Seasonality in the early Holocene climate of Northwest Sudan: interpretation of Etheria elliptica shell isotopic data

The oxygen isotope ratios in the incremental growth layers in the shells of Etheria elliptica constitute a proxy record of rainfall patterns, and thus a record of seasonality. Analyses of shells of early Holocene age (6800 C- 14 years BP or 5600 BC) collected from the lower reaches of Wadi Howar, nea r the confluence of that now-extinct river with the Nile, show an annual pa ttern of two rainy seasons in the present-day hyperarid southeastern Sahara , similar to that which prevails today in much of East Africa. (C) 2000 Els evier Science B.V. All rights reserved.