LIVING IN A SWAMPY PARADISE: ASSOCIATIONS BETWEEN ARCHAEOLOGY AND MARSHES FROM THE AFRICAN HUMID PERIOD, WEST TURKANA, KENYA

The shift towards wetter climatic conditions during the African Humid Period (AHP) created environments conducive to human exploitation in what are today harsh places to inhabit. The Turkana Basin is a striking example of this as throughout the AHP (~15-5 Kyr cal BP), Lake Turkana periodically rose ~100 m to overflow through an outlet to the northwest of the modern lake and into the Nile drainage system. This study adds new data from West Turkana outcrops of the Late Pleistocene/Early Holocene Galana Boi Formation that compliment existing lake level curves and allow for landscape reconstruction through lateral facies associations. The Kabua Gorge/Delit/Kakito study area is linked by relatively well-exposed sections with multiple concurrent archaeological sites through AMS radiocarbon dating of charcoal and molluscs. Four lacustrine intervals (Phase 1-4) were identified and a date from the base of laminated silty clays, which contained ostracods, molluscs, diatomaceous laminae and fish remains, characterize Phases 1-3. Phase 1 pushes back the onset of the AHP to at least 13.9 Kyr in the Turkana Basin and the depositional hiatus between Phase 1 and Phase 2 corresponds to the Younger Dryas (YD) event indicating that the Turkana Basin was responding to global paleoclimatic forcing. Phase 4 is distinct because it is comprised of black clay containing ~14% TOC, cm scale soil carbonate nodules, and abundant mollucs. This unit is indicative of a low energy, organic-rich, reducing environment. By coupling sedimentology, δ¹³C and ^δ18O isotope geochemistry, ostracod paleoecology, and paleotopography of the area, the paleoenvironment of Kabua Gorge is interpreted as a shallow marshy embayment connected to the main body of Lake Turkana. Ultimately, understanding the paleoenvironmental implications of the AHP and YD in the Turkana Basin helps to contextualize this basin’s response to global climatic events and how these events may have supported or stressed the ecosystems in which hominins evolved both physically and culturally.