Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A.
Velocity and strain-rate patterns in a small temperate valley glacier display flow effects of channel geometry, ice thickness, surface slope, and ablation. Surface velocities of 20–55 m/year show year-to-year fluctuations of 1.5–3 m/year. Transverse profiles of velocity have the form of a higher-ord...
Published in: | Journal of Glaciology |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
1974
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s0022143000023029 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000023029 |
id |
crcambridgeupr:10.1017/s0022143000023029 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/s0022143000023029 2024-03-03T08:46:07+00:00 Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. Meier, Mark F. Barclay Kamb, W. Allen, Clarence R. Sharp, Robert P. 1974 http://dx.doi.org/10.1017/s0022143000023029 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000023029 en eng Cambridge University Press (CUP) Journal of Glaciology volume 13, issue 68, page 187-212 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1974 crcambridgeupr https://doi.org/10.1017/s0022143000023029 2024-02-08T08:40:23Z Velocity and strain-rate patterns in a small temperate valley glacier display flow effects of channel geometry, ice thickness, surface slope, and ablation. Surface velocities of 20–55 m/year show year-to-year fluctuations of 1.5–3 m/year. Transverse profiles of velocity have the form of a higher-order parabola modified by the effects of flow around a broad bend in the channel, which makes the velocity profile asymmetric, with maximum velocity displaced toward the outside of the bend. Marginal sliding rates are 5–22 m/year against bedrock and nil against debris. Velocity vectors diverge from the glacier center-line near the terminus, in response to surface ice loss, but converge toward it near the firn line because of channel narrowing. Plunge of the vectors gives an emergence flow component that falls short of balancing ice loss by about 1 m/year. Center-line velocities vary systematically with ice thickness and surface slope. In the upper half of the reach studied, effects of changing thickness and slope tend to compensate, and velocities are nearly constant; in the lower half, the effects are cumulative and velocities decrease progressively down-stream. Where the slope increases down-stream from 7° to 9°, reflecting a bedrock step, there is localized longitudinal extension of 0.03 year –1 followed by compression of 0.08 year –1 where the slope decreases. Marginal shear (up to 0.5 year –1 ) is strongly asymmetric due to flow around the bend: the stress center-line, where one of the principal axes becomes longitudinal, is displaced 150 m toward the inside of the bend. This effect is prominently visible in the crevasse pattern. Ice fluxes calculated independently by “laminar” flow theory and by continuity disagree in a way which shows that internal deformation of the ice is controlled not by local surface slope but by an effective slope that is nearly constant over the reach studied. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Blue Glacier ENVELOPE(164.167,164.167,-77.833,-77.833) Journal of Glaciology 13 68 187 212 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Meier, Mark F. Barclay Kamb, W. Allen, Clarence R. Sharp, Robert P. Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. |
topic_facet |
Earth-Surface Processes |
description |
Velocity and strain-rate patterns in a small temperate valley glacier display flow effects of channel geometry, ice thickness, surface slope, and ablation. Surface velocities of 20–55 m/year show year-to-year fluctuations of 1.5–3 m/year. Transverse profiles of velocity have the form of a higher-order parabola modified by the effects of flow around a broad bend in the channel, which makes the velocity profile asymmetric, with maximum velocity displaced toward the outside of the bend. Marginal sliding rates are 5–22 m/year against bedrock and nil against debris. Velocity vectors diverge from the glacier center-line near the terminus, in response to surface ice loss, but converge toward it near the firn line because of channel narrowing. Plunge of the vectors gives an emergence flow component that falls short of balancing ice loss by about 1 m/year. Center-line velocities vary systematically with ice thickness and surface slope. In the upper half of the reach studied, effects of changing thickness and slope tend to compensate, and velocities are nearly constant; in the lower half, the effects are cumulative and velocities decrease progressively down-stream. Where the slope increases down-stream from 7° to 9°, reflecting a bedrock step, there is localized longitudinal extension of 0.03 year –1 followed by compression of 0.08 year –1 where the slope decreases. Marginal shear (up to 0.5 year –1 ) is strongly asymmetric due to flow around the bend: the stress center-line, where one of the principal axes becomes longitudinal, is displaced 150 m toward the inside of the bend. This effect is prominently visible in the crevasse pattern. Ice fluxes calculated independently by “laminar” flow theory and by continuity disagree in a way which shows that internal deformation of the ice is controlled not by local surface slope but by an effective slope that is nearly constant over the reach studied. |
format |
Article in Journal/Newspaper |
author |
Meier, Mark F. Barclay Kamb, W. Allen, Clarence R. Sharp, Robert P. |
author_facet |
Meier, Mark F. Barclay Kamb, W. Allen, Clarence R. Sharp, Robert P. |
author_sort |
Meier, Mark F. |
title |
Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. |
title_short |
Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. |
title_full |
Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. |
title_fullStr |
Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. |
title_full_unstemmed |
Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A. |
title_sort |
flow of blue glacier, olympic mountains, washington, u.s.a. |
publisher |
Cambridge University Press (CUP) |
publishDate |
1974 |
url |
http://dx.doi.org/10.1017/s0022143000023029 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000023029 |
long_lat |
ENVELOPE(164.167,164.167,-77.833,-77.833) |
geographic |
Blue Glacier |
geographic_facet |
Blue Glacier |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 13, issue 68, page 187-212 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000023029 |
container_title |
Journal of Glaciology |
container_volume |
13 |
container_issue |
68 |
container_start_page |
187 |
op_container_end_page |
212 |
_version_ |
1792502018983591936 |