This paper is based on stratigraphic studies conducted at the Merrell Locaility and other locations in Centennial Valley. The Merrell Locality is situated in southwest Montana, on the western end of Centennial Valley (Figure 30). It is notable for containing the fossil vertebrate remains of mammoth (Mammuthus cf. M. columbi), scimitar cat (a member of the sabretooths, Homotherium serum), horse (Equidae) and Yesterday's camel (Camelops cf. hesternus), as well as other plant and animal fossils of Pleistocene age (Dundas 1990; Dundas, Hill, and Batten 1996). Summaries and reports of research conducted at the locality include Albanese (1995); Albanese, Davis, and Hill (1995); Batten and Davis (1996); Bump (1989); Davis et al. (1995); Dundas (1990); Dundas (1992); Hill, Davis, and Albanese (1995); Hill and Albanese (1996); Hill (1999, 2001a, 2001b).