IN SEARCH OF LOST TIME: AN INVESTIGATION OF MID- TO LATE PLEISTOCENE DEPOSITS IN EAST TURKANA

Geologic investigations of the East Turkana Basin were initiated in the 70’s to provide a background for archaeological and anthropological interpretations. While most of the investigations focused on the early phases of human evolution, little is known about the last 1 million years - the critical period that includes the decline of Homo erectus, the origin of our species, Homo sapiens, and the last ice age. This gap is partly due to the difficulty of dating non-volcanic sediment directly, limiting our understanding of how fauna and human groups responded to past environmental changes. Our objective is to address these long-standing issues by combining luminescence-based dating methods and petrologic analyses of sedimentary deposits along the Turkana Basin. As part of a pilot study, we conducted three weeks of fieldwork near Ileret in 2024 to assess the thickness and integrity of the sedimentary deposits from the upper Chari Mb to the Galana Boi.

Using high-resolution RGB and lidar images, maps (Raynolds et al., 2024; Gathogo, 2017), and Google Earth© images, we identified potential outcrops in Areas 4 and 7. In the field, we dug trenches to to expose stratigraphic sequences below and above the Silbo and Kale tuffs. We identified a more than 10-meter thick sedimentary record above the Kale Tuff, covered by the Galana Boi, with fossils and stone tool artifacts indicating Late Stone Age deposits. We conducted high-resolution stratigraphic descriptions and collected over 200 samples for luminescence dating and petrographic analysis. Our preliminary observations will be presented at the symposium. This research has provided critical insights into the sedimentary record and chronology of the Turkana Basin during the Middle and possibly Late Pleistocene, emphasizing the need for further innovative research to fill existing knowledge gaps.

References:

Feibel, C. S., Brown, F. H., & McDougall, I. (1989). American Journal of Physical Anthropology, 78(4), 595–622.

Gathogo, P.N. (2017). Geology of the Omo-Turkana Basin of Eastern Africa: Tectonics and climate in the evolution of a Pliocene and Pleistocene sequence (Doctoral dissertation, The University of Utah).

Raynolds, R. G. (2024). Journal of African Earth Sciences, 105296.

Acknowledgment: RC is supported by the Dr. W. Burghardt Turner Fellowship and OVPR seed grant award 93214, project 1187279, awarded to MF.