Starch grain analysis of bedrock mortars in the Sierra Nevada Mountains: experimental studies to determine their function

Starch grain analysis is a growing field in California archaeology and can answer some long-standing questions pertaining to bedrock mortars, a prehistoric feature found throughout California. For the purposes of this study, research efforts were concentrated on extracting starch grain residues from bedrock mortar features found in the Sierra Nevada, more specifically within the tribal area of the Mi-wuk and Washoe Native Americans along the State Highway 4 and the Mokelumne River watershed. This thesis determines whether or not starch grain residues can be extracted from bedrock mortars and identified. A case study is provided to one demonstrate the implications of this research on our current understanding of the function of bedrock mortars and whether they reflect a reliance primarily on acorn subsistence or a more formalized technology for processing a variety of resources. The extraction process is non-destructive, using distilled water and sonic cleaning techniques. Identification is made based on an ethnographically informed reference collection through microscopy analysis. This research demonstrates that starch grain residue can be extracted from bedrock mortars and identified. As for the case study, the results do not support a simplistic acorn processing assumption; however, results indicate that a formalized technology is not supported either. Future research in this field will further clarify the function of bedrock mortars.