The Olsen-Chubbuck Site, properly speaking, consisted of a bone bed contained in an ancient arroyo (Fig. 1). As previously mentioned, this arroyo did not follow the locally normal, north-to-south drainage pattern. Rather, it had its origin near the center of a small catchment basin and flowed eastward through and across the ridge which formed the eastern side of the basin, to debouch on the eastern slope of that ridge (Fig. 7).