The 89th Annual Meeting of the American Association of Physical Anthropologists (2020)

The Chronostratigraphic and Depositional History of the FxJj20 Site Complex, Northern Kenya


1Department of Anthropology, University of Victoria, 2School of Geosciences, University of the Witwatersrand, 3Department of Anthropology, Rutgers University, 4Department of Geology, University of Kansas, 5Department of Geological Sciences, University of Cape Town, 6Department of Anthropology, The George Washington University, 7Archaeology Section, National Museums Kenya

April 17, 2020 , Diamond 6 Add to calendar

The Koobi Fora Formation, in northern Kenya’s Turkana Basin, documents an extensive Plio-Pleistocene hominin record. Previous research has documented evidence of combustion features at the FxJj20 site complex that may be associated with hominin behaviour. Despite the extensive research on these archaeological finds, the area has seen minimal lithostratigraphic and sedimentological investigation, and its broader environmental context is not as clear. Initial studies describe a series of floodplain deposits associated with a nearby fluvial channel, but a channel feature was never located. Furthermore, there has been contention on the stratigraphic relationship between the site complex and the Morotut Tuff (1.6 Ma). Thus, this study adopted a geological investigation into contributing to this site complex through comprehensive lithostratigraphic and sedimentological investigations. The stratigraphic sequence has been revised to include an underlying Okote Tuff deposit (1.64 Ma) and an overlying Morotut Tuff deposit, comfortably placing the site between 1.64 Ma and 1.6 Ma. Additionally, a nearby channel was documented with facies associations indicating the presence of either a braided stream, or a small fluvial channel draining into a larger fluvial system (potentially the paleo-Omo River). The excavation areas comprise sequences of floodplain deposits which would have provided hominins with a stable landscape containing fresh water and associated resources. Ultimately, this investigation clarifies the geological succession of the FxJj20 site complex and provides an environmental context that is critical to understanding the stimulus behind novel hominin adaptations, such as pyrotechnology.

This research was funded in part by NSF Archaeology grant #1624398 and REU #1930719.

Slides/Poster (pdf)