Maxwell Gage, 1965. "Accordant and Discordant Glacial Sequences", International Studies on the Quaternary: Papers Prepared on the Occasion of the VII Congress of the International Association for Quaternary Research Boulder, Colorado, 1965, H. E. Wright, Jr., David G. Frey
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Climatic variation has been claimed as a necessary basis for chronological subdivision and correlation within the Pleistocene Period. However, the available geochronological methods for directly testing the underlying assumption that climatic oscillations were in fact synchronous and similarly phased throughout the world are at present applicable only for a small fraction of late Pleistocene time. The hypothesis of synchronism does not require world-wide occurrence and exact coincidence of all glacial oscillations because of the many factors that determine whether or not local response to any degree of general climatic deterioration will take the form of glacier advances, but it does lead one to expect that glacial histories generally followed a similar course in all regions where the main geographical controls operated similarly. To compare the kinds of sequences indicated by glacial records in various regions as objectively as possible without attempting correlations, a modified scheme based on traditional qualitative criteria is suggested to classify field evidence for glaciations in terms of relative age. Examples of sequences from different geographical situations show a generally accordant pattern of glacial events, regardless of correlation, throughout most or all of the Pleistocene. Some are anomalous in showing only a brief late Pleistocene episode of glaciation. Examination of a few critical examples of discordance suggests the most probable reason is relatively late increase in altitude, either by volcanic upbuilding or by tectonic upheaval, so that the rising summits failed to encounter depressed snow lines until late in the Pleistocene. The contrast between accordant and discordant histories illustrates the “topographic” element in Flint’s “solar-topographic” generalization of the causes of glaciations.