Quantifying the effect of heating temperature on silcrete blank production

In southern Africa, heat treatment of silcrete is documented by ~ 164 ka and is considered an important technological innovation, allowing knappers to improve the flaking properties of rocks for lithic blank production. Previous research has explored structural, mechanical, and geochemical changes in silcrete during heat treatment, but most studies have not explored the implications of those transformations for the blanks produced. Experiments that have examined the effects of heat treatment on blank production tend to rely on replicative flintknapping, where small changes in the way a blank is removed can create “noise.” In this study, we provide quantitative data to understand the effects of silcrete source and heating temperature on blank production using a flaking machine to isolate the effects of heat treatment on blank morphology. Our results show changes in absolute blank dimensions, and in the frequency of abrupt terminations as a result of heat treatment. However, the benefits of heat treatment may only occur within a limited temperature range and are heavily source dependent. This suggests that we should reconsider broad generalizations about the role of heat treatment in lithic technology and its supposed benefits and focus more on silcrete source and source-based effects on blank production.