bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Slip-Line Field Analysis of the Deformation at the Confluence of two Glacier Streams
Authors: Collins I. F. 
Published: September 2017

The deformation and state of stress at the confluence of two glacier streams are analysed using the techniques of slip-line theory. The valley walls are taken to be vertical parallel planes and the deformation is supposed independent of depth. The mechanical behavior of ice is modeled by the ideal rigid/perfectly plastic material.Detailed solutions are presented for the deformation at the confluence of one or more tributaries with a main stream and of two main streams. Attention is concentrated on predicting the number, position and magnitude of the bands of intense shear which emanate from some of the junction corners. The predictions of this idealized theory are compared with field data from a confluence on the Kaskawulsh Glacier, Yukon Territory, Canada.
The Pleistocene Epoch in East Anglia
Authors: West R. G. 
Published: September 2017

AbstractThe sequence of Pleistocene deposits in East Anglia is tabulated. The following aspects of the Pleistocene are discussed and summarized: boundaries of the Pleistocene, glacial and preglacial, ice advances, interglacials, glaciations, marine horizons, climate and periglacial features. Correlations are given between the Pleistocene deposits of East Anglia and the continent.
Late-Glacial Cwm Glaciers In Wales
Authors: Seddon Brian 
Published: September 2017

AbstractThe evidence for the existence of small glaciers in the cwms of the Caernarvonshire mountains during the Late-glacial Period is presented, and by an analysis of their distribution some of the factors responsible for their formation are deduced. These were primarily protection from insolation, drifting of snow into the cirques by wind and the distribution of precipitation.
Ice Recession in Dronning Louise Land, North-East Greenland
Authors: Wyllie P. J. 
Published: September 2017

AbstractThe existence of high rock thresholds beneath the glaciers of Dronning Louise Land is established and examples are described. It is concluded that decrease in the height of the Greenland Ice Cap and the consequent emergence of the rock thresholds is the dominant factor in the final stages of recession of the glaciers of Dronning Louise Land. It is tentatively suggested that this process has more than local significance, and may be an important factor in the recent recession of the glaciers in other parts of east Greenland.
Activity of the Coleman Glacier, Mt. Baker, Washington, U.S.A., 1949–1955
Authors: Bengtson Kermit B. 
Published: September 2017

AbstractThe Coleman Glacier on Mt. Baker in the State of Washington began to advance about 1949 after a long period of rapid retreat. Since that year the terminus has advanced continuously a total of about 300 m. and considerable thickening of the entire glacier has occurred. The continued advance of the Coleman Glacier and other evidence are interpreted as manifestations of a trend during the last decade towards a slightly cooler and moist climate in the north-west of the United States.
Measurement of the Deformation of Ice in a Tunnel at the Foot of an Ice Fall
Authors: Glen J. W. 
Published: September 2017

AbstractDuring the Cambridge Austerdalsbre Expedition 1955, a tunnel was dug horizontally into the ice at the foot of a large ice fall, and its subsequent movements were surveyed. The axis of the tunnel was rotating very fast, as might be expected from the change in surface slope under the ice fall, but as well as this the tunnel was being bent, i.e. the tunnel axis was an active anticline. As the local surface of the glacier above the tunnel was convex, this bending was tending to increase the convexity, and as it is in this region that waves form across the glacier under the ice fall this observation is interpreted as showing that the wave ogives are actually being formed in the ice surrounding the tunnel. The distances between pegs in the tunnel walls were also measured. There was a compressive strain occurring along the tunnel axis (i.e. the tunnel was decreasing in length) and the tunnel was also closing far more rapidly than would be predicted from the weight of overlying ice alone. These two observations suggest that a large compressive stress is acting in the glacier in a longitudinal direction. Measurements on surface stakes, though not of the same accuracy as the internal measurements, confirmed these predictions, and also allow the strain rate tensor to be estimated. From this the magnitude of the stresses can be computed, and the longitudinal compressive stress is estimated to be about 3 bars. Observations of the banding on the walls of the tunnel showed that the fine bands were within 10° of being perpendicular to the maximum compressive stress.
The Stability of Ice-Dammed Lakes and other Water-Filled Holes in Glaciers
Authors: Glen J. W. 
Published: September 2017

