| Lakota Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Geological formation |
| Sub-units | Chilson Member. Fuson Member |
| Underlies | Fall River Formation |
| Overlies | Morrison Formation |
| Thickness | 200 to 500 feet (60 to 150 m) |
| Lithology | |
| Primary | Sandstone |
| Other | Shale, Coal, Conglomerate |
| Location | |
| Region | North America |
| Country |  United States |
| Type section | |
| Named for | Lakota Native American tribe |
| Named by | Darton |
| Year defined | 1899 |
The Lakota Formation is a sequence of rocks of early Cretaceous (Berriasian to Barremian) age from Western North America. Located in South Dakota, the name of the formation is derived from the Lakota Native American tribe.
There are two units of the Lakota Formation, the Chilson Member (upper Berriasian to Valanginian) and the underlying Fuson Member (upper Valanginian to early Barremian). A Berriasian-Valanginian age for the Chilson Member has been extrapolated by means of ostracods and charophytes.[1]
- ^ Sames, B.; Cifelli, R. L.; Schudack, M. (2010). "The nonmarine Lower Cretaceous of the North American Western Interior foreland basin: new biostratigraphic results from ostracod correlations, and their implications for paleontology and geology of the basin—an overview". Earth-Science Reviews. 101 (3–4): 207–224. doi:10.1016/j.earscirev.2010.05.001.