(ESH) Effects of Glacial Lake Agassiz on the Climatic History of Minnesota

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9508216 Wright Glacial Lake Agassiz was a huge lake fronting the retreating Laurentide ice sheet. Its southern and eastern arms in northwestern Minnesota were occupied from about 11,600 to 11,000 radiocarbon years ago, but following a dry period contemporaneous with Younger Dryas interval only the southern arm was occupied, from 10,000 to 9,500 radiocarbon B.P. This proposal aims to evaluate the effects of the cold glacial meltwaters of light 18O on the climate, vegetation, and small-lake limnology downwind on the adjacent moraines by stratigraphic analysis of varved sediments of small deep lakes. analysis of pollen, stable-isotope and trace-element composition of ostracodes, stable isotope composition of cellulose in organic matter, and species composition of ostracode assemblages will be used along with varve counts and AMS radiocarbon dates to establish a dated stratigraphy to correlate with Lake Agassiz phases of expansion and reduction. A site downwind of the eastern arm should show one interval of lake effects, of Lake Agassiz on the climate of the adjacent landscape.