A CONTEMPORARY STORY OF A HISTORICAL LAKE WARREN STRANDLINE FROM NORTHWEST OHIO

During the initial mapping campaign of Leverett and Taylor circa 1900, Lake Warren was identified as a proglacial lake stage in the Lake Erie basin from the last deglaciation. No significant changes have been made to the understanding of Lake Warren within the framework of the deglacial sequence and the current knowledge is based on limited stratigraphic information from strandlines and a wide range of radiocarbon ages. Recent work includes a detailed study into the Oak Openings Ridge (OOR), a former strandline of Lake Warren in northwestern Ohio. The purpose of this study is to use ground-penetrating radar (GPR) and optically stimulated luminescence (OSL) dating to reconstruct the stratigraphy, depositional environment, and age of the (OOR). Both sedimentary exposures and >4 km of GPR data were used to demonstrate that the OOR is a barrier spit that migrated from the northeast to the southwest, and is currently blanketed by an aeolian sand sheet and dunes. Sediments observed in exposures show a shallowing-up sequence attributed to the retreat of proglacial lakes from the area. Corresponding GPR data reveal three distinct GPR facies. A sandy barrier spit platform of a lower beach face prograding across finer-grained lacustrine mud or till, an upper beach face, and low-relief, aeolian dunes and sandsheets. Four OSL ages from the upper beach face average 14.2 ± 0.5 ka, consistent with an earlier published OSL age of 14.1 ± 1.0 ka from the same unit. From earlier work, the overlying aeolian dunes record westerly winds after formation of the OOR, and OSL dating records episodic activity from the Younger Dryas chronozone to ~8000 years ago. The results suggest that the OOR formed in two phases. First, a barrier spit prograded into Lake Warren from the northeast. Second, the barrier surface sourced parabolic sand dunes and sand sheets that formed episodically for ~5000 years thereafter. The sediment source for the sand body is from southeast Michigan, but it is of uncertain origin.