bluuebunny/crossref_metadata_2025 huggingface dataset:
Regime of an Afghan Glacier
Authors: Gilbert O. , Jamieson D. , Lister H. , Pendlington A.
Published: September 2017

The climatic snow line is a little above the highest peaks in this region (Mir Samir, 5 809 m, lat. 35° 35′ N., long. 70° 10′ E.) but steep north-facing slopes provide a topographie reason for small glaciers persisting, with a snow line a little below 4 900 in (16 000 ft). Snow accumulation at this height averages 1 300 kg m−2, most of this falling in late winter and spring. Gross ablation reaches 40 kg m−2 d−1. Net ablation (July–August), measured as stream discharge, averages 3 600 m3 d−1 = 9 kg m−2 d−1. Slow recession is the average condition. Halt stages at 4 800, 4 600 and 4 000 m are interpreted from the topography. Dating of moraines by lichen distribution indicates for the highest of these a minimum age of 400 years.

The vertical flux of heat and of water vapour were calculated through an air layer 30–100 cm over a melting firn surface for 24 h. The source of heat available at the surface expressed as a percentage of the total was: net radiation 87, condensation 5, forced convection 1, conduction through snow 6 and unexplained 1. The heat sink was: long-wave radiation 4, evaporation 6, forced convection 6, conduction into snow 2 and melting 82%.
Errors in Short-Term Ablation Measurements on Melting Ice Surfaces
Authors: Müller Fritz , Keeler Charles M.
Published: September 2017

Rapid changes in time and space in the micro-relief of an ablating glacier surface and radiation-induced melt within the uppermost ice layer, termed the “weathering crust”, seriously affect the accuracy of the short-term ablation measurements. The various measuring techniques commonly used (stakes, ablatometers, ablatographs) and some new methods (measurement of discharge from a small supra-glacial drainage basin, and mass loss directly measured on core samples) are critically reviewed and assessed in the light of these phenomena. The implications for studies of heat and mass balance are discussed.

It appears that the direct measurement of mass flux is the most accurate means of assessing short-terni ablation rates. The errors in short-term ablation measurements by any method are largely compensatory and consequently do not influence long-period mass-balance estimates.
Effect of Temperature on the Creep of Ice
Authors: Mellor Malcolm , Testa Richard
Published: September 2017

Creep tests on homogeneous, isotropic polycrystalline ice gave an apparent activation energy for creep of 16.4 kcal/mol (68.8 kJ/mol) over the temperature range −10° to −60° C. Above −10° C the Arrhenius relation for temperature dependence is invalid, and creep rate becomes progressively more temperature dependent as the melting point is approached. Between −20° and −50° C the apparent activation energy for creep of a single crystal of ice was found to be 16.5 kcal/mol (69.1 kJ/mol). A complete creep curve for a single crystal loaded in uniaxial compression parallel to the basal plane was qualitatively similar to the classical creep curve; creep rate at all stages was very much faster than for polycrystalline ice under the same conditions. Creep tests on polycrystalline ice at 0° C gave a stress/strain-rate relation for that temperature, but its precise meaning is unclear, since recrystallization complicated the results.
Creep of Ice under Low Stress
Authors: Mellor Malcolm , Testa Richard
Published: September 2017

Uniaxial compressive creep tests on fine-grained polycrystalline ice indicate that secondary strain-rate is proportional to σ1.8, where σ is applied stress, for the range 0.1 < σ < 0.5 kgf/cm2 (10 < σ < 50 kN/m2). On the basis of the present tests, earlier results suggesting linear viscous behaviour at low stress are believed to be invalid.
Geometry and Dynamics of a Surge-type Glacier
Authors: Bindschadler R. , Harrison W. D. , Raymond C. F. , Crosson R.
Published: September 2017

Measurement of geometry, motion, and mass balance from Variegated Glacier, Alaska portray conditions in this surge-type glacier close to the mid-point of its 20 year surge cycle. Comparison of longitudinal profiles of ice depth, surface slope, and surface speed indicate that the motion occurs largely by internal deformation assuming the ice deforms according to the experimental law of Glen. Surface speed is not noticeably affected by local surface slope on the scale of the ice thickness or smaller, but correlates well with slope determined on a longitudinal averaging scale about one order of magnitude larger than the ice depth. The rate of motion on Variegated Glacier agrees well with rates on non-surge type temperate glaciers which have similar depth and slope. Although the (low regime at the time of the measurements is apparently typical of temperate glaciers, a large discrepancy between the balance flux needed for steady state and the actual flux is indicative of a rapidly changing surface elevation profile and internal stress distribution.
The Distribution of Glaciers in the Rocky Mountains of the United States
Authors: Graf W. L.
Published: September 2017

Evidence from aerial photographs, maps, and field checks indicates that 319 glaciers lie in cirques of the Rocky Mountains, south of the United States-Canadian border. On a subcontinental scale, the distribution of glaciers is highly clustered, with larger and denser clusters located in the northern Rocky Mountains. Lesser concentrations of small glaciers occur in the southern Rocky Mountains. The total area of glaciers in the Rocky Mountains of the U.S.A. is 78.9 km2.
Stress in an Elastic Bedrock Hump Due to Glacier Flow
Authors: Morland L. W. , Morris E. M.
Published: September 2017

