Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet
Abstract Drumlin shape has been hypothesized to correlate with ice‐flow duration and slip speed, but modern‐day analogues and the Coulomb nature of till render the basis of these correlations in question. The evolution of flow‐parallel subglacial landforms is of importance for ice flow because the f...
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crwiley:10.1002/esp.5192 2024-09-15T18:12:30+00:00 Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet Zoet, Lucas K. Rawling, J. Elmo Woodard, Jacob B. Barrette, Nolan Mickelson, David M. 2021 http://dx.doi.org/10.1002/esp.5192 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5192 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/esp.5192 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Earth Surface Processes and Landforms volume 46, issue 13, page 2540-2550 ISSN 0197-9337 1096-9837 journal-article 2021 crwiley https://doi.org/10.1002/esp.5192 2024-09-05T05:04:56Z Abstract Drumlin shape has been hypothesized to correlate with ice‐flow duration and slip speed, but modern‐day analogues and the Coulomb nature of till render the basis of these correlations in question. The evolution of flow‐parallel subglacial landforms is of importance for ice flow because the form drag they provide may be a dominant factor in regulating glacier slip speeds. Here we examine the relationship between drumlin shape and cumulative slip displacement (i.e. time‐integrated slip speed) as a dominant glaciological control on drumlin shape. First, a new method is developed that allows slip speed to be estimated for deformable bedded glaciers along a flow line from an ice surface profile. Then, reconstructed surface profiles for ice margin chronologies of the Green Bay Lobe (GBL) are used to construct and estimate the spatially varying cumulative slip displacement for use in comparison with drumlin elongation ratios. We focus on a sector of the GBL near the central flow line where the geology is simple and glaciological controls are likely to dominate bedform development. Using Bayesian statistical analysis, a positive and statistically robust relationship between cumulative slip displacement and drumlin elongation ratio is found. Our analysis indicates that drumlin shape could be used to infer palaeo glacier slip speeds if time under the ice can be well constrained and geologic influences are minimal. These findings also suggest that drumlin‐supplied drag could decrease with increased cumulative slip displacement in the absence of rigid geologic features that fix drumlin positions. Article in Journal/Newspaper Ice Sheet Wiley Online Library Earth Surface Processes and Landforms |
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English |
description |
Abstract Drumlin shape has been hypothesized to correlate with ice‐flow duration and slip speed, but modern‐day analogues and the Coulomb nature of till render the basis of these correlations in question. The evolution of flow‐parallel subglacial landforms is of importance for ice flow because the form drag they provide may be a dominant factor in regulating glacier slip speeds. Here we examine the relationship between drumlin shape and cumulative slip displacement (i.e. time‐integrated slip speed) as a dominant glaciological control on drumlin shape. First, a new method is developed that allows slip speed to be estimated for deformable bedded glaciers along a flow line from an ice surface profile. Then, reconstructed surface profiles for ice margin chronologies of the Green Bay Lobe (GBL) are used to construct and estimate the spatially varying cumulative slip displacement for use in comparison with drumlin elongation ratios. We focus on a sector of the GBL near the central flow line where the geology is simple and glaciological controls are likely to dominate bedform development. Using Bayesian statistical analysis, a positive and statistically robust relationship between cumulative slip displacement and drumlin elongation ratio is found. Our analysis indicates that drumlin shape could be used to infer palaeo glacier slip speeds if time under the ice can be well constrained and geologic influences are minimal. These findings also suggest that drumlin‐supplied drag could decrease with increased cumulative slip displacement in the absence of rigid geologic features that fix drumlin positions. |
format |
Article in Journal/Newspaper |
author |
Zoet, Lucas K. Rawling, J. Elmo Woodard, Jacob B. Barrette, Nolan Mickelson, David M. |
spellingShingle |
Zoet, Lucas K. Rawling, J. Elmo Woodard, Jacob B. Barrette, Nolan Mickelson, David M. Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet |
author_facet |
Zoet, Lucas K. Rawling, J. Elmo Woodard, Jacob B. Barrette, Nolan Mickelson, David M. |
author_sort |
Zoet, Lucas K. |
title |
Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet |
title_short |
Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet |
title_full |
Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet |
title_fullStr |
Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet |
title_full_unstemmed |
Factors that contribute to the elongation of drumlins beneath the Green Bay Lobe, Laurentide Ice Sheet |
title_sort |
factors that contribute to the elongation of drumlins beneath the green bay lobe, laurentide ice sheet |
publisher |
Wiley |
publishDate |
2021 |
url |
http://dx.doi.org/10.1002/esp.5192 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5192 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/esp.5192 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Earth Surface Processes and Landforms volume 46, issue 13, page 2540-2550 ISSN 0197-9337 1096-9837 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/esp.5192 |
container_title |
Earth Surface Processes and Landforms |
_version_ |
1810450089333751808 |