Santa Cruz Island chert

Santa Cruz Island chert comes from outcrops on the eastern end of Santa Cruz Island, off Santa Barbara, in the Channel Islands National Park. The best-known sources lie on the west slope of El Montanon and at various places east of its crest. Because good chert is scarce elsewhere on the Channel Islands, these outcrops were vital to the Chumash, and 26 chert quarries have been documented on eastern Santa Cruz. Quarrying began early and lasted through the Holocene. Middle Holocene quarrying was scattered and opportunistic; late Holocene quarrying became more concentrated as people mass-produced tiny microblades, used as drill tips to make shell beads. Site CA-SCRI-610 is probably the largest chert quarry site in the islands, used from about 7,000 years ago into the Late period.

Chert outcrops on eastern Santa Cruz Island, on the west slope of El Montanon and east of the crest. The opened sources give locations and quarrying history but no formation name or description of the stone.