The stress field in an isotropic elastic hump representing a typical bedrock feature is obtained for plane strain conditions. Gravity effects are included and the applied load is a normal pressure distribution deduced from an idealized model of glacier flow. A Coulomb failure criterion is applied, including the effective stress change due to pore-water pressure, and stresses on the predicted failure planes determined for different pressure amplitudes and relative gravity contributions. The latter make little difference to the maximum “failure stress" but influence the regions where such stress levels occur. Levels of cohesive stress required to inhibit Coulomb failure are obtained, and are low in general, implying that coherent rock in the adopted hump profile, subject to the model pressure, would not fail. That is, this profile is stable unless jointing introduces an easier failure mechanism.
A Snow-bank Push Mechanism for the Formation of Some “Annual” Moraine Ridges
Authors: Birnie Richard V.
Published: September 2017

Ice-marginal features in South Georgia include minor moraine ridges running approximately parallel to the ice margin and developed as superficial forms in various depths of till. It is suggested that these developed as ice-contact landforms, some being created by the interaction of the ice edge and abutting marginal snow bank, whilst the glacier is advancing. This advance is essentially short-term, being part of a seasonal variation in the position of the ice margin. “Snow-bank push” is the term proposed to describe this mechanism of ridge formation.
Impurity Concentrations In Sea Ice
Authors: Addison J.R.
Published: September 2017

Three different types of saline ice were cut into sections a few millimeters thick along planes parallel to the surface. The resulting melts were analyzed quantitatively for chloride, sulphate, sodium, potassium, magnesium, and calcium. Two of the specimens were artificial sea ice, grown in the laboratory at ambient temperatures of —30°C and - 15°C, respectively. A portion of the latter exhibited a clear, glassy, fresh-ice structure. The third was natural sea ire. The resulting ion concentration profiles and ion ratios are presented. For sections of widely varying salinity, the various ion ratios assumed values fairly close to those in natural sea-water.
The Movement of Melting Ice Over Rough Surfaces
Authors: Chadbourne B. D. , Cole R. M. , Tootill S. , Walford M. E. R.
Published: September 2017

Laboratory experiments show that pieces of melting ice about one centimetre across, moving under normal loads across roughened glass surfaces, travel much faster than regelation theory predicts. The discrepancy is as much as 40 times for the finest scale surfaces, (prepared by grinding with carborundum particles of 60 μm mean diameter) and increases further if the load is reduced below three bars. On the other hand melting ice moves, under similar conditions, across rough porous glass surfaces at approximately the speed predicted by regelation theory. We suggest the reason is that melt water, produced by the dissipation of frictional energy, accumulates at the interface between ice and ground glass where it promotes sliding, but can easily drain away from a porous surface. Similar effects at the bed of a temperate glacier may cause the contribution of regelation to the bed-slip process to depend sensitively upon the melt-water regime.
Sediments Exposed on the Surface of the Ross Ice Shelf, Antarctica
Authors: Gaylord David R. , Robertson James D.
Published: September 2017

A highly crevassed region near a grounded ice rise on the Ross Ice Shelf, Antarctica was investigated and found to contain poorly sorted sediments. Preliminary analysis of a 27 g sample of sediments was undertaken using megascopic, microscopic, and X-ray diffraction methods. Igneous and meta-morphic rock fragments, their constituent minerals, and micro-fossils were noted in the sample. Insufficient data have been collected at this time to denote a particular source area for the sediments.
The Relationship between the Visco-Elastic and Structural Properties of Fine-Grained Snow
Authors: Kry P. R.
Published: September 2017

New and felt-like snow was sieved and sintered at a constant temperature in order to produce homogeneous samples of fine, rounded-grain snow with a density in the range 270–340 kg m−3. The structure of single samples was changed in stages by non-destructive uniaxial compression. This deformation, which amounted to 30%, took place within 8 hours (thus limiting temperature metamorphism). At each stage the Young’s modulus was measured quasi-statically and the creep behaviour under constant uniaxial compression was recorded. Stereological analysis of sections from the samples provided mean values for both grain-bond and grain properties. The Young’s modulus increased with density slightly more strongly than linearly, whereas the low-stress viscosity in unconfined compression increased nearly exponentially for densities less than 380 kg m−3. The maximum densification resulted in a 15-fold increase in the measured visco-elastic properties. However, the number of grain bonds per unit mass increased linearly by a factor in the range 1.5 to 2 while the average grain-bond size remained constant. It is concluded that only a fraction of the grain bonds in a snow sample transmit an applied stress, and that the new grain bonds formed during the deformation of a snow sample determine the visco-elastic properties of snow. The hypothesis that chains, defined as series of stress-bearing grains, are the basic units of snow structure is developed. Semi-quantitative calculations developed from the chain concept explain the observed variations in the visco-elastic properties.
Mechanism of Till Deposition Related to Thermal Conditions in a Pleistocene Glacier
Authors: Shaw John
Published: September 2017

