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)
Includes dune sand and silt and Peoria Loess
Morrison, Wanakah, and Entrada Fms
Summerville Fm: Shale and siltstone
Arkosic sandstone, siltstone, and conglomerate
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, shale, sandstone, and limestone-pellet conglomerate
Dakota Sandstone or Group
Intermediate to felsic compositions
Arkosic sandstone, conglomerate, shale, and limestone. Includes at base in some areas siltstone and shale of Molas Fm or Larsen Quartzite
In southwest, Glen Canyon Group consists of Navajo Sandstone, Kayenta Fm (red siltstone, shale, and sandstone) and Wingate Sandstone; Chinle is red siltstone
Variegated claystone, mudstone, sandstone, and local beds of limestone
Mainly intermediate to felsic compositions; some mafic
Locally includes talus, rock-glacier, and thick colluvial 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 Piney Creek Alluvium and younger deposits
Includes some unclassified glacial deposits
Intermediate to felsic compositions
Dakota Ss and Cedar Mtn or Burro Canyon Formations.
Eolian deposits
Morrison Formation (Brushy Basin and Salt Wash Members).
Quartzite, slate, and phyllite
Includes several named units
Alluvium and colluvium