bluuebunny/crossref_metadata_2025 huggingface dataset:
A Kinematic Wave Model of Glacier Surges
Authors: Palmer Andrew C.
Published: September 2017

The existing theory of kinematic waves on glaciers does not account for self-induced instability of the flow, or for surges which are not the result of external disturbances. Surges do however have much in common with kinematic waves. Unstable behaviour of glaciers can be explained by a straightforward modification of kinematic wave theory. In this modification the relation between the ice flow and the ice depth is not the same when the ice is accelerating as when it is slowing down. A similar effect has previously been shown to explain observed instabilities in the flow of highway traffic, a phenomenon which is otherwise adequately described by a simple kinematic wave theory.
A Statistical Analysis of Some Measures of the State of A Glacier’s “Health”
Authors: Dugdale R. E.
Published: September 2017

Data from Norwegian glaciers and statistical tests are presented which suggest that vertical net-budget gradient, ablation gradient and equilibrium-line altitude can be taken as characteristic for any particular glacier. The usefulness of these conceptual models as predictive techniques for the regional determination of glacier net budget when only a small sample is available, and in palaeo-net-budget studies, is shown to be limited.
The Effect of Non-Hydrostatic Stress on Intergranular Water Veins and Lenses in Ice
Authors: Nye J. F. , Mae S.
Published: September 2017

Polycrystalline ice at the melting point has been observed in the laboratory to contain veins of water at the places where three grains meet. Under uniaxial compression lenticular water inclusions appeared at grain boundaries perpendicular to the stress, while the nearby vein began to freeze. A similar effect occurred in tension on grain boundaries parallel to the stress. When the stress on the plane of the boundary was a pure shear stress, no effect was observed. The water lenses produced by stress increased in size and decreased in number after the stress was removed. The effect under compression is explained quantitatively by the combined effects of curvature and pressure on the melting point of an ice–water interface. The rate of formation of the lenses and of their coarsening is greatly reduced by the internal pressures set up in the lenses as a result of expansion on freezing and contraction on melting; transient creep to accommodate volume changes is an essential part of the process. The effect in a grain boundary under tension may arise from pressure caused by sliding on other grain boundaries; it was absent in a bicrystal.

It is concluded that internal melting and freezing at grain boundaries and veins will occur in temperate glacier ice, with some effect, not discussed here, on its permeability to water. Any pure solid at its melting point which has a dihedral angle for the liquid phase in contact with a grain boundary between 0° and 60° should show similar behaviour, in that non-hydrostatic stress should cause liquid to move away from triple junctions between grains and into grain boundaries. There may be implications for the Frank theory of the upwelling of melt fluid in the Earth’s upper mantle.
Deformation and Fracture of Ice Under Uniaxial Stress
Authors: Hawkes Ivor , Mellor Malcolm
Published: September 2017

Techniques for making precise uniaxial tests for strength and deformability of ice are described. Results are given for tests made in uniaxial tension and uniaxial compression at constant displacement rate, using bubbly polycrystalline ice. These results include stress/strain curves, elastic moduli, rupture or yield strengths, and failure strains, all for a range of strain-rates. A few results for ice doped with hydrogen fluoride are also given. The fracture mechanism for ice is discussed, and the test results are compared with data reported by previous investigators.
Radio Echo Sounding: Absorption and Scattering by Water Inclusion and Ice Lenses
Authors: Smith B. M. Ewen , Evans S.
Published: September 2017

The absorption of radio waves propagating through naturally occurring waters varies greatly with the electrical conductivity. Glacier melt water is very transparent and the attenuation by melt water layers is due to reflexion of power, whereas the attenuation of sea-water layers is due to absorption. The attenuation of soaked firn is usually prohibitive if the liquid is brine but it should not be a serious obstacle to radio echo strength if the liquid is rain-water or melt water. However, the magnitude of the scattered power can become greater than that from continuous (bedrock) reflectors if the size of the irregularities in the medium is large (approaching the radio wavelength in ice). Echo power formulae show that ice lenses may have the most serious effect and that low radio frequencies will be necessary to combat this.
Cyclic Surging of Glaciers
Authors: Robin G. de Q. , Weertman J.
Published: September 2017

