In 1979-1980 Archeo-Tec excavated a prehistoric site in the geographic center of the ethnographic Costanoan range. The site consisted of a discrete, tightly concentrated cemetery containing 64 interments with a surprisingly low number of burial associated artifacts. Two clusters of obsidian bifaces (arrowheads), comprising a total of 29 bifaces, were recovered and deemed to be associated with the cemetery itself and not any one individual. Although some ambiguity exists, obsidian source and hydration techniques date the cemetery complex to around the closure of the first millennium A.D.
For further reading on CA-SCL-131, see the Journal of California and Great Basin Anthropology, "Two Biface Clusters and Their Relation to Mortuary Practices in the San Francisco Bay Area." Allen G. Pastron and Michael R. Walsh.
