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Open Access Publications from the University of California

The Cico Chert Source on San Miguel Island, California


A major source of high quality chert was recently identified on San Miguel Island, where archaeological sites spanning much of the Holocene contain artifacts of this same material. Some varieties of this translucent chert are macroscopically similar to Santa Cruz Island chert, leading to possible confusion about the origin of some Channel Island lithic assemblages. Preliminary petrographic studies suggest that Cico cherts can be differentiated from Santa Cruz Island cherts microscopically, but additional research is needed to document the variability inherent in both chert types. Although the Chumash appear to have used Cico chert to make microblade drills and shell beads, the extent of such activities has yet to be determined.

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