Workers of the Pleistocene of Iowa must use several criteria for distinguishing the different drift sheets. The working criteria are, (1) surface topography of the drift, (2) distinctive lithological characteristics, (3) degree and depth of leaching and oxidation, (4) distinctive interglacial deposits and, (5) pronounced erosional and weathered zones. It was formerly thought to be quite an easy matter to distinguish one drift sheet from another by means of criteria (1), (2) and (3), with great emphasis upon (1) and (3). Too much emphasis, however, cannot be placed upon the lithological characters, since a careful study of the drift sheets, with the possible exception of the Wisconsin, has revealed a certain consanguinity existing among them.
Proceedings of the Iowa Academy of Science
©1919 Iowa Academy of Science, Inc.
Cable, E. J.
"The Iowan-Wisconsin Border,"
Proceedings of the Iowa Academy of Science, 26(1), 399-404.
Available at: https://scholarworks.uni.edu/pias/vol26/iss1/40