Deadwood Formation
| Deadwood Formation | |
|---|---|
| Stratigraphic range: Late Cambrian-Early Ordovician ~ | |
The Deadwood Formation at Fallingrock cliff in Dark Canyon in the Black Hills, South Dakota. | |
| Type | Formation |
| Underlies | Red River, Winnipeg & Englewood Formations & Elk Point Group |
| Overlies | Precambrian rocks, or Lebold Formations Earlie and Pika Formations |
| Lithology | |
| Primary | Sandstone |
| Other | Conglomerate, shale, limestone |
| Location | |
| Region | Williston Basin and Western Canada Sedimentary Basin |
| Country | United States Canada |
| Type section | |
| Named for | Deadwood, South Dakota |
| Named by | Darton, N.H. and Paige, S. (1925) |
The Deadwood Formation is a geologic formation of the Williston Basin and Western Canada Sedimentary Basin. It is present in parts of North and South Dakota and Montana in the United States, and in parts of Alberta, Saskatchewan, and southwestern corner of Manitoba in Canada. It is of Late Cambrian to Early Ordovician age and was named for exposures in Whitewood Creek near Deadwood, South Dakota. It is a significant aquifer in some areas, and its conglomerates yielded significant quantities of gold in the Black Hills of South Dakota.
It preserves trace fossils such as Skolithos, and remains of Late Cambrian trilobites and brachiopods, as well as Ordovician fossils.
A 20 MW geothermal power plant is under construction, drilling 3.5 kilometers down.