Measuring prehistoric mobility strategies based on obsidian geochemical and technological signatures in the Owens Valley,California

We compare the organization of obsidian flaked stone technologies in two different time periods at CA-INY-30, a village site in southern Owens Valley, eastern California. Previous archaeological studies suggest a reorganization in settlement patterns between the Newberry (ca. 3500–1500 BP) and Marana (ca. 650-contact) periods, from a highly mobile to a more residentially sedentary one. New geochemical data, based on laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of obsidian artifacts associated with discrete house floors, support this basic settlement model, but reveal new detail in how people moved across the landscape and accessed, extracted, reduced and used obsidian resources. In the earlier Newberry period, there is no relationship between flake size and distance-to-source, and the falloff curve relating frequency of obsidian against distance is more gradual, as expected, but contrary to our expectations, source diversity is not higher. These factors suggest extremely high mobility, but also selective extraction of particular sources. Newberry obsidian may have been acquired by groups of hunters who embedded quarrying within long-distance trips to distant hunting grounds, and subsequently transported bifacial cores to base camps. By contrast, Marana patterns show strong relationships between flake size and distance from source and steeper fall-off curves, suggesting groups acquired their obsidian primarily from closer sources, likely via exchange networks. At the same time, geochemical diversity, especially among smaller resharpening flakes, is higher in the Marana period, highlighting the wide-ranging conveyance systems through which obsidian moved.