North american pleistocene stages reconsidered in light of probable pliocene-pleistocene continental glaciation

Science. 1978 Oct 20;202(4365):305-7. doi: 10.1126/science.202.4365.305.

Abstract

Confusion due to the conceptual usage of classic North American Pleistocene stage terms indicates the need for a new or revised terminology. The Pliocene-Pleistocene boundary has tentatively been dated about 2.5 +/- 0.1 x 10(6) years. Glacial deposits in the central United States older than about 2.2 x 10(6) years may span that boundary.