A partly phenomenological theory and model are constructed of cyclically surging glaciers. During the after-surge portion of a surge cycle the lower portion of a glacier becomes increasingly stagnant. The upper part of the glacier gradually becomes more active as both its thickness and the magnitude of its basal shear stress increase. In the region between these two parts, called by us the trigger zone, the value of the derivative of the basal shear stress in the longitudinal direction of the glacier gradually increases with time. The pressure gradient in the water at the base of a glacier is related to the derivative of the basal shear stress. The pressure gradient decreases as the basal shear-stress gradient increases. The pressure gradient actually can take on negative values, a condition which produces “up-hill” water flow at the base of a glacier. A surge is started in the trigger zone when water is dammed there by a zero water-pressure gradient. The zone of fast-sliding velocities propagates up the glacier from the trigger zone with a velocity of the order of a surge velocity. The fast-sliding velocity zone also propagates down the glacier because of increased melt-water production.
Ice Volcanoes of the Lake Erie Shore Near Dunkirk, New York, U.S.A.
Authors: Fahnestock R. K. , Crowley D. J. , Wilson M. , Schneider H.
Published: September 2017

Conical mounds of ice have been observed to form in a few hours during violent winter storms along the edge of shore-fast ice near Dunkirk, New York. They occur in lines which parallel depth contours, and are evenly spaced in the manner of beach cusps. The height and spacing of mounds and number of rows vary from year to year depending on such factors as storm duration and intensity, and the position of the edge of the shore-fast ice at the beginning of the storm.

The evenly sloping conical mounds have central channels which increase in width lakeward. The ice between the channels forms headlands above the lake surface. Spray-formed levees develop along the headlands and slope gently away from the lake margin. Lake marginal walls of ice are usually vertical.

Spray, slush and ice blocks are ejected over the cone as each successive wave is focused by the converging channel walls. Ice blocks, interlayered with frozen slush and dirt, form bedding paralleling the sloping surface of cones, headlands and levees. These features are here termed “ice volcanoes” because their origin is in so many ways analogous to that of true volcanoes.
Instruments and Methods Glacier Bore-Hole Photography
Authors: Harrison W. D. , Kamb Barclay
Published: September 2017

A 51 mm diameter bore-hole camera allows observation of subglacial conditions, measurement of basal sliding rates, and study of internal structure and debris in ice at depth. The camera is simple in construction, field operation and maintenance. Water turbidity is a significant problem but it can be overcome by pumping.
“Postglacial”—A Term with Three Meanings
Authors: Mörner Nils-Axel
Published: September 2017

“Postglacial”, with a capital “P”, is a chrono-stratigraphical unit starting with the Preboreal at 10 000 B.P. De Geer used the same name for a period covering approximately the last 8 900 years. The same word “postglacial”, with a small “p”, is a genetic facies term telling us that the sediments were deposited without influence of the receding ice (in contrast to glacial deposits).
Radio Echo Sounding: Brine Percolation Layer
Authors: Clough John W.
Published: September 2017

An abrupt change in radio echo sounding travel time was observed on the ice shelf near McMurdo station, Antarctica, and was mapped by a zig-zag traverse. This boundary corresponds to the horizontal extent of brine penetration into the edge of the ice shelf.
A Technique for Producing Strain-Free Flat Surfaces on Single Crystals of Ice
Authors: Tobin T. M , Itagaki K.
Published: September 2017

The top surface of an accurately aligned ice crystal is melted by an aluminum surface and then frozen to a warm “Lucite” plate ant! tapped free. Etch-pit development shows that the dislocation density on the resulting surface is similar to die bulk dislocation density determined by X-ray topographic methods.
Ice on Mars
Authors: Sharp Robert P.
Published: September 2017

Ice unquestionably exists on Mars. Annual polar-region frost blankets are principally solid CO2, and perennial residual ice caps near each pole are probably water ice, except for a part of the north polar cap which may consist of a 1 km thick mass of solid CO2. Minor amounts of carbon-dioxide clathrate (CO2 · ≈ 6H2O) presumably accompany the solid CO2. The annual frost blankets may have a concentric banding with an outermost very thin layer of water frost, an intermediate narrow zone of clathrate, and a major central core of solid CO2.

Layered deposits and underlying homogeneous materials mantle large areas within both polar regions. These blankets are probably composed of dust, volcanic ash, or both, and possibly contain frozen volatiles. They may comprise the largest reservoir of water substance on the Martian surface.

Ground ice formed by the freezing of ascending de-gassed water substance may underlie the surface of Mars. Localized collapse of small areas may be due to ground-ice deterioration, and recession of steep slopes may have been caused by ground-ice sapping.

If liquid water ever existed in significant quantities on the Martian surface, intense frost shattering, widespread creep, and prolific development of patterned structures should have occurred because the thermal regimen of the surface is highly favorable to the freeze–thaw process. It is ineffective at present owing to the lack of liquid water.

