Journal of California and Great Basin Anthropology

Previous assessments of the age of bedrock mortars (BRMs) on the central California coast have limited them to post cal A.D. 1250 contexts. Recent investigations from a single-component late Middle Period site with associated bedrock mortars (CA-SLO-5) on the San Luis Obispo coast, and the stratigraphic position of a bedrock mortar cup beneath dated midden residues at Swordfish Cave (CA-SBA-503) in northern Santa Barbara County, indicate that these features were used as early as 1,385 cal B.C. and that their overall age encompasses the late Early, Middle, Middle-Late Transition, and Late/Early Historic periods in this region.