Periglacial Features Indicative of Permafrost: Ice and Soil Wedges
Ice wedges are wedge-shaped masses of ice, oriented vertically with their apices downward, a few millimeters to many meters wide at the top, and generally less than 10 m vertically. Ice wedges grow in and are confined to humid permafrost regions. Snow, hoar frost, or freezing water partly fill winte...
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Cambridge University Press (CUP)
1976
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crcambridgeupr:10.1016/0033-5894(76)90037-5 2024-09-15T18:11:20+00:00 Periglacial Features Indicative of Permafrost: Ice and Soil Wedges Black, Robert F. 1976 http://dx.doi.org/10.1016/0033-5894(76)90037-5 http://api.elsevier.com/content/article/PII:0033589476900375?httpAccept=text/xml http://api.elsevier.com/content/article/PII:0033589476900375?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400035055 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Quaternary Research volume 6, issue 1, page 3-26 ISSN 0033-5894 1096-0287 journal-article 1976 crcambridgeupr https://doi.org/10.1016/0033-5894(76)90037-5 2024-08-07T04:04:22Z Ice wedges are wedge-shaped masses of ice, oriented vertically with their apices downward, a few millimeters to many meters wide at the top, and generally less than 10 m vertically. Ice wedges grow in and are confined to humid permafrost regions. Snow, hoar frost, or freezing water partly fill winter contraction cracks outlining polygons, commonly 5–20 m in diameter, on the surface of the ground. Moisture comes from the atmosphere. Increments of ice, generally 0.1–2.0 mm, are added annually to wedges which squeeze enclosing permafrost aside and to the surface to produce striking surface patterns. Soil wedges are not confined to permafrost. One type, sand wedges, now grows in arid permafrost regions. Sand wedges are similar in dimensions, patterns, and growth rates to ice wedges. Drifting sand enters winter contraction cracks instead of ice. Fossil ice and sand wedges are the most diagnostic and widespread indicators of former permafrost, but identification is difficult. Any single wedge is untrustworthy. Evidence of fossil ice wedges includes: wedge forms with collapse structures from replacement of ice; polygonal patterns with dimensions comparable to active forms having similar coefficients of thermal expansion; fabrics in the host showing pressure effects; secondary deposits and fabric indicative of a permafrost table; and other evidence of former permafrost. Sand wedges lack open-wedge, collapse structures, but have complex, nearly vertical, crisscrossing narrow dikelets and fabric. Similar soil wedges are produced by wetting and drying, freezing and thawing, solution, faulting, and other mechanisms. Many forms are multigenetic. Many socalled ice-wedge casts are misidentified, and hence, permafrost along the late-Wisconsinan border in the United States was less extensive than has been proposed. Article in Journal/Newspaper Ice permafrost wedge* Cambridge University Press Quaternary Research 6 1 3 26 |
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English |
description |
Ice wedges are wedge-shaped masses of ice, oriented vertically with their apices downward, a few millimeters to many meters wide at the top, and generally less than 10 m vertically. Ice wedges grow in and are confined to humid permafrost regions. Snow, hoar frost, or freezing water partly fill winter contraction cracks outlining polygons, commonly 5–20 m in diameter, on the surface of the ground. Moisture comes from the atmosphere. Increments of ice, generally 0.1–2.0 mm, are added annually to wedges which squeeze enclosing permafrost aside and to the surface to produce striking surface patterns. Soil wedges are not confined to permafrost. One type, sand wedges, now grows in arid permafrost regions. Sand wedges are similar in dimensions, patterns, and growth rates to ice wedges. Drifting sand enters winter contraction cracks instead of ice. Fossil ice and sand wedges are the most diagnostic and widespread indicators of former permafrost, but identification is difficult. Any single wedge is untrustworthy. Evidence of fossil ice wedges includes: wedge forms with collapse structures from replacement of ice; polygonal patterns with dimensions comparable to active forms having similar coefficients of thermal expansion; fabrics in the host showing pressure effects; secondary deposits and fabric indicative of a permafrost table; and other evidence of former permafrost. Sand wedges lack open-wedge, collapse structures, but have complex, nearly vertical, crisscrossing narrow dikelets and fabric. Similar soil wedges are produced by wetting and drying, freezing and thawing, solution, faulting, and other mechanisms. Many forms are multigenetic. Many socalled ice-wedge casts are misidentified, and hence, permafrost along the late-Wisconsinan border in the United States was less extensive than has been proposed. |
format |
Article in Journal/Newspaper |
author |
Black, Robert F. |
spellingShingle |
Black, Robert F. Periglacial Features Indicative of Permafrost: Ice and Soil Wedges |
author_facet |
Black, Robert F. |
author_sort |
Black, Robert F. |
title |
Periglacial Features Indicative of Permafrost: Ice and Soil Wedges |
title_short |
Periglacial Features Indicative of Permafrost: Ice and Soil Wedges |
title_full |
Periglacial Features Indicative of Permafrost: Ice and Soil Wedges |
title_fullStr |
Periglacial Features Indicative of Permafrost: Ice and Soil Wedges |
title_full_unstemmed |
Periglacial Features Indicative of Permafrost: Ice and Soil Wedges |
title_sort |
periglacial features indicative of permafrost: ice and soil wedges |
publisher |
Cambridge University Press (CUP) |
publishDate |
1976 |
url |
http://dx.doi.org/10.1016/0033-5894(76)90037-5 http://api.elsevier.com/content/article/PII:0033589476900375?httpAccept=text/xml http://api.elsevier.com/content/article/PII:0033589476900375?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400035055 |
genre |
Ice permafrost wedge* |
genre_facet |
Ice permafrost wedge* |
op_source |
Quaternary Research volume 6, issue 1, page 3-26 ISSN 0033-5894 1096-0287 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1016/0033-5894(76)90037-5 |
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Quaternary Research |
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6 |
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26 |
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