Silcrete use and heat treatment in the middle stone age at Nelson Bay cave, South Africa

The heat treatment of lithic raw materials to modify their physical properties was a major technological innovation of the Middle Stone Age (MSA) and was present by at least ~ 130 ka in southern Africa. Most research on the heat treatment of silcrete in MSA lithic technology have come from sites in western South Africa. Less data is available about the context in which silcrete was acquired and modified along the southern coast, raising questions regarding how widespread the heat treatment of silcrete was in the MSA. This paper examines how silcrete was used at Nelson Bay Cave, South Africa and the role of heat treatment in MSA technology at the site. Silcrete was a minor component of Early MSA lithic technology but makes a comparatively high contribution to the assemblage in the earliest Howiesons Poort layers at the site. Frequencies of silcrete use decrease in the later Howiesons Poort. The application heat treatment remains relatively consistent, despite variation in the contribution of silcrete to the lithic assemblage. Results from Nelson Bay Cave support data from other sites in southern Africa indicating the widespread use of heat treatment in the Early MSA with little change in frequency through the Howiesons Poort.