Sandstone, shale, and conglomerate. In northwest and west-central: Lower Cretaceous. In southwest: Lower and Upper Cretaceous.
Includes several named units
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)
Locally includes talus, rock-glacier, and thick colluvial deposits
Intra-ash flow andesitic lavas
Dakota, Purgatoire, Morrison, Ralston Creek, and Entrada Fms in southeast. Dakota, Morrison, and Entrada Fms in central mountains. Dakota, Burro Canyon, Morrison, Wanakah, and Entrada Fms in Gunnison River area. Dakota, Morrison, Curtis, And Entrada Fm
Includes many named units
Includes Piney Creek Alluvium and younger deposits
Summerville Fm: Shale and siltstone
Includes Broadway and Louviers Alluviums
Red siltstone, sandstone, and conglomerate
Mainly intermediate to felsic compositions; some mafic
Morrison, Wanakah, and Entrada Fms
Includes some unclassified glacial deposits
Intermediate to felsic compositions
In northwestern San Juan Mountains. Cimarron Ridge Fm: volcanic breccia and conglomerate.
Variegated claystone, mudstone, sandstone, and local beds of limestone
Older glacial drift
Quartzite, slate, and phyllite
South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)
Arkosic sandstone, conglomerate, shale, and limestone; gypsum and salt in Paradox Member present in salt anticlines near Utah border
Parting Fm: quartzite and shale.
Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest