Pleistocene chronology: Long or short?

European geologists, in general, have tended to favor a “short” chronology for the glacial Pleistocene, with four major glacial cycles in the past 500,000 or 600,000 yr. Interpretation of ocean floor sediments by Emiliani and others has accorded with this view, in contrast to the “long” chronology of Ericson and Wollin and their followers, who spread the four North American glacial episodes over a 2-m.y. period. An examination of the available radiometric dates and age estimates from paleomagnetic polarity zones serves to confirm Richmond's view that the four major European glacials do not equate with the four North American glacials in a simple one-to-one manner, but that the Illinoian matches the Elster (Mindel) rather than the Saale (Riss). The Alpine Günz is then equated broadly with the Kansan and overlaps in time with the Jaramillo normal polarity event at about 900,000 y.a. The Nebraskan is older than 1.2 m.y. and is thus coeval with the European Upper Villafranchian, within which the Donau and Biber glacial events may be traced. Montane glaciation certainly extended back into the Tertiary but cold pulses of sufficient duration to produce continental glaciation were more marked through the past 1.5 m.y. More critical studies of the terrestrial record are needed before firm correlations can be made.