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.
","abstract_html":"<p>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.</p> <p>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.</p> <p>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.</p>","abstract_has_math":false,"creators":["Day, Sarah"],"institution":null,"degree_name":"Master of Science","degree_level":"thesis","degree_discipline":null,"degree_department":"Department of the Earth, Atmosphere, and Climate","school":null,"contributors":[],"advisors":["Neal R. Iverson"],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-01-01","date_published":"2014-01-01","updated_at":"2026-07-24T02:38:46Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.31274/etd-180810-2391"],"render_values":[{"text":"https://doi.org/10.31274/etd-180810-2391","href":"https://doi.org/10.31274/etd-180810-2391","code":true}]},{"key":"dc:identifier","label":"Identifier","values":["archive/lib.dr.iastate.edu/etd/13653/"],"render_values":[{"text":"archive/lib.dr.iastate.edu/etd/13653/","href":null,"code":true}]}]},"links":{"outbound_url":"https://dr.lib.iastate.edu/handle/20.500.12876/27840","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Neal R. Iverson"]},{"key":"dc:contributor.department","label":"Department","values":["Department of the Earth, Atmosphere, and Climate"]},{"key":"dc:creator","label":"Author","values":["Day, Sarah"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-08-11T14:18:06.000"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-06-30T02:51:13Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-06-30T02:51:13Z"]},{"key":"dc:date.issued","label":"Date","values":["2014-01-01"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["archive/lib.dr.iastate.edu/etd/13653/"]},{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.31274/etd-180810-2391"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://dr.lib.iastate.edu/handle/20.500.12876/27840"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data"]}]}],"canonical_facts":{"dc:contributor.advisor":["Neal R. Iverson"],"dc:contributor.department":["Department of the Earth, Atmosphere, and Climate"],"dc:creator":["Day, Sarah"],"dc:date":["2018-08-11T14:18:06.000"],"dc:date.accessioned":["2020-06-30T02:51:13Z"],"dc:date.available":["2020-06-30T02:51:13Z"],"dc:date.issued":["2014-01-01"],"dc:description.abstract":["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.
"],"dc:format.mimetype":["application/pdf"],"dc:identifier":["archive/lib.dr.iastate.edu/etd/13653/"],"dc:identifier.doi":["https://doi.org/10.31274/etd-180810-2391"],"dc:identifier.uri":["https://dr.lib.iastate.edu/handle/20.500.12876/27840"],"dc:language.iso":["en"],"dc:title":["Assessing the style of advance and retreat of the Des Moines Lobe using LiDAR topographic data"],"dc:type":["thesis"],"thesis:degree_level":["thesis"],"thesis:degree_name":["Master of Science"]},"updated_at":"2026-07-24T02:38:46Z"}