‘Megafloods and Mighty Rivers of the Upper Midwest’ presentations

Upper Iowa University (UIU) Delano Professor of Science Kata McCarville will present “Megafloods and Mighty Rivers of the Upper Midwest” at the Fayette Community Library Tuesday, April 19, and at Osborne Nature Center Thursday, April 28. McCarville expects to be joined by UIU alumnus Zachary Dingbaum ’20, who co-authored the results of their work on the origins of the Iowan Erosion Surface. The study was previously presented at the 2021 Geological Society of America meeting in Portland, Oregon. Dingbaum, who is now employed as a Clayton County Conservation park ranger, also presented some of the research at the 2019 International Glaciological Society meeting in Madison, Wisconsin.

McCarville explains that geomorphology, the study of landscapes, contributes to a better understanding of the Upper Midwest, and the histories of its major rivers and their tributaries.  These modern rivers surround the Iowan Erosion Surface (IES) landform region, with its enigmatic geomorphology and sediments.  Many of these features resemble those that have been identified and described at other locations that were subject to megaflooding related to the sudden and catastrophic drainage of glacial lakes.

The recent research included use of optically stimulated luminescence (OSL), which can reveal the last time a quartz or feldspar crystal “saw” the Sun.  This technique has an effective range of up to 500,000 years, compared to 50,000 years or less for carbon dating. In partnership with the US Geological Survey Luminescence Laboratory, these preliminary studies provide insight into the interpretation of the origins of the Iowan Erosion Surface.

The April 19 presentation is scheduled to begin at 2 p.m. at the Fayette Community Library, while the April 28 event is scheduled to begin at 5 p.m. at Osborne Nature Center, rural Elkader.