bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical Distribution of Velocity in Salmon Glacier, British Columbia
Authors: Mathews W. H.
Published: September 2017

Observations have been made in one of several deep holes drilled in Salmon Glacier in the course of mining development. Surveys, particularly of the displacement of a 481.5 m. length of pipe in this hole over a 94 day period, show movement diminishing downward from a maximum value of 0.225 m./day at the surface, through a slightly lower value at mid depth to 45 per cent of this value at the bottom of the pipe. By extrapolation movement on the glacier floor, 490 m. below the surface, is believed to be about 44 per cent of the surface rate. The data closely approximate Nye’s (1952) theoretical formula for laminar flow:

in which u0=78 m./yr., α=2°00′, n=2.8 and K=1.25×10−4. Maximum shear stress at the glacier floor is calculated to be about 1.42 bars.
Preliminary Notes on the Glaciology of Kilimanjaro
Authors: Humphries D. W.
Published: September 2017

Glaciological studies during the Sheffield University Expeditions to Kilimanjaro in 1953 and 1957 included a survey of the glaciers and a close examination of the Penck Glacier and the stagnant remnants of the ice cap on the summit. The Penck Glacier has done little downcutting although it rests on friable rock. The glaciers and summit remnants are rapidly retreating, the Penck Glacier having retreated 3 m. in 3 months in 1957, and nearly 300 m. since 1912. The main accumulation zone appears to be at about 4,500–5,000 m. with a local “low level” firn line and an upper firn line above the top of the mountain. Maps of the glaciers, their recent fluctuations and moraines are being prepared. The glaciological and meteorological observations in 1957 form part of the I.G.Y. programme for East Africa.
A Grid Technique for Measuring Ice Tunnel Deformation
Authors: Butkovich T. R. , Landauer J. K.
Published: September 2017

A new method for measuring ice tunnel deformation and closure is described. It includes cutting slots into a smooth vertical wall, forcing wet dyed string into the slots and freezing it in. Results of one year’s installation are given for each of 13 grids installed throughout a 366 m. ice tunnel. Two important visual observations are reported. The first is that no differential shearing was found; and the second, that heavy dirt bands that occurred throughout the tunnel appeared to have extruded into the tunnel opening. A possible explanation is that dirty ice is more plastic than clear ice.
Recent Changes in the Glaciers of Svartisen
Authors: Theakstone W. H.
Published: September 2017

The history of glaciological studies in the Svartisen area is outlined, and observations made by earlier workers are summarized. The present position of the ice limit in the area is indicated and is compared with those of the past Evidence of extensive, and almost continuous, retreat of the glaciers is presented, and emphasis is placed on the rapidity of the changes since the 1930’s. In the present century, the formation of marginal lakes and the detachment of glacier tongues have characterized the decay of many of the Svartisen outlets.
On The Origin of Bullet Crystals At The South Pole
Authors: Gow Anthony J.
Published: September 2017

Art examination of bullet crystals in precipitation at the South Pole indicates that combinations of bullets originate as primary growth structures and that individual bullets are formed as a result of the disintegration of these primary growth forms rather than by independent crystallization of pyramidally terminated columns.
Stability of a circular cylindrical hole in a Glacier
Authors: Nye J. F.
Published: September 2017

If a bore hole of circular cross-section is made in an ice sheet or glacier, will it remain circular, or will it perhaps by some process of instability tend to depart from the circular shape? An argument is given to show that the circular shape is stable.
Some Tests on the Compactibility and Hardness after Compaction of Different Types of Snow
Authors: Ager B. H:son
Published: September 2017

Compaction of different types and mixtures of snow including snow collected from the natural snow cover and waste from an ice milling machine, was carried out in a cold room with a small model compactor. Density, cone hardness and shear strength were measured, generally 24 hours after compaction, for specimens compacted in different ways. When the snow was compacted to maximum, densities between 0.55 and 0.60 g./cm.3 were achieved, except for mixtures including more than one third new snow for which densities were lower. For snow collected from the natural cover the highest hardness values after compaction were found for new snow and for mixtures including more than 50 per cent of new snow or fine-grained granular snow. The maximum hardness was obtained with specimens prepared from fine-grained mill waste.

The influence of temperature on density and hardness was also studied.
The Mass Budget of Blue Glacier, Washington
Authors: LaChapelle E.
Published: September 2017

Blue Glacier has an area of 4.3 km.2, a volume of 0.57 km.3, a mean density of 0.88 g. cm.−3 and an altitude range of 1,275 to 2,350 m. above sea-level. It is an active temperate glacier in a strongly maritime climate where the net budget gradient varies from 10 mm. m.−1 in the ablation zone to 7 or 8 mm. m.−1 in the accumulation zone. There is a very large snow accumulation each winter and a large snow melt each summer which exceeds by several times the ice melt. The annual mass budget is strongly influenced by altitudes of the freezing level during spring and autumn storms, for these determine whether the heavy precipitation falls as rain or snow. Recent glacier variations are quantitatively consistent with climate trends but there is no clear cause-and-effect relation. Since 1958 the glacier has been gaining mass by an average of 0.4 per cent per year.
Studies of the Mass Budget of Arctic Pack-Ice Floes
Authors: Hanson Arnold M.
Published: September 2017

