Recent field study has resulted in the reclassification of the glacial drifts of northwestern Iowa. The Bemis moraine of Leverett (1932, pp. 57-61) is believed to be the Cary drift, and the Altamont and younger moraines (Leverett, 1932, pp. 67-7 5) have been designated the Mankato drift. The Cary and Mankato drifts are both overlain by discontinuous loess mantles. Loess has not been recognized previously on the Des Moines lobe either by geologists (Kay and Graham, 1943, p. 205) or by soil scientists (Riecken and Smith, 1949, pp. 2a, 3a, 13-16; McMiller, 1945). The loess overlying the Cary drift does not differ materially from the loess on the Mankato drift in field examination. Both loesses are brown, leached, and poorly to well-sorted silts. Thicknesses generally vary from 24 to 36 inches; maximum thickness observed in the field was 51 inches and the minimum identifiable was 15 inches. Quantitative textural and mineralogical analyses were made of samples collected during field study. Characteristics of the loesses are here recorded.
Proceedings of the Iowa Academy of Science
© Copyright 1950 by the Iowa Academy of Science, Inc.
Ruhe, Robert V.
"Petrographic Notes on the Loesses of the Des Moines Drift Lobe,"
Proceedings of the Iowa Academy of Science, 57(1), 277-281.
Available at: https://scholarworks.uni.edu/pias/vol57/iss1/34