PALEOENVIRONMENTS AND ARCHAEOLOGY OF SHORT-TERM OCCUPATION SITES, IMPLICATIONS OF SUBSISTENCE STRATEGIES UNDER HOLOCENE CLIMATE CHANGE, NORTHERN KENYA

The Holocene was a time of dramatic climate change in East Africa shifting from wetter climate characterized by high lake levels in the early-mid Holocene (>5000 BP) to drier climate with lower lake levels in late Holocene. The high Lake Turkana levels were maintained by the (450 m) elevation of the rock-floored spillway channel into the White and Blue Nile drainage system. By ~4500 BP the lake level lowered leaving successively younger perched beach deposits on the landscape. A slight increase in lake level <1000 BP indicates that increased moisture followed the dry period. The mid-late Holocene was also a time of cultural change from hunter–gatherers and fishing folk to agro-pastoralists, but a cause and effect link between climatic conditions and type of subsistence practices is not clear. Recent excavations in the sediments along the shores of Lake Turkana (4º N) provide new archaeological materials, a high-resolution stratigraphic and paleoenvironmental analyzes, OSL dates and new insights into the timing of cultural change in the context of documented environmental change. Two representative archeological sites, that bookend the dry period (~4500-1000 BP) reflect a distinct change in lifestyle during this period. Site FwJj25 (~4500 BP) was a likely a short-term occupation site on the lake shore used by hunter-gatherers for a fishing camp. Although found in a beach/dune setting, the faunal remains were 50% mammal (wild animals) and ~ 40% fish and crocodile. The bone harpoons recovered indicate fishing, but chert awls may have been used for either crafting fishing gear or working with leather. Site FwJj5 (~900 BP) called the “Stone Bowl Site”, was situated over 5 km from the lakeshore and considerable closer to the basin margin. The site was located in a river valley that contained a spring or seep. Carbonate (tufa) deposits record the presence of a persistent, groundwater-fed freshwater source. FwJj5 was likely a multi-purpose site. The presence of lithic artifacts, decorated pottery, bone harpoons, fish bones (60%), and domesticated cattle and goat remains may reflect a “cultural melting pot” of inhabitants drawn to a refuge of fresh water during time of regional drought. Basalt stone bowls were surface finds and appear to have been brought by immigrant population from the north during the last millennium.