More than acorns and small seeds: A diachronic analysis of mortuary associated ground stone from the south San Francisco Bay area

The archaeological record of central California contains a rich variety of ground stone milling tools—from highly expedient cobble tools to large ornate mortars and finely finished pestles more than half a meter in length. Historical trends in research objectives, along with assumptions about the entirely mundane character of ground stone tools, have caused much of the variability and many “extra-utilitarian” aspects of these artifacts to be overlooked. This study analyzed grave-associated ground stone from the southern San Francisco Bay Area and employed use-wear analysis (macroscopic and microscopic) and morphological comparisons to investigate potential distinctions in form, manufacturing effort, use, and association over approximately 6000 years of prehistory. Ground stone morphologies, patterns of use-wear, and the way that ground stone was interred with people changed between the earliest and the latest periods analyzed in this study. During the Late Holocene, ground stone underwent a diversification of form and perhaps purpose. An overtly symbolic dimension associated with mortars and pestles seems to emerge with the addition of highly formalized and expensive flower-pot mortars, very long shaped pestles, and additional embellishments such as shell bead appliqué and painted designs. Large, costly, highly formalized, and embellished mortars exist alongside smaller, less costly, less formalized milling tools. Archaeological and ethnographic evidence supports the inferred association of certain mortars with feasting and ritual activities. Differences in the representation of some of these forms in male and female graves may reflect changes in the roles of women and men in community ritual and politics.