Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales
Abstract In Europe, ramparted depressions have traditionally been interpreted as the relict forms of periglacial ground‐ice mounds. In many cases, however, such interpretations have been based on limited subsurface evidence. We present detailed sedimentological and geophysical investigations of ramp...
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crwiley:10.1002/ppp.708 2024-09-15T18:11:30+00:00 Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales Ross, N. Harris, C. Brabham, P.J. Sheppard, T.H. 2011 http://dx.doi.org/10.1002/ppp.708 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.708 https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.708 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Permafrost and Periglacial Processes volume 22, issue 4, page 291-305 ISSN 1045-6740 1099-1530 journal-article 2011 crwiley https://doi.org/10.1002/ppp.708 2024-07-25T04:19:15Z Abstract In Europe, ramparted depressions have traditionally been interpreted as the relict forms of periglacial ground‐ice mounds. In many cases, however, such interpretations have been based on limited subsurface evidence. We present detailed sedimentological and geophysical investigations of ramparted depressions from Llanpumsaint, Wales. These data are used to establish internal structure and to evaluate possible mechanisms for landform formation. Borehole and geophysical data have revealed a thick (∼30 m) sequence of glaciolacustrine sediments beneath the study site. The geological context (drainage of a large proglacial lake) would have been conducive to the formation of: (i) permafrost‐related ground‐ice mounds, at times when exposed frost‐susceptible glaciolacustrine sediments were subject to permafrost aggradation; and (ii) craters associated with the in‐situ meltout of blocks of glacier ice grounded in the lake during periods of falling water levels. Rampart deformation structures are consistent with both models, but units of sand and gravel within the ramparts favour a hypothesis that these landforms represent the collapsed remains of ground‐ice mounds. This study highlights the importance of recognising and evaluating all possible (periglacial and non‐periglacial) models for the development of ramparted depressions. We recommend that future studies carefully consider all possible mechanisms of formation, particularly where subsurface information is limited. Copyright © 2011 John Wiley & Sons, Ltd. Article in Journal/Newspaper Ice permafrost Permafrost and Periglacial Processes Wiley Online Library Permafrost and Periglacial Processes 22 4 291 305 |
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English |
description |
Abstract In Europe, ramparted depressions have traditionally been interpreted as the relict forms of periglacial ground‐ice mounds. In many cases, however, such interpretations have been based on limited subsurface evidence. We present detailed sedimentological and geophysical investigations of ramparted depressions from Llanpumsaint, Wales. These data are used to establish internal structure and to evaluate possible mechanisms for landform formation. Borehole and geophysical data have revealed a thick (∼30 m) sequence of glaciolacustrine sediments beneath the study site. The geological context (drainage of a large proglacial lake) would have been conducive to the formation of: (i) permafrost‐related ground‐ice mounds, at times when exposed frost‐susceptible glaciolacustrine sediments were subject to permafrost aggradation; and (ii) craters associated with the in‐situ meltout of blocks of glacier ice grounded in the lake during periods of falling water levels. Rampart deformation structures are consistent with both models, but units of sand and gravel within the ramparts favour a hypothesis that these landforms represent the collapsed remains of ground‐ice mounds. This study highlights the importance of recognising and evaluating all possible (periglacial and non‐periglacial) models for the development of ramparted depressions. We recommend that future studies carefully consider all possible mechanisms of formation, particularly where subsurface information is limited. Copyright © 2011 John Wiley & Sons, Ltd. |
format |
Article in Journal/Newspaper |
author |
Ross, N. Harris, C. Brabham, P.J. Sheppard, T.H. |
spellingShingle |
Ross, N. Harris, C. Brabham, P.J. Sheppard, T.H. Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales |
author_facet |
Ross, N. Harris, C. Brabham, P.J. Sheppard, T.H. |
author_sort |
Ross, N. |
title |
Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales |
title_short |
Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales |
title_full |
Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales |
title_fullStr |
Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales |
title_full_unstemmed |
Internal Structure and Geological Context of Ramparted Depressions, Llanpumsaint, Wales |
title_sort |
internal structure and geological context of ramparted depressions, llanpumsaint, wales |
publisher |
Wiley |
publishDate |
2011 |
url |
http://dx.doi.org/10.1002/ppp.708 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.708 https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.708 |
genre |
Ice permafrost Permafrost and Periglacial Processes |
genre_facet |
Ice permafrost Permafrost and Periglacial Processes |
op_source |
Permafrost and Periglacial Processes volume 22, issue 4, page 291-305 ISSN 1045-6740 1099-1530 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/ppp.708 |
container_title |
Permafrost and Periglacial Processes |
container_volume |
22 |
container_issue |
4 |
container_start_page |
291 |
op_container_end_page |
305 |
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1810449094399754240 |