Stratigraphy
Koobi Fora encompasses a small depocenter, underlain by Pliocene basalts and filled with nearly 600 meters of Pliocene-Pleistocene sediments, dating from about four-million to one-million years ago. These sediments are attributed to the Koobi Fora Formation, which consists of eight members that are delimited by water-lain tuffs (volcanic ash).
Most early human fossils and archaeological remains derive from the upper portion of the Burgi Member, the KBS Member, and the Okote Member. The members reflect changing environments in the Turkana Basin, from lake and delta ones during Burgi Member times to rivers and floodplains in Okote Member times.
The stratigraphy of the Koobi Fora Formation is one of the best studied and calibrated in East Africa, with publication of some extensive listings at various times. Controversial dating of the KBS Tuff during the 1970s helped to spearhead the development of modern potassium/argon and argon/argon geological dating methods. In addition, the unique fusion between geochronology and mammal evolutionary studies has made the Koobi Fora Formation a standard for interpreting biochronology, environmental change, and ecology for all of Pliocene-Pleistocene Africa.
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