Lakota Formation
The Lakota Formation is a sequence of rocks of early Cretaceous age from Western North America. Located in South Dakota, the name of the formation is derived from the Lakota Native [Americans in the United States|Native American] tribe.
There are two units of the Lakota Formation, the Chilson Member and the underlying Fuson Member. A Berriasian-Valanginian age for the Chilson Member has been extrapolated by means of ostracods and charophytes.
The Fuson Member takes its name from rock exposures in Fuson Canyon, a valley on the eastern side of the Black Hills.