The processes of melting, freezing, precipitation, evaporation and condensation were considered in the computation of the mass budget of an ice floe in the northern Chukchi Sea. It was bound that condensation and evaporation contribute negligible amounts, and that melting accounted for the largest loss from the upper surface of the floe. From an original mass of 270 g. cm.−2 a unit ice column lost 9.2 g. cm.−2 by melting of snow and 35.2 g. cm.−2 by melting of ice during the melt season. During the freezing period 5.8 g. cm.−2 were regained by the accumulation of snow and frost. Measurements at the bottom of the ice indicate an estimated net loss of 5 g. cm.−2 over a seven-month study. A comparison of six summers at three stations shows no obvious correlation of ablation and latitude, and an average loss of ice at the surface of 40 g. cm.−2.
A Heat-Balance Study on Sørbreen, Jan Mayen
Authors: Dibben P. C.
Published: September 2017

The techniques and results of a heat-balance programme on Sørbreen, Jan Mayen, are presented and discussed. Estimates of 24 hr. heat-transfer totals under frontal and non-frontal weather conditions are then made. Transfer is found to be higher during frontal conditions, due to an increase in latent and to a lesser extent sensible heat transfer. Consideration of upper air temperatures and humidities suggests this higher transfer is experienced by the glacier as a whole. It is then proposed that summer rainfall totals will provide an index of frontal activity which may be used to indicate relative ablation from one summer to another. A statistical comparison of ablation measured on the glacier and rainfall recorded at the Jan Mayen meteorological station supports this suggestion.
Photo-Interpretation of two Types of Rock Glacier in the Colorado Front Range, U.S.A.
Authors: Outcalt Samuel I. , Benedict James B.
Published: September 2017

Two types of rock glacier occur in the Colorado Front Range. Rock glaciers on the floors of modern cirques closely resemble the tongues of small valley glaciers. Because they contain cores of banded glacial ice and grade up-valley into lateral moraines, rock glaciers of this type are believed to represent the debris-covered tongues of former glaciers. Most consist of two or more superimposed lobes, bounded by longitudinal furrows, and resulting from independent ice advances. Despite their compound nature, the complexes now appear to be moving down-slope as single units. Two generations of “cirque-floor” rock glaciers, both tentatively dated as being of post-Pleistocene age, occur in the Front Range.

Rock glaciers of an entirely different character occur beneath steep valley walls, where they are supplied with debris by avalanche couloirs. Interstitial ice, responsible for the movement of “valley-wall” rock glaciers, probably results from the metamorphism of snow buried beneath rock-fall debris or supplied by winter avalanching.
The Brine Content of Sea Ice Measured with a Nuclear Magnetic Resonance Spectrometer
Authors: Richardson Charles , Keller E. E.
Published: September 2017

Nuclear magnetic properties of hydrogen are used for the quantitative analysis of the water content of sea ice from 0° C. to −40° C. The data on water content are utilized to calculate the brine volume and brine weight content of the samples. Over a range of water contents of 2% to 96% the standard deviation of the nuclear magnetic resonance data from chemical analysis data is ±0.6%, An estimate of water content in a sample of sea ice at −70° C. is given, and the value of nuclear magnetic resonance measurements for field studies is discussed.
Wind Speed, Stability and Eddy Viscosity over Melting Ice Surfaces
Authors: Grainger M. E. , Lister H.
Published: September 2017

The laws of wind-speed variation with height and their modification with stability are discussed and applied to observations in the first 2 m. over various cold surfaces. An exponential law is superior save in frequent, near-neutral conditions, but the logarithmic law is superior in neutral and again in really stable conditions. A power law and a logarithmic-plus-linear law give the best fit with the data only at moderate stabilities. A logarithmic-plus-cubic law of wind speed is evolved that permits suppression of linear additions to the logarithmic law at two distinct stabilities. A power form of variation of Richardson number with height is found and compared with a linear form. The former is applied with the logarithmicplus-cubic law to the observed data, though with limited success. Eddy-viscosity coefficients for the different laws are compared.
Analysis of a 20 m. Firn Pit on the Kesselwandferner (Ötztal Alps)
Authors: Ambach W. , Eisner H.
Published: September 2017

The firn stratification in the accumulation area of an alpine glacier was studied in a 20 m. deep, vertical pit dug in the summer of 1963 on the Kesselwandferner (3,240 m. above sea-level in the Ötztal Alps). The firn is traversed by ice layers up to 25 cm. in thickness which have been formed by the damming up and freezing of melt water. Firn density increases with depth. At a depth of 13 m. (8 yr. old firn) the density reaches 0.80 g./cm.3 as a mean value of one annual net accumulation. Excluding the ice layers, the firn reaches a density of 0.82 g./cm.3 in a 10 yr. old layer at a depth of 16 m. The firn stratification in relation to seasons was studied by analyses of the pollen content in the lower part of the pit, beginning with the horizon “late summer 1954”. The late summer horizons obtained from the firn stratification were confirmed by the pollen analyses.
Theoretical Studies of Ice Segregation in Soil
Authors: Arakawa Kiyoshi
Published: September 2017

