Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions
Abstract Initially a matter of intellectual curiosity, but now important for understanding ice‐sheet dynamics, the formation of subglacial bedforms has been a subject of scientific enquiry for over a century. Here, we use a numerical model of the coupled flow of ice, water, and subglacial sediment t...
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crwiley:10.1002/esp.5529 2024-09-15T18:12:32+00:00 Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions Ely, Jeremy C. Stevens, David Clark, Chris D. Butcher, Frances E. G. H2020 European Research Council Natural Environment Research Council 2023 http://dx.doi.org/10.1002/esp.5529 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5529 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/esp.5529 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Earth Surface Processes and Landforms volume 48, issue 5, page 956-978 ISSN 0197-9337 1096-9837 journal-article 2023 crwiley https://doi.org/10.1002/esp.5529 2024-08-30T04:12:12Z Abstract Initially a matter of intellectual curiosity, but now important for understanding ice‐sheet dynamics, the formation of subglacial bedforms has been a subject of scientific enquiry for over a century. Here, we use a numerical model of the coupled flow of ice, water, and subglacial sediment to explore the formation of subglacial ribs (i.e., ribbed moraine), drumlins and mega‐scale glacial lineations (MSGLs). The model produces instabilities at the ice–bed interface, which result in landforms resembling subglacial ribs and drumlins. We find that a behavioural trajectory is present. Initially subglacial ribs form, which can either develop into fields of organized drumlins, or herringbone‐type structures misaligned with ice flow. We present potential examples of these misaligned bedforms in deglaciated landscapes, the presence of which means caution should be taken when interpreting cross‐cutting bedforms to reconstruct ice flow directions. Under unvarying ice flow parameters, MSGLs failed to appear in our experiments. However, drumlin fields can elongate into MSGLs in our model if low ice–bed coupling conditions are imposed. The conditions under which drumlins elongate into MSGLs are analogous to those found beneath contemporary ice streams, providing the first mechanism, rather than just an association, for linking MSGLs with ice stream flow. We conclude that the instability theory, as realized in this numerical model, is sufficient to explain the fundamental mechanics and process‐interactions that lead to the initiation of subglacial bedforms, the development of the distinctive types of bedform patterns, and their evolutionary trajectories. We therefore suggest that the first part of the longstanding ‘drumlin problem’ – how and why they come into existence – is now solved. However, much remains to be discovered regarding the exact sedimentary and hydrological processes involved. Article in Journal/Newspaper Ice Sheet Wiley Online Library Earth Surface Processes and Landforms 48 5 956 978 |
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Wiley Online Library |
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English |
description |
Abstract Initially a matter of intellectual curiosity, but now important for understanding ice‐sheet dynamics, the formation of subglacial bedforms has been a subject of scientific enquiry for over a century. Here, we use a numerical model of the coupled flow of ice, water, and subglacial sediment to explore the formation of subglacial ribs (i.e., ribbed moraine), drumlins and mega‐scale glacial lineations (MSGLs). The model produces instabilities at the ice–bed interface, which result in landforms resembling subglacial ribs and drumlins. We find that a behavioural trajectory is present. Initially subglacial ribs form, which can either develop into fields of organized drumlins, or herringbone‐type structures misaligned with ice flow. We present potential examples of these misaligned bedforms in deglaciated landscapes, the presence of which means caution should be taken when interpreting cross‐cutting bedforms to reconstruct ice flow directions. Under unvarying ice flow parameters, MSGLs failed to appear in our experiments. However, drumlin fields can elongate into MSGLs in our model if low ice–bed coupling conditions are imposed. The conditions under which drumlins elongate into MSGLs are analogous to those found beneath contemporary ice streams, providing the first mechanism, rather than just an association, for linking MSGLs with ice stream flow. We conclude that the instability theory, as realized in this numerical model, is sufficient to explain the fundamental mechanics and process‐interactions that lead to the initiation of subglacial bedforms, the development of the distinctive types of bedform patterns, and their evolutionary trajectories. We therefore suggest that the first part of the longstanding ‘drumlin problem’ – how and why they come into existence – is now solved. However, much remains to be discovered regarding the exact sedimentary and hydrological processes involved. |
author2 |
H2020 European Research Council Natural Environment Research Council |
format |
Article in Journal/Newspaper |
author |
Ely, Jeremy C. Stevens, David Clark, Chris D. Butcher, Frances E. G. |
spellingShingle |
Ely, Jeremy C. Stevens, David Clark, Chris D. Butcher, Frances E. G. Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
author_facet |
Ely, Jeremy C. Stevens, David Clark, Chris D. Butcher, Frances E. G. |
author_sort |
Ely, Jeremy C. |
title |
Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
title_short |
Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
title_full |
Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
title_fullStr |
Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
title_full_unstemmed |
Numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
title_sort |
numerical modelling of subglacial ribs, drumlins, herringbones, and mega‐scale glacial lineations reveals their developmental trajectories and transitions |
publisher |
Wiley |
publishDate |
2023 |
url |
http://dx.doi.org/10.1002/esp.5529 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.5529 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/esp.5529 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Earth Surface Processes and Landforms volume 48, issue 5, page 956-978 ISSN 0197-9337 1096-9837 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/esp.5529 |
container_title |
Earth Surface Processes and Landforms |
container_volume |
48 |
container_issue |
5 |
container_start_page |
956 |
op_container_end_page |
978 |
_version_ |
1810450120604385280 |