Distribution and origin of patterned ground on Mullins Valley debris-covered glacier, Antarctica: the roles of ice flow and sublimation

2006 ◽  
Vol 18 (3) ◽  
pp. 385-397 ◽  
Author(s):  
Joseph S. Levy ◽  
David R. Marchant ◽  
James W. Head
Keyword(s):  
Patterned Ground ◽  
Ice Flow ◽  
Victoria Land ◽  
Material Weaknesses ◽  
Rapid Flow ◽  
Glacier Ice ◽  
Ice Velocity ◽  
Formation And Evolution ◽  
Structural Stresses ◽  
Glacier Flow

We map polygonally patterned ground formed in sublimation tills that overlie debris-covered glaciers in Mullins Valley and central Beacon Valley, in southern Victoria Land, Antarctica, and distinguish five morphological zones. Where the Mullins Valley debris-covered glacier debouches into Beacon Valley, polygonal patterning transitions from radial (orthogonal) intersections to non-oriented (hexagonal) intersections, providing a time-series of polygon evolution within a single microclimate. We offer the following model for polygon formation and evolution in the Mullins Valley system. Near-vertical cracks that ultimately outline polygons are produced by thermal contraction in the glacier ice. Some of these cracks may initially be oriented radial to maximum surface velocities by pre-existing structural stresses and material weaknesses in the glacier ice. In areas of relatively rapid flow, polygons are oriented down-valley forming an overall fan pattern radial to maximum ice velocity. As glacier flow moves the cracks down-valley, minor variations in flow rate deform polygons, giving rise to deformed radial polygons. Non-oriented (largely hexagonal) polygons commonly form in regions of stagnant and/or near-stagnant ice. We propose that orientation and morphology of contraction-crack polygons in sublimation tills can thus be used as an indicator of rates of subsurface ice flow.

Formation of patterned ground and sublimation till over Miocene glacier ice in Beacon Valley, southern Victoria Land, Antarctica

2002 ◽  
Vol 114 (6) ◽  
pp. 718-730 ◽  
Author(s):  
D.R. Marchant ◽  
A.R. Lewis ◽  
W.M. Phillips ◽  
E.J. Moore ◽  
R.A. Souchez ◽  
...  
Keyword(s):  
Patterned Ground ◽  
Victoria Land ◽  
Glacier Ice

scholarly journals Some Comments on Glacier Flow

1950 ◽  
Vol 1 (07) ◽  
pp. 383-388 ◽  
Author(s):  
Richard Finsterwalder
Keyword(s):  
Shear Stress ◽  
Shear Plane ◽  
Critical Value ◽  
Ice Flow ◽  
Crystalline Materials ◽  
Fundamental Point ◽  
Glacier Ice ◽  
Slow Moving ◽  
Glacier Flow ◽  
Streaming Flow

Abstract Drs. Orowan and Perutz have shown that glacier ice does not behave as a viscous fluid but is plastic like all crystalline materials. The present author discusses two observed types of ice flow:—(1) the normal, regular streaming flow in slow-moving glaciers; (2) Block-Schollen * movement in swiftly flowing ice. Mention is made of the shear plane or laminar flow theory of Philipp. lt appears that Orowan s thesis is also applicable to Block-Schollen flow. The author agrees with Orowan on the fundamental point that when ice is subjected to shear stress a critical value of the shear stress exists beyond which the ice alters its consistency. But the author disagrees with Orowan in that he believes that below this critical value ice behaves as a viscous material, and he supports this view by reference to many phenomena, measurements and calculations.

scholarly journals Some Comments on Glacier Flow

1950 ◽  
Vol 1 (7) ◽  
pp. 383-388
Author(s):  
Richard Finsterwalder
Keyword(s):  
Shear Stress ◽  
Shear Plane ◽  
Critical Value ◽  
Ice Flow ◽  
Crystalline Materials ◽  
Fundamental Point ◽  
Glacier Ice ◽  
Slow Moving ◽  
Glacier Flow ◽  
Streaming Flow

