SIGNIFICANCE AND AGES OF MID-WISCONSINAN ORGANIC DEPOSITS IN SOUTHERN MICHIGAN

摘要: Four recently drilled, closely spaced wells near Kalkaska, Michigan encountered a thick zone of organic-rich sediments at depth about 130 m; all are interpreted as part the same unit. Two radiocarbon dates and botanical data derived from carbonaceous material along with associated indicate that 35,000 B.P. site was ice-free, poorly drained, supported first an open later closed boreal forest. These two eight additional determinations (four finite four “infinite”) wood recovered during other research compared previously published for Middle Wisconsinan southern Michigan. This array ages suggests least parts state were not glaciated much if Wisconsinan, including Cherrytree Stadial. Botanical evidence also indicates climate in northwest Southern Peninsula considerably cooler than present, possibly being i...