Using Surface Roughness to Identify Heat Treatment in Lithic Technology

Summary

The heat treatment of stone to enhance flaking attributes was an important advancement in the adaptive toolkit of early humans. The earliest evidence for this is the heat treatment of silcrete 164 ka at the Middle Stone Age site Pinnacle Point 13B in South Africa. Heating stone prior to knapping alters the physical and chemical composition of the stone, and it has long been recognized that flaked heat-treated stone has a glossier surface. We expect this glossiness to result from a smoother flaked surface. Thus, we investigated whether surface roughness, as measured by a 3D microscope, can be used as a proxy to identify the presence of heat treatment in the archaeological record. The results of our unpublished pilot study suggested roughness parameters differ significantly between untreated and treated silcrete. In the present study, we record values for multiple surface texture parameters on a sample of experimentally created stone tools from paired heat-treated and untreated silcrete nodules. A Bayesian probability model, trained on the experimental sample, was then used to evaluate the probability individual artifacts have undergone heat treatment. This research provides a novel, probabilistic, cheap, and non-invasive technique for identifying heat treatment.

This Resource is Part of the Following Collections

• Society for American Archaeology 83rd Annual Meeting, Washington, DC (2018)

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Record Identifiers

Abstract Id(s): 20356