The discussion following the preceding papers on the Oelwein section was participated in by Calvin, Fink, Bain, Shimek, Beyer, Finch and others. The facts developed during the discussion may be summarized as follows: A few years ago geologists were content to look upon the glacial period as a unit, and the drift mantle of Iowa was regarded as the effect of a single invasion and retreat of glacial ice. Some time ago, however, McGee demonstrated that in northeastern Iowa there are two distinct drift sheets separated by a soil horizon and forest bed which represent an interglacial period of considerable length.
Proceedings of the Iowa Academy of Sciences
©1896 Iowa Academy of Science, Inc.
"Summary of Discussion,"
Proceedings of the Iowa Academy of Science, 4(1), 66-68.
Available at: https://scholarworks.uni.edu/pias/vol4/iss1/13