Geologic units in Uinta county, Wyoming

Additional scientific data in this geographic area

Bridger Formation (Eocene) at surface, covers 24 % of this area

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

Wasatch Formation (Eocene) at surface, covers 24 % of this area

(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.

Alluvium and Colluvium (Pleistocene-Holocene) at surface, covers 17 % of this area

Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.

Green River and Wasatch Formations (Eocene) at surface, covers 6 % of this area

Green River Formation (Thrust Belt) - Buff laminated marlstone and limestone, brown oil shale, and siltstone. Includes Angelo and Fossil Butte Members. Wasatch Formation (Thrust Belt) - 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). Green River Formation (in southwest Wyoming) - Oil shale, light-colored tuffaceous marlstone, and sandstone. Wasatch Formation (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.

Landslide deposits (Pleistocene-Holocene) at surface, covers 4 % of this area

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

Green River Formation - Laney Member (Eocene) at surface, covers 3 % of this area

Oil shale and marlstone.

Evanston Formation (Upper Cretaceous-Paleocene) at surface, covers 3 % of this area

Gray siltstone, sparse red sandstone, and lignite beds.

Hillard Shale (Upper Cretaceous) at surface, covers 3 % of this area

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

Terrace gravel (Pliocene-Pleistocene) at surface, covers 2 % of this area

Partly consolidated gravel above and flanking some major streams.

Undivided surficial deposits (Pleistocene-Holocene) at surface, covers 2 % of this area

Mostly alluvium, colluvium, and glacial and landslide deposits. Primarily in Yellowstone area and Bighorn Mountains.

Frontier Formation (Upper Cretaceous) at surface, covers 2 % of this area

(Thrust Belt) - White to brown sandstone and dark-gray shale; oyster coquina in upper part; coal and lignite in lower part. (North and South Wyoming) - Gray sandstone and sandy shale.

Fowkes Formation (Eocene) at surface, covers 2 % of this area

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

Glacial deposits (Pleistocene-Holocene) at surface, covers 1 % of this area

Till and outwash of sand, gravel, and boulders.

Sage Junction, Quealy, Cokeville, Thomas Fork, and Smiths Formations (Lower Cretaceous) at surface, covers 1 % of this area

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 Form Formation - Variegated mudstone and gray sandstone. Smiths Formation - Ferruginous black shale and tan to brown sandstone.

Gannett Group (Lower Cretaceous) at surface, covers 1 % of this area

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.

Gravel, pediment, and fan deposits (Pleistocene-Holocene) at surface, covers 1.0 % of this area

Mostly locally derived clasts. Includes some glacial deposits along east flank of Wind River Range. Locally includes some Tertiary gravels.

Green River Formation - Wilkins Peak Member (Eocene) at surface, covers 0.6 % of this area

Green, brown, and gray tuffaceous sandstone, shale, and marlstone; contains evaporites in subsurface sections.

Adaville Formation (Upper Cretaceous) at surface, covers 0.6 % of this area

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

Bishop Conglomerate (Oligocene) at surface, covers 0.5 % of this area

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

Aspen Shale (Lower Cretaceous) at surface, covers 0.5 % of this area

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

Dune sand and loess (Pleistocene-Holocene) at surface, covers 0.3 % of this area

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

Bear River Formation (Lower Cretaceous) at surface, covers 0.2 % of this area

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

Stump Formation, Preuss Sandstone or Redbeds, and Twin Creek Limestone (Middle Jurassic-Upper Jurassic) at surface, covers < 0.1 % of this area

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.

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

Older alluvial deposits

Wasatch Formation (Late Paleocene to Early Eocene) at surface, covers < 0.1 % of this area

Wasatch Formation.

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

Alluvium and colluvium

Wasatch/Colton Formations and Flagstaff Limestone (Early to Middle Eocene) at surface, covers < 0.1 % of this area

Wasatch/Colton Formations and Flagstaff Limestone.

Fowkes Formation (Eocene) at surface, covers < 0.1 % of this area

Fowkes Formation.