Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A.
Abstract Late Wisconsin-age drumlins west of Milwaukee are clustered atop uplands bounded by discrete scarps. Gravel operations within the uplands have exposed drumlin cores of undeformed till and outwash beds which are truncated at the sides of the drumlin. In a few areas, clastic dikes, faults, ov...
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Cambridge University Press (CUP)
1979
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Online Access: | http://dx.doi.org/10.1017/s0022143000014337 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000014337 |
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crcambridgeupr:10.1017/s0022143000014337 2024-03-03T08:46:03+00:00 Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. Richard Whittecar, G. Mickelson, David M. 1979 http://dx.doi.org/10.1017/s0022143000014337 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000014337 en eng Cambridge University Press (CUP) Journal of Glaciology volume 22, issue 87, page 357-371 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1979 crcambridgeupr https://doi.org/10.1017/s0022143000014337 2024-02-08T08:36:10Z Abstract Late Wisconsin-age drumlins west of Milwaukee are clustered atop uplands bounded by discrete scarps. Gravel operations within the uplands have exposed drumlin cores of undeformed till and outwash beds which are truncated at the sides of the drumlin. In a few areas, clastic dikes, faults, overturned bedding and shear folds disturb the original layering. The drumlin shapes are blanketed with a basal till 1–3 m thick (“retreat” till) which truncates all internal structures. This till covering cannot be distinguished from the youngest truncated till (“advance” till). Truncation of all of these structures shows that these drumlins are erosional forms carved from pre-existing drift. Apparently, during erosion under compressive flow, some beds became unstable and initiated large-scale movements of material into the drumlin from beneath the drumlin form. Failure and mobilization of the finer-grained beds may have been due to increased pore pressures, differing stages of dilatancy, or differing bulk densities. A growth relationship for drumlins may exist that is based upon the rates of material moving into the drumlin from below and rates of erosion of the drumlin form. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 22 87 357 371 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Richard Whittecar, G. Mickelson, David M. Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. |
topic_facet |
Earth-Surface Processes |
description |
Abstract Late Wisconsin-age drumlins west of Milwaukee are clustered atop uplands bounded by discrete scarps. Gravel operations within the uplands have exposed drumlin cores of undeformed till and outwash beds which are truncated at the sides of the drumlin. In a few areas, clastic dikes, faults, overturned bedding and shear folds disturb the original layering. The drumlin shapes are blanketed with a basal till 1–3 m thick (“retreat” till) which truncates all internal structures. This till covering cannot be distinguished from the youngest truncated till (“advance” till). Truncation of all of these structures shows that these drumlins are erosional forms carved from pre-existing drift. Apparently, during erosion under compressive flow, some beds became unstable and initiated large-scale movements of material into the drumlin from beneath the drumlin form. Failure and mobilization of the finer-grained beds may have been due to increased pore pressures, differing stages of dilatancy, or differing bulk densities. A growth relationship for drumlins may exist that is based upon the rates of material moving into the drumlin from below and rates of erosion of the drumlin form. |
format |
Article in Journal/Newspaper |
author |
Richard Whittecar, G. Mickelson, David M. |
author_facet |
Richard Whittecar, G. Mickelson, David M. |
author_sort |
Richard Whittecar, G. |
title |
Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. |
title_short |
Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. |
title_full |
Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. |
title_fullStr |
Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. |
title_full_unstemmed |
Composition, Internal Structures, and an Hypothesis of Formation for Drumlins, Waukesha County, Wisconsin, U.S.A. |
title_sort |
composition, internal structures, and an hypothesis of formation for drumlins, waukesha county, wisconsin, u.s.a. |
publisher |
Cambridge University Press (CUP) |
publishDate |
1979 |
url |
http://dx.doi.org/10.1017/s0022143000014337 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000014337 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 22, issue 87, page 357-371 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000014337 |
container_title |
Journal of Glaciology |
container_volume |
22 |
container_issue |
87 |
container_start_page |
357 |
op_container_end_page |
371 |
_version_ |
1792501884689317888 |