MIDDLE STONE AGE SITE PRESERVATION OF GAJJ17: STRUCTURAL AND DEPOSITIONAL HISTORY OF THE NORTHEASTERN TURKANA BASIN

The East African Rift System is an active continental rift basin documenting key events in the field of paleoanthropology during the Plio-Pleistocene. This is possible due to discoveries of several hominin species and archaeological remains in the Koobi Fora Formation (the northeastern region of the Turkana Basin), establishing and refining the study of human evolution over time. However, the Mid-Late Pleistocene, characterized by the Middle Stone Age (MSA), is poorly represented in the stratigraphic record, limiting the understanding of modern human occupation and behavior at this time. Ongoing research since 2016 of an in situ MSA site (GaJj17) has concluded that this site was buried by an arenaceous eolian system, capped by a caliche, which lithified archaeological material at the modern surface. Here, the structural and sedimentological history of this site was investigated, giving evidence of the selective preservation processes of the Mid-Late Pleistocene of the Koobi Fora Formation. Mapping of associated structural and sedimentological features determined that a locally-faulted regime facilitated preservation by selective post-depositional erosion leading to the preservation of GaJj17 and likely erosion of other contemporary sites on the eastern side of the basin. This research represents the beginning stages of investigation necessary to understanding the history of the Turkana Basin. This will explore depositional centers, as well as their contributing tectonic controls, which requires more detailed investigation.