceous claystone; conglomeratic in upper part; coal-bearing in lower part.

Wasatch Formation (SW) (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers 0.4 % of this area

WASATCH FORMATION La Barge and Chappo Members--Red, gray, and brown mudstone and conglomerate and yellow sandstone. La Barge Member tongues out to north at about T. 35 N. Lower part of Chappo is Paleocene.

Salt Lake Formation (Phanerozoic | Cenozoic | Tertiary | Miocene Pliocene) at surface, covers 0.3 % of this area

SALT LAKE FORMATION--White, gray, and green limy tuff, siltstone, sandstone, and conglomerate.

Dune sand and loess (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.2 % of this area

DUNE SAND AND LOESS--Includes active and dormant sand dunes. In northwestern Wyoming is chiefly loess (age 12,000-19,000 years).

Lithology: dune sand; loess

Conglomerate of Sublette Range (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers < 0.1 % of this area

CONGLOMERATE OF SUBLETTE RANGE (EOCENE AND PALEOCENE)--Locally derived indurated angular conglomerate.

Lithology: conglomerate

Wasatch Formation (SW) (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area

WASATCH FORMATION Cathedral Bluffs Tongue--Variegated claystone and lenticular sandstone; conglomeratic near south margin of Wind River Range.

Laketown Dolomite (Phanerozoic | Paleozoic | Silurian) at surface, covers < 0.1 % of this area

LAKETOWN DOLOMITE--Light-gray thick-bedded finely crystalline dolomite.

Sandstone, siltstone, shale, limestone, and coal ; Early Cretaceous Cordilleran retroarc-foreland-basin deposits; southeastern Idaho (Early Cretaceous) at surface, covers < 0.1 % of this area

Lower Cretaceous shale, siltstone, red-bed sandstone and fresh-water limestone.

Wayan and Smiths Formations (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers < 0.1 % of this area

WAYAN AND SMITHS FORMATIONS. WAYAN FORMATION--Variegated mudstone, siltstone, and sandstone. SMITHS FORMATION--Ferruginous black shale and tan to brown sandstone.

Lithology: mudstone; sandstone

Madison Limestone or Group (S) (Phanerozoic | Paleozoic | Carboniferous Mississippian-Early Mississippian-Middle(?) Mississippian-Late) at surface, covers < 0.1 % of this area

MADISON LIMESTONE OR GROUP--Group includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite).

Gravel, sand, and silt; Quaternary; alluvium (Quaternary) at surface, covers < 0.1 % of this area

Quaternary alluvium; may contain some glacial deposits and colluvium in uplands

Madison Limestone, Darby Formation, Bighorn Dolomite, Gallatin Limestone, Gros Ventre Formation, and Flathead Sandstone (N), Madison Limestone and Cambrian rocks (S), Minnekahta Limestone, Opeche Shale, Minnelusa Formation, Pahasapa and Englewood Limestones, Whitewood Dolomite, Winnipeg and Deadwood Formations (NE), or Paleozoic, undifferentiated (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous(?) Permian) at surface, covers < 0.1 % of this area

MADISON LIMESTONE, DARBY FORMATION, BIGHORN DOLOMITE, GALLATIN LIMESTONE, GROS VENTRE FORMATION, AND FLATHEAD SANDSTONE (north Wyoming). MADISON LIMESTONE OR GROUP--Group includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite). DARBY FORMATION--Yellow and greenish-gray shale and dolomitic siltstone underlain by fetid brown dolomite and limestone. BIGHORN DOLOMITE--Gray massive cliff-forming siliceous dolomite and locally dolomitic limestone. GALLATIN LIMESTONE--Blue-gray and yellow mottled hard dense limestone. GROS VENTRE FORMATION--Soft green micaceous shale (Upper and Middle Cambrian Park Shale Member), underlain by blue-gray and yellow mottled hard dense limestone (Middle Cambrian Death Canyon Limestone Member), and soft green micaceous shale (Middle Cambrian Wolsey Shale Member). FLATHEAD SANDSTONE--Dull-red quartzitic sandstone. MADISON LIMESTONE AND CAMBRIAN ROCKS (south Wyoming). MADISON LIMESTONE--Includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite). CAMBRIAN ROCKS--On south flank of Granite Mountains, blue-gray and yellow mottled hard dense limestone interbedded with soft green micaceous shale; dull-red quartzitic sandstone at bae. On and south of Rawlins uplift, glauconitic quartzitic sandstone. MINNEKAHTA LIMESTONE, OPECHE SHALE, MINNELUSA FORMATION, PAHASAPA AND ENGLEWOOD LIMESTONES, WHITEWOOD DOLOMITE, AND WINNIPEG AND DEADWOOD FORMATIONS--Various combinations (northeast Wyoming). MINNEKAHTA LIMESTONE--Gray slabby hard limestone. Locally is a member of the Goose Egg Formation. OPECHE SHALE--Red soft sandy shale. Locally is a member of the Goose Egg Formation. MINNELUSA FORMATION--Buff and red limy sandstone; some thin limestone beds, solution breccias, and gypsum. PAHASAPA LIMESTONE--Gray massive dolomititc limestone. ENGLEWOOD LIMESTONE--Pink slabby dolomitic limestone. WHITEWOOD DOLOMITE--Buff massive fossiliferous dolomite. WINNIPEG FORMATION--Pink to yellow siltstone and shale. DEADWOOD FORMATION--Red and brown quartzitic sandstone. PALEOZOIC ROCKS, undifferentiated (Thrust Belt).

