Publication Date:
2013-11-01
Description:
Areal mapping of the middle Wisconsin varved clay site along Sixmile Creek near Ithaca, New York, has revealed a much more widespread and varied array of sediments than previously thought. Lacustrine clays, some varved, are interbedded with sands and gravels interpreted as sub-aqueous fan deposits, and both are overlain by a deformation till. Nine radiocarbon dates indicate a 34–37 14C ka BP age for the lacustrine sediment, with the deformation till less than a few thousand years younger. Beneath this sequence is a deposit dated at ± 42 14C ka BP. Both strata represent a tundra climate with a mean July temperature of about 10°C. The Sixmile Creek deformation till must correlate with the 35 14C ka BP till along the Genesee River, 125 km to the NW, and defines a Cherrytree stade glacial advance into the Appalachian Plateau, much further south than what has generally been accepted. Such an advance would require drainage from a proglacial lake in the western Ontario basin to flow westward instead of northeastward. The Sixmile strata suggest a colder than accepted middle Wisconsin stage. Recent data indicate that this stage is one of progressive cooling, with large climatic fluctuations.
Print ISSN:
0033-5894
Electronic ISSN:
1096-0287
Topics:
Geography
,
Geosciences
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