A record of sedimentation from pro-glacial sandur deposits through pro-glacial lake deposits to final deposition of till is used to interpret changing environmental conditions, and depositional processes, during the development of the “Little Welsh Advance” in the Shrewsbury area, England. The relationship between lacustrine sediments and till establishes till deposition by flowage. However, the most important conclusions are derived from the deduction that lacustrine sediments were incorporated into the basal part of the ice sheet and transported across previously deposited end moraines. A discussion of this deduction, based on the findings of Weertman (1961), establishes that during the advancing phase the ice sheet was of the polar type. Final melting is thought to have occurred by both top-melt and under-melt as a result of climatic amelioration.
The Morphological Effects of Surges of the Donjek Glacier, St Elias Mountains, Yukon Territory, Canada
Authors: Johnson P. G.
Published: September 2017

The present surge of the Donjek Glacier on the north-east side of the St Elias Mountains, first noticed in 1969, is producing a number of morphological effects adjacent to the glacier in the terminus area. Although the effects of the surge are minimized by the lobate form of the glacier terminus, several types of push structure, erosional forms and certain drainage changes are being produced. These forms are similar to older forms close to, or on, the Neoglacial maximum moraine. It is considered that the similarities suggest that surges may have occurred throughout most of the Neoglacial period.
Proposal for Measuring the Movement of a Large Ice Sheet by Observing Radio Echoes
Authors: Nye J. F. , Kyte R. G. , Threlfall D. C.
Published: September 2017

The proposed method is to use a radio-echo sounder located on the surface of the ice sheet and to record the shape of the pulses returned from the rock bed. If the instrument is moved horizontally, the shape of the returning pulse will change, large differences occurring in horizontal distances of the order of the wavelength of the radiation, say 5 m. The spatial pattern of this variation, being largely determined by the details of the reflecting rock bed, is expected to remain fixed in position while the ice moves. It thus forms a fixed reference against which ice movement can be measured at places far removed from fixed landmarks. Analogue experiments in the laboratory, using ultrasonic waves in air in place of radio waves in ice, suggest that it should be easy to detect a movement of λ/10, 0.5 m, and, with further refinement, much smaller movements. A field test is in preparation.
Temperature of a Temperate Glacier
Authors: Harrison W. D.
Published: September 2017

The closure of water-filled glacier bore holes is considered and it is concluded that freezing due to conduction to the surrounding ice is usually the dominant process. On this basis englacial temperatures are obtained from a bore hole near the equilibrium line of Blue Glacier, U.S.A., where the ice thickness is about 125 m. Temperatures range from −0.03° C near the surface to −0.13° C at a depth of 105 m, with an estimated uncertainty of 0.02 or 0.03 deg. On the average the temperature is about 0.05 deg colder than the equilibrium temperature of ice and pure water. It is shown that at this temperature small amounts of water-soluble impurities play an important role in the thermal behavior of the ice. This leads to a new definition of temperate ice in terms of its effective heat capacity. The effective heat capacity of the Blue Glacier ice is apparently much larger than that of pure ice at the same temperature.
Acoustic Emission in Snow at Constant Rates of Deformation
Authors: Lawrence W. F. St. , Lang T. E. , Brown R.L. , Bradley C. C.
Published: September 2017

Acoustic emissions in the audio spectrum are reported from observations of laboratory experiments conducted on snow samples in uniaxial compression. A number of tests show the pattern of acoustic emissions to be a function of the rate of deformation. Over the frequency range 20 to 7 000 Hz acoustic emissions are associated with rates of deformation corresponding to brittle fracture of the snow sample. Though probably present, no acoustic emissions were detected from samples deforming plastically.
An Inventory of the Present and Past Glacierization of Home Bay and Okoa Bay, East Baffin Island, N.W.T., Canada, and Some Climatic and Palaeoclimatic Considerations
Authors: Andrews J. T. , Barry R.G. , Drapier Lyn
Published: September 2017

An air-photograph inventory of the present glacierization of areas of east Baffin Island adjoining Home Bay and Okoa Bay is described. Ice fields characterize the broad mountain summits of the former while the latter is an area of cirque glaciers. The extent of glacierization is statistically related to various topographic parameters. It is found that there is a 4: 1 ratio between Home Bay and Okoa Bay in the area of ice as a percent of the land area above 600 m a.s.l. Trend-surface analyses are made of the distribution of snow-banks and of cirques (empty and with ice bodies) in the two areas. The orientation of the cirques and of the ice-field glaciers in Home Bay is also examined. 39% of empty cirques in Okoa Bay face south, whereas those with existing glaciers are restricted to orientations with azimuths between 310°-145°. Neither glacier length nor the observable recession in the Home Bay area show any significant difference with regard to; aspect.

