Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska
Abstract The vast Bering piedmont glacier, which has large folds in the medial moraines in its terminal lobe, recently experienced two surges with a combined ice displacement of as much as 13 km. Vertical aerial photographs taken before and after the surges disclose the direction and magnitude of ic...
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Language: | English |
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Cambridge University Press (CUP)
1972
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Online Access: | http://dx.doi.org/10.1017/s0022143000022218 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000022218 |
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crcambridgeupr:10.1017/s0022143000022218 2024-09-15T18:07:33+00:00 Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska Post, Austin 1972 http://dx.doi.org/10.1017/s0022143000022218 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000022218 en eng Cambridge University Press (CUP) Journal of Glaciology volume 11, issue 62, page 219-226 ISSN 0022-1430 1727-5652 journal-article 1972 crcambridgeupr https://doi.org/10.1017/s0022143000022218 2024-07-24T04:03:23Z Abstract The vast Bering piedmont glacier, which has large folds in the medial moraines in its terminal lobe, recently experienced two surges with a combined ice displacement of as much as 13 km. Vertical aerial photographs taken before and after the surges disclose the direction and magnitude of ice flow in various parts of the piedmont lobe. The ice moved toward the terminus and expanded in a normal, radial pattern with no evidence of unusual shearing that would result in the formation of large folds. Many surging glaciers display repeated lateral displacements in their medial moraines which result from periodic surging of the main glacier past non-surging tributaries. Moraines of Bering Glacier display small periodic irregularities of this nature. The large “accordion” folds in the moraines in the piedmont lobe are judged to be due to the combined effects of compressive flow and lateral or transverse expansion of these previously formed irregularities. The initially small pre-existing perturbations in the moraines are simply spread laterally and shortened radially into large folds as the ice spreads out. A very large debris band composed of repeatedly folded medial moraines extends across the center of the Bering Glacier lobe. These remarkable folds are thought to result from the deformation of surge-related irregularities in medial moraines as they pass through the zone of intensive shear near the glacier’s margin. Article in Journal/Newspaper glacier glaciers Journal of Glaciology Alaska Cambridge University Press Journal of Glaciology 11 62 219 226 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract The vast Bering piedmont glacier, which has large folds in the medial moraines in its terminal lobe, recently experienced two surges with a combined ice displacement of as much as 13 km. Vertical aerial photographs taken before and after the surges disclose the direction and magnitude of ice flow in various parts of the piedmont lobe. The ice moved toward the terminus and expanded in a normal, radial pattern with no evidence of unusual shearing that would result in the formation of large folds. Many surging glaciers display repeated lateral displacements in their medial moraines which result from periodic surging of the main glacier past non-surging tributaries. Moraines of Bering Glacier display small periodic irregularities of this nature. The large “accordion” folds in the moraines in the piedmont lobe are judged to be due to the combined effects of compressive flow and lateral or transverse expansion of these previously formed irregularities. The initially small pre-existing perturbations in the moraines are simply spread laterally and shortened radially into large folds as the ice spreads out. A very large debris band composed of repeatedly folded medial moraines extends across the center of the Bering Glacier lobe. These remarkable folds are thought to result from the deformation of surge-related irregularities in medial moraines as they pass through the zone of intensive shear near the glacier’s margin. |
format |
Article in Journal/Newspaper |
author |
Post, Austin |
spellingShingle |
Post, Austin Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska |
author_facet |
Post, Austin |
author_sort |
Post, Austin |
title |
Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska |
title_short |
Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska |
title_full |
Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska |
title_fullStr |
Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska |
title_full_unstemmed |
Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska |
title_sort |
periodic surge origin of folded medial moraines on bering piedmont glacier, alaska |
publisher |
Cambridge University Press (CUP) |
publishDate |
1972 |
url |
http://dx.doi.org/10.1017/s0022143000022218 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000022218 |
genre |
glacier glaciers Journal of Glaciology Alaska |
genre_facet |
glacier glaciers Journal of Glaciology Alaska |
op_source |
Journal of Glaciology volume 11, issue 62, page 219-226 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000022218 |
container_title |
Journal of Glaciology |
container_volume |
11 |
container_issue |
62 |
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219 |
op_container_end_page |
226 |
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1810444933985730560 |