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Document Type

Research

Keywords

Des Moines lobe, Iowa, ice thickness, Wisconsonian, glaciation

Abstract

Minimum and maximum limits to Des Moines Lobe ice thickness in Iowa during the Late Wisconsinan glaciation are calculated. These limits are based on minimum and maximum ice thickness calculations for the Des Moines Lobe in eastern North Dakota using crustal depression indicated by Lake Agassiz strandlines. Minimum and maximum basal shear stresses for the Des Moines Lobe are calculated by projecting a flow line from the terminus of the Des Moines Lobe back up-ice to the study site in northeastern North Dakota. Ice thickness in Iowa is then calculated with a method that uses the basal shear stress values. The ice thickness limits calculated in this study assume that 1) post-glacial rebound in North Dakota is complete, 2) restrained rebound in eastern North Dakota did not exceed 73 %, 3) basal shear stress controlled ice thickness in the marginal portions of the Laurentide Ice Sheet, and 4) the pore water pressure in the basal till of the reconstructed ice sheet was very close to the glaciostatic pressure. Ice thickness is calculated at between 131 and 484 m at the Iowa-Minnesota border. The results of this study are then compared to results from other Des Moines Lobe ice thickness studies.

Publication Date

June 2000

Journal Title

Journal of the Iowa Academy of Science

Volume

107

Issue

2

First Page

46

Last Page

50

Copyright

© Copyright 2000 by the Iowa Academy of Science, Inc.

Language

EN

File Format

application/pdf