Sub-units Chilson Member. Fuson Member Named for Lakota Native American tribe | ||
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 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.
References
Lakota Formation Wikipedia(Text) CC BY-SA