Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948
Abstract Аn excellent photographic database, comprising 12 sets of vertical aerial photographs taken between 1948 and 1993, has enabled the structural glaciology of surge-type Variegated Glacier, Alaska, U.S.A., tо be analyzed for a period that spans two surge cycles and includes the effects of thre...
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Cambridge University Press (CUP)
1996
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Online Access: | http://dx.doi.org/10.1017/s0022143000004123 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004123 |
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crcambridgeupr:10.1017/s0022143000004123 2024-03-03T08:44:33+00:00 Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 Lawson, Wendy 1996 http://dx.doi.org/10.1017/s0022143000004123 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004123 en eng Cambridge University Press (CUP) Journal of Glaciology volume 42, issue 141, page 261-270 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1996 crcambridgeupr https://doi.org/10.1017/s0022143000004123 2024-02-08T08:41:37Z Abstract Аn excellent photographic database, comprising 12 sets of vertical aerial photographs taken between 1948 and 1993, has enabled the structural glaciology of surge-type Variegated Glacier, Alaska, U.S.A., tо be analyzed for a period that spans two surge cycles and includes the effects of three surges. The glacier-wide patterns of crevasse development at the end of each of these surges, which occurred in 1947–48, 1964–65 and 1982–83, were remarkably similar, despite differences in surge intensities and extents. At the end of each surge a three-fold longitudinal zonation of crevasse orientation characterised that part of the glacier that had been affected by surge activity. This zonation comprises: (i) transverse crevasses in a narrow upper zone, (ii) superimposed longitudinal and transverse crevasses in an extensive middle zone, and (iii) longitudinal crevasses in a narrow lower zone. The main difference between patterns produced by successive surges was small variations in the extent оf the three zones. During quiescence, the most intense crevasse development occurs in the upper glacier in the latter part of quiescence, and is a function of increasingly steep down-glacier velocity gradients developing in the buildup to the impending surge. Some crevassing also develops in the central part of the glacier in mid-quiescence that is not related to the surge nature of the glacier, but to normal flow processes over bedrock. There is no structural evidence to indicate that any of the tributaries of Variegated Glacier surge. This observation suggests that the bulb-like loops in the medial moraines at Variegated Glacier form during quiescence as a result of the steady flow of the tributaries into the stagnant trunk glacier, rather than as a result of tributary surges. Article in Journal/Newspaper glacier Journal of Glaciology Alaska Cambridge University Press Journal of Glaciology 42 141 261 270 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Lawson, Wendy Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 |
topic_facet |
Earth-Surface Processes |
description |
Abstract Аn excellent photographic database, comprising 12 sets of vertical aerial photographs taken between 1948 and 1993, has enabled the structural glaciology of surge-type Variegated Glacier, Alaska, U.S.A., tо be analyzed for a period that spans two surge cycles and includes the effects of three surges. The glacier-wide patterns of crevasse development at the end of each of these surges, which occurred in 1947–48, 1964–65 and 1982–83, were remarkably similar, despite differences in surge intensities and extents. At the end of each surge a three-fold longitudinal zonation of crevasse orientation characterised that part of the glacier that had been affected by surge activity. This zonation comprises: (i) transverse crevasses in a narrow upper zone, (ii) superimposed longitudinal and transverse crevasses in an extensive middle zone, and (iii) longitudinal crevasses in a narrow lower zone. The main difference between patterns produced by successive surges was small variations in the extent оf the three zones. During quiescence, the most intense crevasse development occurs in the upper glacier in the latter part of quiescence, and is a function of increasingly steep down-glacier velocity gradients developing in the buildup to the impending surge. Some crevassing also develops in the central part of the glacier in mid-quiescence that is not related to the surge nature of the glacier, but to normal flow processes over bedrock. There is no structural evidence to indicate that any of the tributaries of Variegated Glacier surge. This observation suggests that the bulb-like loops in the medial moraines at Variegated Glacier form during quiescence as a result of the steady flow of the tributaries into the stagnant trunk glacier, rather than as a result of tributary surges. |
format |
Article in Journal/Newspaper |
author |
Lawson, Wendy |
author_facet |
Lawson, Wendy |
author_sort |
Lawson, Wendy |
title |
Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 |
title_short |
Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 |
title_full |
Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 |
title_fullStr |
Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 |
title_full_unstemmed |
Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948 |
title_sort |
structural evolution of variegated glacier, alaska, u.s.a., since 1948 |
publisher |
Cambridge University Press (CUP) |
publishDate |
1996 |
url |
http://dx.doi.org/10.1017/s0022143000004123 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004123 |
genre |
glacier Journal of Glaciology Alaska |
genre_facet |
glacier Journal of Glaciology Alaska |
op_source |
Journal of Glaciology volume 42, issue 141, page 261-270 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000004123 |
container_title |
Journal of Glaciology |
container_volume |
42 |
container_issue |
141 |
container_start_page |
261 |
op_container_end_page |
270 |
_version_ |
1792500050502352896 |