PRESQUE ISLE, ERIE, PA: GEOLOGIC HISTORY INVESTIGATED

Located in north western Pennsylvania, Presque Isle State Park is a migrating sand spit in Lake Erie. With its beaches and trails, locals and tourists often come to this State Park to enjoy a nice summer day; however they are not aware of the geologic processes that created this scenic area. Presque Isle has been migrating episodically at least over the past 3000 years, and continues migrating today. Unfortunately, little is known about the geometry and character of sedimentary facies of the many dune/inter-dune, pond, and shoreface environments that are present, and even less is known about the timing of major dune/spit migration episodes.

In order to address this lack of information, and to reconstruct the nature and timing of spit migration, several field excursions were undertaken to collect stratigraphic and sedimentological data. Vibracores were collected from inter-dune areas, and ground penetrating radar (GPR) surveys were conducted across an interdune-dune complex. A large pit was also opened to sample soils and sediments and to compare those with horizons found in cores and in GPR data. Sediments were analyzed for grain size by dry sieving, and by laser diffraction. Magnetic susceptibility of core sediments was also measured, and compared with the sedimentology to establish facies/landform associations. Samples for Optically Stimulated Luminescence (OSL) dating were also recovered.

Field and laboratory data were used to construct a cross section of the research site which illustrate the geometry of sedimentary environments as the result of shoreline progradation. This data will provide a better understanding of past depositional environments. OSL dating will provide an estimation of the rate of pre-historic migration. Combined, stratigraphy and dating will allow for comparison of the timing of major episodes of dune formation and spit migration with environmental events within the Erie basin, in order to better interpret the mechanisms behind them.