An Examination of the Effects of Temperature Variation on the Hydration Characteristics of Two California Obsidians

Abstract
New hydration rates are proposed for obsidians from the Casa Diablo and Coso source areas in California's Sierra Nevada range. Obsidians from these two sources were used extensively throughout central California and western Nevada during prehistoric times. The new hydration rates presented here differ from earlier California hydration rates in that they account simultaneously for the effects of chemical source variation, climatic regime, and soil temperature. As a result of this greater degree of control over possible sources of variation, the two new hydration rates should provide archaeologists working in the Coso and Casa Diablo areas with reliable and highly accurate chronometric dating techniques.