A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England

Abstract Staircases of gravelly river terrace deposits in southern England occupy valleys typically underlain by frost-susceptible and brecciated bedrocks. The valleys developed during the Quaternary by alternating episodes of (1) brecciation, incision and planation through the bedrock, forming wide...

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Published in:Quaternary Research
Main Authors: Murton, Julian B., Belshaw, Roger K.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 2011
Subjects:
Ice
Online Access:http://dx.doi.org/10.1016/j.yqres.2010.10.002
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spelling crcambridgeupr:10.1016/j.yqres.2010.10.002 2024-09-15T18:11:29+00:00 A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England Murton, Julian B. Belshaw, Roger K. 2011 http://dx.doi.org/10.1016/j.yqres.2010.10.002 http://api.elsevier.com/content/article/PII:S0033589410001341?httpAccept=text/xml http://api.elsevier.com/content/article/PII:S0033589410001341?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400007213 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Quaternary Research volume 75, issue 2, page 385-394 ISSN 0033-5894 1096-0287 journal-article 2011 crcambridgeupr https://doi.org/10.1016/j.yqres.2010.10.002 2024-07-31T04:01:29Z Abstract Staircases of gravelly river terrace deposits in southern England occupy valleys typically underlain by frost-susceptible and brecciated bedrocks. The valleys developed during the Quaternary by alternating episodes of (1) brecciation, incision and planation through the bedrock, forming wide low-relief erosion surfaces; and (2) aggradation in braidplains of gravel a few meters thick that bury the erosion surfaces. A conceptual model to account for some of the terraces proposes that brecciation resulted from ice segregation in the ice-rich layer in the upper meters of Pleistocene permafrost, making them vulnerable to fluvial thermal erosion and therefore predisposing the bedrock to planation. The low gradients of the valleys were adjusted such that rivers transferred fine materials out of the basins but lacked the competence to remove gravel, which therefore accumulated within floodplains. The model challenges the prevailing view of incision during climate transitions. It attributes incision and planation to very cold and arid permafrost conditions, when rivers had limited discharges and hillslopes supplied limited volumes of stony debris into valley bottoms. Article in Journal/Newspaper Ice permafrost Cambridge University Press Quaternary Research 75 2 385 394
institution Open Polar
collection Cambridge University Press
op_collection_id crcambridgeupr
language English
description Abstract Staircases of gravelly river terrace deposits in southern England occupy valleys typically underlain by frost-susceptible and brecciated bedrocks. The valleys developed during the Quaternary by alternating episodes of (1) brecciation, incision and planation through the bedrock, forming wide low-relief erosion surfaces; and (2) aggradation in braidplains of gravel a few meters thick that bury the erosion surfaces. A conceptual model to account for some of the terraces proposes that brecciation resulted from ice segregation in the ice-rich layer in the upper meters of Pleistocene permafrost, making them vulnerable to fluvial thermal erosion and therefore predisposing the bedrock to planation. The low gradients of the valleys were adjusted such that rivers transferred fine materials out of the basins but lacked the competence to remove gravel, which therefore accumulated within floodplains. The model challenges the prevailing view of incision during climate transitions. It attributes incision and planation to very cold and arid permafrost conditions, when rivers had limited discharges and hillslopes supplied limited volumes of stony debris into valley bottoms.
format Article in Journal/Newspaper
author Murton, Julian B.
Belshaw, Roger K.
spellingShingle Murton, Julian B.
Belshaw, Roger K.
A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England
author_facet Murton, Julian B.
Belshaw, Roger K.
author_sort Murton, Julian B.
title A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England
title_short A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England
title_full A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England
title_fullStr A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England
title_full_unstemmed A conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of Pleistocene southern England
title_sort conceptual model of valley incision, planation and terrace formation during cold and arid permafrost conditions of pleistocene southern england
publisher Cambridge University Press (CUP)
publishDate 2011
url http://dx.doi.org/10.1016/j.yqres.2010.10.002
http://api.elsevier.com/content/article/PII:S0033589410001341?httpAccept=text/xml
http://api.elsevier.com/content/article/PII:S0033589410001341?httpAccept=text/plain
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400007213
genre Ice
permafrost
genre_facet Ice
permafrost
op_source Quaternary Research
volume 75, issue 2, page 385-394
ISSN 0033-5894 1096-0287
op_rights https://www.cambridge.org/core/terms
op_doi https://doi.org/10.1016/j.yqres.2010.10.002
container_title Quaternary Research
container_volume 75
container_issue 2
container_start_page 385
op_container_end_page 394
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