RECENT STRATIGRAPHIC AND CHRONOLOGIC RESULTS FROM THE HURON-ERIE LAKE PLAIN OF ANCESTRAL LAKE ERIE, OHIO

An understanding of deglacial events in the Huron-Erie Lake Plain is known in general, but poorly understood in detail. During east–northeast recession of the Erie and Huron lobes of the Laurentide Ice Sheet, Ancestral Lake Erie evolved through fluctuating lake levels and changing outlets. Strandlines are well known, having been mapped ~100 years ago, but detailed stratigraphic and sedimentologic analyses and age control is left wanting. To increase our knowledge of this lake, and in the process develop a more four-dimensional understanding of the surficial geology, we have been dating strandlines and sand dunes using mostly OSL techniques. To evaluate the Ypsilanti low event, rhythmic lake sediments were analyzed at elevations that would have experienced subaerial emergence during this low event. Most of the sand dunes are 4000–9000 years younger than the oldest strandlines. Because sand was sourced from older ice marginal and strandline deposits, dunes either initially formed or were remobilized under a deteriorating climate during stadials, and post-date disappearance of Ancestral Lake Erie. Only 507 rhythmites were observed between till and the overlying dune sand and shallow water sediment, which is fewer than expected. A stratigraphic break within the lacustrine sedimentary sequence necessary to support the low-water Ypsilanti Phase was not observed. In summary, our data thus far suggests that stable water levels were short lived and that the lake evolved over a shorter period of time than is commonly assumed.