Consideration of climatic parameters (snowfall and degree days) and synoptic-climatological results provide no reason for the strong contrast between the two areas. Cool, cloudy summer conditions are associated with easterly flow components that should affect both areas. A possible model for the inception of the mountain ice fields of Home Bayc. 2000-4000 years ago is outlined and it is suggested that differential lag effects between the ice bodies in the two areas may be responsible for some of the observed difference. The many paradoxical relationships between glacierization. topography and climate in these areas, and the rather negative results, emphasize the dangers of facile palaeoclimatic interpretations.
Gravity Measurements on “Fox Glacier”, Yukon Territory, Canada
Authors: Crossley David J. , Clarke Garry K. C.
Published: September 2017

“Fox Glacier”, Yukon Territory, has a history of surging and is at present in a quiescent period. In 1968 a gravity survey was carried out over the glacier, in order to find ice depths. The results indicate the glacier is thin with a maximum depth of 88 m.
Fluctuations of Coleman Glacier, Mt Baker, Washington, U.S.A.
Authors: Harrison A. E.
Published: September 2017

Thickness variations above an ice fall in the terminal tongue of Coleman Glacier on Mt Baker, Washington, have been quite small (±5 m) in contrast to the rapid expansion and shrinkage of the tongue itself during the last 20 years. The tongue has not responded as actively to recent, larger thickness changes above the ice fall as it did during its period of most active expansion between 1954 and 1956. There is no apparent relationship between the glacier thickness and the type of flow in the terminal tongue.
Renewed Activity of Muldrow Glacier, Alaska, After the 1956 Surge
Authors: Harrison A. E.
Published: September 2017

Recovery of the Muldrow Glacier in the area below the lower Muldrow ice fall is progressing at a rapid rate. About one-third of the lost ice thickness at the base of the ice fall has been replaced during the 10 years since the surge. The ice velocity in this region is apparently quite rapid, but quickly decreases down-stream and is barely detectable at McGonagall Pass, 6.5 km from the base of the ice fall. Muldrow Glacier still offers an excellent opportunity to study the recovery from a surge, and the flow of a normal wave into stagnant ice.
The Combined Heat, Ice and Water Balance of McCall Glacier, Alaska: A Contribution to the International Hydrological Decade
Authors: Wendler Gerd , Ishikawa Nobuyoshi
Published: September 2017

The combined heat, ice and water balance was calculated for the McCall Glacier basin (30.6 km²) for a 36 day period in summer of 1971. This period represents about half the ablation period in this region. The heat balance was measured by detailed observations over ice, and secondary stations were established over snow and moraine surfaces. The heat balances calculated for stations located respectively on ice and snow surfaces were assumed to be representative of all such surfaces. The moraine station was only used to obtain evaporation data for areas of the basin not covered by glacier (totalling about 70%). Corrections were made to the radiative fluxes owing to screening of the surrounding mountains and the exposure of the glacier. The ice balance was calculated using 80 ablation/accumulation stakes and the discharge was measured with a water-level recorder, which was calibrated with a current meter. The precipitation was measured with seven rain gauges. Compared with the direct run-off measurements, the values calculated from the heat balance gave a value 5.5% higher, and the stake measurements a value 8.9% lower. This agreement is considered satisfactory and strengthens confidence in the methods employed in each of the three individual calculations.
Instruments and Methods: The Measurement of Vertical Strain in Glacier Bore Holes
Authors: Rogers James C. , LaChapelle Edward R.
Published: September 2017

A method to measure the vertical strain in glacier bore holes is described that entails placement of passive markers at varying depths. The position of these markers with respect to a surface reference is measured by an electronic sensor lowered into the hole. These measurements can be combined with inclinometer measurements to yield the total velocity vector in the ice surrounding the hole. Although the method was designed for use in a 0.05 m diameter hole, it can easily be applied to holes of different diameters and to winter snow covers as well as glacier ice.
Observations on the Internal Structure and Origin of Some Flutes in Glacio-Fluvial Sediments, Blomstrandbreen, North-West Spitsbergen
Authors: Paul M.A. , Evans H.E
Published: September 2017

Some flutes which occur on the surface of a series of glacio-fluvial sediments at the margin of Blomstrandbreen, north-west Spitsbergen, are described. A section in one has revealed a complex internal structure, in which originally horizontal beds have been folded into an anticline whose axis is normal to the ice margin, and whose structure is related to the morphology of the flute.

Comparison of the observed deformation with the theoretical distribution of stresses around the base of a subglacial tunnel shows that this deformation could have resulted from How under such a stress system. It is considered that these observations support the hypothesis that flutes are formed when unfrozen, water-soaked materials deform subglacially due to the pressure differences which exist in the vicinity of an ice tunnel formed in the lee of some rigid obstruction to ice flow.
Nucleation and Growth of Bubbles at an Ice–Water Interface
Authors: Bari S. A. , Hallett J.
Published: September 2017

Nucleation and growth of bubbles during freezing of solutions of air and helium in water has been investigated experimentally using different techniques to give freezing rates between 1 μ m s−1 and 10 mm s−1. Bubbles grow as cylinders below 5 μ m s−1, becoming egg shaped, the narrow ends towards the freezing interlace, at higher ice growth velocities. Bubble concentration increases and size decreases with increase of growth rate. The detail of bubble size and concentration is influenced appreciably by the particulate content of the water sample. Very high freezing rates give initially clear ice. Subsequently, bubbles nucleate and grow at grain boundaries within the ice. Bubbles do not move with recrystallization, their spatial distribution showing the grain boundary positions at the time of nucleation.

