TESTING LAKE-LEVEL FLUCTUATIONS IN ANCESTRAL LAKE ERIE, NORTHWEST OHIO

Understanding the deglacial lake sequences in the western end of the ancestral Lake Erie basin is inseparable from understanding ice-margin recession in the southern Great Lakes region. While the general scheme of deglaciation is understood, ice-margin recession and lake-level fluctuations are weakly constrained in time or order. Geophysical analysis of ‘washed’ Lake Maumee strandlines indicate these landforms reflect littoral processes over a short time period and do not have the sedimentologic or geomorphic characteristics of being flooded. Here 14 new optically stimulated luminescence (OSL) ages are assigned to the deglacial lake sequence and sand dunes in the Wauseon, OH area. Ages from this study and the literature reveal approximately 1000 years (16.9–15.9 ka) for formation of the Maumee, Arkona, and Whittlesey beaches. The traditional model of lake-level fluctuation would also include the Ypsilanti lowstand within this sequence, but little time is available for that event. The stratigraphy associated with ~500 rhythmites interpreted as varves from below the Warren Beach does not contain sedimentary features that would support the inferred ~100-m drop in lake level to the Ypsilanti lowstand. Some OSL-dated sand dunes record lake-level fall from below the Maumee level at ~15–14 ka, while five OSL ages record aeolian activity during the Younger Dryas stadial, consistent with previous results in the study area and Indiana.