The mathematical theory of heat conduction is applied to the analysis of ice segregation processes in soil. A diffusion equation is first employed for the flow of soil moisture. Two new quantities, the rate of ice segregation,σ and the segregation efficiency, E, are introduced. The first is the rate of ice growth measured as mass per area per time. The latter is defined as E = σL/(K1∂T1/∂x−K2∂T2/∂x), where L is the latent heat of fusion of ice, T1and K1are the temperature and thermal conductivity of frozen soil, and T2 and K2 are the temperature and thermal conductivity of unfrozen soil. Three types of soil freezing can be classified in terms of E: freezing of non-frost-susceptible soil (E = 0), perfect segregation (E = 1) and imperfect segregation (0 < E < 1). Finally, the mathematical boundary conditions at an advancing frost line are obtained in freezing, frost-susceptible soil (E ≠ 0). Two parameters related to the structure of soil are pointed out, which seem to be valid criteria of frost susceptibility. The amount of frost-heaving is derived under special conditions.
The Dynamics of the Amery Ice Shelf
Authors: Budd W.
Published: September 2017

A general survey of the preliminary results of a three-year program of measurements on the Amery Ice Shelf by A.N.A.R.E. are presented, together with theoretical considerations of the velocity and stress distributions and the mass and energy regimes of the ice shelf.

In order to explain the observed velocity distribution it has been found necessary to extend Weertman’s theory of ice-shelf creep to an ice shelf bounded at its sides. The resulting theoretical velocity profile applied to the results of the Amery Ice Shelf provides estimates of the average values of the power flow-law parameters for the ice shelf.

The energy and mass budget considerations, together with the recorded change in form of the ice front, suggest that the ice-shelf regime is not in a continual state of balance but may fluctuate as the ice shelf changes in form over a period of about forty years.
The Determination of the Direction of Movement on Glacier Surfaces by Terrestrial Photogrammetry
Authors: Voigt Ulrich
Published: September 2017

In order to determine longitudinal profiles of movement on glacier surfaces from photogrammetric surveys, it is necessary to know the direction of movement. The present method requires at least two base lines with overlapping ranges of photographs. The establishment of a base-line system for a given glacier form depends on the demands of accuracy. The method is applied to the movement of the glacier Kongsvegen (Vestspitsbergen) and the accuracy obtained is discussed. The movement direction of the points on the medial moraine of Kongsvegen does not coincide with the moraine direction.
The Sintering Process in Snow
Authors: Ramseier René O. , Keeler Charles M.
Published: September 2017

The growth of bonds between snow grains or ice spheres has been variously attributed to surface diffusion, volume diffusion, and evaporation–condensation. To distinguish among these possible mechanisms the unconfined compressive strength of two groups of snow samples was determined as a function of time. One group was allowed to sinter under atmospheric conditions while the other group was kept immersed in silicone oil. The much lower rate of strengthening of the latter group suggests that evaporation–condensation must be the major mechanism of mass transport in snow under atmospheric conditions. The possible magnitudes of the various mass transfer coefficients are discussed.
The Application of Optical Filtering in Coherent Light to the Study of Aerial Photographs of Greenland Glaciers
Authors: Bauer A. , Fontanel A. , Grau G.
Published: September 2017

The principles that underlie the analysis of aerial photographs using the coherent light from a laser are summarized, and then a study of such a filtering technique applied to an aerial photograph of Jakobshavn Isbræ is given as an example.

Two systems of crevasses, respectively parallel and perpendicular to the direction of flow of the southern lobe of the glacier can be detected after filtering. These two crevasse systems were not apparent at first sight on the original photograph as they were obliterated by a network of curved crevasses. It appears that this latter network are not true crevasses, but surface undulations formed by differential ablation of bands of black (or blue) and white ice.
Basal Sliding and Movement Near the Margin of the Glacier Østerdalsisen, Norway
Authors: Theakstone W. H.
Published: September 2017

Observations in and around natural caves beneath the glacier Østerdalsisen in 1961 and 1962 indicated that, within the marginal zone, basal sliding played a major part in the movement measured at the upper surface. Sliding rates apparently were influenced by the availability of water at the glacier. The contribution of differential movement within the ice, which was unimportant within the outermost part (about 10 m.) of the glacier, increased with distance from the edge. Movement at the bottom was free from macroscopic irregularities, except where local conditions at the bed influenced the mode of flow. Air temperatures within the innermost parts of subglacial caves were almost constant, below 0°C. Studies indicated that large gaps are unlikely to exist between the glacier and its bed when the ice is more than 50 m. thick.
Dielectric Relaxation in Temperate Glaciers
Authors: Gribbon P. W. F.
Published: September 2017

The dielectric relaxation of névé and glacial ice has been studied on two temperate glaciers in Greenland and France. Measurement of the capacitance and loss tangent in the audio-frequency range of thin parallel wires placed on the surface of a glacier gave ϵ′, the relative permittivity, and ϵ″, the loss factor of the névé. The relaxation time can be expressed in terms of the frequency fm at the maximum ϵ″ value of the Cole-Cole ϵ″−ϵ′ diagram, and its variation with depth was derived from the Cole-Cole diagrams obtained for different wire separations.

