A multi-proxy reconstruction of coastal processes and Lake Erie flood events from Magee Marsh, northern Ohio

Along the margins of the Great Lakes of North America, lake level fluctuations and flood events threaten coastal environments and infrastructure. However, little is known about coastal processes over centennial (or longer) timescales along these Great Lakes. In order to document overwash from Lake Erie that predates historical records, sediment cores MG19-3 and MG21-2 were extracted from Magee Marsh Wildlife Area on Lake Erie’s southwestern shore. Both cores were subjected to loss-on-ignition and x-ray fluorescence analysis; for core MG21-2, microfossils were analyzed, and chronology was established by ¹⁴C and ²¹⁰Pb_xs dating, while grain size was analyzed for core MG19-3. Cores consist of uniform clayey silt at the base overlain successively by a layer of sandy silt with sparse pebbles and shells, a thin layer of dark clay and silt, and a layer of coarse sand, pebbles, and shells. The uppermost sediments are organic-rich silt and peaty material. Sand layers contain low organic content, elevated carbonate content, and unique geochemical signatures relative to adjacent sediment depths. The sand layer signatures demonstrate that at least two intervals of overwash from Lake Erie occurred between 1430 CE (∼520 cal yr BP) and 1867 CE, attributed to separate processes of normal wave action and storm surge impact. These findings reveal that Magee Marsh serves as a repository to capture and preserve overwash deposits from Lake Erie. Future work investigating other Great Lakes coastal sites will enable regional correlation and insight into the periodicity and long-term impacts of these extreme events.