Refining the Chronology of the Agate Basin Complex: Radiocarbon Dating the Frazier Site, Northeastern Colorado

The Frazier site (5WL268) has been interpreted as a single component bison kill and processing site representative of the Paleoindian Agate Basin complex in northeastern Colorado. The site was excavated in the 1960s by H. Marie Wormington. An examination of six accelerator mass spectrometry C-14 radiocarbon dates recently obtained on bison bone (amino acids) and charcoal collected during Wormington's investigations suggest the Frazier site dates between 10,200 and 10,100 C-14 B.P. The traditionally established age range for the Agate Basin complex, uncalibrated 10,500-10,000 years B.P., was defined in the 1960s and 1970s primarily as a result of investigations at two multicomponent sites in Wyoming: the Agate Basin type site and the Hell Gap site. The Frazier site dates suggest the Agate Basin complex fits within the established age range and may be up to 200 radiocarbon years (ca. 400 calendar years) younger than the Beacon Island site in North Dakota, which radiometrically dates to uncalibrated ca. 10,300 years B.P.