bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impurity Concentrations In Sea Ice
Authors: Addison J.R. 
Published: September 2017

AbstractThree 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

Abstract 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

Abstract 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.
Mechanism of Till Deposition Related to Thermal Conditions in a Pleistocene Glacier
Authors: Shaw John 
Published: September 2017

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractAcoustic 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.
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

AbstractSome 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.
Heating and Melting of Floating Ice Shelves
Authors: Wexler H. 
Published: September 2017

AbstractBased 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

AbstractMeasurements 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.
Measurement of the Slip of a Glacier Past its Side Wall
Authors: Glen J. W. 
Published: September 2017

AbstractThe 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

AbstractRecent 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

AbstractPleistocene 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.
Observations in North Greenland Relating to Theories of the Properties of Ice
Authors: Bull C. 
Published: September 2017

AbstractTo 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractWork 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

AbstractA 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

AbstractD.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

AbstractSeveral 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

AbstractModified 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

AbstractSimultaneous 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

AbstractSlab 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.