For wet 0°C. surface snow in Greenland, fm ≈ 4 kHz. and decreased with the increase in density and form factor at greater depths, while for the low-density, cold surface névé in France fm ≈ 2 kHz. and increased with the increase in temperature at greater depths. All Cole-Cole diagrams showed both impurity-ion losses at low frequencies below 6 kHz., and a spreading factor of the distribution in relaxation times caused by the changes in the physical properties of the glacier with depth. Although the method could not measure temperatures absolutely, relative temperature differences and the position of the 0°C. isotherm were detected when a temperature gradient existed in a glacier.
Avalanche Activity on the Vaughan Lewis Icefall, Alaska
Authors: Pinchak Alfred C.
Published: September 2017

Avalanche data were obtained by direct observation of the Vaughan Lewis Icefall. Magnitude, time and location of each ice fall were recorded and the resulting data were analyzed statistically. An inverse relationship was found between the relative frequency and the magnitude of the avalanches. A significant diurnal variation in avalanche rate was also detected. During the early morning hours the avalanche rate reached a maximum. No secondary increase in the avalanche frequency was observed during the evening cooling period. The data indicated that a given ice fall results in an increased probability of an ice fall occurring shortly thereafter. After approximately 4 min the effect of a given avalanche no longer correlates with succeeding avalanches.
Instruments and Methods: The Resistograph and the Compressive Strength of Snow
Authors: Bradley Charles C.
Published: September 2017

A recent field comparison of snow strength as measured by the snow resistograph and compressive strength as measured by direct loading to failure indicates good agreement in the range 25–400 g/cm2.
A Direct Determination of an Upper Limit for the Electrical Charge on Dislocations in Ice
Authors: Joncich D.M. , Holder J. , Granato A.V.
Published: September 2017

A direct determination of the upper limit for the electric charge density along dislocations in ice has been carried out by measuring the simultaneous effects of an electric field and a mechanical stress on the movement of a low-angle tilt boundary in an ice single crystal. The determination is independent of the geometry of the dislocations or the distribution of the charge along them. No measurable effects of the electric field on boundary motion were found, requiring that the charge density be less than one unit of charge for every 300 atomic lengths of dislocation. This estimate is less than large previous estimates, but is consistent with smaller proposed values.
Ice-wedge Ice, Mackenzie Delta-Tuktoyaktuk Peninsula Area, N.W.T., Canada
Authors: Gell W. Alan
Published: September 2017

Petrologic analysis was performed on ice-wedge ice in order to investigate changes in fabric across wedges in relation to the growth mechanism. Crystal size increased from the centre outward and strongly preferred dimensional orientations developed parallel to the sides of wedges. c-axis orientations changed from a horizontal girdle at the wedge centre to a point maximum normal to the foliation at the boundary. These changes are related to recrystallization and grain growth associated with the horizontal stress field. In massive ice penetrated by an ice wedge, crystal size and complexity of crystal shape decreased toward the wedge, dimensional orientations tended to become parallel to the wedge, and c-axes formed a point maximum normal to the wedge boundary.
Fabrics of Icing-Mound and Pingo Ice in Permafrost
Authors: Gell W. Alan
Published: September 2017

Crystallization histories of some ice layers in permafrost are inferred from crystal size, shape, dimensional and lattice orientation, and inclusion patterns. In an icing mound, formed by injection of water beneath frozen active-layer soil, early growth was rapid, indicated by copious small crystals and bubbles, followed by slower growth giving rise to crystals and bubbles elongate parallel to the freezing direction, c-axes were normal to crystal long axes. In a small pingo, bulk water existed temporarily at the freezing interface and freezing was unidirectional. In a larger pingo, variations in freezing rate were inferred. Later flow of ice modifies growth fabrics.
Experiments on the Origin of Kettle-holes
Authors: Maizels Judith K.
Published: September 2017

Several theories exist on the origin of kettle-holes in pro-glacial outwash deposits. The most widely accepted origin involves the melting of buried ice. The author carried out some experiments in which ice blocks were placed on or in outwash sediments in a tank in order to determine which mechanisms of ice melt would be most likely to give rise to kettle-hole features. The largest kettle-holes were produced by the melting of buried ice blocks; smaller transient depressions were formed from ice blocks melting in streams of flowing water; while, rather than depressions, ridges resembling pingos and moraines were created by ice blocks melting on a dry or saturated gravel surface.
Pleistocene Mountain Glaciation in Ethiopia
Authors: Hastenrath Stefan
Published: September 2017

During a field survey in High Semyen, northern Ethiopia, two moraine complexes were mapped, the lower one extending down to around 3 750 m. Glacial morphology is best developed in the north-western and western quadrants. Moraines are deeply weathered and carry abundant vegetation. For Mounts Badda, Cilalo, Cacca and Enguolo in southern Ethiopia, possible moraines are inferred from air photographs; there are indications for more pronounced glaciation in the western quadrant, and moraines seem to extend further down than in High Semyen. Highest moraines at Mount Elgon in northern Kenya/ Uganda were found to below 3 600 m. Major moraine complexes in the mountains of Ethiopia and East Africa suggest some spatial correlation in elevation and appearance, but absolute dates are absent.
Present and Past Glaciation Threshold in the Cascade Range, Washington, U.S.A.: Topographic and Climatic Controls, and Paleoclimatic Implications
Authors: Porter Stephen C.
Published: September 2017

Isoglacihypses depicting the configuration of the glaciation threshold (= “glaciation limit”) in Washington broadly parallel the crest of the Cascade Range and curve around the west and south flanks of the Olympic Mountains. In both uplands the glaciation threshold rises inland (eastward) with a mean gradient of 10-12 m/km. However, the gradient in the Cascades is more variable (7-25 m/km) due to five east-trending troughs in the glaciation threshold surface that coincide with topographic depressions along the range crest and that apparently result from greater eastward penetration of moist maritime air.

