Paper No. 27-6
Presentation Time: 8:00 AM-12:00 PM
GEOPHYSICAL ANALYSIS OF GLACIAL LAKE ARKONA BARRIER ISLANDS SOUTHEAST OF NAPLOEON,OH
Lake Arkona is characterized by a subtle or “washed” appearance and can be traced throughout the Lake Erie basin as a discontinuous ridge. The traditional interpretation of Lake Arkona is that lake level dropped approximately 100ft from its previous highest stand to Lake Arkona levels, then Lake Arkona was overtopped by a subsequent highstand, Lake Whittlesey. To assess the traditional interpretation of Lake Arkona, underlying sediments of Lake Arkona barrier islands are used to determine the presence of a ravinement surface induced by the Lake Whittlesey highstand. Ridges located southeast of Napoleon, OH are interpreted as Lake Arkona barrier islands based on elevation, geomorphic form and orientation to the lake water plane. Sensors & Software’s pulseEKKO 100 ground penetrating radar (GPR) was used to perform a series of transects across the barrier islands extending from the back basin to the shoreface. GPR transect orientations were set perpendicular to the long axis of ridge and parallel to the long axis of the ridge to evaluate the internal sedimentary structure. Evaluated GPR transect results show no evidence of a strong reflector interrupting the inherent stratigraphy of the barrier islands. A strong reflector associated with a ravinement surface induced by a Lake Whittlesey highstand was not observed in any of the GPR transects. These results have several implications 1) Due to the lack of a strong reflector interrupting the internal stratigraphy of the barrier island, it is unlikely that the barrier island 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 will need to be re-evaluated. 4) An alternative to the traditional interpretation of Lake Arkona is it was a short-lived immature beach that was created as a step down from Lake Whittlesey to Lake Warren.