ESR DATING THE MOUSTERIAN INDUSTRY AND NEANDERTHAL FOSSILS IN LAYER J AT GROTTE DU BISON, ARCY-SUR-CURE, YONNE, FRANCE

Along the modern Cure River near Arcy-sur-Cure, Yonne, France, 13 caves sit < 10 m above the floodplain. In Grotte du Bison (GdB), clast- and matrix-supported conglomerates house 12 archaeological layers, some of which correlate with layers in the Grotte du Renne next door. In GdB, the Mousterian and Châtelperronian layers have yielded hearths, ochre, manuports, and lithics, including bifaces, scrapers, cortical and retouched flakes. Many extremely small resharpening flakes were recovered, suggesting that erosion was minimal for exposed surfaces during their deposition. The Charentian Mousterian industry was made with Levallois techniques mainly on flint and chert. In Layer J, sidescrapers, endscrapers, and manuported granite cobbles dominate the finds, but tool frequencies and densities vary across the unit. A few pockets of forest, mainly willow and pine, scattered among plentiful grasses and chenopods on a cold steppe hosted roughly equal numbers of Rangifer, Equus, and bovids, plus cave bear, mammoth, roe and red deer, birds, fish, lemmings, susliks, and carnivores. The Mousterian layers have yielded 20 Neanderthal remains, including a partial adult maxilla, plus 13 isolated teeth, from at least five people, ranging from an infant 2-4 years old to an adult. A large roof collapse sealed Layer J post-depositionally. From Layer J, the deepest Mousterian layer, 39 independent subsamples from eight ungulate teeth were dated by standard ESR. Enamel U concentrations averaged from 0.2-0.6 ppm, while those in the dentine ranged from 6.3-18.9 ppm. Isochron analyses hint that some recent U remobilization has affected some teeth. External dose rates were determined by measuring the radioactivity by NAA in > 30 associated bulk sediment or single mineralogical component samples. For each tooth, volumetrically averaged sediment dose rates were calculated with a multi-component model using éboulis and cobble sizes and positions, as determined from photographs coupled with the total station data. A time-averaged cosmic dose rate was calculated for each tooth. Assuming linear U uptake, GdB's Layer J averages 62 ± 1 ka, correlating with MIS 4.