AbstractIt is well known that an empty hole in a glacier will fill in if it is more than some 15 to 20 m. deep, due to the rapid variation of strain rate with shear stress. It is pointed out that a water-filled hole or lake will tend to enlarge itself by the same mechanism, if it is more than 150 to 200 m. deep. This phenomenon is believed to be responsible for the periodical and complete emptying of some glacier lakes, such as has been reported for the Tulsequah Lake in British Columbia, and Graenalón and Grilmsvötn in Iceland.
Snow and Ice in The Monte Fitz Roy Region (Patagonia)
Authors: Lliboutry Louis 
Published: September 2017

AbstractThe Fitz Roy district, on the margin of the Patagonian ice field (“Hielo continental”), is subject to continual and very strong west winds of high humidity. Glaciers descend to a very low level. Ablation by rain plays an important part, and contributes to some surface features, such as thin vertical sheets of ice, hummocks and dirt cones (a new theory of the origin of which is given). The summits of aiguilles, always covered with glazed frost in the Fitz Roy area, are incrusted with very heavy deposits of rime in the Cerro Torre and especially in the Cerro Grande areas. This forms huge comices and “feathered snow” to leeward.
Part I: Method of Nourishment of the Barnes Ice Cap
Authors: Baird P. D. 
Published: September 2017

AbstractThe Barnes Ice Cap on Baffin Island, N.W.T., Canada, was investigated during the summer of 1950. This ice cap, some 6000 sq. km. in extent, appears to have an approximately balanced budget, and yet there is no firn on its surface. It is postulated that its nourishment is by superimposed ice due to immediate refreezing of much of the melt water of summer. It is further inferred that a similar process nourishes many Arctic glaciers and ice caps where elevation, precipitation and temperature are all low. The name “Baffin Type” is proposed for these in the classification of glaciers.
Variations in the Glacier Mass of Jostedalsbreen
Authors: Rogstad Olaf 
Published: September 2017

AbstractBy comparing the recorded run-off from a precipitation district, about 55 per cent of which is covered by glaciers, to the run-off from a neighbouring district without glaciers it has been possible to determine the changes in the glacier mass of Jostedalsbreen. In the period 1900 to 1940 the annual decrease of the glacier mass was equivalent to 0.4 m. of water times the glaciated area. A close relationship is established between the change of the glacier mass and the length of one of the outflow glaciers, Brikadalsbreen. It is shown that the change in the glacier mass is related to the summer temperature and, to a minor extent, to the amount of winter snowfall.
The Sliding Velocity of Athabasca Glacier, Canada
Authors: Paterson W. S. B. 
Published: September 2017

AbstractA method of estimating siding velocity is presented. It rests on few assumptions, one of which is that longitudinal strain-rate varies linearly with depth. The flow law of ice is not used. To apply it, the sliding velocity at one point must be known. The method is used to calculate the sliding velocity at twelve points on Athabasca Glacier. These values are not related to calculated basal shear stresses. Thus one or more of the following statements must be true: (1) basal shear stress cannot be calculated by the conventional formula, (2) the roughness of the glacier bed varies from place to place, (3) sliding velocity does not obey Weertman's formula. Analysis of seven published measurements of sliding velocity leads to the same conclusion.
Solute Segregation in Ice Observed by Autoradiography
Authors: Mizuno Yukiko , Kuroiwa Daisuke 
Published: September 2017

AbstractSegregation of chemical impurities in ice formed from very dilute solutions was observed autoradiographically, using radioactive 22NaCl or H36Cl as β-ray tracers. When water containing such radioactive solutes was frozen, the segregation of solute occurred primarily along grain boundaries and partly in grains. Successive autoradiography enabled us to observe the heterogeneous distributions of segregated impurities in ice.
The Meighen Ice Cap, Arctic Canada: Accumulation, Ablation and Flow
Authors: Paterson W. S. B. 
Published: September 2017

