Origin of Foliation in Glaciers
Abstract Laboratory studies suggest that neither bubbles nor dirt particles migrate rapidly enough in glacier ice to be responsible for the alternating layers of bubbly and clear ice or dirty and clean ice which constitute foliation. We therefore suggest that these variations in bubble or dirt conte...
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Cambridge University Press (CUP)
1978
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crcambridgeupr:10.1017/s0022143000013848 2024-03-03T08:46:05+00:00 Origin of Foliation in Glaciers Leb. Hooke, Roger Hudleston, Peter J. 1978 http://dx.doi.org/10.1017/s0022143000013848 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000013848 en eng Cambridge University Press (CUP) Journal of Glaciology volume 20, issue 83, page 285-299 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1978 crcambridgeupr https://doi.org/10.1017/s0022143000013848 2024-02-08T08:36:10Z Abstract Laboratory studies suggest that neither bubbles nor dirt particles migrate rapidly enough in glacier ice to be responsible for the alternating layers of bubbly and clear ice or dirty and clean ice which constitute foliation. We therefore suggest that these variations in bubble or dirt content are inherited from primary inhomogeneities such as may occur in sedimentary stratification in the accumulation region, in crevasse fillings, or during debris entrainment at the base of the glacier: the appearance of these inhomo-geneities is later modified by strain during flow to produce foliation. We consider six types of inhomogeneity, or components of foliation, and show that, at the very large total strains expected in glaciers, all are eventually flattened, stretched out, and rotated to form a layered structure roughly perpendicular to the direction of maximum total shortening. Most characteristics of observed foliation can be explained by this hypothesis. For example, in the marginal zones of polar ice sheets the rapid decrease in dip of foliation with depth and with distance up-glacier from the margin can he explained by a model in which the foliation is assumed to be nearly parallel to the base of the glacier some distance from the margin, and is deformed passively with the ice thereafter. However, some observations of cross-cutting foliations may require localized inhomogeneous shear parallel to the "new" foliation. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 20 83 285 299 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Leb. Hooke, Roger Hudleston, Peter J. Origin of Foliation in Glaciers |
topic_facet |
Earth-Surface Processes |
description |
Abstract Laboratory studies suggest that neither bubbles nor dirt particles migrate rapidly enough in glacier ice to be responsible for the alternating layers of bubbly and clear ice or dirty and clean ice which constitute foliation. We therefore suggest that these variations in bubble or dirt content are inherited from primary inhomogeneities such as may occur in sedimentary stratification in the accumulation region, in crevasse fillings, or during debris entrainment at the base of the glacier: the appearance of these inhomo-geneities is later modified by strain during flow to produce foliation. We consider six types of inhomogeneity, or components of foliation, and show that, at the very large total strains expected in glaciers, all are eventually flattened, stretched out, and rotated to form a layered structure roughly perpendicular to the direction of maximum total shortening. Most characteristics of observed foliation can be explained by this hypothesis. For example, in the marginal zones of polar ice sheets the rapid decrease in dip of foliation with depth and with distance up-glacier from the margin can he explained by a model in which the foliation is assumed to be nearly parallel to the base of the glacier some distance from the margin, and is deformed passively with the ice thereafter. However, some observations of cross-cutting foliations may require localized inhomogeneous shear parallel to the "new" foliation. |
format |
Article in Journal/Newspaper |
author |
Leb. Hooke, Roger Hudleston, Peter J. |
author_facet |
Leb. Hooke, Roger Hudleston, Peter J. |
author_sort |
Leb. Hooke, Roger |
title |
Origin of Foliation in Glaciers |
title_short |
Origin of Foliation in Glaciers |
title_full |
Origin of Foliation in Glaciers |
title_fullStr |
Origin of Foliation in Glaciers |
title_full_unstemmed |
Origin of Foliation in Glaciers |
title_sort |
origin of foliation in glaciers |
publisher |
Cambridge University Press (CUP) |
publishDate |
1978 |
url |
http://dx.doi.org/10.1017/s0022143000013848 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000013848 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 20, issue 83, page 285-299 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000013848 |
container_title |
Journal of Glaciology |
container_volume |
20 |
container_issue |
83 |
container_start_page |
285 |
op_container_end_page |
299 |
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1792501979643117568 |