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Document Type

Research

Keywords

Till, Tazewell Till. Kansan Till, Till of Iowa

Abstract

11 Compositional and

Kansan and Tazewell tills can be distinguished by compositional and textural properties throughout portions of Buena Vista, Cherokee, Clay and O'Brien counties in northwest Iowa. Kansan till contains more clay than silt or sand while Tazewell till is composed of nearly equal portions of clay, silt and sand. Coarse sand is more abundant in Tazewell till than Kansan till. Siliceous rounded shale grains are common in Tazewell till but scarce or absent in Kansan till. Igneous and metamorphic rock fragments are more common in the coarse sand of Kansan than Tazewell till. Significantly more carbonate grains occur in the medium sand fraction of Tazewell till than Kansan till. The lithology of Tazewell till suggests ice occupied the Minnesota-Des Moines rivers' lowland by 20,000 radiocarbon years before the present.

Publication Date

September 1974

Journal Title

Proceedings of the Iowa Academy of Science

Volume

81

Issue

3

First Page

122

Last Page

126

Copyright

© Copyright 1974 by the Iowa Academy of Science, Inc.

Language

EN

File Format

application/pdf

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