Observations are interpreted in terms of nucleation on particles in suspension in the water and a significant incorporation of air molecules into the ice lattice. The relevance of the results to bubble-containing ice formed under natural conditions is discussed.
Stability of the Junction of an Ice Sheet and an Ice Shelf
Authors: Weertman J.
Published: September 2017

An analysis is made of the steady-state size of a two-dimensional ice sheet whose base is below sea-level and which terminates in floating ice shelves. Under the assumption of perfect plasticity it is found that an ice sheet placed on a bed whose surface was initially flat cannot exist if the depth of the bed below sea-level exceeds a critical depth. If this depth is less than the critical level, the ice sheet extends out to the edge of the continental shelf. Similar results are found with more realistic assumptions about the laws governing the flow of ice. If the bed slopes away from the centre, the ice sheet can have a stable width that increases in value as the accumulation rate increases or as sea-level is lowered. It is not possible to decide whether or not the West Antarctic ice sheet is in stable equilibrium. It is entirely possible that this ice sheet is disintegrating at present, as suggested by Hughes.
A Heat-Balance Study on Mccall Glacier, Brooks Range, Alaska: A Contribution to the International Hydrological Decade
Authors: Wendler Gerd , Weller Gunter
Published: September 2017

On the McCall Glacier, an Arctic glacier in the eastern Brooks Range, northern Alaska, a heat balance study was carried out during the summer of 1970 to investigate quantitatively the relationship between energy transfer, climatic parameters and melting processes. Considering the individual energy balance terms, it was found that radiation is the most important heat source for snow and ice melt. The melting period itself is only 11 weeks long, which is quite short. The evaporation overcompensates for what little condensation occurs, and amounts to about 2% of the total ablation. Evaporation is more important in the spring, but becomes decreasingly so during the summer. The melt water which percolates into the snow-pack and refreezes at a lower level is a more effective way of transporting energy into the ground than conduction, and is of importance during the beginning of the melt period. The summer balance is considerably less energetic than over the tundra north of the Brooks Range. The main difference is a higher surface albedo, and to a lesser extent the protected nature of the glacier in a deep valley on a N–S axis, which reduces the duration of possible sunshine by 39% in summer. These are the important factors in maintaining the McCall Glacier and other similar glaciers in an otherwise low precipitation area.
Erebus Glacier Tongue, Mcmurdo Sound, Antarctica
Authors: Holdsworth G.
Published: September 2017

Examination of the past and present behaviour of the Erebus Glacier tongue over the last 60 years indicates that a major calving from the tongue appears to be imminent. Calculations of the regime of the tongue indicate that bottom melt rates may exceed 1 m a−1. By successive mapping of the ice tongue between the years 1947 and 1970, longitudinal strain-rates were determined using the change in distance between a set of 15 teeth, which are a prominent marginal feature of the tongue. Assuming a flow law for ice of the form where τ is the effective shear stress and is the effective shear strain-rate, values of the exponent n = 3 and B = 1 × 108 N m−2 are determined. These are in fair agreement with published values.
The Influence of Cloudiness on the Net Radiation Balance of a Snow Surface with High Albedo
Authors: Ambach W.
Published: September 2017

The short-wave and long-wave radiant fluxes measured in the accumulation area of the Greenland ice sheet during a mid-summer period are discussed with respect to their dependence on cloudiness. At a cloudiness of 10/10, a mean value of 270 J/cm2 d is obtained for the daily totals of net radiation balance, whereas a mean value of only 75 J/cm2 d is observed at 0/10. The energy excess of the net radiation balance with overcast sky is due to the significant influence of the incoming long-wave radiation and the high albedo of the surface (average of 84%). High values of net radiation balance are therefore correlated with high values of long-wave radiation balance and low values of short-wave radiation balance.
On the temperature gradient in the upper part of cold ice sheets
Authors: Philberth K. , Fédérer B.
Published: September 2017

The influence of the surface slope on the temperature profile in the upper part of a cold ice sheet can be described by a function which is independent of the geothermal heat and the heat of friction. This function is calculated for the two-dimensional and the axisymmetric cases. In the two-dimensional case its simplest form is proportional to the horizontal velocity and to the height above bedrock reduced by a constant; another form of this function is approximately proportional to the square of velocity and height.
Screen Temperatures and 10m Temperatures
Authors: Loewe F.
Published: September 2017

At places with an annual mean temperature lower than −20°C on the Greenland and Antarctic ice sheets, the temperature at a depth of 10 m is close to the annual mean at the surface and at the level of the meteorological shelter. With temperatures higher than about −35°C the size and sign of the différences vary. With lower temperatures the 10 m temperature becomes increasingly lower than the air temperature, at the coldest Antarctic station, “Plateau”, by nearly 4 deg.
Heating and Melting of Floating Ice Shelves
Authors: Wexler H.
Published: September 2017

Based on an observed temperature profile through the Ross Ice Shelf at Little America and partial profiles in the Maudheim Is-shelf and the Filchner Ice Shelf near the Ellsworth I.G.Y. station, various models of heating with and without melting from below are analysed to find the residence time of the respective ice shelves over the ocean. Estimated movements are compared with observed shelf movements seaward. 100 and 200 yr. melting rates for an ice shelf initially 20.5° C. below the freezing point of seawater are found as functions of the deviation of sea-water from its freezing point and the eddy conductivity of the ocean below the ice shelf. Steady-state solutions based on constant accumulation and sinking in an ice shelf of constant thickness are discussed.

