Enhanced Radiocarbon Chronology from Ohio: A Northern Hemisphere Glacial Geologic Test of Alternate Glacial Climate Hypothesis

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The goal of the proposed research is to recover a detailed record of Laurentide Ice Sheet fluctuations in southern Ohio during the last glacial cycle to test climate-change hypotheses. Multiple (~150) radiocarbon ages from organic materials associated with glacial deposits of the Miami and Scioto sublobes will delineate a high-resolution chronology (e.g. glacial phases dated to within 30014C years) and architecture of these ice marginal changes through the last glacial maximum. This record by itself will clarify the behavior of southern sector of the huge Laurentide Ice Sheet (a key component of the ice-age climate system). It may also be an important repository of climatic change. If so, this basic stratigraphic record will be the basis for tests between at least two current hypotheses of ice-age climate. The first suggest that orbital changes drive ice sheets which in turn drive climate, thus predicting specific leads and lags between ice sheet growth and climate change. The second view suggests that ice-age climate changes result from abrupt ocean-atmospheric reorganizations, thus predicting widespread, synchronous changes across the global cryosphere-atmosphere-hydrosphere system. For example, the second hypothesis requires that glacial fluctuations in various parts of the Northern Hemisphere will be in phase and that these in turn, will be concurrent with glacial fluctuations in the Southern Hemisphere. Present stratigraphic interpretations of southern Laurentide fluctuations in Ohio are inadequate to delineate ice- sheet dynamics or test any climate theories because they have not fully considered the genesis of glacial deposits and have only weak (+2,00014C years) chronologic control.