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Mineral Resources > Online Spatial Data > Geology > by state > Wyoming Geology

Geologic units in Uinta county, Wyoming

Sage Junction, Quealy, Cokeville, THomas Fork, and Smiths Formations (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 1 % 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.

Lithology: mudstone; sandstone; limestone; bentonite; coal

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: Laney Member (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 3 % of this area

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

Lithology: oil shale; mixed clastic/carbonate

Bishop Conglomerate (Phanerozoic | Cenozoic | Tertiary | Oligocene ) at surface, covers 0.5 % of this area

BISHOP CONGLOMERATE--Clasts of red quartzite, gray chert, and limestone in a gray to white tuffaceous sandstone matrix.

Lithology: conglomerate

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

Lithology: alluvium

Green River and Wasatch Formations (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 6 % 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.

Lithology: mudstone; sandstone; oil shale; limestone; coal; conglomerate

Evanston Formation (Phanerozoic | Mesozoic Cenozoic | Cretaceous-Late Tertiary | Paleocene) at surface, covers 3 % of this area

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

Lithology: siltstone; sandstone; coal

Green River Formation: Wilkins Peak Member (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 0.6 % 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.

Lithology: fine-grained mixed clastic; mixed clastic/carbonate; mixed clastic/volcanic; evaporite

Adaville Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.6 % of this area

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

Lithology: sandstone; fine-grained mixed clastic; conglomerate; coal

Tertiary (2) sedimentary rocks in Salt Lake City-Coalville-Randolph region (Eocene) at surface, covers < 0.1 % of this area

Lithology: fine-grained mixed clastic; conglomerate; tuff; limestone

Tertiary (1) sedimentary rocks in Uinta Mountains-Unita Basin region (Early to Middle Eocene) at surface, covers < 0.1 % of this area

Lithology: fine-grained mixed clastic; limestone; coal

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

Gravel, pediment, and fan deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 1.0 % 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.

Lithology: unconsolidated deposit

Landslide deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 4 % of this area

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

Lithology: landslide; glacial drift

Bridger Formation (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 24 % of this area

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

Lithology: fine-grained mixed clastic; mixed clastic/volcanic; mixed clastic/carbonate

Dune sand and loess (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.3 % 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

Stump Formation, Preuss Sandstone or Redbeds, and Twin Creek Limestone (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late) at surface, covers < 0.1 % 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.

Lithology: fine-grained mixed clastic; limestone; sandstone; evaporite

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

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

Lithology: alluvium; colluvium; glacial drift; landslide

Alluvium and Colluvium (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 17 % of this area

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

Lithology: alluvium; colluvium

Wasatch Formation (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers 24 % 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.

Lithology: mudstone; sandstone; conglomerate; coal

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

Bear River Formation (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 0.2 % of this area

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

Lithology: shale; sandstone; limestone; bentonite

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

Lithology: alluvium; colluvium

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

Lithology: mudstone; conglomerate; limestone

Aspen Shale (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 0.5 % of this area

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

Lithology: mudstone; mixed clastic/volcanic; sandstone

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.

Lithology: fine-grained mixed clastic; medium-grained mixed clastic; mixed clastic/volcanic

Terrace gravel (Phanerozoic | Cenozoic | Tertiary Quaternary | Pliocene Pleistocene) at surface, covers 2 % of this area

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

Lithology: gravel

Gannett Group (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers 1 % 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.

Lithology: mudstone; sandstone; conglomerate; limestone