No evidence suggests that the residual ice caps have ever acted like terrestrial glaciers in terms of erosion and deposition. Currently, they are too thin, too cold, and presumably frozen to their substrates. Their most important function is to buffer the atmosphere in terms of its H2O and CO2 content, thereby exerting a modifying influence on the surface environment of the entire planet.
Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A.
Authors: Meier Mark F. , Barclay Kamb W. , Allen Clarence R. , Sharp Robert P.
Published: September 2017

Velocity and strain-rate patterns in a small temperate valley glacier display flow effects of channel geometry, ice thickness, surface slope, and ablation. Surface velocities of 20–55 m/year show year-to-year fluctuations of 1.5–3 m/year. Transverse profiles of velocity have the form of a higher-order parabola modified by the effects of flow around a broad bend in the channel, which makes the velocity profile asymmetric, with maximum velocity displaced toward the outside of the bend. Marginal sliding rates are 5–22 m/year against bedrock and nil against debris. Velocity vectors diverge from the glacier center-line near the terminus, in response to surface ice loss, but converge toward it near the firn line because of channel narrowing. Plunge of the vectors gives an emergence flow component that falls short of balancing ice loss by about 1 m/year. Center-line velocities vary systematically with ice thickness and surface slope. In the upper half of the reach studied, effects of changing thickness and slope tend to compensate, and velocities are nearly constant; in the lower half, the effects are cumulative and velocities decrease progressively down-stream. Where the slope increases down-stream from 7° to 9°, reflecting a bedrock step, there is localized longitudinal extension of 0.03 year–1 followed by compression of 0.08 year–1 where the slope decreases. Marginal shear (up to 0.5 year–1) is strongly asymmetric due to flow around the bend: the stress center-line, where one of the principal axes becomes longitudinal, is displaced 150 m toward the inside of the bend. This effect is prominently visible in the crevasse pattern. Ice fluxes calculated independently by “laminar” flow theory and by continuity disagree in a way which shows that internal deformation of the ice is controlled not by local surface slope but by an effective slope that is nearly constant over the reach studied.
The Effect of Slope, Exposure and Mountain Screening on the Solar Radiation of McCall Glacier, Alaska: A Contribution to the International Hydrological Decade
Authors: Wendler Gerd , Ishikawa Nobuyoshi
Published: September 2017

The McCall Glacier is located in the Brooks Range, north Alaska. Most of its slopes have a northerly exposure with an inclination between 5°and 15°. The reduction in direct solar radiation owing to this northerly exposure is small (1.7%) in summer (ablation period, solar declination 20°), as the reduction in radiation received on a north slope during the noon hours is mostly compensated by the increase of energy during the “night” hours, as the sun does not set at that latitude in summer. With the shortening of the solar path, the decrease in direct solar radiation as compared with a horizontal surface becomes more important. At the equinox the loss is 24.8%, and at a solar declination of —10° (20 October or 24 February) even higher with 32.6%.

A further reduction in solar radiation is caused by the steep mountains, which surround the McCall Glacier. The duration of sunshine is reduced during the ablation period by nearly 40%, which, however, represents an energy loss of only 13.4%, as the screening effect of the mountains is most important with low solar angles, i.e. at times when the total energy received at the surface is small. The screening effect of the mountains becomes more severe with lower sun angles and shorter paths of the sun. During the equinox a loss in duration of 67.6%, and in energy of 55.7% is observed. For a solar declination of —10°, there is hardly any direct sunshine on the glacier at all. There is then a loss in duration of 93.6%, resulting in a loss of energy of 87.8%.

Together, these two components reduce the direct solar radiation by about 15% in the ablation period, 67% at the equinox and more than 90% at a solar declination of —10°.
Recent “Annual” Moraine Ridges at Austre Okstindbreen, Okstindan, North Norway
Authors: Worsley Peter
Published: September 2017

A series of minor moraine ridges lying on a lodgement till surface in front of the glacier Austre Okstindbreen are described. The available chronological control suggests that from 1957 through to 1970 a new ridge was formed each winter and that this pattern of annual production is probably also applicable to the period back to circa 1950. During the winter months of 1970/71 and 1971/72 the glacier advanced and deformed the ice cover of a marginal lake which now isolates the till areas from the ice margin. It is concluded that the ridges are true “annual” moraines formed primarily by ice push although the operation of a squeeze process during their genesis is not rejected.
Ice Fabrics and Petrography, Meserve Glacier, Antarctica
Authors: Anderton P.W.
Published: September 2017

