A database of marine shell from 70 archaeological assemblages at Vandenberg Air Force Base reveals substantial temporal and spatial variability in the distribution of turban snails (Tegula spp.). Consideration of both variables is crucial to identi cation of diet breath expansion in the context of subsistence stress and resource diversification. At Vandenberg AFB, increased use of Tegula during late prehistory strongly correlates with spatial proximity to prime Tegula habitat (Purisima Point) at sites on a landform that is less than 2,000 years old. When sites near prime habitat are excluded, increased Tegula use correlates very poorly with time, and long-term diet breath expansion to include a lower-ranked species is not supported. However, the evidence does point to short-term increased use of Tegula during the Medieval Climatic Anomaly, a time of known environmental stress.

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.