Speakers: Patrick O'Grady and Thomas W. Stafford, Jr.
Camelops sp. and Bison spp. tooth enamel fragments recovered from late Pleistocene alluvial deposits at Rimrock Draw Rockshelter (35HA3855) in the northern Great Basin region of Oregon were used for AMS 14C dating. Five specimens yielded eleven AMS 14C dates ranging from 11,190±25 RCYBP (13,170 – 13,080 Cal. BP [95% CI]) to 15,150±40 RCYBP (18,650 – 18,260 Cal. BP [95% CI). The youngest enamel dates are coeval with Clovis occupations elsewhere in North America; the older specimens pre-date Clovis by 5000 years or more. Our results indicate that the geochemistry of basalt terrains in the northern Great Basin enables accurate 14C dating of enamel bioapatite (carbonate hydroxyapatite) from extinct megafauna tooth enamel from valley alluvium otherwise devoid of bone, wood, and charcoal. The sample preparation process is likely effective in other non-carbonate (basalt) terrains and expands the range of geochronology options for archaeologists needing reliable dates on non-conventional fossil material. The presentation will focus on two themes: A survey of the site characteristics and context, and the recent advances made in AMS14C chemistry as embodied in this research.