Sandstone and siltstone; west of Park Range
Claystone, shale, and sandstone
Claystone, mudstone, and sandstone; in Sand Wash basin
In northwest and west-central: Intertongues complexly with units of overlying Mesaverde Group or Fm; lower part consists of a calcareous Niobrara equivalent and Frontier Sandstone and Mowry Shale Members; in areas where the Frontier and Mowry Members (Kmfm), or these and the Dakota Sandstone (Kfd) are distinguished, map unit (Km) consists of shale above Frontier Member. In Southwest: Lower part contains Juana Lopez Member (Kmj)
Sandstone, shale, and major coal beds
Quartzite, conglomerate, and shale
Claystone, oil shale, and sandstone; in Sand Wash basin
Includes Piney Creek Alluvium and younger deposits
Claystone and mudstone; in Sand Wash basin
Shale, sandstone, and local coal beds
Morgan Fm: limestone, sandstone, and shale. In far northwest.
Sandstone and shale. Trout Creek Sandstone Member at top; coal beds in upper half
Claystone and oil shale; in Sand Wash basin. In extreme northwest includes rocks of Wilkins Peak Member
Glen Canyon Sandstone; In northwest
Upper part includes equivalents of Upper Mississippian Doughnut and Humbug Fms (shale, limestone, and sandstone)
Shale, sandstone, and minor coal beds; Fox Hills equivalent at base
Carbonaceous shale and marlstone; in Sand Wash basin
Mudstone, sandstone, and carbonaceous shale; in Sand Wash basin
In extreme southwestern Moffat County, includes thin wedge of Carmel Fm (red siltstone and sandstone) beneath Entrada
Locally includes, at base, Burro Canyon Fm (shale and sandstone) or, in western Moffat County, Cedar Mountain Fm (conglomerate and shale)
Marlstone, sandstone, and oil shale
Madison Limestone and Lodore Fm
Red and gray siltstone, shale, and sandstone
Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest
Locally includes talus, rock-glacier, and thick colluvial deposits
In Moffat and Rio Blanco Counties, sandstone, shale, and coal beds above Sego Sandstone. Along Grand Hogback south of Colorado River, sandstone and shale above coal-bearing sequence
Sandstone, shale, and conglomerate
Includes Broadway and Louviers Alluviums
Calcareous siltstone and sandstone
Includes dune sand and silt and Peoria Loess
Sego Sandstone, Buck Tongue of Mancos Shale, and Castlegate Sandstone
Red siltstone, mudstone, sandstone, and local gypsum
Mainly of intermediate compositions
Curtis is absent along Grand Hogback
In northwest and west-central: Major coal beds in lower part; Rollins Sandstone Member at base in Delta, Gunnison, and Pitkin Counties. In southwest: sandstone and shale.
Red siltstone, sandstone, and limestone-pellet conglomerate
Shale, sandstone, marlstone, and limestone in Anvil Points, Garden Gulch, and Douglas Creek Members; in Piceance basin
Northwest: includes Duchesne River Fm (sandstone and shale; includes some rocks of Eocene age) and Bishop Conglomerate near Utah border. South-central: includes Florissant Lake Beds (tuffaceous shale and tuff) and Antero Fm (limestone tuff, tuffaceous sandstone, and conglomerate). Southwest: includes Creede Fm (tuffaceous siltstone, sandstone, conglomerate) and gravels interbedded with volcanic rocks northeast and southeast of Gunnison
Arkosic sandstone, conglomerate, shale, and limestone. Includes Madera Fm and Sharpsdale Fm of Chronic (1958) in Sangre de Cristo Range and Gothic Fm of Langenheim (1952) in Elk Mountains. Other units of Middle Pennsylvanian age.
Includes basalts of Hinsdale Fm in San Juan Mountains - Servilleta Fm in San Luis Valley and many other occurrences
Parachute Creek Member--Oil shale, marlstone, and siltstone; in Piceance basin
Drab sandstone, drab to variegated claystone and siltstone; locally derived conglomerate around basin margins. Lower part is Paleocene.
Variegated claystone, mudstone, sandstone, and local beds of limestone
Intermediate to felsic compositions
Leadville Limestone, Williams Canyon Limestone , Manitou Limestone, and Sawatch Quartzite
Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.
Uinta Mountain Group (24,000 feet thick along the Green River). Red Pine Shale (950 my).
Morgan Formation and Round Valley Limestone.
Metaquartzite, amphibolite, and mica schist. Present only in small area at Utah border in Uinta Mountains
Mainly Lower Cretaceous, Jurassic, and Triassic Fms
Southwest Wyoming: Southern Rock Springs uplift--Pale-green to tan tuffaceous sandstone and claystone of Miocene(?) age. Conglomerate of uncertain correlation locally at base. Saratoga Valley and west and southwest to Colorado--White massive soft tuffaceous sandstone and lesser amounts of white marl; lower part conglomeratic. Underlies North Park Formation in Saratoga Valley. To the west and southwest is called Browns Park Formation. Rawlins area--White massive soft tuffaceous sandstone; Central Wyoming: White soft tuffaceous sandstone. Locally derived conglomerate in upper and lower parts of sequence; in places lower conglomeratic sequence may be of Oligocene age. In Granite Mountains K/Ar age of tuff in lower part of sandstone sequence about 17 Ma and fission-track age of lower conglomerate about 24 Ma.
Alluvium and colluvium
Oil shale, carbonaceous shale, and sandstone.
Mesaverde Formation (north Wyoming) - Light-colored massive to thin-bedded sandstone, gray sandy shale, and coal beds. In Jackson Hole locally contains gold-bearing quartzite conglomerate. North of North Fork Powder River east of the Bighorn Mountains, consists solely of the Parkman Sandstone Member. Mesaverde Group (South Wyoming) - Includes Almond Formation, Ericson Sandstone, Rock Springs and Blair Formations in Rock Springs uplift; Almond Formation (white and brown soft sandstone, gray sandy shale, coal and carbonaceous shale), Pine Ridge Sandstone (light-gray sandstone and thin coal beds), and Allen Ridge (gray sandstone, shale, and thin coal beds) and Haystack Mountains (gray marine sandstone and shale) Formations in Rawlins uplift; Pine Ridge Sandstone (light-gray sandstone and thin coal beds) and Rock River Formation (soft sandstone and sandy shale) in Laramie Basin.
Variegated claystone and lenticular sandstone; conglomeratic near south margin of Wind River Range.
Older alluvial deposits
Brown sandstone, carbonaceous shale, and coal.
(Northwest, Southwest, and Central Wyoming) - Brown to gray sandstone, gray to black shale, and thin coal beds. (East Wyoming) - Light-colored massive sandstone, drab shale, and thick coal beds.
Oil shale and marlstone.
Browns Park Formation.
Morrison Formation (Dinosaur National Monument).
Dakota and Cedar Mountain Formations.
Mancos Shale (Hilliard Shale and Blair Formation north of Uinta Mountains), Frontier Ss, and Mowry Shale.
Curtis Fm, Entrada Ss, and Carmel Fm.
Oil shale and marlstone.
Park City Formation.
Gray marine shale containing many gray and brown lenticular concretion-rich sandstone beds.
Basalt flows and intrusive igneous rocks
Green, brown, and gray tuffaceous sandstone, shale, and marlstone; contains evaporites in subsurface sections.