Vegetation and Seasonality Shifts during the Late Quaternary Deduced from ¹³C/¹²C Ratios of Grazers at Equus Cave, South Africa

Abstract Season of rainfall can be a major influence on the relative proportions of C 3 and C 4 grasses in a landscape, since their relative distribution is essentially constrained by temperatures during the growing season; cool growing seasons favor C 3 grasses, whereas warm ones favor C 4 grasses. 13 C/ 12 C ratios in tooth enamel carbonate of grazers from the site of Equus Cave, northern Cape Province, South Africa, were used to determine vegetation and rainfall seasonality shifts during the late Quaternary. The results show shifts in the relative proportion of C 3 and C 4 grasses during the latter stages of the Pleistocene, and domination by C 4 grasses in the Holocene. The data show that the northwestern Cape did not fall within a winter rainfall zone during this period as has been postulated in recent climate models. Instead, a more complex situation is suggested in which at least two periods of enhanced winter rainfall occurred within a predominantly summer rainfall regime.