Sandstone, shale, and conglomerate. In northwest and west-central: Lower Cretaceous. In southwest: Lower and Upper Cretaceous.
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)
Summerville Fm: Shale and siltstone
Includes dune sand and silt and Peoria Loess
Morrison, Wanakah, and Entrada Fms
Includes several named units
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.
Intermediate to felsic compositions
In southwest, Glen Canyon Group consists of Navajo Sandstone, Kayenta Fm (red siltstone, shale, and sandstone) and Wingate Sandstone; Chinle is red siltstone
Locally includes talus, rock-glacier, and thick colluvial deposits
Dakota Sandstone or Group
Red siltstone, shale, sandstone, and limestone-pellet conglomerate
Includes Piney Creek Alluvium and younger deposits
Arkosic sandstone, siltstone, and conglomerate
Arkosic sandstone, conglomerate, shale, and limestone; gypsum and salt in Paradox Member present in salt anticlines near Utah border
Includes some unclassified glacial deposits
South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)
Includes many named units
Variegated claystone, mudstone, sandstone, and local beds of limestone
Kayenta Fm: red siltstone, shale, and sandstone. Chinle Fm: red siltstone and sandstone
Dakota Ss and Cedar Mtn or Burro Canyon Formations.
Mancos Shale (Masuk Shale Mbr, Emery Sandstone Mbr, Blue Gate Shale Mbr, Ferron Sandstone Mbr, and Tununk Shale Mbr).