AbstractDrs. Orowan and Perutz have shown that glacier ice does not behave as a viscous fluid but is plastic like all crystalline materials. The present author discusses two observed types of ice flow:—(1) the normal, regular streaming flow in slow-moving glaciers; (2) Block-Schollen movement in swiftly flowing ice. Mention is made of the shear plane or laminar flow theory of Philipp. lt appears that Orowan s thesis is also applicable to Block-Schollen flow. The author agrees with Orowan on the fundamental point that when ice is subjected to shear stress a critical value of the shear stress exists beyond which the ice alters its consistency. But the author disagrees with Orowan in that he believes that below this critical value ice behaves as a viscous material, and he supports this view by reference to many phenomena, measurements and calculations.

scholarly journals Surging Glaciers—The Dilemma Continues

1979 ◽  
Vol 24 (90) ◽  
pp. 502-503 ◽  
Author(s):  
M. F. Meier
Keyword(s):  
Shear Stress ◽  
Phenomenological Approach ◽  
Sliding Velocity ◽  
Recent Interest ◽  
Normal Behavior ◽  
Rapid Flow ◽  
Basal Sliding ◽  
Ice Velocity ◽  
Glacier Flow ◽  
Basal Shear

AbstractA glacier surge, according to most definitions, is a short-lived phase of unusually rapid glacier flow, after which the glacier returns to more normal behavior, with the surge–non-surge phases recurring on a regular or periodic basis. Recent interest is largely directed toward analyzing the effect of water at the bed on the periodic change in flow regime and on the rapid flow during a surge phase. For instance, study of a local depression of basal shear stress that dependson a “friction lubrication factor” which becomes important as the ice velocity increases, is one promising phenomenological approach. An important physical approach focuses on a water “collection zone” that occurs where and when the longitudinal pressure gradient in the subglacial wtaer film approaches zero. The data necessary for properly verifying these and other similar theories do not yet exist. Computer modeling of rapidly-surging glaciers based on a “friction lubrication factor” has been quite successful in duplicating their major features. Once rapid movement (102–103m a–1) has begun, sufficient water is generated at the bed, from ice melted by heat dissipated in sliding, to produce some decoupling of the glacier from its bed and to maintain the surge, but only if this water is not lost by rapid drainage. Some glaciers exhibit periodic pulses in which the basal sliding velocity during the fastest part of the pulses appears to be in the range for “normal” glaciers (<102m a–1). Some evidence suggests a continuum of behavior from steady (normal) glaciers through these “mini-surges” to classic surges. This continuum and the “mini-surges” seem to be difficult to explain quantitatively by existing theories. A few glaciers flow continuously at surging speeds (>103m a–1) in certain reaches. The up-glacier transition reaches show speeds decreasing to “nonrmal” with no indication of intermediate surging regime, but the down-glacier transition reaches may be areas where surges are triggered.

scholarly journals Surging Glaciers—The Dilemma Continues

1979 ◽  
Vol 24 (90) ◽  
pp. 502-503
Author(s):  
M. F. Meier
Keyword(s):  
Shear Stress ◽  
Phenomenological Approach ◽  
Sliding Velocity ◽  
Recent Interest ◽  
Normal Behavior ◽  
Rapid Flow ◽  
Basal Sliding ◽  
Ice Velocity ◽  
Glacier Flow ◽  
Basal Shear

AbstractA glacier surge, according to most definitions, is a short-lived phase of unusually rapid glacier flow, after which the glacier returns to more normal behavior, with the surge–non-surge phases recurring on a regular or periodic basis. Recent interest is largely directed toward analyzing the effect of water at the bed on the periodic change in flow regime and on the rapid flow during a surge phase. For instance, study of a local depression of basal shear stress that dependson a “friction lubrication factor” which becomes important as the ice velocity increases, is one promising phenomenological approach. An important physical approach focuses on a water “collection zone” that occurs where and when the longitudinal pressure gradient in the subglacial wtaer film approaches zero. The data necessary for properly verifying these and other similar theories do not yet exist. Computer modeling of rapidly-surging glaciers based on a “friction lubrication factor” has been quite successful in duplicating their major features. Once rapid movement (102–103 m a–1) has begun, sufficient water is generated at the bed, from ice melted by heat dissipated in sliding, to produce some decoupling of the glacier from its bed and to maintain the surge, but only if this water is not lost by rapid drainage. Some glaciers exhibit periodic pulses in which the basal sliding velocity during the fastest part of the pulses appears to be in the range for “normal” glaciers (<102 m a–1). Some evidence suggests a continuum of behavior from steady (normal) glaciers through these “mini-surges” to classic surges. This continuum and the “mini-surges” seem to be difficult to explain quantitatively by existing theories. A few glaciers flow continuously at surging speeds (>103 m a–1) in certain reaches. The up-glacier transition reaches show speeds decreasing to “nonrmal” with no indication of intermediate surging regime, but the down-glacier transition reaches may be areas where surges are triggered.

