Celebration of Scholarship and Creative Activity 2023
During the ice age, glaciers carried sediments that shaped Wisconsin’s landscape. These sediments provide clues to the source and specific ice flow patterns. The purpose of this project is to determine the glacial flow paths using mineral assemblages. I collected samples containing sandy to gravelly sediment from glacial meltwater deposits (outwash). From these samples, I separated the grains into size fractions and used the smallest fraction, silt to sand. From these, I had microscope grain mount slides made for study using a petrographic microscope to identify minerals. The same size fractions were also used in X-Ray diffraction analyses for mineral identification. I compared the resulting mineral data to maps of the Upper Midwest and Canada where the glaciers originated. These results show original rock sources.
Many previous studies have shown that a large amount of glacial sediments in Wisconsin were sourced from the Upper Midwest and Canada. It was surprising to find that much of the sediment came from areas closer to home, including Door County and northern Wisconsin. The remaining material was transported greater distances (Upper Midwest and Canada). Knowing specific pathways of glacial ice flow and associated sediment transport is useful in considering the economic impact of these sand- and gravel-rich sediments; many are used for construction, road building, and in agriculture.