Ancient long-distance trade in Western North America: new AMS radiocarbon dates from Southern California

Eleven Olivella biplicata spire-lopped shell beads from six sites located 250-365 km inland from the Pacific coast of southern California produced AMS dates between 11,200 and 7860 CAL BP. Olivella shell beads were well-documented items of prestige and media of exchange in Native California, and recovery of these examples from inland contexts indicates low-level exchange between resident populations of the coast and the southwestern Great Basin by at least 10,300-10,000 CAL years BP. These findings represent some of the earliest unequivocal evidence for long-distance trade in western North America and push the antiquity of this important form of inter-group interaction back several thousand years earlier than previously thought.