The Late Silurian to Early Devonian Keyser Formation is a mapped limestone bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
The Mancos Shale or Mancos Group is a Late Cretaceous geologic formation of the Western United States.
Treasure Mountain, elevation 13,535 ft (4,125 m), is a summit in the Elk Mountains of western Colorado. The mountain is in the Raggeds Wilderness southeast of Marble. The massif has been the site of marble mining and a legend of lost French gold.
The Surprise Canyon Formation is a geologic formation that consists of clastic and calcareous sedimentary rocks that fill paleovalleys and paleokarst of Late Mississippian (Serpukhovian) age in Grand Canyon. These strata outcrop as isolated, lens-shaped exposures of rocks that fill erosional valleys and locally karsted topography and caves developed in the top of the Redwall Limestone. The Surprise Canyon Formation and associated unconformities represent a significant period of geologic time between the deposition of the Redwall Limestone and the overlying Supai Group.
The Bluefield Formation is a geologic formation in West Virginia. It preserves fossils dating back to the Mississippian subperiod of the Carboniferous period. Sediments of this age formed along a large marine basin lying in the region of what is now the Appalachian Plateau. The Bluefield Formation is the lowest section of the primarily siliciclastic Mauch Chunk Group, underlying the Stony Gap Sandstone Member of the Hinton Formation and overlying the limestone-rich Greenbrier Group.
The Kinzers Formation is a geologic formation in Pennsylvania. It preserves fossils dating back to the Cambrian Period.
The Odenville Limestone is a geologic formation in Alabama. It preserves fossils dating from the early Ordovician Period.
The Greenhorn Limestone or Greenhorn Formation is a geologic formation in the Great Plains Region of the United States, dating to the Cenomanian and Turonian ages of the Late Cretaceous period. The formation gives its name to the Greenhorn cycle of the Western Interior Seaway.
The Sangre de Cristo Formation is a geologic formation in Colorado and New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian.
The Troublesome Formation is a geologic formation in Colorado. It preserves fossils dating back to the Neogene period. It consists of Pale shades of pink, tan, gray, green, and white interbedded siltstone and mudstone, less abundant arkosic sandstone and conglomerate, and sparse limestone and altered crystal-vitric ash and tuff; generally poorly consolidated. It includes atypical deposits containing abundant pink, granitic cobbles and boulders along the western parts of the outcrop in the west-central and southwestern parts of the Granby Quadrangle, Fossil mammals from three sites indicate a late Oligocene age.
The Manitou Limestone is a geologic formation in Colorado. It preserves fossils dating back to the Ordovician period.
The San Pedro Arroyo Formation is a geologic formation in south-central New Mexico. It preserves fossils dating back to the late Triassic period.
The Deseret Limestone, also known as the Pine Canyon Formation, is a geologic formation in Utah. It was formed by the Panthalassa ocean around 340 Ma. It preserves marine fossils dating back to the Carboniferous period or Mississippian age, mostly consisting of tabulate and rugose corals, and other marine invertebrates; vertebrates are represented by conodonts. The Deseret is a 500-foot thick layer of dolomitic limestone with chert, with a basal layer of black shale that is host rock for many Utah caves such as Timpanogos Cave National Monument.
The Virgin Formation is a geologic formation in Utah. It preserves fossils dating back to the Triassic period.
The Madera Group is a group of geologic formations in northern New Mexico. Its fossil assemblage dates the formation to the middle to late Pennsylvanian period.
The Al Rose Formation is a geologic formation in California. It consists mostly of siltstone, mudstone and shale, with some chert and occasional limestone. In it are found graptolite and trilobite fossils dating back to the Ordovician period.
The Badger Flat Limestone is a limestone geologic formation in California.
The Renton Formation is a geologic formation in Washington (state) within the Puget Group. It preserves fossils dating back to the Paleogene period.
The Santa Susana Formation is a Paleogene period geologic formation in the Simi Hills and western Santa Susana Mountains of southern California.
The Fort Hays Limestone is a member of the Niobrara Formation of the Colorado Group exposed in Colorado, Kansas, Nebraska, and South Dakota and is named for the bluffs near the old Fort Hays, a well-known landmark in western Kansas.
![Outcrop in the Uncompahgre Gorge with key geological formations], including the Ouray Formation, Elbert Formation, and the Leadville Limestone Uncompahgre outcrop.jpg](http://upload.wikimedia.org/wikipedia/commons/thumb/9/99/Uncompahgre_outcrop.jpg/350px-Uncompahgre_outcrop.jpg)
