East: Ashy claystone and sandstone. Includes Castle Rock Conglomerate in region southeast of Denver. Northwest: Ashy claystone in North Park
Includes dune sand and silt and Peoria Loess
Loose to well-cemented sand and gravel
Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest
Includes Broadway and Louviers Alluviums
Shale, claystone, sandstone, and major coal beds
Arkosic sandstone, shale, mudstone, conglomerate, and local coal beds
Includes Piney Creek Alluvium and younger deposits
Sandstone; contains abundant volcanically derived material
Sandstone, mudstone, claystone, and conglomerate; Denver is characterized by andesitic materials
WHITE RIVER FORMATION (AGE 31 TO 35 Ma)--White to pale-pink blocky tuffaceous claystone and lenticular arkosic conglomerate.
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.
ALLUVIUM AND COLLUVIUM--Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.
UPPER MIOCENE ROCKS--Southwest Wyoming: South end of Wind River Range--Siliceous, arkosic, and locally radioactive sandstone, claystone, and conglomerate. Fission-track age about 27 Ma. Recent work suggests that part of these deposits may be of Eocene age. Pliocene and Miocene (as originally defined 2) South Pass Formation. Saratoga Valley--White to greenish-gray tuffaceous sandstone, siltstone, and claystone; locally conglomeratic. North Park Formation; Central Wyoming: Arkosic sandstone, conglomerate, and siltstone; some light-colored tuffaceous radioactive claystone and white cherty limestone. North of Sweetwater River in Granite Mountains--Light-colored tuffaceous radioactive claystone, siltstone, sandstone, and arkose. Moonstone Formation; East Wyoming: Light-colored tuffaceous claystone, sandstone, and conglomerate. Ogallala Formation in Denver Basin.