Results of petrographic and fabric analysis of fine-grained cold ice from the tongue of Meserve Glacier, Antarctica, are described. Most of the basal ice is remarkably uniform in texture and shows an optic-axis fabric with a single strong maximum, which is consistent with the steady-state conditions of flow. Within 0.5 m of the ice–rock interface, irregularities in the bed cause flow perturbations which are correlated with recrystallization and changes in fabric of the ice. Optic-axis fabrics in the basal ice show close symmetry relationships with dimensional fabric and deformation symmetry. Grain-size of the ice increases towards the surface of the glacier and the single maximum of the optic-axis fabric undergoes a rotation about the flow vector. In the near surface, where strain-rates are relatively much lower, the optic-axis fabric symmetry is not closely related to either deformation symmetry or the dimensional fabric. Syntectonic recrystallization of ice throughout the glacier tongue characteristically produces a strong single-maximum fabric, the orientation of which in relation to the stress field is apparently determined by stress level. Under steady-state conditions of flow, the strength of the maximum also appears to be a function of stress level.
Chemical Profile of the Ross Ice Shelf at Little America V, Antarctica
Authors: Langway C. C. , Herron M. , Cragin J. H.
Published: September 2017

Measurements of the concentrations of Na+ K+, Mg2+, and Ca2+ were made on 28 samples from the 255 m deep ice core from Little America V. All concentrations decrease sharply with depth from the firn–ice transition at 52 m to somewhere between 125 m and 150 m. From 150 m to 250 m the cationic concentrations are relatively constant. This is interpreted to indicate that the ice above 125 m fell as snow on the Ross Ice Shelf and that ice below 150 m originated inland on Marie Byrd Land.
Differential Sea-Ice Drift. I. Spatial and Temporal Variations in Sea-Ice Deformation
Authors: Hibler W. D. , Weeks W. F. , Kovacs A. , Ackley S. F.
Published: September 2017

Measurements of mesoscale sea-ice deformation over a region approximately 20 km in diameter were carried out over a five-week period in the spring of 1972 at the main AIDJEX camp in the Beaufort Sea. They have been analyzed to determine non-linearities in the ice velocity field (due to the discrete small-scale nature of the ice pack), as well as a continuum mode of deformation represented by a least-squares strain-rate tensor and vorticity. The deformation-rate time series between Julian day 88 and 112 exhibited net areal changes as large as 3% and deformation rates up to 0.16% per hour. In the principal axis co-ordinate system, the strain-rate typically exhibited a much larger compression (or extension) along one axis than along the other. Persistent cycles at ≈ 12 h wavelengths were observed in the divergence rate.

A comparison of the average residual error with the average strain-rate magnitude indicated that strains measured on a scale of 10 km or greater can serve as a valid measure of the continuum motion of the sea ice. This conclusion is also substantiated by a comparison between the mesoscale deformation, and macroscale deformation measured over a ≈ 100 km diameter region.

Regarding pack-ice rotation, vorticity calculations indicate that at low temporal frequencies (0.02 h−1), the whole mesoscale array rotates essentially as an entity and consequently the low-frequency vorticity can be estimated accurately from the rotation of a single floe.
Effects of Oil Under Sea Ice
Authors: Stephen Wolfe L. , Hoult David P.
Published: September 2017

This paper describes laboratory research performed to determine the effects of crude and diesel oils on the porous sub-structure of Arctic sea ice. It includes a qualitative description of what occurs when oil is placed under the ice and an evaluation of some quantitative measurements made to determine the maximum extent to which crude oil can spread in an Arctic environment.
Surface profiles of the laurentide ice sheet in its marginal areas
Authors: Mathews W. H.
Published: September 2017

Surface slopes of ice lobes can be estimated from the gradients of their margins as shown by ice limits, by contemporaneous recessional moraines, or by lateral melt-water channels, with allowance being made for the dip of an ice lobe laterally, as well as forward, toward its extremities. Profiles can be fitted approximately to a parabola with the equation

in which h is the height above and x the distance up-stream from the terminus, in the same units, and A is a coefficient which varies from glacier to glacier. The coefficient A has a value of 4.7 m1 for both the Antarctic ice sheet inland from Mirny and the west central Greenland ice sheet. Several examples of late Pleistocene ice lobes within mountainous terrain of North America and New Zealand have values of A ranging from 2.9 ml to about 4.1 m1. For several ice lobes in the south-western part of the late Pleistocene Laurentide ice sheet, however, values are from about 0.3 to 1.0 m1, corresponding to basal shear stress of from about 0.07 to 0.22 bar. A major problem exists in accounting for the active movement of ice here under such low surface gradients and basal shear stresses. Evidence of basal slip, aided by high subglacial water pressure, should be looked for in the field. Alternatively, other possibilities for the explanation of such low surface gradients should be sought.
Heat Exchange over a Melting Snow Surface
Authors: De La CasinièRe A. C.
Published: September 2017

