Observation of Basal Sliding of Variegated Glacier, Alaska
Abstract Variegated Glacier is a surge-type glacier in the St Elias mountain range in Alaska. The interval between surges is about 20 years; the last one occurred in 1964 to 1965. This glacier has been studied extensively since 1973 (Bindschadler and others, 1977). Thus far, measurements of ice velo...
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Cambridge University Press (CUP)
1979
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Online Access: | http://dx.doi.org/10.1017/s0022143000030033 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030033 |
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crcambridgeupr:10.1017/s0022143000030033 2024-04-07T07:52:35+00:00 Observation of Basal Sliding of Variegated Glacier, Alaska Engelhardt, H. Kamb, B. Raymond, C. F. Harrison, W. D. 1979 http://dx.doi.org/10.1017/s0022143000030033 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030033 en eng Cambridge University Press (CUP) Journal of Glaciology volume 23, issue 89, page 406-407 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1979 crcambridgeupr https://doi.org/10.1017/s0022143000030033 2024-03-08T00:35:31Z Abstract Variegated Glacier is a surge-type glacier in the St Elias mountain range in Alaska. The interval between surges is about 20 years; the last one occurred in 1964 to 1965. This glacier has been studied extensively since 1973 (Bindschadler and others, 1977). Thus far, measurements of ice velocities have been restricted to the surface. They have been analyzed using geophysically measured ice depths, in order to estimate ice velocities in the ice mass and at the base (Bindschadler and others, 1978). From 1973 to 1977 the distribution of annual ice velocities along most of the length of the glacier can be explained primarily by internal deformation without major contribution from sliding at the base. However, the variation of surface velocity with time gives definite indication that sliding occurs in summer and that the average summer rate is increasing progressively from summer to summer and that in a zone 5 to 7 km below the head of the glacier the summer-to-summer increase in inferred sliding rate is especially rapid. This is a notably distinguishing feature, which is probably indicative of a build-up toward the next surge. In order to obtain direct information about sliding-rates and water pressures at the base in this zone, a bore hole was drilled to the bottom of the glacier about 6 km below the glacier head. Observations in the hole started in June 1978 and were continued until 31 July 1978. The hole connected to an englacial water system at a depth of 204 m whereupon the water level dropped gradually to about 100 m below the surface. The last 6 m above-the base at 356 m could be drilled only by means of a cable tool because of the presence of debris-rich ice. Upon reaching the bottom, the water level increased rapidly to the firn water table at about 8 m below surface. Large variations in water level of about 200 m occurred during the following period of observation of 35 d. Major events such as audible icequakes, heavy rainfalls, and a period of unusually high ablation were associated with abrupt ... Article in Journal/Newspaper glacier Journal of Glaciology Alaska Cambridge University Press Journal of Glaciology 23 89 406 407 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Engelhardt, H. Kamb, B. Raymond, C. F. Harrison, W. D. Observation of Basal Sliding of Variegated Glacier, Alaska |
topic_facet |
Earth-Surface Processes |
description |
Abstract Variegated Glacier is a surge-type glacier in the St Elias mountain range in Alaska. The interval between surges is about 20 years; the last one occurred in 1964 to 1965. This glacier has been studied extensively since 1973 (Bindschadler and others, 1977). Thus far, measurements of ice velocities have been restricted to the surface. They have been analyzed using geophysically measured ice depths, in order to estimate ice velocities in the ice mass and at the base (Bindschadler and others, 1978). From 1973 to 1977 the distribution of annual ice velocities along most of the length of the glacier can be explained primarily by internal deformation without major contribution from sliding at the base. However, the variation of surface velocity with time gives definite indication that sliding occurs in summer and that the average summer rate is increasing progressively from summer to summer and that in a zone 5 to 7 km below the head of the glacier the summer-to-summer increase in inferred sliding rate is especially rapid. This is a notably distinguishing feature, which is probably indicative of a build-up toward the next surge. In order to obtain direct information about sliding-rates and water pressures at the base in this zone, a bore hole was drilled to the bottom of the glacier about 6 km below the glacier head. Observations in the hole started in June 1978 and were continued until 31 July 1978. The hole connected to an englacial water system at a depth of 204 m whereupon the water level dropped gradually to about 100 m below the surface. The last 6 m above-the base at 356 m could be drilled only by means of a cable tool because of the presence of debris-rich ice. Upon reaching the bottom, the water level increased rapidly to the firn water table at about 8 m below surface. Large variations in water level of about 200 m occurred during the following period of observation of 35 d. Major events such as audible icequakes, heavy rainfalls, and a period of unusually high ablation were associated with abrupt ... |
format |
Article in Journal/Newspaper |
author |
Engelhardt, H. Kamb, B. Raymond, C. F. Harrison, W. D. |
author_facet |
Engelhardt, H. Kamb, B. Raymond, C. F. Harrison, W. D. |
author_sort |
Engelhardt, H. |
title |
Observation of Basal Sliding of Variegated Glacier, Alaska |
title_short |
Observation of Basal Sliding of Variegated Glacier, Alaska |
title_full |
Observation of Basal Sliding of Variegated Glacier, Alaska |
title_fullStr |
Observation of Basal Sliding of Variegated Glacier, Alaska |
title_full_unstemmed |
Observation of Basal Sliding of Variegated Glacier, Alaska |
title_sort |
observation of basal sliding of variegated glacier, alaska |
publisher |
Cambridge University Press (CUP) |
publishDate |
1979 |
url |
http://dx.doi.org/10.1017/s0022143000030033 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030033 |
genre |
glacier Journal of Glaciology Alaska |
genre_facet |
glacier Journal of Glaciology Alaska |
op_source |
Journal of Glaciology volume 23, issue 89, page 406-407 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000030033 |
container_title |
Journal of Glaciology |
container_volume |
23 |
container_issue |
89 |
container_start_page |
406 |
op_container_end_page |
407 |
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1795667994776436736 |