Abstract In 1926, Byron Cummings discovered artifacts associated with the remains of mammoth (Mammuthus), horse (Equus), camel (Camelops), and bison (Bison) in Whitewater Draw, an arroyo near the town of Double Adobe in the semiarid Sulphur Springs Valley, Arizona (Figs. 1 and 2). Unlike the Folsom projectile points discovered with the bones of extinct bison that same year, these artifacts were milling stones and handstones, not projectile points. Sayles and Antevs (1941) later assigned the early artifacts from Double Adobe and from several other localities in Whitewater Draw to the Sulphur Spring stage of the Cochise Culture. They believed that the Sulphur Spring stage artifacts occurred in primary association with extinct megafaunal remains and that the Sulphur Spring stage dated between 12,500 and 11,000 B.P. Since the investigations of Sayles and Antevs, many questions arose concerning the Sulphur Spring stage as the archaeological data base for the American Southwest expanded, especially with the recognition of the Clovis Culture and the establishment of a timetable of late Pleistocene extinctions. Some researchers (Martin and Plog, 1973; Haury, 1983) suggested that the sites of the Sulphur Spring stage may be specialized plantprocessing stations of the Clovis Culture, based on the apparent age of the Sulphur Spring stage artifacts and their association with extinct megafauna. However, other researchers (Willey and Phillips, 1958; Whalen, 1971; Irwin-Williams, 1979) questioned the temporal association of extinct fauna with artifacts of the Sulphur Spring stage and suggested that the artifacts belong to the Early Archaic period and postdate the Clovis