scholarly journals Seasonal and interannual ice velocity changes of Polar Record Glacier, East Antarctica

2014 ◽  
Vol 55 (66) ◽  
pp. 45-51 ◽  
Author(s):  
Chunxia Zhou ◽  
Yu Zhou ◽  
Fanghui Deng ◽  
Songtao AI ◽  
Zemin Wang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Seasonal Variations ◽  
Seasonal Changes ◽  
Satellite Images ◽  
East Antarctica ◽  
Ice Flow ◽  
Glacier Tongue ◽  
Ice Velocity ◽  
Velocity Changes ◽  
Glacier Flow

AbstractWe present a study of seasonal and interannual ice velocity changes at Polar Record Glacier, East Antarctica, using ERS-1/2, Envisat and PALSAR data with D-InSAR and intensity tracking. Ice flow showed seasonal variations at the front of the glacier tongue. Velocities in winter were 19% less than velocities during summer. No significant interannual changes were detected. Ice velocities in the grounding zone and grounded glacier did not show clear seasonal or interannual changes. The distribution of the seasonal variations suggests that the cause for the changes should be localized. Possible causes are seasonal sea-ice changes and iceberg blocking. Satellite images show that the sea ice surrounding Polar Record Glacier undergoes seasonal changes. Frozen sea ice in winter slowed the huge iceberg, and provided increased resistance to the glacier flow. The interaction between the glacier tongue, iceberg and sea ice significantly influences their flow pattern.

scholarly journals Three-dimensional deformation time series of glacier motion from multiple-aperture DInSAR observation

2019 ◽  
Vol 93 (12) ◽  
pp. 2651-2660 ◽  
Author(s):  
Sergey Samsonov
Keyword(s):  
Time Series ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Three Dimensional ◽  
Data Sets ◽  
Ice Flow ◽  
The North ◽  
Glacier Ice ◽  
Deformation Component ◽  
3D Deformation

AbstractThe previously presented Multidimensional Small Baseline Subset (MSBAS-2D) technique computes two-dimensional (2D), east and vertical, ground deformation time series from two or more ascending and descending Differential Interferometric Synthetic Aperture Radar (DInSAR) data sets by assuming that the contribution of the north deformation component is negligible. DInSAR data sets can be acquired with different temporal and spatial resolutions, viewing geometries and wavelengths. The MSBAS-2D technique has previously been used for mapping deformation due to mining, urban development, carbon sequestration, permafrost aggradation and pingo growth, and volcanic activities. In the case of glacier ice flow, the north deformation component is often too large to be negligible. Historically, the surface-parallel flow (SPF) constraint was used to compute the static three-dimensional (3D) velocity field at various glaciers. A novel MSBAS-3D technique has been developed for computing 3D deformation time series where the SPF constraint is utilized. This technique is used for mapping 3D deformation at the Barnes Ice Cap, Baffin Island, Nunavut, Canada, during January–March 2015, and the MSBAS-2D and MSBAS-3D solutions are compared. The MSBAS-3D technique can be used for studying glacier ice flow at other glaciers and other surface deformation processes with large north deformation component, such as landslides. The software implementation of MSBAS-3D technique can be downloaded from http://insar.ca/.

