Palaeolimnology of Lake Bogoria (Kenya) during the 4500 BP high lacustrine phase

Abstract
Lake Bogoria (altitude 990 m) lies within the Kenya Rift Valley (0°15′N, 36°10′E). A high lake stage is marked by a double stromatolite belt: the first, occurring at 999 m, is radiocarbon dated 4140 ± 60 BP and the second, at 995 m, is dated 3880 ± 60 and 3750 ± 180 BP. Palynological data from shoreline stromatolites and lacustrine sediments recovered in three 15 m cores permit a reconstruction of former limnological conditions. They show that the lacustrine extension resulted from a positive water balance brought about by runoff under climatic conditions more humid than today but drier than those prevailing during the early and mid-Holocene.