Mean accumulation-season precipitation correlates strongly (r2= 0.86) with altitude of the glaciation threshold in the North Cascade Range, but the correlation of glaciation threshold with altitude of the July freezing isotherm, determined from the calculated July lapse rate within the mountains, is much weaker (r2= 0.40). Multiple regression analysis relating independent climatic variables that affect the height of the glaciation threshold indicates that 90.4% of variance is explained by accumulation-season precipitation and estimated mean annual temperature at the glaciation threshold.

The glaciation threshold during the greatest ice advance of the last (Fraser) glaciation in the southern North Cascade Range (c.18 000-22 000 years B.P.) was 900 ± 100 m below that of the present. Depression of the glaciation threshold by this amount most likely resulted from a change in accumulation-season precipitation of no more than 30% from present values and a decrease in mean ablation-season temperature of 5-5 ± 1.5 deg.
Interesting Features Of Radar Imagery Of Ice-Covered North Slope Lakes
Authors: Weeks W. F. , Sellmann P. , Campbell W. J.
Published: September 2017

Side-looking airborne radar (SLAR) imagery obtained in April-May 1974 from the North Slope of Alaska between Barrow and Harrison Bay indicates that tundra lakes can be separated into two classes based on the strength of the radar returns. Correlations between the areal patterns of the returns, limited ground observations on lake depths and water compositions, and information obtained from LANDSAT imagery strongly suggest that areas of fresh-water lakes giving weak returns are frozen completely to the bottom while areas giving strong returns are not. This is a reasonable interpretation inasmuch as the reflection coefficient associated with the high-dielectric-contrast ice-water interface would be roughly twelve times that associated with the low-contrast ice-soil interface. Brackish lakes also give weak returns even when they are not completely frozen. This is the result of the brine present in the lower portion of the ice cover limiting the penetration of the X-band radiation into the ice. The ability to separate tundra lakes rapidly and easily into these two classes via SLAR should be useful in understanding a wide variety of problems.
Instruments and Methods: Measurement of Ice Movement in Subglacial Cavities: A New Cavitometer Beneath the Glacier D’Argentière (Mt Blanc, France)
Authors: Bocquet G. , Ricq J.C.
Published: September 2017

The study of subglacial movements taking place in regions of cavitation beneath the Glacier d’Argentière, has demonstrated the necessity for using several cavitometers. The very unusual conditions in which such apparatus is installed to measure simultaneously the velocity and the position of the ice vault have led us to design and produce a prototype of a portable cavitometer which records the data on magnetic tape (cassettes).
Some Observations on the Behavior of the Liquid and Gas Phases in Temperate Glacier Ice
Authors: Raymond C. F. , Harrison W. D.
Published: September 2017

Microscopic and textural observations were made on ice samples cored from Blue Glacier slightly below the equilibrium line to depths of 60 m. Observations were started within a few minutes after collection. Water was found in veins along three-grain intersections, in lenses on grain boundaries and in irregular shapes. Gas was found in bubbles in the interior of crystals, in bubbles touching veins, and locally in veins. Vein sizes showed some spread; average cross-sectional area was about 7 × 10−4 mm2 with no discernible, trend with texture or depth except within 7 m of the surface. Before the samples were examined they could have experienced a complex relaxation which could have changed them significantly. As a result it is not possible to determine the in situ size of veins, but an upper limit can be determined. Also it is not possible to predict intergranular water flux per unit area, but 1 × 10−1 m a−1 represents an upper limit. In coarse-grained ice the water flux density is likely to be even smaller, because of a low density of veins, and blocking by bubbles. This indicates that only a very small fraction of the melt-water production on a typical summer day can penetrate into the glacier on an intergranular scale except possibly near the surface. The existence of conduit-like features in several cores suggests that much melt water can nevertheless penetrate the ice locally without large-scale lateral movements along the glacier surface. The observed profile of ice temperature indicates that the intergranular water flux may be much smaller than the upper limit determined from the core samples.
The Thermal Regime of Trapridge Glacier and its Relevance to Glacier Surging
Authors: Jarvis. Gary T. , Clarke Garry K. C.
Published: September 2017

A deep-ice temperature measurement program has been conducted on Trapridge Glacier, Yukon Territory. Large regions of temperate ice are predicted at the base of the otherwise cold glacier, The glacier snout, frozen to bedrock, appears to act as an ice dam allowing the build up of an ice reservoir in the upper regions. Thermal regulation of the surges of Trapridge Glacier is suggested and the relevance of basal temperatures in large surging glaciers is discussed.
Equilibrium-Line Altitudes, Mass Balance, and July Freezing-Level Heights in the Canadian High Arctic
Authors: Bradley R. S.
Published: September 2017