AbstractAccumulation on the Meighen Ice Cap appears to be about normal for the region, but ablation seems abnormally low. Statistical analyses of several years’ data reveal the following trends: accumulation increases towards the north; ablation decreases with increase of elevation, decreases towards the north and west, and is greater on south-facing slopes than elsewhere. Because ice movement is very small, these trends explain the surface topography of the ice cap quite well. Other topics discussed are the significance of changes in the margins of a stagnant ice cap, and the rate at which net mass balance changes with elevation.
The Contact of the Ross Ice Shelf with the Continental Ice Sheet, Antarctica
Authors: Thiel Edward , Ostenso Ned A. 
Published: September 2017

AbstractA profile of ice thickness along the 647 mile trail from Little America V to Byrd Station has been obtained from altimetric, seismic, and gravity measurements, and detailed studies made at the junction of the Ross Ice Shelf and the Marie Byrd Land plateau. The surface elevation profile clearly shows the depression characteristic of this contact. The thickness of the floating ice shelf has been determined from the elevations assuming hydrostatic equilibrium; for this purpose the accurately known density-depth relationship obtained from a deep borehole at Little America V was employed. The buried rock topography at the contact has been deduced from a seismic sounding and variations in the gravity anomaly. Movement studies over a 22 month period are presented, and the crevasse pattern of the contact is analyzed in terms of ice movement. Suggestions are given for traversing the region by vehicle.
Movement of the Sefstrøms Gletscher North-East Greenland
Authors: Paterson W. S. B. 
Published: September 2017

AbstractWeekly observations were made on the horizontal and vertical components of surface movement of the Sefstrøms Gletscher, north-east Greenland. It is concluded that in the area in question the state of the glacier is consistent with Nye’s concept of extending flow. Melting observations were also made. An estimate of ice thickness, derived from measurements of surface slope, is given.
Heat Flux Distribution Near a Crevasse
Authors: Pings C. J. 
Published: September 2017

AbstractPreviously reported experimental temperature data were used to compute the two components of the heat flux vector in the ice body adjacent to a crevasse in a glacier of the ice sheet of northern Greenland. Graphical differentiation techniques were employed. The computed components were used to synthesize values of the beat flux vector, including magnitude and direction. Improved accuracy was achieved over the previously reported technique of sketching heat flow lines orthogonal to the isotherms.
Structure and Fabric on the Burroughs Glacier, South-East Alaska
Authors: Taylor Lawrence D. 
Published: September 2017

AbstractThe Burroughs Glacier, south-east Alaska, is a slow-moving remnant (14×3km.) of a much more extensive glacier. It is now entirely below the firn line; ablation has revealed ice structures and fabric once 300 m. or more below the glacier surface.At the present glacier surface three kinds of ice are identified—foliated ice, coarse-grained border ice and very coarse-grained basal ice.Two systems of fine-grained foliation are present. Differential movement in the glacier has caused recrystallization along closely spaced planes. At the glacier surface this produces a steeply dipping longitudinal foliation. A gently dipping foliation, having a regional trough-like structure, may be associated with former stratification planes or with former spoon-shaped shear surfaces.The optic orientation of crystals in the coarser layers of the foliated ice shows three weak maxima, and in the finer layers a single weak maximum, corresponding to one of the coarse layer maxima, and normal to the gently dipping foliation plane. The other maxima in the coarse layers are orientated close to the poles of principal fracture planes.In the coarse ice the fabric shows a pattern with three maxima similar to that obtained in torsion shear experiments. In the glacier the pattern may be formed by shear near the glacier bottom or along gently dipping foliation planes. Grain-size increases towards the glacier terminus, especially in the stagnant ice zone.Structural evidence suggests that in the early stages of the Little Ice Age the ice flow was from west to east. Later it was to east and west from an ice crest in the upper Burroughs Glacier. Structures produced by present movement have been superimposed on older structures.
Some Physical and Mechanical Properties of Polar Snow
Authors: Ramseier René O. 
Published: September 2017

AbstractSpecimens of polar snow from the South Pole, Antarctica, were tested to investigate air permeability K (cm.sec.−1), ultimate compressive strength σc (g.cm.−2) and dynamic Young’s modulus E (g.cm.−2) as a function of density. Anisotropy in a single layer of snow (snow between two summer crusts) was found in all three properties. Comparison with data for snow from Site 2, Greenland showed an empirical relation for both areas:Air permeabilities are different at the two sites because of time and meteorological effects.
Glaciological Reconnaissance of the Sukkertoppen Ice Cap, South-West Greenland
Authors: Bull C. 
Published: September 2017

