Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation
Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated; ranging between outbu...
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ftdoajarticles:oai:doaj.org/article:b53e2afca784468fb53c218b219be1cd 2023-05-15T16:40:41+02:00 Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation S. J. Livingstone C. D. Clark 2016-07-01T00:00:00Z https://doi.org/10.5194/esurf-4-567-2016 https://doaj.org/article/b53e2afca784468fb53c218b219be1cd EN eng Copernicus Publications http://www.earth-surf-dynam.net/4/567/2016/esurf-4-567-2016.pdf https://doaj.org/toc/2196-6311 https://doaj.org/toc/2196-632X 2196-6311 2196-632X doi:10.5194/esurf-4-567-2016 https://doaj.org/article/b53e2afca784468fb53c218b219be1cd Earth Surface Dynamics, Vol 4, Iss 3, Pp 567-589 (2016) Dynamic and structural geology QE500-639.5 article 2016 ftdoajarticles https://doi.org/10.5194/esurf-4-567-2016 2022-12-31T02:04:31Z Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated; ranging between outburst flood events through to gradually occurring channel propagation. We have mapped and analysed the spatial pattern and morphometry of tunnel valleys and associated glacial landforms along the southern sector of the former Laurentide Ice Sheet from high-resolution digital elevation models. Around 2000 tunnel valleys have been mapped, revealing an organised pattern of sub-parallel, semi-regularly spaced valleys that form in distinctive clusters. The tunnel valleys are typically < 20 km long, and 0.5–3 km wide, although their width varies considerably down-valley. They preferentially terminate at moraines, which suggests that formation is time dependent; while we also observe some tunnel valleys that have grown headwards out of hill-hole pairs. Analysis of cross-cutting relationships between tunnel valleys, moraines and outwash fans permits reconstruction of channel development in relation to the retreating ice margin. This palaeo-drainage reconstruction demonstrates incremental growth of most valleys, with some used repeatedly or for long periods, during deglaciation, while others were abandoned shortly after their formation. Our data and interpretation support gradual (rather than a single-event) formation of most tunnel valleys with secondary contributions from flood drainage of subglacial and or supraglacially stored water down individual tunnel valleys. The distribution and morphology of tunnel valleys is shown to be sensitive to regional factors such as basal thermal regime, ice and bed topography, timing and climate. Article in Journal/Newspaper Ice Sheet Directory of Open Access Journals: DOAJ Articles Earth Surface Dynamics 4 3 567 589 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Dynamic and structural geology QE500-639.5 |
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Dynamic and structural geology QE500-639.5 S. J. Livingstone C. D. Clark Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation |
topic_facet |
Dynamic and structural geology QE500-639.5 |
description |
Tunnel valleys have been widely reported on the bed of former ice sheets and are considered an important expression of subglacial meltwater drainage. Although known to have been cut by erosive meltwater flow, the water source and development of channels has been widely debated; ranging between outburst flood events through to gradually occurring channel propagation. We have mapped and analysed the spatial pattern and morphometry of tunnel valleys and associated glacial landforms along the southern sector of the former Laurentide Ice Sheet from high-resolution digital elevation models. Around 2000 tunnel valleys have been mapped, revealing an organised pattern of sub-parallel, semi-regularly spaced valleys that form in distinctive clusters. The tunnel valleys are typically < 20 km long, and 0.5–3 km wide, although their width varies considerably down-valley. They preferentially terminate at moraines, which suggests that formation is time dependent; while we also observe some tunnel valleys that have grown headwards out of hill-hole pairs. Analysis of cross-cutting relationships between tunnel valleys, moraines and outwash fans permits reconstruction of channel development in relation to the retreating ice margin. This palaeo-drainage reconstruction demonstrates incremental growth of most valleys, with some used repeatedly or for long periods, during deglaciation, while others were abandoned shortly after their formation. Our data and interpretation support gradual (rather than a single-event) formation of most tunnel valleys with secondary contributions from flood drainage of subglacial and or supraglacially stored water down individual tunnel valleys. The distribution and morphology of tunnel valleys is shown to be sensitive to regional factors such as basal thermal regime, ice and bed topography, timing and climate. |
format |
Article in Journal/Newspaper |
author |
S. J. Livingstone C. D. Clark |
author_facet |
S. J. Livingstone C. D. Clark |
author_sort |
S. J. Livingstone |
title |
Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation |
title_short |
Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation |
title_full |
Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation |
title_fullStr |
Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation |
title_full_unstemmed |
Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation |
title_sort |
morphological properties of tunnel valleys of the southern sector of the laurentide ice sheet and implications for their formation |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/esurf-4-567-2016 https://doaj.org/article/b53e2afca784468fb53c218b219be1cd |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Earth Surface Dynamics, Vol 4, Iss 3, Pp 567-589 (2016) |
op_relation |
http://www.earth-surf-dynam.net/4/567/2016/esurf-4-567-2016.pdf https://doaj.org/toc/2196-6311 https://doaj.org/toc/2196-632X 2196-6311 2196-632X doi:10.5194/esurf-4-567-2016 https://doaj.org/article/b53e2afca784468fb53c218b219be1cd |
op_doi |
https://doi.org/10.5194/esurf-4-567-2016 |
container_title |
Earth Surface Dynamics |
container_volume |
4 |
container_issue |
3 |
container_start_page |
567 |
op_container_end_page |
589 |
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1766031099738193920 |