Pictured Cliffs Sandstone and Lewis Shale
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 several named units
Arkosic sandstone, shale, and conglomerate; contains abundant volcanic materials; Upper Cretaceous volcaniclastic McDermott Member at base
Sandstone, shale, and conglomerate. In northwest and west-central: Lower Cretaceous. In southwest: Lower and Upper Cretaceous.
Siltstone, shale, and sandstone
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.
Locally includes talus, rock-glacier, and thick colluvial deposits
Morrison, Wanakah, and Entrada Fms
Includes Piney Creek Alluvium and younger deposits
Shale, sandstone, and major coal beds
Intermediate to felsic compositions
Includes many named units
Arkosic sandstone, conglomerate, shale, and limestone. Includes at base in some areas siltstone and shale of Molas Fm or Larsen Quartzite
Arkosic sandstone, siltstone, and conglomerate
South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)
Red siltstone, shale, sandstone, and limestone-pellet conglomerate
Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest
Older glacial drift
Includes some unclassified glacial deposits
Volcaniclastic sedimentary rocks of intermediate composition in northern San Juan Basin.
Elbert Fm: shale and sandstone.
San Juan Basin
Wanakah Fm: Sandstone, shale, limestone, and local gypsum
Intra-ash flow andesitic lavas
Quartzite, slate, and phyllite
Includes basalts of Hinsdale Fm in San Juan Mountains - Servilleta Fm in San Luis Valley and many other occurrences
Includes Silver Plume, Sherman, Cripple Creek, St. Kevin, Vernal Mesa, Curecanti, Eolus, and Trimble Granites or Quartz Monzonites; also, San Isabel Granite of Boyer (1962) and unnamed granitic rocks
Includes Cliff House Sandstone, Menefee Formation, and Point Lookout Sandstone.
Marine shale and mudstone.
Landslide deposits on western flanks of Socorro Mountains not shown for clarity.
Divided into Upper and Lower parts by Gallup Sandstone.
Includes many long basaltic andesite dikes of Oligocene age near Pie Town, Acoma, Riley, Chupadera, Truth or Consequences, Roswell, Raton, and Dulce; and several elongate or shoestring-like sills of basalt or basaltic andesite. Also includes basaltic necks of Pliocene age that dot the landscape northeast of Mount Taylor. Where dikes extend into Quaternary alluvium the contact is an unconformity.
Mostly intermediate lavas of the lower Datil Group and intermediate volcaniclastic sediments of the lower Spears Group (Tla+Tvs). Locally includes ash-flow tuffs of the upper Datil Group (Tlrp). Includes intermediate volcaniclastic sedimentary rocks of the Conejos Formation in northern New Mexico.
Includes deposits of higher gradient tributaries bordering major stream valleys, alluvial veneers of the piedmont slope, and alluvial fans. May locally include uppermost Pliocene deposits.
Includes Baca, Galisteo, El Rito, Blanco Basin, Hart Mine, Love Ranch, Lobo, Sanders Canyon, Skunk Ranch, Timberlake, and Cub Mountain Formations.
Prominent cliff-forming marine sandstone.
Coal-bearing, primarily in the Fruitland.