James Walters, Department of Earth Science, will discuss his research on "Reconstructing Northeast Iowa's Periglacial Environment."
During late Pleistocene time, the landform region known as the Iowan Surface of Northeast Iowa, situated between the Des Moines Lobe glacial ice to the west and the Lake Michigan glacial lobe to the east, experienced a periglacial environment. The characteristics of this former environment are not well known, but the presence of features known as “ice-wedge casts” indicates that permanently frozen ground (permafrost) was present. The actual timing of this event is also not well known, but recent optically stimulated luminescence dating of sands from sand stringers overlying the pre-Illinoian till suggests that these events were taking place between about 24,000 and 16,500 years ago.
For the last several years, Walters has investigated the relict periglacial features of the Iowan Surface in an attempt to reconstruct the severity, timing and other characteristics of this environment.