The effect of heating of an ice shelf from above and below as it moves to a warmer atmospheric environment is described and it is concluded that the decreasing temperature with depth found only in the Ellsworth ice is a result of its rapid motion from the cold region to the south-east of the station (Coats Land).
Snow Accumulation in North Greenland
Authors: Bull C.
Published: September 2017

Measurements of the annual snow accumulation have been made at many points on a traverse of north Greenland. In lat. 77–78° N. the annual accumulation above 1800 m. was about 13 gm. cm.−2 in the years 1948–53 and, in contrast to results which have been obtained further south, did not vary with longitude. In 1953–54 the accumulation was greater. The annual accumulation in north and central Greenland has varied significantly over the last 50 years, but similar variations are not shown in the precipitation records at coastal stations. Using all the available information, the mean annual accumulation on the Greenland Ice Sheet has been calculated as 29±3 gm. cm.−2.
Compactibility of Newly Fallen Snow in Eastern Canada
Authors: Williams G. P.
Published: September 2017

The critical density of newly fallen snow was measured during the 1956–57 winter season at two stations: Montreal Road Laboratories of the National Research Council, Ottawa, and the University of New Brunswick, Fredericton, New Brunswick. The relative compacted density or compactibility of newly fallen snow was found to depend on undisturbed density and snow temperature. A statistical equation was developed relating snow temperature and undisturbed density to the compacted density of the snow sample. Additional tests under cold room conditions indicate that grain size and grain-size distribution also have an appreciable effect on compacted density.
Measurement of the Slip of a Glacier Past its Side Wall
Authors: Glen J. W.
Published: September 2017

The velocity of flow of a glacier was measured at two places where the ice margin had no moraine debris between clear ice and unfragmented rock. In one of these places the point at which the measurement was made was only about 1 m. from the solid rock. It was found that at both sites the ice was flowing past the rock at a velocity of the same order of magnitude as the velocity of flow in the centre of the glacier in this region. Although conditions at the side of a glacier are not the same as at the bed, this large amount of slip is evidence for a high rate of slip all along the ice-rock interface, and this is in accordance with current ideas of the flow of ice below ice falls.
The Ice of the Central Polar Basin
Authors: Armstrong Terence
Published: September 2017

Recent investigations of the ice of the central polar basin have been largely done by Russians, and some of their results are given here. General characteristics of the ice and of the currents and bathymetry of the area are outlined. Attention is directed to advances in knowledge in two spheres; the effect of currents and local winds on ice drift, and the growth and structure of floes. To illustrate the latter, an explanation of the stratification of a 3 m. vertical section is quoted. In conclusion, the prospects of the work continuing, and of its results being made available, are assessed.
Pleistocene Glaciation in the Commonwealth of Australia
Authors: Browne W. R.
Published: September 2017

Pleistocene glaciation in the Commonwealth of Australia is confined to Tasmania and a small area on the mainland, chiefly in the Kosciusko plateau of New South Wales. Three glacial stages of decreasing intensity have been recognized—the Malannan, Yolande and Margaret Stages. These are characterized by ice cap, valley glacier and cirque conditions respectively. At its maximum the ice cover extended down to sea-level in western and southern Tasmania, but in New South Wales traces are not known below 1448 m. From consideration of snow line etc. it is estimated that during the maximum glaciation the temperature was about 13° F. (7.2° C.) lower than it is to-day.
A New Method for Recording the Grain-Structure of Ice
Authors: Higuchi Keiji
Published: September 2017

Separated etch pits can be produced by a simple operation using a plastic replica film. Combining this etching technique with Schaefer’s replica method, it is possible to record both the size distribution and the orientation of crystal axes of individual grains of ice.
On the Sliding of Glaciers
Authors: Weertman J.
Published: September 2017

A model is proposed to explain the sliding of any glacier whose bottom surface is at the pressure melting point. Two mechanisms are considered. One is pressure melting and the other is creep rate enhancement through stress concentrations. Neither of the mechanisms operating alone is sufficient to explain sliding. If both mechanisms operate together appreciable sliding can occur.
Observations in North Greenland Relating to Theories of the Properties of Ice
Authors: Bull C.
Published: September 2017

To test Nye’s formula relating maximum surface slope at a point on an ice sheet with the thickness at that point, observations were made of the surface slope in north Greenland. Values of the shear stress on the bed at these points are calculated. It is unlikely that variations of the shear stress can be related with rates of movement. It is suggested that the difference between values of shear stress in north Greenland and those in south Greenland is at least partly due to the presence of bottom melting in the north.
The Structure of Moraines in Lyngsdalen, North Norway
Authors: Galloway R. W.
Published: September 2017

The structure of some moraines in and around two glaciers in northern Norway was studied by the method of fabric analysis. It was found that englacial material tends to lie parallel to the direction of movement of the ice, and material in lateral and terminal moraines shows orientations which appear to be related to the conditions under which it was deposited.
The Determination of the Thickness of a Glacier from Measurements of the Value of Gravity
Authors: Bull C. , Hardy J. R.
Published: September 2017

