Fire Affected Rock: An Investigation into Diagnostic Utility

RM 218

The post-firing variability of fire affected rock (FAR); specifically recovered from stone-grilling platforms (SGP) within prehistoric stone grills was examined. This examination tests the physical properties of FAR recovered from prehistoric stone grills in the Crowder Canyon Archaeological District in San Bernardino California. There is a lack of archaeological research in this area of Southern California; however, this project will establish a fundamental perspective of facility reuse and episodes of firing activity for prehistoric cooking features by examining the physical changes fire affected rock (FAR) experience due to various heat exposure. Regional archaeologists encounter these features often as they speckle the landscape of upland desert mountain regions in California. This examination moves further to compare these cultural stones’ properties to those of non-cultural origin, which have been fired various times during controlled replicative experimentation. The end comparison identifies the FARs’ change in physical conditions. Repeated exposure to high temperatures has a direct relationship to the stability and matrices of rock in this particular case schist. As the stone is exposed repeatedly its durability and structural components begin to deteriorate allowing these physical manifestations measurable qualities, in particular the stones’ porosity which is measuring by testing their varying ability to absorb water after various numbers of firing, e.g. cooking. As a result, it is proposed that FAR can now be used as a diagnostic artifact to infer multiple firing episodes, confirm facility reuse, and or support suggested mobility with respect to available resources and temporal episodes through AMS dating, and other analytical contributors such as seasonal micro-botanical analysis.