Thermally Modified Rock: The Experimental Study of "Fire-Cracked" Byproducts of Hot Rock Cooking*

By: Tianna DiMare '15

Advising Faculty: Anthony Graesch

Thermally modified rock (TMR), or rock that cracks or fractures when exposed to intense heat and abrupt temperature changes, is among the most ubiquitous but least studied material recovered during archaeological investigations in many parts of North America. This project outlines the results of experimental research aimed at understanding the conditions by which TMR assemblages were created at ancient residential settlements in the Pacific Northwest.

Drawing from over 30 days of experimentation, DiMare and collaborators present baseline data addressing the thermal properties of the hearth, the rate and circumstances of cobble fracturing, the extent to which different kinds of cobbles break when exposed to hear for varying durations, and the effectiveness of hot cobbles for achieving cooking temperatures.

*  published in North American Archaeologist 35(2)

Related Fields: Anthropology