A 3000-YEAR CLIMATIC RECORD FROM BIOGENIC SILICA OXYGEN ISOTOPES IN AN EQUATORIAL HIGH-ALTITUDE LAKE

A record of oxygen isotopes in biogenic opal, 4200 to 1200 calibrated years before the present, from a high-altitude proglacial Lake on Moun t Kenya, East Africa, exhibits short-term fluctuations on a time scale of centuries as well as Long-term variations. The short-term fluctuat ions are attributed to changes in the glacier meltwater input, and the Long-term variations are related to changes in Lake temperature. The record indicates that the climate was warm in Equatorial East Africa f rom 2300 to 1500 years before the present.