Sedimentologic and geochemical analyses of four cores from Lake Edward, Uganda-Congo, document a complex record of moisture balance in the Edward basin from 11 000 cal yr BP to present. Highly organic, diatomaceous muds provide evidence for shifts in wind intensity and stratification within an early Holocene wet phase. Lake level variations within this period may have shifted due to tectonic lowering of the lake's outlet level. The onset of mid-Holocene aridity, as documented by the appearance of authigenic calcite at 5200 cal yr BP, initiated a period of falling lake levels that culminated in a late Holocene lowstand between 4000 and 2000 cal yr BP. This lowstand is documented by coarse sediments whose fabric and mineralogy depend on the core site. Although different cores yield different ages for this regression, it appears that declining lake levels culminated in a maximum lake lowstand of -14 m. Lake levels then rose rapidly, attaining modern positions by 1700 cal yr BP. This lake level history suggests that although many paleoclimatic changes in Africa are apparently synchronous throughout northern hemispheric Africa, other events may be spatially heterogeneous. These patterns highlight the need for a well-dated network of paleoclimate sites within the African continent.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the wisdom and inspiration of the late Kerry R. Kelts to whom this work is greatly indebted. We wish to thank the Government of Uganda and Petroleum Exploration and Development Department, especially Mr. Honey Malinga, for their assistance and granting permits during fieldwork. John Mothersill is thanked for donating cores E96-5M and E96-6M during field operations in 1996. This paper benefited from insightful reviews by Françoise Gasse, Frank Sirocko, Steve Colman, and Douglas W. Schnurrenberger. This research was funded by NSF ATM # 9805293 to Dr. Kerry R. Kelts. J.M.R. acknowledges the National Science Foundation Graduate Research Fellowship Program and the Graduate School of the University of Minnesota for salary support. M.R.T. and T.L. thank the Norwegian Research Council for financial support for fieldwork and a Ph.D. scholarship for T.L. This is IDEAL publication no. 111.
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