Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica
Nonsorted polygons with sand-filled wedges were investigated in Beacon Valley, Antarctica (77.82°S, 160.67°E) using field observations coupled with 2-m resolution aerial photography. A gasoline-powered concrete breaker was employed to expose the sediments of four polygon centres and six wedges from...
Published in: | Permafrost and Periglacial Processes |
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Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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2009
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Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/genesis-of-active-sandfilled-polygons-in-lower-and-central-beacon-valley-antarctica(41ecd500-a57f-447f-bbfc-0ae85b40402f).html https://doi.org/10.1002/ppp.661 http://onlinelibrary.wiley.com/doi/10.1002/ppp.661/abstract |
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ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/41ecd500-a57f-447f-bbfc-0ae85b40402f 2023-05-15T13:58:40+02:00 Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica Bockheim, James G. Kurz, Mark D. Soule, S. Adam Burke, Andrea 2009 https://risweb.st-andrews.ac.uk/portal/en/researchoutput/genesis-of-active-sandfilled-polygons-in-lower-and-central-beacon-valley-antarctica(41ecd500-a57f-447f-bbfc-0ae85b40402f).html https://doi.org/10.1002/ppp.661 http://onlinelibrary.wiley.com/doi/10.1002/ppp.661/abstract eng eng info:eu-repo/semantics/restrictedAccess Bockheim , J G , Kurz , M D , Soule , S A & Burke , A 2009 , ' Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica ' , Permafrost and Periglacial Processes , vol. 20 , no. 3 , pp. 295-308 . https://doi.org/10.1002/ppp.661 sand-wedge polygons patterned ground nonsorted polygons thermal-contraction fissures McMurdo dry valleys permafrost article 2009 ftunstandrewcris https://doi.org/10.1002/ppp.661 2021-12-26T14:23:12Z Nonsorted polygons with sand-filled wedges were investigated in Beacon Valley, Antarctica (77.82°S, 160.67°E) using field observations coupled with 2-m resolution aerial photography. A gasoline-powered concrete breaker was employed to expose the sediments of four polygon centres and six wedges from geomorphic surfaces containing tills of two different ages. The excavated polygons ranged from 9 to 16 m in diameter; the sand-filled wedges ranged from 0.2 to 2.5 m in width. The top of ice-bonded permafrost ranged from 12 to 62 cm in depth in the polygon centres and from 64 to >90 cm in wedges. One active thermal-contraction fissure generally was apparent at the surface, but excavations revealed numerous inactive fissures. The wedges contain sand laminations averaging 3 mm in width when viewed in cross-section. Although most of the polygons were of the sand-wedge type, some contained ice veins up to 1 cm in width and could be classed as composite wedges. Three stages of polygon development were observed, including well-developed polygons on Taylor II surfaces (ca. 117 ka), moderately developed polygons on Taylor III surfaces (ca. 200 ka) and poorly expressed polygons on Taylor IVa and older (ca. >1.1 Ma) surfaces. This retrogressive development may be due to sublimation of ice-bonded permafrost following thermal cracking. With the drop in ice content, the thermal coefficient of expansion of the permafrost may be lowered, which would result in a reduction in tensile stresses. Article in Journal/Newspaper Antarc* Antarctica Ice McMurdo Dry Valleys permafrost Permafrost and Periglacial Processes wedge* University of St Andrews: Research Portal Beacon Valley ENVELOPE(160.650,160.650,-77.817,-77.817) Breaker ENVELOPE(-67.257,-67.257,-67.874,-67.874) McMurdo Dry Valleys Permafrost and Periglacial Processes 20 3 295 308 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
sand-wedge polygons patterned ground nonsorted polygons thermal-contraction fissures McMurdo dry valleys permafrost |
spellingShingle |
sand-wedge polygons patterned ground nonsorted polygons thermal-contraction fissures McMurdo dry valleys permafrost Bockheim, James G. Kurz, Mark D. Soule, S. Adam Burke, Andrea Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica |
topic_facet |
sand-wedge polygons patterned ground nonsorted polygons thermal-contraction fissures McMurdo dry valleys permafrost |
description |
Nonsorted polygons with sand-filled wedges were investigated in Beacon Valley, Antarctica (77.82°S, 160.67°E) using field observations coupled with 2-m resolution aerial photography. A gasoline-powered concrete breaker was employed to expose the sediments of four polygon centres and six wedges from geomorphic surfaces containing tills of two different ages. The excavated polygons ranged from 9 to 16 m in diameter; the sand-filled wedges ranged from 0.2 to 2.5 m in width. The top of ice-bonded permafrost ranged from 12 to 62 cm in depth in the polygon centres and from 64 to >90 cm in wedges. One active thermal-contraction fissure generally was apparent at the surface, but excavations revealed numerous inactive fissures. The wedges contain sand laminations averaging 3 mm in width when viewed in cross-section. Although most of the polygons were of the sand-wedge type, some contained ice veins up to 1 cm in width and could be classed as composite wedges. Three stages of polygon development were observed, including well-developed polygons on Taylor II surfaces (ca. 117 ka), moderately developed polygons on Taylor III surfaces (ca. 200 ka) and poorly expressed polygons on Taylor IVa and older (ca. >1.1 Ma) surfaces. This retrogressive development may be due to sublimation of ice-bonded permafrost following thermal cracking. With the drop in ice content, the thermal coefficient of expansion of the permafrost may be lowered, which would result in a reduction in tensile stresses. |
format |
Article in Journal/Newspaper |
author |
Bockheim, James G. Kurz, Mark D. Soule, S. Adam Burke, Andrea |
author_facet |
Bockheim, James G. Kurz, Mark D. Soule, S. Adam Burke, Andrea |
author_sort |
Bockheim, James G. |
title |
Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica |
title_short |
Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica |
title_full |
Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica |
title_fullStr |
Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica |
title_full_unstemmed |
Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica |
title_sort |
genesis of active sand-filled polygons in lower and central beacon valley, antarctica |
publishDate |
2009 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/genesis-of-active-sandfilled-polygons-in-lower-and-central-beacon-valley-antarctica(41ecd500-a57f-447f-bbfc-0ae85b40402f).html https://doi.org/10.1002/ppp.661 http://onlinelibrary.wiley.com/doi/10.1002/ppp.661/abstract |
long_lat |
ENVELOPE(160.650,160.650,-77.817,-77.817) ENVELOPE(-67.257,-67.257,-67.874,-67.874) |
geographic |
Beacon Valley Breaker McMurdo Dry Valleys |
geographic_facet |
Beacon Valley Breaker McMurdo Dry Valleys |
genre |
Antarc* Antarctica Ice McMurdo Dry Valleys permafrost Permafrost and Periglacial Processes wedge* |
genre_facet |
Antarc* Antarctica Ice McMurdo Dry Valleys permafrost Permafrost and Periglacial Processes wedge* |
op_source |
Bockheim , J G , Kurz , M D , Soule , S A & Burke , A 2009 , ' Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica ' , Permafrost and Periglacial Processes , vol. 20 , no. 3 , pp. 295-308 . https://doi.org/10.1002/ppp.661 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1002/ppp.661 |
container_title |
Permafrost and Periglacial Processes |
container_volume |
20 |
container_issue |
3 |
container_start_page |
295 |
op_container_end_page |
308 |
_version_ |
1766267012636475392 |