AbstractGravity studies indicate that the Sukkertoppen ice cap is about 400 m. thick. The annual snow accumulation increases westwards from about 13 g. cm.−2 near the eastern edge of the ice cap to about 34 g. cm. −2 near Mount Atter, in the south-west. Probably all of the ice cap is “temperate”.
Arctic Sea Ice of Various Ages: I. Ultimate Strength
Authors: Langleben M. P. , Pounder E. R. 
Published: September 2017

AbstractA comparison of polar ice (several years old) with biennial ice (between one and two years old) was made in the field at lat. 79°N., long. 104° W. Vertical cores were extracted from the ice cover and sectioned. Their ultimate tensile strengths were measured by the ring-tensile method. Supporting measurements were made of the salinity, density, and crystal structure of the ice. Tensile strength values averaged 6 per cent higher for the polar ice and 21 per cent higher for the biennial ice than comparable results for annual sea ice. A few horizontal cores of biennial ice were analysed similarly with inconclusive results.
Karst Topography on Stagnant Glaciers
Authors: Clayton Lee 
Published: September 2017

AbstractKarst topography may occur on stagnant, drift-covered parts of glaciers such as the Martin River Glacier in south-central Alaska. Glacial karst features there include ice sink-holes, tunnels, caves, sinking streams, blind valleys, large springs, natural bridges, lapiés, hums, and residual “soils” or ablation till. The glacial karst cycle is essentially the same as the limestone karat cycle. Glacial karst is rare today but was widespread on stagnant glaciers in areas such as the northern Great Plains of North America in late Wisconsin time.
Direct Observation of the Mechanism of Glacier Sliding Over Bedrock
Authors: Kamb Barclay , LaChapelle E. 
Published: September 2017

AbstractAt the head of a tunnel driven to bedrock in Blue Glacier, Washington, the mechanism of sliding of the glacier over bedrock has been investigated. This mechanism involves (1) regelation-slip, which operates through the combined action of heat transport and mass transport (liquid and solid) in the immediate neighborhood of the glacier sole; (2) plastic flow, promoted by stress concentrations in the basal ice. We have observed and/or measured the following features of the basal slip process: 1. Slip rate in relation to internal deformation of the ice; 2. Time-variations of the slip rate; 3. Freezing of basal ice to bedrock upon release of overburden pressure; 4. Formation of a regelation layer in the basal ice, and detailed behavior of this layer in relation to bedrock obstacles and to incorporated debris particles; 5. Local separation of ice from bedrock and continuous formation of regelation spicules in the open cavities thus created; 6. Plastic deformation of basal ice as recorded in the warping of foliation planes and of the regelation layer. Simple experiments to test our interpretation of the regelation layer have been carried out, in which regelation flow of solid cubes of different materials frozen into blocks of ice was produced. The field measurements and laboratory results are used to test the theory by Weertman (1957, 1962) of the basal slip mechanism. It is found that the theoretical “controlling obstacle size” and “controlling obstacle spacing” that should correspond to our observations are about an order of magnitude too small. This quantitative failure represents an overemphasis in the theory on the importance of plastic flow as compared to regelation. A new theory has been constructed which gives results in better agreement with observation.
Recession of Glacier Tasîssârssik A, East Greenland
Authors: Gribbon P. W. F. 
Published: September 2017

AbstractThe maximum diameters of a lichen of known growth rate have been measured on the bedrock flanking glacier Tasîssârssik A (lat. 66° 06′ N., long. 36° 58′ W.) in East Greenland. The estimated age of the lateral trimline of this glacier is 133±20 yr., indicating that the recent recession of this and other glaciers in the Caledonian alps, East Greenland, appears to be synchronous with the overall recession in West Greenland.
Correlation between Crystallographic Axes and the shape of a Single Crystal in Glaciers
Authors: Mutsumi Ohtomo , Gorow Wakahama 
Published: September 2017

