Palynology of Middle Stone Age spring deposits in grassland at the Florisbad hominin site, South Africa

Abstract

New pollen evidence and a review of past palynological research at the Pleistocene Florisbad thermal spring mound, which produced faunal, hominin and archaeological remains, allow a reconstruction of past conditions in the central Free State grassland, South Africa. Pollen sequences at the spring consist of alternating pollen-rich organic peaty horizons interrupted by hiatuses or pollen-poor layers of sandy and clayey deposits. The paleoclimatic interpretation of pollen sequences in springs like Florisbad, which contain a mixture of local and regional pollen and are influenced by spring mound cycles and changes in swamp configuration, requires consideration of taphonomy and site geomorphology to separate local from regional influences. By correlating the pollen stratigraphy in different parts of the site we suggest that the lower layers containing the Florisbad hominin (dated to 259 ka) and its associated Middle Pleistocene fauna, experienced cool moist and grassy conditions. Dating of some of the overlying Middle Stone Age layers suggest that they encompass the Last Interglacial period (MIS 5e; ca. 124–119 ka). In these levels the pollen evidence of upland fynbos shrubs unexpectedly suggests that cool conditions prevailed. This raises questions about the taphonomy, precision of the age estimate of occupation or the way we interpret pollen spectra.