The Pierre Shale is the host formation for commercial
petroleum deposits in the Florence and Cañon City fields in
Fremont County, Colorado, and the
Boulder Oil Field in
Boulder County, Colorado. More recently, natural gas has been extracted in the
Raton Basin in southern
Colorado. The shale formation is usually too impermeable for hydrocarbon extraction, but produces in areas where it is naturally fractured or
fractured by artificial means. ==Paleofauna==