ABSTRACT

Conceptual application of North American Pleistocene stage terms has resulted in most of them having greatly overlapping time spans. Moreover, the classic North American Pleistocene stages, as defined in their type areas, represent less than the last half of Pleistocene time, which began about 2.5 ± 0.1 m. y. ago, based on fission-track dating of volcanic ash shards occurring near the Pliocene/ Pleistocene boundary in its stratotype area, Calabria, Italy. Therefore, presently used North American Pleistocene stage terms need either to be redefined and stratotypified, or abandoned.

Ongoing research indicates a close correlation between the chronology of the paleotemperature record in the Gulf of Mexico and the chronology of glacial and nonglacial conditions in the central United States.

Because of the close correlation of these chronologies, it appears that a revised stage terminology based on the chronology of major climatic changes could be formulated, which would allow the retention of the current North American stage terms and permit their usage in the conceptual sense. This would necessitate their being redefined and perhaps modified -- possibly by adding the prefix "Neo" -- for the purpose of alerting readers to a new definition. In addition, a system of chronozones would be useful in the Midcontinent.