SEASONALITY OF RAINFALL AROUND THE LAST GLACIAL MAXIMUM AS RECONSTRUCTED FROM CARBON-ISOTOPE ANALYSES OF ANIMAL BONES FROM NELSON BAY CAVE

The history of the extent of the winter rainfall region of South Afric a, at present confined to the south-western Cape, is of interest to sc ientists in a range of disciplines. Nelson Bay Cave on the Robberg pen insula, currently in a year-round rainfall zone, has yielded archaeolo gical remains which contain information about the seasonality of rain in the past. Carbon isotope analyses of the bones of grazing animals o f Holocene and late Pleistocene age show that there has been a mixture of C-3 and C-4 grasses in this area throughout the Holocene, and c. 1 6 000 to 18 000 sp. Since the proportions of C-3 and C-4 grasses depen d primarily upon the season of rainfall, this finding is consistent wi th the hypothesis that year-round rainfall in the southern Cape dates back at least as far as the Last Glacial Maximum, in contradiction to models suggesting that the winter rainfall region may have been much m ore extensive at the LGM.(1)