The relative importance of the principal elements of the thermal balance above snow during a period of melting has been evaluated using recent studies of the turbulent transfer in the boundary layer. Several anomalies in the profiles prove the continuing presence, near to the surface, of a thick layer of air apparently re-heated by the radiative flux. It is shown that the upper surface of this “exchange layer” ought to be considered as the new level for the origin of profiles, and taken as the exchange surface. The importance of nocturnal refreezing has been quantified. Excellent correlations have been found between mean air temperature and total energy balance; they have allowed the establishment of an approximate, non-linear expression for the effective daily ablation of snow as a function of mean air temperature. This relation gives satisfactory results at high and intermediate altitudes, in horizontal uncovered terrain. The measurements were made in the French Alps at 3550 m and in Spain at the latitude of Madrid à 1860 in.
Radio-Frequency Interferometry—A new technique For studying glaciers
Authors: Strangway D. W. , Simmons Gene , Latorraca G. , Watts R. , Bannister L. , Baker R. , Redman J. D. , Rossiter J. R.
Published: September 2017

A new method of electromagnetic sounding in resistive electrical environments has been developed for use in lunar exploration. It is applicable to the study of terrestrial glaciers and ice sheets. A horizontal electric dipole antenna on the ground is used to transmit power at frequencies of 1, 2, 4, 8, 16 and 32 MHz. A set of orthogonal receiving coils is mounted on a vehicle which traverses away from the transmitter. Field strength is recorded as a function of distance. Waves which travel above the surface interfere with waves from the subsurface, generating interference patterns which can be used to determine the dielectric constant, the loss tangent, and depth to reflecting horizons.

The technique was tested on the Athabasca Glacier in western Canada. At 1, 2 and 4 MHz the ice was found to have a dielectric constant of about 3.3, a loss tangent (tan δ) which is roughly inversely proportional to frequency giving values of f tan δ in the range 0.25 to 0.35 (where f is in MHz). These values correspond well with the known properties of ice near 0° C, which is a temperature typical of temperate glaciers. It has been possible to determine the depth of the ice but results are not always consistent with previous seismic and gravity surveys and with drilling. At frequencies of 16 and 32 MHz, scattering is the dominant feature of the results. At 8 MHz there is a transition from clear-cut interference patterns to the scattering patterns. From these findings, we suggest that the Athabasca Glacier has a large number of dielectric scatterers with dimensions less than about 35 m, probably due in large part to crevasses.
The temperature dependence of seismic waves in ice
Authors: Kohnen Heinz
Published: September 2017

In this paper all available seismic velocity data from Greenland and Antarctica are used to determine the relation between seismic velocities and temperatures in the ice.
On the Origin and Transport of Englacial Debris in Svalbard Glaciers
Authors: Boulton G. S.
Published: September 2017

Very considerable amounts of englacial debris derived from the glacier bed are contained in the polar glaciers of Svalbard. It is suggested that this debris is largely incorporated by basal freezing on the down-glacier flanks of bedrock obstructions, although other freezing mechanisms and thrusting may be important. The basal freezing hypothesis predicts that vertical and lateral variations in englacial debris content should reflect the variation in subglacial rocks over which the glacier passes; this prediction is tested against an actual englacial debris sequence. The mode of transport of debris, including its stone orientation fabrics, is described, and also the way in which it reacts in zones of intense compression.

A generalization is suggested: that polar glaciers tend to contain much larger amounts of basally derived debris than temperate glaciers. This supports the view that the englacial incorporation of debris is controlled by the temperature regime of the glacier, and could be of considerable importance in the interpretation of the regimes of ancient glaciers from their deposits.
On the Deposition of Subglacial and Melt-Out tills at the Margins of Certain Svalbard Glaciers
Authors: Boulton G. S.
Published: September 2017

Two types of basal till are described. First, melt-out tills released by the melting of masses of buried, debris-rich stagnant ice. Top melting of these ice masses is of greatest importance at the present day, and this produces tills which retain some of their englacial fabrics although some are changed by the melting process. Bottom melting of these masses could also produce such tills but these are likely to be much less important. Secondly, tills are also formed subglacially when basal debris-rich glacier ice becomes stationary beneath the over-riding active glacier. When these subglacial masses melt, water is expelled from the resultant till which also shows tectonic shear fractures induced by the over-riding ice. The mode of deposition of these latter tills could also be responsible for the production of certain rock-cored drumlins. Subglacial tills in Svalbard are relatively rare and, except under special conditions, are likely to react to ice loading by water expulsion, compaction and shear fracture rather than by fluid flow.