Equilibrium-line altitudes on the White Glacier, Axel Heiberg Island, and the north-west sector of the Devon Ice Cap are shown to be closely related to mean July freezing-level heights at nearby upper-air weather stations. An inverse relationship between July freezing-level heights and mass balance on the Devon Ice Cap is also shown. Reasons for such correlations are suggested and some limitations of the relationship are outlined. Recent lowering of the freezing level in July is discussed in relation to the theoretical “steady-state” equilibrium-line altitudes in the Canadian high Arctic. It is suggested that positive mass-balance years have predominated over a large part of northern Ellesmere Island and north-central Axel Heiberg Island since 1963, and some glaciological evidence supporting this hypothesis is given.
Temperature Measurements in Athabasca Glacier, Alberta, Canada
Authors: Paterson W. S. B.
Published: September 2017

The temperature in the ablation area of Athabasca Glacier is about —0.5°C at a depth of 10 m. Below 17 m the temperature is slightly below the calculated pressure melting point (average difference 0.01 deg) in some places. Heat produced by ice deformation is calculated as a function of depth in two bore holes. Only in about the lower half of the glacier thickness is this heat sufficient to maintain the ice at the observed temperature as the hydrostatic pressure is reduced by ablation. Freezing of water within the ice must provide heat for this purpose elsewhere in the glacier; it must also provide heat to maintain the deeper ice close to the melting point even though the 10 m temperature is negative. The minimum water content needed is estimated to be between 0.5 and 1%. It is argued that most of this water must be water trapped between grains when the ice formed from firn. The small difference from the pressure melting temperature measured below 17 m probably arises either from impurities or because, as a result of heat supplied for pressure-melting of ice around air bubbles, the ice is at the melting point corresponding to the bubble pressure rather than to the hydrostatic pressure.
The Relationship between Density and Tensile Strength in Snow
Authors: Sommerfeld R. A.
Published: September 2017

“Weakest link” theories predict that the brittle fracture of snow is inherently a statistical problem. The probability of failure of snow in centrifugal tensile tests is shown to be a function of σ/σm where σ is the applied stress and σm is a characteristic strength (a maximum strength) which is a function of density ρ alone. Similar probabilities of failure are obtained for measurements at Alta, Utah, and Berthoud Pass, Colorado where the characteristic strength is obtained from the relationship
.
Water Pressure in Intra- and Subglacial Channels
Authors: Röthlisberger Hans
Published: September 2017

Water flowing in tubular channels inside a glacier produces frictional heat, which causes melting of the ice walls. However the channels also have a tendency to close under the overburden pressure. Using the equilibrium equation that at every cross-section as much ice is melted as flows in, differential equations are given for steady flow in horizontal, inclined and vertical channels at variable depth and for variable discharge, ice properties and channel roughness. It is shown that the pressure decreases with increasing discharge, which proves that water must flow in main arteries. The same argument is used to show that certain glacier lakes above long flat valley glaciers must form in times of low discharge and empty when the discharge is high, i.e. when the water head in the subglacial drainage system drops below the lake level. Under the conditions of the model an ice mass of uniform thickness does not float, i.e. there is no water layer at the bottom, when the bed is inclined in the down-hill direction, but it can float on a horizontal bed if the exponent n of the law for the ice creep is small. It is further shown that basal streams (bottom conduits) and lateral streams at the hydraulic grade line (gradient conduits) can coexist. Time-dependent flow, local topography, ice motion, and sediment load are not accounted for in the theory, although they may strongly influence the actual course of the water. Computations have been carried out for the Gornergletscher where the bed topography is known and where some data are available on subglacial water pressure.
Some Effects of Multiple Scattering on the Distribution of Solar Radiation in Snow and Ice
Authors: Barkstrom Bruce R.
Published: September 2017

Multiple scattering of the solar flux in snow and “bubbly” ice can account for the variable albedo, the non-specular reflection, the non-exponential flux decrease near the surface, and the large upward flux within the medium. The scattering problem has been formulated and solved exactly, assuming isotropic scattering in a plane-parallel, semi-infinite, grey medium. The solution shows a non-exponential flux decrease near the surface and an exponential decrease deep in the medium. For such a medium, the albedo will increase with decreasing solar altitude in a manner which agrees to within one per cent of observed snow albedos in the Antarctic.
A Theory of Water Percolation in Snow
Authors: Colbeck S. C.
Published: September 2017

A theory is developed to describe the vertical percolation of water in isothermal snow. The general theory of Darcian flow is reviewed to establish a reasonable physical basis for the construction of a model. It is shown that in simple gravity drainage, capillarity is negligible compared with gravity since values of water saturation are generally in the “mid-range”. It is postulated that the permeability to the water phase increases as a certain function of the water saturation, and porosity is assumed to decrease linearly with depth. Ice layers and other inhomogeneities are treated in the theory by considering the permeability of the snow with the inhomogeneities included. A method by which this value of permeability can be calculated is presented using the method of characteristics.