AbstractStudies were made of the correlation between the crystallographic axes and the shape of an individual single crystal of a crystalline aggregate in a temperate glacier and an Antarctic deep core, both of which have the typical fabric pattern of the four-maxima type, by approximating the crystal shape to an ellipsoid and then measuring misorientations between the axes of the ellipsoid and the crystallographic axes of the crystal. The result shows that the crystallographic axes are correlated with the axes of the ellipsoid; that is, in most cases the longest and the shortest axis of the ellipsoid are coincident with one of the a-axes and the c-axis of a crystal, respectively.
A case for cold-based continental ice sheets — a transient thermal model
Authors: Heine Jan T. , Mctigue David F. 
Published: September 2017

AbstractA finite-difference numerical model is used to simulate the temperature profile at the center of an ice sheet throughout the course of a glaciation. The ice sheet is gradually built to a thickness of 3000 m over about 10 000 years, starting on permafrost. A geothermal heat flux is applied at large depth. For an initial surface temperature of –12.5°C, our model shows that basal melting occurs 72000 years after the onset of the glaciation. The important parameters determining the basal temperatures are the initial temperature of the ice and substrate, the rate of downward advection of cold ice and, to a lesser extent, the thickness of the ice sheet. The growth history of the ice sheet does not significantly influence the time at which basal melting occurs. Our results show the possibility that the central parts of the continental ice sheets were cold-based for a significant part of their existence. Heating due to the geothermal heat flux cannot account for basal melting during most or all of a glacial cycle. These results may help to explain the existence of preserved land forms under the ice sheets.
Shear margins in glaciers and ice sheets
Authors: Raymond Charles 
Published: September 2017

AbstractAnalytical and numerical techniques are used to examine the flow response of a sloped slab of power-law fluid (power n) subjected to basal boundary conditions that vary spatially across the flow direction, as for example near an ice-stream margin with planar basal topography. The primary assumption is that basal shear stress is proportional to the basal speed times a spatially variable slip resistance. The ratio of mean basal speed to the speed originating from shearing through the thickness. denoted as r, gives a measure of how slippery the bed is. The principal conclusion is that a localized disturbance in slip resistance affects the basal stress and speed in a zone spread over a greater width of the flow. In units of ice thickness H, the spatial scale of spreading is proportional to a single dimensionless number Rn ≡ (r/n+ 1)1/n+1 derived from n and r. The consequence for a shear zone above a sharp jump in slip resistance is that the shearing is spread out over a boundary layer with a width proportional to Rn. For an ice stream caused by a band of low slip resistance with a half-width of w H, the margins influence velocity and stress in the central part of the band depending on Rn in comparison to w. Three regimes can be identified, which for n = 3 are quantified as follows: low r defined as R3 < 0.1w, for which the central flow is essentially unaffected by the margins and the driving stress is supported entire by by basal drag; high r defined as R3 > 1w, for which the boundary layers from both sides bridge across the full flow width and the driving stress in the center is supported almost entirely by side drag; intermediate r, for which the driving stress in the center is supported by a combination of basal and side drag. Shear zones that are narrower than predicted on the basis of this theory (≈ R3) would require localized softening of the ice to explain the concentration of deformation at a shorter scale.
Computations of the Possible Future Behaviour of Berendon Glacier, Canada
Authors: Untersteiner N. , Nye J. F. 
Published: September 2017

If the surface of Berendon Glacier, British Columbia, Canada, rose by 19 m above its 1963 level at a certain point near the terminus it would reach the entrance to a mining tunnel. Computations are made to see whether this is likely in the near future.We calculate the changes in mass balance that would be necessary to make the glacier, which is now retreating, start to advance and reach the tunnel in 40 years and 20 years respectively. The method fits polynomials to the advance—retreat data and then uses the λ coefficients of Nye (1963[b]) to infer the corresponding mass balance behaviour. It is concluded that if the mean mass balance should increase smoothly to +70 cm/year, which is a high but possible value, by the year 2003, the ice would reach the tunnel portal in 2003. But, even assuming a rather drastic deterioration in the climate in the future and a concomitant increase of the mean mass balance, the ice will not reach the tunnel portal within the next 20 years.