Intrusive and extrusive igneous rocks (Phanerozoic | Cenozoic | Tertiary | Miocene Pliocene) at surface, covers < 0.1 % of this area

INTRUSIVE AND EXTRUSIVE IGNEOUS ROCKS--Composition ranges from hornblende monzonite to basalt. In Yellowstone area includes andesite and basalt of Emerald Lake (age about 2 Ma), rhyolite of Broad Creek, Pliocene Junction Butte Basalt, and gravel of Mount Everts. Age of basalt on Crescent Mountain 3.6 Ma.

Lithology: granitoid; basalt

Devonian sedimentary rocks in Salt Lake City-Coalville-Randolph region (Devonian) at surface, covers < 0.1 % of this area

Quaternary alluvium and colluvium (Quaternary) at surface, covers < 0.1 % of this area

Lithology: alluvium; colluvium

Undivided surficial deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area

UNDIVIDED SURFICIAL DEPOSITS--Mostly alluvium, colluvium, and glacial and landslide deposits. Primarily in Yellowstone area and Bighorn Mountains.

Clastic debris; Quaternary colluvium, fanglomerate, talus, and glacial deposits; upland-valley margins (Quaternary) at surface, covers < 0.1 % of this area

Quaternary colluvium, fanglomerate, and talus plus some glacial debris in upland valleys.

Camp Davis Formation (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers < 0.1 % of this area

CAMP DAVIS FORMATION--Upper 5,000 ft chiefly red conglomerate and red claystone; underlain by white tuff, limestone, claystone, and basal gray conglomerate.

Lithology: conglomerate; claystone

Siltstone, evaporites, and redbeds; Late Jurassic Cordilleran retroarc-foreland-basin deposits; southeastern Idaho (Late Jurassic) at surface, covers < 0.1 % of this area

Upper Jurassic shallow-marine to non-marine sediments; glauconitic and variegated sandstone, siltstone and oolitic limestone of eastern Idaho.

Tertiary (1) sedimentary rocks in Salt Lake City-Coalville-Randolph region (Late Paleocene to Early Eocene) at surface, covers < 0.1 % of this area

Older Quaternary alluvial deposits (Quaternary) at surface, covers < 0.1 % of this area

Lithology: alluvium

Coralline Limestone, sandstone, siltstone, shale, chert, and phosphorite; Mississippianshallow marine inner continental-shelf deposits; east-central Idaho, central Idaho (Mississippian ) at surface, covers < 0.1 % of this area

Mississippian shallow-water coralline limestone interval of southern Idaho.

Open Water (Holocene) at surface, covers < 0.1 % of this area

Lakes and streams

Lithology: water

Pennsylvanian and Permian sedimentary rocks in Salt Lake City-Coalville-Randolph region (Pennsylvanian to Permian) at surface, covers < 0.1 % of this area

Sandstone, conglomerate, siltstone, tuff, claystone, limestone, and diatomite; Pliocene tuffaceous alluvial and lacustrine deposits; Snake River Plain and vicinity, southeastern Idaho (Pliocene ) at surface, covers < 0.1 % of this area

Pliocene stream and lake deposits; may be due to volcanic and block-faulting events.

Shale, limestone, and sandstone; Triassic marine to non-marine epicontinental deposits (subunits are TRl and TRu) (Triassic) at surface, covers < 0.1 % of this area

Triassic shallow-marine to non-marine sediments of eastern Idaho; subdivisions are (TRu and TRl).

Mississippian (1) carbonate rocks in Salt Lake City-Coalville-Randolph region (Mississippian) at surface, covers < 0.1 % of this area

Lithology: limestone

Tertiary (1) sedimentary rocks in Logan-Huntsville Allochthon (Late Cretaceous to Early Eocene) at surface, covers < 0.1 % of this area