If a basal freezing hypothesis is accepted for the origin of most englacial debris, the lateral and vertical variations in erratic content can be predicted for many melt-out tills.
Electrical Phenomena accompanying the Phase Change of Dilute KCl Solutions into Single Crystals of Ice
Authors: Osterkamp T. E. , Weber A. H.
Published: September 2017

The Workman-Reynolds effect was investigated during the phase change of dilute (about 2 × 10-4 N) KCl solutions into single crystals of ice. The ice crystals were oriented with the c-axes either parallel or perpendicular to the growth direction. The solute distribution in the liquid phase. near the interface (within 10 mm), was obtained with a wire-type conductivity cell. For a crystal growth rate 8.8 μm/s the freezing potentials were + 10.0 V and + 6.0 V and the specific charge séparations were 1.3 ± 0 1 × 10-6 C/g of ice and 1 4 ± 0.1 × 10-6 C/g of ice for growth parallel and perpendicular. Respectively, to the c-axes of the ice crystals . The equilibrium solute distribution coefficient was found to be 4 × 10-3 for KCl solutions for both crystal orientations. An “apparent” (because of convection in the liquid phase) distribution coefficient ranged from 0.031- 0.074. The “apparent” diffusion coefficients ranged from 1.3–4.9 × 10-3 mm2/s and varied linearly with growth rate. The ionic distribution coefficients. K+ and K-, were approximately K+ - K- = - 2 × 10-5 and K+ + K - = 8 × 10-3 for the KCl solutions.
Frontal Recession of Sermikavsak, West Greenland
Authors: Gribbon P. W. F.
Published: September 2017

The results of two surveys of the frontal margin of a valley glacier in West Greenland are reported. If they indicate a constant or decreasing mass loss rate, the glacier shows similar behaviour to that of the nearby ice lobes on the ice sheet.
Air Temperature and Precipitation on the Greenland Ice Sheet
Authors: Diamond Marvin
Published: September 2017

Mean annual air temperatures and precipitation on the Greenland Ice Sheet, as estimated from snow profile studies and long-term meteorological records at coastal stations, have been used to prepare mean annual air temperature and mean annual precipitation charts for the Greenland Ice Sheet. It is shown that melting of surface snow may occur at elevations of about 1,300 m. in north Greenland and up to 2,700 m. in south Greenland. The warming trend in the Arctic, as indicated by increases in mean annual air temperature, may have occurred to a lesser extent on the ice sheet than at sea-level coastal stations. Annual accumulation of precipitation is two or three times as great at 2,700 m. on the west side of the ice sheet as at the crest. South of lat. 66° N., precipitation may be about twice as great on the east side of the crest as on the west side.
Density of Glacier Ice
Authors: Shumskiy P. A.
Published: September 2017

The density of glacier ice containing a given amount of air can be computed if it is assumed that both ice and air are subjected to a pressure due to the weight of overlying material. In this way it is possible to deduce the form that a curve of density versus depth should have for ice of a constant air content. Reasons for the divergence of observed depth-density profiles from those predicted by this theory are discussed, in particular the effect of the plastic-viscous behaviour of ice, which results in an air pressure differing from the hydrostatic pressure of the ice above. The empirical power-law relation between depth and density is discussed in the light of this theory, and is also used to derive relations for useful parameters characterizing the densification process such as rate of subsidence and rate of densification in terms of the depth, accumulation, and the constants entering the power law.
Applied Glaciology—the Utilization of Ice and Snow in Arctic Operations
Authors: Kingery W. David
Published: September 2017

In addition to field observations and quantitative analyses of natural phenomena, an opportunity exists for the application of glaciological knowledge. Major problems preventing the widespread use of ice and snow as structural materials are related to processing methods, properties of ice and snow, and deterioration during the melt season. These difficulties have been considered and an experimental program carried out to determine the feasibility of developing practical methods for using ice and snow as engineering materials. Results show that the development of improved processing methods for both ice and snow, the development of ice alloys with improved properties, and the extension of the use season provide real opportunities for applied glaciology.
Studies of Englacial Profiles in the Lake Hazen Area of Northern Ellesmere Island
Authors: Hattersley-Smith G.
Published: September 2017

Glaciological research on the ice cap to the north of Lake Hazen in northern Ellesmere Island was one of the main objectives of the Canadian I.G.Y. expedition to this area in 1957–1958. The method of nourishment of this ice cap and of Gilman Glacier, one of its southward-flowing outlets, was studied in pit and bore hole profiles above and below the equilibrium line, which was found at an elevation of about 1,200 m. Between an elevation of about 1,450 and 2,000 m. accumulation is by firn formation, while between about 1,280 and 1,450 m. interfingering of firn and superimposed ice occurs. At 1,800 m. the mean annual accumulation over the past twenty years is estimated as 12.8 g. cm.–2. On Gilman Glacier below the equilibrium line variations in density and crystal structure in an ice core to a depth of 25 m. are seen to depend on the proportion of firn to superimposed ice formed during accumulation. These variations correspond to past changes in the position of the equilibrium line. Englacial temperature measurements indicate a mean annual temperature of about –18.5° C. at an elevation of 1 ,040 m. A budget deficit for Gilman Glacier during two years of observations may be related to the increased summer melting of the last 20 years, deduced from pit studies at 1,800 m.
A Subglacial Gorge: La Gorge Du Guil (Hautes-Alpes)
Authors: Tricart J. , Soons J. M.
Published: September 2017