Basal processes beneath an Arctic glacier and their geomorphic imprint after a surge, Elisebreen, Svalbard

2005 ◽  
Vol 64 (2) ◽  
pp. 125-137 ◽  
Author(s):  
Poul Christoffersen ◽  
Jan A. Piotrowski ◽  
Nicolaj K. Larsen
Keyword(s):  
Flow Instability ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water System ◽  
Water Drainage ◽  
Ice Dynamics ◽  
Ice Flow ◽  
Glacier Ice ◽  
Water Saturated ◽  
Arctic Glacier

AbstractThe foreground of Elisebreen, a retreating valley glacier in West Svalbard, exhibits a well-preserved assemblage of subglacial landforms including ice-flow parallel ridges (flutings), ice-flow oblique ridges (crevasse-fill features), and meandering ridges (infill of basal meltwater conduits). Other landforms are thrust-block moraine, hummocky terrain, and drumlinoid hills. We argue in agreement with geomorphological models that this landform assemblage was generated by ice-flow instability, possibly a surge, which took place in the past when the ice was thicker and the bed warmer. The surge likely occurred due to elevated pore-water pressure in a thin layer of thawed and water-saturated till that separated glacier ice from a frozen substratum. Termination may have been caused by a combination of water drainage and loss of lubricating sediment. Sedimentological investigations indicate that key landforms may be formed by weak till oozing into basal cavities and crevasses, opening in response to accelerated ice flow, and into water conduits abandoned during rearrangement of the basal water system. Today, Elisebreen may no longer have surge potential due to its diminished size. The ability to identify ice-flow instability from geomorphological criteria is important in deglaciated terrain as well as in regions where ice dynamics are adapting to climate change.

scholarly journals Ground ice in the Northern Foothills, northern Victoria Land, Antarctica

2004 ◽  
Vol 39 ◽  
pp. 495-500 ◽  
Author(s):  
Mauro Guglielmin ◽  
Hugh M. French
Keyword(s):  
Oxygen Isotope ◽  
Ross Sea ◽  
Progress Report ◽  
Ground Ice ◽  
Lake Ice ◽  
Near Surface ◽  
Victoria Land ◽  
Different Types ◽  
Glacier Ice ◽  
Surface Ice

AbstractThis progress report classifies the different types of ground-ice bodies that occur in the Northern Foothills, northern Victoria Land, Antarctica. Oxygen isotope variations are presented, but interpretation is kept to a minimum pending further investigations. Surface ice, as distinct from moving glacier ice, occurs in the form of widespread buried (‘dead’) glacier ice lying beneath ablation (sublimation) till, together with perennial lake ice, snow banks and icing-blister ice.’Dry’ permafrost is uncommon, and interstitial ice is usually present at the base of the active layer and in the near-surface permafrost. This probably reflects the supply of moisture from the Ross Sea and limited sublimation under today’s climate. Intrusive ice occurs as layers within perennial lake-ice covers and gives rise to small icing blisters. Small ice wedges found beneath the furrows of high-centered polygons appear to agree with the model of sublimation-till development proposed by Marchant and others (2002).

scholarly journals Crystal Orientation in Glacier and in Experimentally Deformed Ice

1960 ◽  
Vol 3 (27) ◽  
pp. 589-606 ◽  
Author(s):  
George P. Rigsby
Keyword(s):  
Crystal Orientation ◽  
Laboratory Experiments ◽  
Ice Crystals ◽  
Equal Area ◽  
Fine Grained ◽  
Planar Structures ◽  
Glacier Ice ◽  
Glacier Flow ◽  
High Shearing ◽  
Universal Stage

AbstractMore than 8,000 ice crystals have been oriented and measured for crystal fabric studies from widely separated temperate and polar glaciers, using a large universal stage and thin-section techniques. Very strong fabrics have been found and a number of laboratory experiments on deformation and recrystallization of ice were conducted in an attempt to solve some of the perplexing problems raised concerning glacier flow.In polar glaciers the c or optic axes of the ice crystals tend to be perpendicular to the foliation plane (alternating planar structures of bubbly and clear ice). In areas of high shearing stress the preferred orientation of the axes reached 39 per cent in 1 per cent of the area when plotted on a Schmidt equal-area projection. In temperate glaciers the optic axes tend to form three or four strong maxima which also appear related to the foliation.Patterns from ice deformed in the laboratory resemble some of the fabric patterns found in polar glaciers. During deformation of laboratory specimens, large crystals have been observed recrystallizing into many smaller ones, while fine-grained ice, after completion of deformation (both glacier ice and laboratory deformed ice), has been annealed at melting temperature into a few large crystals with different orientations from the original pattern.

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