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Silcretes from Nearby Sources Display Different Responses to Rapid Heating: Implications for Models of Early Human Heat Treatment

Author(s): Alex Mackay ; Sam Lin ; Lachlan Kenna ; Alex Blackwood

Year: 2017

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Summary

Heat treatment of silcrete in the Middle Stone Age of southern Africa has been taken to indicate cognitive complexity. This inference is based on the argument that silcretes require well-regulated heating and cooling rates to avoid thermal fracture. Alternative arguments have been made that silcrete can be heat treated with limited control over temperature gradients, and thus that heat treatment may have been a relatively simple process. These apparently contrasting positions elide the fact that different silcretes may respond differently to heating. To test this proposition, we replicated a series of past experiments in which silcrete blocks of specific size were heated rapidly to high temperatures. We used silcretes from two nearby sources on the south coast of Australia, and three from sources around the Middle Stone Age site of Varsche Rivier 003 (South Africa). Our results demonstrate sufficient variability in heating tolerance between sources that both the simple and complex models of silcrete heat treatment can be supported, albeit in relation to rocks from different sources. The results imply that when silcretes from multiple sources were used – as at Varsche Rivier 003 – optimal approaches to heat treatment may have required the application of more than one method.


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Silcretes from Nearby Sources Display Different Responses to Rapid Heating: Implications for Models of Early Human Heat Treatment. Alex Mackay, Sam Lin, Lachlan Kenna, Alex Blackwood. Presented at The 81st Annual Meeting of the Society for American Archaeology, Vancouver, British Columbia. 2017 ( tDAR id: 430540)


Keywords

Geographic Keywords
AFRICA


Spatial Coverage

min long: -18.809; min lat: -38.823 ; max long: 53.262; max lat: 38.823 ;

Record Identifiers

Abstract Id(s): 16148

Arizona State University The Andrew W. Mellon Foundation National Science Foundation National Endowment for the Humanities Society for American Archaeology Archaeological Institute of America