A method is described of determining the thickness of a valley glacier from measurements of gravity. On a Norwegian glacier approximately 4 km. long and km. wide values of gravity were measured at points on four transverse lines. For comparison, values were measured at points on three lines in the valley below the snout of the glacier. The positions and altitudes of these gravity stations were determined by triangulation. After making corrections for the altitudes of stations and for the effect of the valley walls, the differences between the gravity values obtained on the glacier and those obtained in the valley below the glacier are attributed to the thickness of the ice. Four transverse sections of the glacier, obtained in this way, are given. Errors in the estimates of ice thickness should not exceed 20 per cent on the two lower cross-sections, nor 40 per cent on the upper two.
Part I: A Description of the Penny Ice Cap, its Accumulation and Ablation
Authors: Ward W. H. , Baird P. D.
Published: September 2017

The Penny Ice Cap on the Cumberland Peninsula of Baffin Island, N.W.T., Canada, was studied during the summer of 1953. This ice cap has an area of some 5900 sq. km. and rests on a 2000 m. high mountain range. It has ten major outflowing glaciers, three of which reach the sea in fjords. The progress of snow accumulation and ablation and the net annual loss or gain of water at various altitudes on the ice cap are recorded. The firn line is at about 1550 m. and the outflowing glaciers are noticeably retreating.
Glacier Movement in North-East Greenland, 1949: With a Note on Some Subglacial Observations
Authors: Battle W. R. B.
Published: September 2017

Work on the Fröya Gletscher, N.E. Greenland, appears to substantiate the evidence already brought forward for the irregular flow of glaciers over short periods. It appears possible to correlate the daily temperature regime with the flow of some “polar glaciers.” The distribution of thrust planes seems to have no noticeable effect on the flow. It is suggested that Block-Schollen movement may underlie the jerky motion of some of even the slower moving glaciers. A subglacial stream bed on the Skille Gletscher was explored from the snout for a distance of 500 m. It is estimated that at the farthest point the ice was 76 m. thick. There appears to be good observational evidence for de Martonne’s theory of medial moraines extending to the bed of the glacier.
The Classification of Snow Metamorphism
Authors: Sommerfeld R. A. , LaChapelle E.
Published: September 2017

A new classification of snow on the ground is based on the major physical processes involved in the metamorphism of a snow cover. The major divisions are based on (I) the mechanical damage to snow crystals during precipitation, (II) the transport of water vapor at constant temperature because of surface-energy differences, (III) the transport of water vapor along a thermal gradient, and (IV) firnification because of melting and refreezing, and pressure consolidation.
Ice-Resistivity Measurements on Paris Gletscher, East Greenland
Authors: Clark M. C. , Keyt M. H. , Pert G. J.
Published: September 2017

D.C. ice-resistivity measurements on the polar Paris Gletscher in East Greenland are presented. It is found that the observed profile is well described by a four-layer system. Near the surface there are two layers resulting from the penetration of the summer temperatures into the polar ice. Below this the ice has constant resistivity until the bed is reached, where contrary to expectation a high-resistivity layer is found.
Flexure of a Floating Ice Tongue
Authors: Holdsworth G.
Published: September 2017

Several analyses are given for the flexure of a floating polar ice tongue with the general dimensions of several kilometers wide by 200 in in thickness. The lengths considered are from 2 km to in excess of 10 km which is referred to as a long slab. The analyses are made under the separate assumptions that ice behaves as (1) an elastic material, (2) an elastic-plastic material, and (3) a fully plastic material, when reacting to flexure due to changes in sea-level. The elastic analysis shows that hinge-line stresses could become very high of the order of 15 bar) for slab lengths up to about 3·5 km reacting to sea-level changes of the order of ±50 cm. For slab lengths greater than this, the stresses at the hinge, as well as being significantly less than before, become independent of the length of the slab, dependent only on the slab thickness and the amount of deflection of sea-level. In the elastic-plastic analysis, the hinge-line stress cannot exceed a value of about 2 bar. This yield value is reached when sea-level departs about 50 cm from the mean. The fully plastic analysis requires more accurate knowledge of the constants in the flow law and their variation with density, temperature and salinity within the ice. However, the theory may be tested by measuring the diurnal change in strain-rate across the hinge-line zone. The process of calving of large tabular icebergs from such glacier tongues may demand sea-level changes of more than ± 1 m, or bending about more than one axis of the shelf.
Strength Tests on Newly Fallen Snow
Authors: Perla R.
Published: September 2017

Modified versions ofin situstrength tests previously applied to metamorphosed snow were developed to measure the mechanical properties of newly fallen snow during storm periods. A large drop-cone penetrometer, protected from the wind by an aluminum shell, was used to determine snow “hardness”. A lightweight model of the Haefeli ram penetrometer measured “ram numbers”. Shear strengths were obtained from large, light-weight frames. Some preliminary tests were made with a shear vane driven by a torque wrench. A new technique was devised for measuring tensile strength whereby a cantilever beam of snow is undercut until it fails under its own weight. Comparisons between the cantilever test and the shear-frame test show high ratios for tensile to shear strength. Cantilever strength plotted against density shows an order of magnitude variation in strength at all densities.
The Growth of Bonds and the Increase of Mechanical Strength in a Dry Seasonal Snow-Pack
Authors: Keeler Charles M.
Published: September 2017

