major division of Pleistocene deposits and time (1,600,000 to 10,000 years ago) in North America. The Yarmouth Interglacial was named for deposits that were studied in the region of Yarmouth, Iowa, and is equivalent to the Mindel-Riss Interglacial Stage of Alpine Europe.

The Yarmouth Interglacial is represented by the remains of ancient soil horizons developed on Kansan glacial deposits as well as by deposits of peat. In some localities fossil vertebrates are especially well represented; the composition of these faunas indicates that Yarmouth climates were at least as warm as modern climates. In some regions, the development of distinctive deposits seems to indicate that Yarmouth climates may have been semiarid.