ANALYSIS AND CHRONOLOGY OF GLACIAL LAKE ARKONA IN THE WESTERN LAKE ERIE BASIN, USA

The shoreline of glacial Lake Arkona in the Lake Erie basin is characterized by a subtle, low-relief or “washed” appearance, and can be traced around the basin as a discontinuous ridge. The traditional interpretation of Lake Arkona is that lake level dropped approximately 30 m from its previous highest stand to Lake Arkona level, then Lake Arkona was overtopped by the subsequent highstand associated with Lake Whittlesey. To assess the standard interpretation of Lake Arkona, this study evaluated the Lake Arkona and Lake Whittlesey shorelines in the western Lake Erie basin to evaluate the standard model and compare the geomorphology of the two shorelines. Any overtopping of the Arkona shoreline should be expressed stratigraphically by a truncating erosional surface. Ground penetrating radar was used across the Arkona shoreline to evaluate the internal stratigraphy and determine the presence of a strong reflection indicative of a ravinement surface. Ground truth at each field site was provided by a combination of hand-dug pits, vibrocore and auger transects. To better constrain the lake sequence between the Lake Whittlesey and Lake Arkona, optically stimulated luminescence dates were taken from each shoreline. The geomorphic differences between the Arkona and Whittlesey shorelines were described from field observations and a statistical model. The model incorporated topographic profiles taken perpendicular to the long axis of the shoreline features, and extending 5 km into the lake basin. These topographic profiles were obtained using GIS ArcMap and 3 m LiDAR elevations acquired from the U.S. Geological Survey’s National Map Viewer. The model was used to support interpretations for field observations of pre-existing topography, paleo-wave direction and sediment supply for the shorelines in the western Lake Erie basin. The results of the study have several implications: 1) Due to the lack of a strong GPR reflection interrupting the internal stratigraphy of the Arkona coastal features, it is unlikely that the shoreline was overtopped by a higher lake stand; 2) These results call into question the traditional interpretation of the proglacial lake sequence in the Lake Erie basin; 3) The traditional description of Lake Arkona being a washed shoreline needs to be re-evaluated.