Smith and Riecken (1947) in their revision of the Iowan-drift border in northwestern Iowan, extended a sublobe of the Iowandrift southward to near Roselle and Halbur in Carroll County. During field studies in Carroll County in 1953, the margin of the Iowan-drift sublobe was found to extend as far southward as Manning and Templeton in Carroll County (Figure 1). The Iowan drift is delineated from the loess-mantled Kansan drift on the basis of four lines of evidence: (1) in topographic positions that preclude significant erosion on the Iowan-drift surface, calcareous loess overlies calcareous till. (2) In topographic positions that preclude significant erosion on the Kansan-drift surface, calcareous loess overlies a leached, buried soil in the uppermost part of the Kansan till. (3) An abrupt change in topography occurs at the margin of the Iowan-drift. (4) A discontinuity in loess thickness occurs at the margin of the Iowan-drift.
Proceedings of the Iowa Academy of Science
©1955 Iowa Academy of Science, Inc.
Corliss, J. F. and Ruhe, R. V.
"The Iowan Terrace and Terrace Soils of the Nishnabotna Valley in Western Iowa,"
Proceedings of the Iowa Academy of Science, 62(1), 345-360.
Available at: https://scholarworks.uni.edu/pias/vol62/iss1/37