The Gorge du Guil (Hautes-Alpes) might be regarded as a typical example of a post-glacial gorge. In fact, this is not the case. Systematic and very detailed observations based on maps of the scale of 1 : 5,000 have revealed that the greatest part of the excavation of the defiles, cut across the bands of massive rocks, was accomplished by subglacial melt waters. Remnants of glacial deposits containing well-rounded pebbles, but whose finer constituents have been largely removed, occur a few metres above the present valley floor in each of these defiles. The down-cutting was very powerful, being facilitated by the crevassing of the ice, which was at the most 300 m. thick, over the ridges and in the constricted sections of the valley, and by the load carried in the englacial melt water. The sheltered and sunny climate, and the situation of the area below the limit of permanent snow also favoured erosion by melt water. By comparison, post-glacial down-cutting has been slight, not exceeding some ten metres in the massive strata, and appears to have been far less rapid than the subglacial erosion.
Seilandsjøkulen and Nordmannsjøkulen, Finnmark, Norway
Authors: Ford D. C.
Published: September 2017

Two small plateau ice caps in Arctic Norway are described and the amounts by which their areas have diminished during the past sixty years are assessed.
Effect of Hydrostatic Pressure on Velocity of Shear Deformation of Single Ice Crystals
Authors: Rigsby George P.
Published: September 2017

Apparatus was built for deforming ice crystals under hydrostatic pressures up to 350 atmospheres. Single crystals were placed in the mounts in such a way that the deformation occurred by gliding on the basal glide plane. It was found that the shear strain rate increased as the pressure was increased at constant temperature, but that the rate is practically independent of hydrostatic pressure when the difference between the ice temperature and the melting temperature is kept constant.
Australian Glaciological Contributions in Antarctica Preliminary Report
Authors: Mellor M.
Published: September 2017

The glaciological work of the Australian National Antarctic Research Expedition in 1957–58 is described, and some results are given in general terms.
The Role of Diastrophism in the Regimen of Glaciers in the st. Elias District, Alaska
Authors: Miller Maynard M.
Published: September 2017

The “earthquake avalanche” theory was invoked by Tarr and Martin in 1914 to explain anomalous turn-of-the-century glacier advances in Yakutat Bay, Alaska. The concept was given credence by the fact that this bay was the epicenter of a series of severe earth tremors in the autumn of 1899.

In considering alternative explanations, Tarr and Martin dismissed a record of excessive precipitation along this coast in the late 1870’s and 1880’s in the belief that the measurements were in error due to a “peculiarity in the method of measurement”. The disputed data are now known to be consistent with observed and inferred regional climatological trends in the latter half of the 19th century. The case for the climatological control of glacier fluctuations in the St. Elias District is therefore reassessed. Reference is made to new and extensive evidence from other districts in southern Alaska where the earthquake influence was negligible. It is concluded that the fluctuation pattern in the Yakutat area was not unique and that the diastrophism to which these particular resurgences have been attributed was actually but a supplemental and generally minor factor in a widespread set of glacial advances initiated by climatological causes.

The theoretical implications of changes in load conditioned by climatological parameters over the broad névés of the St. Elias Mountains are briefly discussed with respect to orogenic activity in this tectonically sensitive region.
The Pleistocene Glacial History of Tasmania
Authors: Jennings J. N. , Banks M. R.
Published: September 2017

A. N. Lewis’s scheme of Tasmania’s Pleistocene glacial history in terms of three full glaciations —Malanna (ice cap), Yolande (valley glacier) and Margaret (cirque glacier)—is criticized on a number of specific and general grounds. The area reliably known to be glaciated is thought to be much smaller than Lewis claimed. Future work on Tasmanian glaciations should not be grafted on to Lewis’s scheme and should aim especially to provide more reliable evidence for distinguishing and evaluating the glacial phases.
The Formation of Dirt Cones on Mount Ruapehu, New Zealand
Authors: Krenek L. O.
Published: September 2017

