Fountain Formation

Fountain Formation Stratigraphic range: Late Pennsylvanian
Red rocks typical of The Fountain Formation seen at Roxborough State Park near Littleton, Colorado
Type	sedimentary
Underlies	Lyons Formation
Overlies	Gleneyrie Formation
Thickness	0-4500 ft
Lithology
Primary	sandstone, conglomerate
Other	limestone, shale
Location
Region	Denver Basin
Extent	Colorado, Wyoming
Type section
Named for	Fountain Creek
Named by	C. W. Cross, 1894

The Fountain Formation is a Pennsylvanian bedrock unit consisting primarily of conglomerate, sandstone, or arkose, in the states of Colorado and Wyoming in the United States, along the east side of the Front Range of the Rocky Mountains, and along the west edge of the Denver Basin.

The Fountain Formation was named by geologist W. C. Cross in 1894 for exposures along Fountain Creek in El Paso County, Colorado.

The Fountain unconformably overlies Precambrian granite and gneiss. Outcrops of the formation typically dip steeply to the east.

The formation was formed by the erosion of the Ancestral Rocky Mountains, and deposition by fluvial processes as alluvial fans.

The characteristic predominant red color and the composition of the Fountain reflect that of the granites and gneisses from which it was eroded.

Marine invertebrates have been discovered in a limestone and shale member of the Fountain Formation, cropping out on a low hogback in Perry Park. Invertebrates include bryozoans, brachiopods, crinoids, echinoids, and gastropods.

Plant fossils have been discovered in Garden Park north of Cañon City, including Lepidophloios laricinus, Sigillaria, Syringodendron sp., Lepidophyloides sp., Lepidostrobus sp., Lepidostrobophyllum sp., Calamites, Neuropterus sp., Cyclopteris sp., and Stigmaria ficoides.