Schmidt Hammer exposure-age dating is a calibrated relative-age dating tool in geochronology. When Schmidt Hammer R-values are paired with numerical ages of glacial erratics (usually from cosmogenic exposure-age dating), calibration curves can be constructed. Schmidt Hammer R-values measured on undated rock surfaces can then be plotted against the Schmidt Hammer exposure-age dating calibration curve to estimate the rock exposure age. The Great Lakes region of North America has large areas signficantly underrepresented in the post glacial chronology of ice retreat. The purpose of this project was to measure R-values on previously-dated erratics in Wisconsin to construct a Schmidt Hammer exposure-age dating calibration curve for the Great Lakes region. We were unsuccessful in this endeavour, and we think it has something to do with the long transport distances of erratics in the Great Lakes from their sources and how rounded they have become. Check out the paper below to learn more!
Status: Complete
Participants & Collaborators:
Brianna (Anne) Shepherd (EMU, Professional Geology, BS, '24)
Dr. David Ullman, Burke Center for Ecosystem Research
Dr. Elizabeth Ceperley, Wisconsin Geological and Natural History State Survey
Funding Sources:
Eastern Michigan University, Provost Research Support Award: Developing a Schmidt Hammer Exposure Dating Calibration Curve for the Great Lakes (2022)
Publications
Shepherd, B, Portenga, EW, Ceperley, EG, Ullman, DJ, Clark, CM, ACCEPTED. Challenges in developing a Schmidt hammer exposure-age calibration curve from glacial erratics in the North American Great Lakes: Earth Surface Processes and Landforms.
Presentations
Shepherd, BS, Portenga, EW, Ceperley, EG, Ullman, DJ, 2023. Applications of Schmidt Hammer exposure-age dating in the North American Great Lakes Region: An elusive endeavor. Geological Society of America Annual Meeting: Pittsburgh, Pennsylvania, USA.
Shepherd, BS, 2024. Importance of glacial transport distance and rock fractures in Schmidt hammer exposure-age dating?: Eastern Michigan University Undergraduate Research Symposium, Ypsilanti, Michigan, USA.
Shepherd, BS, Portenga, EW, Ceperley, EG, Ullman, DJ, 2023. Limited application of Schmidt Hammer exposure-age dating in the Great Lakes region. North-Central Geological Society of America Section Meeting: Grand Rapids, Michigan, USA.
Shepherd, BS, 2023. Schmidt hammer exposure dating unsuitable in the Great Lakes region?: Eastern Michigan University Undergraduate Research Symposium, Ypsilanti, Michigan, USA.