Luminescence dating of sediment samples from White Paintings Rockshelter, Botswana

Luminescence dating of sediments from rockshelters is complicated by the possibility of incomplete sunlight bleaching in antiquity and uncertainties in the distribution of radioactivity. Yet such dating is important for the Middle Stone Age in southern Africa when rockshelters provide a large fraction of the known record. Sufficient bleaching is demonstrated for sediments at White Paintings Rockshelter in northwest Botswana by comparing results from slowly bleaching thermoluminescence signals and rapidly bleaching optically stimulated luminescence. Radioactive disequilibrium is also shown to be present in these sediments and believed to result from U-238 and U-234, requiring a small correction to the dose rare. Derived ages are fractionation between in broad agreement with independent dating evidence and archaeological expectations. (C) 1997 Elsevier Science Ltd.