Umhlatuzana rockshelter has an occupation sequence spanning the last 70,000 years. It is one of the few sites with deposits covering the Middle to Later Stone Age transition (~40,000–30,000 years... Show moreUmhlatuzana rockshelter has an occupation sequence spanning the last 70,000 years. It is one of the few sites with deposits covering the Middle to Later Stone Age transition (~40,000–30,000 years BP) in southern Africa. Comprehending the site’s depositional history and occupation sequence is thus important for the broader understanding of the development of Homo sapiens’ behavior. The rockshelter was first excavated in the 1980s by Jonathan Kaplan. He suggested that the integrity of the late Middle Stone Age and Later Stone Age sediments was compromised by large-scale sediment movement. In 2018, we initiated a high-resolution geoarchaeological study of the site to clarify the site formation processes. Here, we present the results of the excavation and propose a revised stratigraphic division of the Pleistocene sequence based on field observations, sedimentological (particle size) analyses, and cluster analysis. The taphonomy of the site is assessed through phytolith and geochemical (pH, loss on ignition, stable carbon isotope) analyses. The results indicate a consistent sedimentological environment characterized by in situ weathering. The analysis of the piece-plotted finds demonstrates semihorizontal layering of archaeologically dense zones and more sterile ones. There was no indication of large-scale postdepositional sediment movement. We show that the low-density archaeological horizons in the upper part of the Pleistocene sequence are best explained by the changing patterns of sedimentation rate Show less
We explore if taxonomic analysis of archaeological mollusc assemblages can be used to reconstruct Late Pleistocene (MIS 5–3) coastal environments at Klasies River in South Africa. To obtain a... Show moreWe explore if taxonomic analysis of archaeological mollusc assemblages can be used to reconstruct Late Pleistocene (MIS 5–3) coastal environments at Klasies River in South Africa. To obtain a balanced reconstruction, we analyse the large molluscs separately from the so-called incidentals, the small mollusc species. Based on modern mollusc habitat preferences and tolerances we identify four different eco-profiles to help characterise sea surface temperatures and the character of the shore: temperature profile; geographical distribution; substrate; wave interaction. We hypothesise that changes in the Klasies River mollusc community/eco-profiles can be linked to global glacial and interglacial events and we define several testable assumptions. We found that in response to global warming and cooling events, the Klasies River mollusc communities change slightly, yet significantly. Other sources of marine environmental data confirm that average sea surface temperatures gradually decreased, but probably remained within the modern southern east coast range of variation. It appears that coastal sea surface temperatures of the warm Agulhas current were not particularly depressed during the occupation sequence. The character of the coastal topography does change more apparently during the occupation sequence of the sites and with it the mollusc assemblages: from an interglacial rocky shore in the Klasies and two Mossel Bay phases to a more glacial sandy environment during the Howiesons Poort and the MSA III. In conclusion, the temperature tolerance levels of many Klasies River mollusc species are too broad to reflect small changes in sea surface temperatures. However, in conjunction with other eco-profiles and environmental proxies, such as substrate requirements and oxygen isotopes, the temperature approximations are useful, particularly when evaluating large scale sea surface temperature fluctuations. For the characterisation of the shore and substrate we found the eco-profile approach very useful. Show less
