Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data
Successive advances of the late-Wisconsinan Des Moines Lobe to form three major end moraines in Iowa--sequentially the Bemis, Altamont, and Algona moraines--are thought to be the result of the lobe surging out of balance with a warming climate. Various styles of hummocky topography, collectively som...
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ftiowastateuniv:oai:lib.dr.iastate.edu:etd-4660 2023-05-15T16:20:39+02:00 Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data Day, Sarah Elizabeth 2014-01-01T08:00:00Z application/pdf https://lib.dr.iastate.edu/etd/13653 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4660&context=etd en eng Iowa State University Digital Repository https://lib.dr.iastate.edu/etd/13653 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4660&context=etd Graduate Theses and Dissertations Des Moines Lobe End Moraine Glacier Minor Moraines Geology Geomorphology text 2014 ftiowastateuniv 2018-11-26T01:37:43Z Successive advances of the late-Wisconsinan Des Moines Lobe to form three major end moraines in Iowa--sequentially the Bemis, Altamont, and Algona moraines--are thought to be the result of the lobe surging out of balance with a warming climate. Various styles of hummocky topography, collectively sometimes called stagnation moraine, are interpreted to be the result of widespread stagnation and down-wasting of ice following surges. Alternatively, end moraines could be recessional--a result of incremental back-wasting of the glacier margin and unrelated to surging. To study the retreat style of the Des Moines Lobe, high resolution LiDAR data were used to re-evaluate the subtle landscape of the lobe's footprint in Iowa. Results indicate that ~90% of the lobe's area, excluding major Holocene stream drainages, consists of stagnation features. Some landforms are more prevalent than mapped previously, including eskers and features interpreted to be subdued ice-walled lake plains. Importantly, subglacially formed minor moraines (a.k.a. washboard moraines), which resulted from sediment filling of transverse crevasses, cover ~60% of the lobe's area with stagnation landforms. Also, ~25 previously unmapped end moraine ridges have been identified. Transverse crevasse-fill ridges in the forefields of modern glaciers form due to longitudinal ice extension associated with surging and are not found in the forefields of non-surge-type glaciers, so minor moraines are good evidence of Des Moines Lobe surges. Most end moraines have minor moraine sets associated with them, consistent with a surge-like advances, and many areas have multiple sets of minor moraines indicating a surge history more complicated than one advance for each of the three major end moraines. Therefore, asserting stagnation and down-wasting after three surge-like advances provides an incomplete characterization of the Des Moines Lobe's advance and retreat. The surge-type Bering Glacier in Alaska is a good but imperfect modern analog for the lobe. Text glacier glaciers Alaska Digital Repository @ Iowa State University |
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Open Polar |
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Digital Repository @ Iowa State University |
op_collection_id |
ftiowastateuniv |
language |
English |
topic |
Des Moines Lobe End Moraine Glacier Minor Moraines Geology Geomorphology |
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Des Moines Lobe End Moraine Glacier Minor Moraines Geology Geomorphology Day, Sarah Elizabeth Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data |
topic_facet |
Des Moines Lobe End Moraine Glacier Minor Moraines Geology Geomorphology |
description |
Successive advances of the late-Wisconsinan Des Moines Lobe to form three major end moraines in Iowa--sequentially the Bemis, Altamont, and Algona moraines--are thought to be the result of the lobe surging out of balance with a warming climate. Various styles of hummocky topography, collectively sometimes called stagnation moraine, are interpreted to be the result of widespread stagnation and down-wasting of ice following surges. Alternatively, end moraines could be recessional--a result of incremental back-wasting of the glacier margin and unrelated to surging. To study the retreat style of the Des Moines Lobe, high resolution LiDAR data were used to re-evaluate the subtle landscape of the lobe's footprint in Iowa. Results indicate that ~90% of the lobe's area, excluding major Holocene stream drainages, consists of stagnation features. Some landforms are more prevalent than mapped previously, including eskers and features interpreted to be subdued ice-walled lake plains. Importantly, subglacially formed minor moraines (a.k.a. washboard moraines), which resulted from sediment filling of transverse crevasses, cover ~60% of the lobe's area with stagnation landforms. Also, ~25 previously unmapped end moraine ridges have been identified. Transverse crevasse-fill ridges in the forefields of modern glaciers form due to longitudinal ice extension associated with surging and are not found in the forefields of non-surge-type glaciers, so minor moraines are good evidence of Des Moines Lobe surges. Most end moraines have minor moraine sets associated with them, consistent with a surge-like advances, and many areas have multiple sets of minor moraines indicating a surge history more complicated than one advance for each of the three major end moraines. Therefore, asserting stagnation and down-wasting after three surge-like advances provides an incomplete characterization of the Des Moines Lobe's advance and retreat. The surge-type Bering Glacier in Alaska is a good but imperfect modern analog for the lobe. |
format |
Text |
author |
Day, Sarah Elizabeth |
author_facet |
Day, Sarah Elizabeth |
author_sort |
Day, Sarah Elizabeth |
title |
Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data |
title_short |
Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data |
title_full |
Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data |
title_fullStr |
Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data |
title_full_unstemmed |
Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data |
title_sort |
assessing the style of advance and retreat of the des moines lobe using lidar topographic data |
publisher |
Iowa State University Digital Repository |
publishDate |
2014 |
url |
https://lib.dr.iastate.edu/etd/13653 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4660&context=etd |
genre |
glacier glaciers Alaska |
genre_facet |
glacier glaciers Alaska |
op_source |
Graduate Theses and Dissertations |
op_relation |
https://lib.dr.iastate.edu/etd/13653 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4660&context=etd |
_version_ |
1766008587868438528 |