The theory is applied to the Seward Glacier firn where Sharp measured water fluxes at various depths. A periodic surface flux is assumed and the particular solution for water flux at any depth is given. From this solution the wave forms passing each depth are constructed and compared with the measured ones. Although the experimental data are affected by the presence of ice layers, the comparison between theory and experiment is favorable and the theory is thought to be essentially correct.
Freezing of Water Drops
Authors: Murray W. A. , List R.
Published: September 2017

Investigations were made of the ice structures, air-bubble size distributions, and heat exchanges of water drops frozen freely-floating in the purified air of a vertical wind tunnel. Drop diameters varied from 1 to 8 mm, air temperature from −1 to −18.5°C; the ice phase was initiated artificially. It was found that the mass of ice in a freezing drop increases linearly with time. Both mean air bubble and crystal sizes decrease in a regular fashion as the air temperature decreases, whereas the bubble concentration increases. Histograms show a preferred tangential orientation of the projections into the plane of observation of the crystallographic hexagonal axis (c′-axes), a preference which weakens as the temperature decreases.
Inversion of flow Measurements for Stress and Rheological Parameters in a Valley Glacier
Authors: Raymond Charles F.
Published: September 2017

Methods are developed for determining the distributions of stress and effective viscosity in a glacier, under the assumptions: the ice is quasi-viscous, the flow is time independent, and acceleration forces are negligible. Measurements of the three-dimensional distribution of velocity are needed for their application. The differential equations of mechanical equilibrium, expressed in terms of viscosity, strain-rate components, mean stress, and their gradients, are viewed as equations to be solved for viscosity and mean stress subject to boundary conditions at the free upper surface. For certain rectilinear flow patterns, unique distributions of stress and effective viscosity can always be derived. For more complicated flow this is not necessarily so. However, it is still possible to choose the best values of rheological parameters in any trial flow law based on the requirement that the residuals to the equations of equilibrium be minimized in a mean-square sense. The techniques are applied to measurements of internal deformation made in nine bore holes on the Athabasca Glacier. At the center line the magnitude of the surface-parallel shear stress increases with depth more slowly than would be expected from a standard shape factor correction or the theoretical distribution of Nye. Correspondingly the lateral distribution of lateral shear stress shows the opposite relationships. In the lower one- to two-thirds of the depth corresponding to a range in effective stress from about 0.5 to 1.2 bars, the gross rheology of the ice is not distinguishably different from the experimentally determined flow law of Glen (n = 4.2, T = 0.02° C) as generalized by Nye. The results do not support the conclusion that the effective viscosity is higher than would be expected from Glen’s experiments as indicated by the more limited measurements of Paterson and Savage. Power-law parameters derived for the different bore holes considered separately show a spread, which suggests some rheological inhomogeneity. However, no definite conclusions can be drawn, because of direct measurement errors at the bore holes and less definable uncertainty in the interpolated distribution of velocity between the holes. The upper one- to two-thirds of the glacier constitutes an anomalous zone in which there is either a strong effect from a complex distribution of stress arising from longitudinal stress gradients or more complicated rheology than in a homogeneous power-law material.
Mass Transfer Along an Ice Surface Observed by a Groove Relaxation Technique
Authors: Itagaki K. , Tobin T. M.
Published: September 2017

The mass transfer on an ice surface was measured using a groove decay technique on (0001) plane and <1010> direction at −10° C. The evaporation–condensation and viscous flow terms in Mullins’ theory were deduced from the change of decay constant as a function of groove wavelength between 16 and 80 μm. A viscous flow term contributes the most to groove decay while an evaporation–condensation term contributes up to 31.5% of the mass transfer for the shortest wavelength measured and other terms were found to be negligible. Large discrepancies between the decay constants obtained from the measurements and constants calculated from theory indicate that other mechanisms not considered in Mullins’ theory may be responsible for the groove decay.
Finger-Rafting in Fresh-water Ice: Observations in Lake Superior
Authors: Green John C.
Published: September 2017

Finger-rafting, similar to that reported in sea ice, is common in thin (2-15 mm) new ice on Lake Superior. It is produced by wind traction alone; neither wave action nor brine is necessary for its initiation or propagation. Fingers have been observed to progress at rates of 0.5-5 cm/s.
Thermal Effects of Crevassing on Steele Glacier, Yukon Territory, Canada
Authors: Jarvis Gary T. , Clarke Garry K. C.
Published: September 2017

Ice temperature measurements have been made in Steele Glacier to a depth of 114 m. All measured temperatures were below 0° C, the coldest being –6.5° C at a depth of 114 m. The temperature profile indicates an anomalously warm layer of ice between 30 m and 50 m, which is probably due to the freezing of water in crevasses opened during the 1965–66 surge. A two-dimensional model of a cold glacier with partially water-filled crevasses predicts temperature profiles very similar to that observed.
The Medial Moraines of the Lower Glacier de Tsidjiore Nouve, Valais, Switzerland
Authors: Small R. J. , Clark M. J.
Published: September 2017

