Radiocarbon Ages of Postglacial Lake Clays near Michigan City, Indiana

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Science  17 Aug 1962:
Vol. 137, Issue 3529, pp. 528-529
DOI: 10.1126/science.137.3529.528


Two radiocarbon dates were obtained for postglacial clays. One sample, 6350 years old, was taken from a bed of compacted and carbonized wood just above a bed of pebbly clay. Overlying the woody bed is 5½ feet of organic bluish clays and beach sands near the present lake level. The upper clay layer contained a younger wood sample, 5475 years old. The blue clays are of shallow swamp origin and were deposited during the late low-water stage of Lake Chippewa; the pebbly clay is assumed to be of Glenwood age (about 11,000 years) or older.