Simultaneous measurements were made of bot the strength and structural properties of a dry, seasonal snow-pack. The densities of the snow studied ranged from 126 to 407 kg m−3. The mechanical strength of this snow as determined by insitu shear-wave test and a centrifugal tensile test increases exponentially with the increase in size of intergranular sands. Bonding increases at a rate substantially greater than that predicted by the classical sintering equations. It is suggested that this is due to the wide variety of stresses present in snow with these relatively low densities.
The Role of Stress Concentration in Slab Avalanche Release
Authors: Sommerfeld R. A.
Published: September 2017

Slab avalanches are shown to be released by brittle fracture. An analogy is drawn in which the snow-pack is considered to be a macroscopic, molecular model of glass. The analogy is examined qualitatively from two viewpoints: the Griffith fracture criterion, and stress concentration theory. The details of fracture propagation in a layered snow-pack are explained by means of stress concentration theory, and many details of slab avalanches are shown to be consistent with the proposed mechanism. The significance of various fracture surface markings is pointed out.
Movement of the Ross Ice Shelf Near Scott Base
Authors: Macdonald W. J. P. , Hatherton T.
Published: September 2017

The rate of movement of the Ross Ice Shelf has been determined at its terminal face to the south-east of Scott Base. An average rate of movement of 23 cm./day in a direction 270° True was determined for the period March 1957 to October 1958. The terminating face of the ice shelf in McMurdo Sound is only about 3 metres thick compared with a thickness of several hundred metres in the Ross Sea. Altimeter heights are used to demonstrate a thinning of the shelf which is attributed to melting from below.
Ice Movement Studies on the Skelton Glacier
Authors: Wilson Charles R. , Crary A. P.
Published: September 2017

The volume of ice that flows annually from the Skelton Glacier on the west side of the Ross Ice Shelf between the Worcester and Royal Society Ranges was determined during 1958–59 traverse operations to be approximately 791 × 106 m.3 or 712 × 106 m.3 water equivalent. Annual accumulation on the Skelton névé field and small cirque glaciers is estimated to be 1,018 × 106 m.3 water equivalent, but this figure can be reduced to 712 × 106 m.3 by assuming that 30 per cent of the expected accumulation in the lower slopes of the glacier is lost to adjacent areas of the Ross Ice Shelf by katabatic winds. It is evident that little or no contribution to the nourishment of the Skelton Glacier comes from the high plateau area of East Antarctica. It is suggested that this condition exists generally in the western Ross Sea and Ross Shelf area, and is responsible for the existence of the present “dry” valleys in the McMurdo Sound area.

Some estimates of local ice regime are made at two sites on the glacier where ice thickness and strain rates are known.
On the Glacial History of Antarctica
Authors: Hollin J. T.
Published: September 2017

The Antarctic Ice Sheet responds quickly to regime changes, and time lags in its fluctuations are relatively small. During the Pleistocene glacial stages of the Northern Hemisphere, world-wide temperature reductions reduced the plasticity of the ice sheet and made it thicker. The amount of thickening depended on the conditions at the ice base but it was small, for mechanical and thermal reasons. Also, during the northern stages, accumulation over Antarctica was probably less than now, but this too had little effect on the thickness of the ice sheet. The mass budget of the ice sheet alone, without the ice shelves, probably remained strongly positive; the ice sheet probably existed throughout the Pleistocene and is unlikely to disappear in the future. The area of the ice sheet is determined chiefly by the elevation of the “grounding line”, where the peripheral ice cliffs and ice shelves begin to float. During the northern stages, world-wide lowerings of sea-level displaced the grounding line downwards and northwards, and allowed the ice sheet to advance by amounts which account for nearly all the evidence for previous greater glaciations. In summary, the glacial history of most ice-free areas is governed not so much by climatic as by sea-level changes. Therefore, Antarctic glacial fluctuations were dependent on and in phase with those of the Northern Hemisphere. The field evidence from Antarctica has little bearing on the ultimate causes of glacial fluctuations, which might however be determined by field work on the planet Mars.
Indications of Recent Extensive Glacierization in North–Central Baffin Island, N.W.T.
Authors: Ives J. D.
Published: September 2017

Studies of the geomorphology and rock lichen development north of the Barnes Ice Cap prompt the conclusion that 70 per cent of this extensive, interior region was covered by permanent ice some 300 to 400 yr. ago. Contemporaneously the northern Barnes Ice Cap was significantly larger than today; it dammed up a lake in the upper Isortoq valley, over 80 km. long and up to 300 m. deep. Excluding the ice cap less than 2 per cent of the area is glacierized today; this represents a dramatic reduction in surface area of the former ice cover. Similarly, significant recession of the ice cap implies that glaciers of the “Baffin type” are in a less healthy budgetary state than hitherto has been assumed.

Proof of former extensive ice cover rests largely upon restricted rock lichen development. When sufficient time has elapsed for complete colonization, few indications of the former existence of an ice cover will remain. This type of glacierization may have affected large areas in the high Arctic. Absence of evidence ofglaciation, therefore, cannot be relied upon to delimit nunatak areas (plant refugia) during the last glaciation.