Sandy aeolian deposition in southeastern Minnesota and western Wisconsin: A forgotten and poorly understood sandy aeolian landscape. Preliminary Results.

Authors: Jason Millett, Minnesota State University, Mankato, Clayton Anzalone, Minnesota State University, Mankato, Kayla Coonen, University of Wisconsin - Eau Claire, Erica Jansen, University of Wisconsin - Eau Claire, Daniel Garnder, Minnesota State University, Mankato, Phillip Larson*, Minnesota State University, Mankato, Garry Running, University of Wisconsin - Eau Claire, Doug Faulkner, University of Wisconsin - Eau Claire, Ronald Schirmer, Minnesota State University, Mankato
Topics: Geomorphology, Paleoenvironmental Change, Physical Geography
Keywords: geomorphology, aeolian, paraglacial, physical geography
Session Type: Poster
Day: 4/12/2018
Start / End Time: 1:20 PM / 3:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

Schaetzl et al. (2017) revealed previously unidentified sandy aeolian landforms within the lower Chippewa River watershed (LCRW), western Wisconsin. They interpreted a NW-SE paleowind direction and a broad depositional chronology ranging from late-Pleistocene to mid-Holocene. Sparse absolute age control and limited field investigation necessitates further examination to understand genesis and paleoenvironmental significance of the landforms identified. In addition, the scope of their work did not extend beyond the LCRW, leaving the broader regional significance of these landforms unknown. One particular landform, identified as “linear dunes,” appears to be the same as "sand stringers" identified by Zanner (1999), whose work has received little recognition, despite the apparent distribution of sand stringers throughout the Midwest. Zanner’s work was accomplished without benefit of modern geospatial and geochronological methods (e.g. LiDAR, OSL). Building on Zanner’s forgotten pioneering contribution, we expand Zanner’s study area to include much of west-central Wisconsin, and use newly created LiDAR DEMs and OSL ages to revisit Zanner’s work and to establish better age control on sand stringers and other sandy aeolian landforms. Sand stringers were mapped and identified based on morphometry and textural characteristics determined with field and SSURGO data. Our results show that sand stringers are oriented NW-SE, are ~1.5-3 m high, up to ~100 m wide, and 10 to 100s of meters in length. Conversely, landforms interpreted as parabolic dunes exhibit variable orientations and morphology, with evidence of multiple episodes of reactivation suggesting more complex genesis. OSL ages from four linear and three parabolic dunes are pending.

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