Late Pleistocene-Holocene chemical stratigraphy and paleolimnology of the Rift Valley lakes of central Africa

The interaction of climate and geology in Central Africa during Late Pleistocene and Holocene is examined. The study is based on sedimentological and limnological work on the main lakes of the Western Branch of the East African Rift Valley, particularly Lake Kivu, Changes in sediment chemistry, mineralogy and diatom assemblage provide a detailed histogram of lake level oscillations. Calculations indicate that the drop in lake level could be as high as 600 m for Tanganyika and 400 m for Kivu, Fluctuations in water levels.are the means for reconstruction of climatic events in tropical Africa of the last 15,000 years. Paleoclimatic comparison between tropical and temperate zones reveals that pluvial times coincide with the prominent interstadials in Europe, e.g. Bølling, Allerød, Climatic Optimum, and reversely, cool and dry periods in equatorial Africa with ice ages in the Northern Hemisphere. The African climatic sequence of pluvials and interpluvials is accompanied by corresponding periods of hydrothermal activity and quiescence. This may suggest that rain water exercises control on hydrothermal. activities.Prepared for the National Science Foundation under Grants GA-30641 and GA-35334