Material conveyance in the Southern California Bight: Obsidian on Alta California's Channel Islands

Inhabited by Native Americans for at least 13,000 years, California's Channel Islands were isolated from the adjacent mainland throughout the Quaternary. A rich archaeological record demonstrates that island peoples thrived for millennia, with access to abundant marine and terrestrial resources. Exchange with mainlanders for various goods is well documented, with long-distance material conveyance occurring very early and intensifying later in time. Obsidian was one exotic material imported to the islands from distant quarries beginning at least similar to 11,750 years ago and continuing until the collapse of native exchange networks after European contact. Geochemical sourcing shows that nearly 94% of obsidian artifacts found on the islands comes from the Coso Volcanic Field located similar to 300 km or more from the islands, with smaller percentages originating from sources as much as >850 km from the islands. Hydration data generally support radiocarbon dates that show that islanders participated in long-distance conveyance networks for millennia. Using these obsidian data, we examine Channel Island conveyance networks through space and time. We argue that conveyance of goods between islanders and mainlanders was a by-product primarily of social networks that functioned as sources of information, innovation, marriage partners, and strategic alliances.