The two medial moraines of the Glacier de Tsidjiore Nouve are nourished by rock debris revealed at the surface by progressive ablation down-glacier. The sources of the moraine appear to be rock outcrops marginal to or above the Pigne d’Arolla ice fall, much of the detritus entering the glacier via crevasses either at the summit or the base of the ice fall. The role of differential ablation in the emergence of the moraines as relief features is illuminated by measurements made in the late summers of 1971 and 1972. The eventual decline of the moraines down-glacier is related to factors of reducing debris supply, lateral sliding and accelerated ablation due to attenuation of the detrital cover to a mean thickness of 1 cm or less. A model of moraine development, different in several respects from that proposed by Loomis (1970) for the Kaskawulsh Glacier, Alaska, is outlined.
Variations in the Sliding of a Temperate Glacier
Authors: Hodge Steven M.
Published: September 2017

Detailed measurements of the positions of stakes along the center-line of the lower Nisqually Glacier were made over a period of two years. Variations in the basal sliding speed were calculated from the measured changes in surface speed, surface slope, and thickness, using the glacier flow model of Nye (1952) and allowing for the effect of the valley walls, longitudinal stress gradients, and uncertainties in the flow law of ice. The flow is predominantly by basal sliding and has a pronounced seasonal variation of approximately ±25%. Internal deformation contributes progressively less to the total motion with distance up-glacier. Neither the phase nor the magnitude of the seasonal velocity fluctuations can be accounted for by seasonal variations in the state of stress within the ice or at the bed, and the variations do not correlate directly with the melt-water discharge from the terminus. A seasonal wave in the ice flow travels down the glacier at a speed too high for propagation by internal deformation or the pressure melting/enhanced creep mechanism of basal sliding.

The rate of sliding appears to be determined primarily by the amount of water in temporary storage in the glacier. The peak in sliding speed occurs, on the average, at the same time as the maximum liquid water storage of the South Cascade Glacier. The data support the idea that glaciers store water in the fall, winter and spring and then release it in the summer. This temporary storage may be greatest near the equilibrium line. The amount of stored water may increase over a period of years and be released catastrophically as a jökulhlaup. Any dependence of sliding on the basal shear stress is probably masked by the effect of variations in the hydrostatic pressure of water having access to the bed.
Multivariate Statistical Analysis of Glacier Annual Balances
Authors: Lliboutry L.
Published: September 2017

A statistical analysis has been made of the annual balances collected during 16 consecutive years at 32 sites on the ablation area of the Glacier de Saint-Sorlin (French Alps). Only 38% of the 32 × 16 balances are known; moreover in 8 cases only the total balance for 2 consecutive years is known, and in one case the balance for 4 consecutive years. A comprehensive study of the errors leads us to assume the following linear model for the annual balance xjt at site j for year t:

where αj and βt are parameters depending upon the site and the year respectively, ηjt and η’jt are random errors with a Gaussian distribution and standard errors σ and σ’ respectively. Assuming some known value for σ’2/σ2 = ρ, the parameters αj and βt, their variance–covariance matrix, and the variance covariance matrix of the residuals are estimated in the most general case. The estimators being stable against variations in ρ, the value ρ = o may be assumed; this value docs not conflict with the behaviour of the estimates of the residuals. A test of the linear model derived from Tukey’s non-additivity test is positive. Although a much more general, non-linear model

gives a better representation of 13 × 6 balances forming a complete table of data, the linear model with σ ≈ 0.20 m is good enough to be used in theoretical studies or in routine work.
A Study of Glacier Flow for an Open-Pit Mine: An Exercise in Applied Glaciology
Authors: Colbeck S. C.
Published: September 2017

As part of the feasibility study for the development of an open-pit mine at the edge of the Greenland ice sheet, a study is made of the ice flow toward the proposed pit. The flow is analyzed by considering the two-dimensional flow along seven cross-sections. The most favorable profile is determined for each cross-section and its flow calculated. The excavation necessary to expose the ore is 106 × 106 m3 of ice. 66 × 106 m3 of ice will have to be removed in order to establish favorable profiles and an additional 7.9 × 106 m3 of ice will have to be removed each year in order to prevent the glacier from thickening and advancing into the mine. Many other glaciological problems must be considered, and field work continues in order to provide more information about the area.
The Yarmouth Drumlin Field, Nova Scotia, Canada
Authors: Gravenor C. P.
Published: September 2017

The Yarmouth drumlinized area is a relatively small field of about 150 drumlins located south and south-east of the town of Yarmouth, Nova Scotia. An analysis of the drumlin shapes indicates that in the majority of cases the stoss end is on the southern extremity of the drumlin. This would suggest that the ice moved in from the south, a concept which is contradictory to pebble lithology and fabric analysis of the till in the drumlins and surrounding ground moraine. The drumlin field is anomalous in other respects in that the drumlin density is very low compared with other fields, and granulometric analysis shows that the drumlins are composed of coarse-grained material with only minor amounts of clay.

It is suggested that the drumlins were originally formed by south to south-easterly flowing ice but during a later phase of glaciation a local centre of outflow, probably short-lived, developed south of Yarmouth on the continental shelf, and the drumlins were reshaped by ice flowing toward the north prior to the disappearance of this centre. Thus this area of drumlins was presumably not affected by the later area of outflow centred on the interior upland of western Nova Scotia which was hitherto believed to account for the Yarmouth drumlins.