Due to the abnormally warm summers of 1955 and 1956 the glaciers of Mount Ruapehu deteriorated to such an extent that the ash layer of the eruption of 1945 was exposed everywhere. This caused a development of ice cones similar to those occurring in Iceland. Various factors, especially heavy crevassing, which took place at the same time, are responsible for the different ways of development of dirt cones on Ruapehu.
New Evidence of High-Level Glacial Drainage in the White Mountains, N.H.
Authors: Hattin Donald E.
Published: September 2017

A newly discovered pothole field in the White Mountains, N.H., is described, and is attributed to action of melt water from the last continental glacier. Discordance of pothole orientation with slope direction is explained by inferring the presence of a retaining wall of ice which controlled stream flow direction during the period of pothole formation. The potholes constitute the highest evidence of continental glacial drainage yet known in New England.
Glacier Mechanics in the Perfect Plasticity Theory
Authors: Lliboutry Louis
Published: September 2017

The author agrees with Nye’s correction of two errors in a previous paper; but disagrees with his other objections. Evidence is put forward for the significance of a second approximation in the theoretical equation for the profile of a glacier; for instance, it explains why bulges of increased thickness travel down glacier faster than the ice. Features of the front of the Glacier de Saint-Sorlin are reported. An attempt is made to explain crevasse formation in glaciers and the upturning of blue bands at the foot of an ice fall.
Precipitation Trends in Greenland During the Past Thirty Years
Authors: Diamond Marvin
Published: September 2017

The record of annual precipitation as obtained from stratigraphic studies on snow profiles in the interior of northern Greenland made in 1954 by SIPRE personnel shows a decreasing precipitation trend since 1920 with the largest decrease occurring since 1932. A residual mass curve analysis of the data indicates that, in spite of large fluctuations in the accumulated precipitation, the decreasing trend may be considered valid over a period of several years.
The Salt Content of Some Ice Samples From Nordaustlandet (North East Land), Svalbard
Authors: Gorham Eville
Published: September 2017

Analyses for pH, Na+, K+, Ca2+, Mg2+, HCO3−, Cl−, SO42− and NO3− have been made on land ice samples from Nordaustlandet, Svalbard. Total ions range from less than 0.02 to 0.46 milli-equivalents per litre, with sea salt generally the dominant component although calcium and magnesium bicarbonates are relatively more abundant in a surface sample heavily contaminated by soil material from an adjacent moraine. These ions, as well as potassium and sulphate, are present in most samples in excess of possible sea-spray supply. From the surface of a crevasse to 14 m. depth down one side the concentrations of all ions except nitrate fluctuate in a similar manner. Some possible implications of the results are examined.
Movement Observations on the Greenland Ice Sheet
Authors: Wallerstein George
Published: September 2017

During the summer of 1955 certain positions on the Greenland Ice Sheet that had been established by the French in 1951 were redetermined by observations of the sun in order to measure the motion of the surface of the ice sheet. A motion of 774 meters in four years in a southerly direction was noted at the Central Station. A motion of 611 meters in a westerly direction was noted at the French Mile 100. The uncertainty of the measures is large when the time scale is as short as four years, and expeditions to this area are urged to remeasure these positions and extend the markers for future use.
Changes in a Shallow Snow Cover Subject to a Temperate Climate
Authors: Gold L. W.
Published: September 2017

Observations were carried out on each significant layer of the snow cover at Ottawa (lat. 45° 24′ N., long. 75° 43′ W.) on the thickness of the layer, and the density, grain size distribution and degree of bonding of the snow in each layer. A logarithmic dependence on time was found for the layer thickness, and the density and grain size distribution. The product of layer thickness times the corresponding snow density was found to be constant when no melting occurred.
Ice Action on New England Lakes
Authors: Goldthwait Lawrence
Published: September 2017

Motion produced by ice expansion and by wind-blown ice cakes has modified the shores of lakes in northern New England, U.S.A. Twenty-six lakes have been studied, the processes observed, and measurements made of the rate and extent of ice action. Conclusions as to the effectiveness of the two processes are brought out.
An Investigation of Some Soil Polygons in Central Iceland
Authors: Dybeck M. W.
Published: September 2017

Near the edge of Langjökull ice cap there are many soil polygons. A cross-section showed them to be only surface features consisting of rocks in polygonal form embedded in silt. The area revealed much evidence that silt and small rocks often behaved like a liquid upon which heavier rocks would float. If the floating heavier rocks were pushed down into the “liquid,” mud would, in certain circumstances, ooze up a metre or so away. If a number of rocks were depressed the mud would ooze at points roughly equidistant from a few of the rocks, and spread to leave a polygon pattern. Conditions favourable for the sinking of heavy stones in this manner probably occur each spring.
Exfoliation Joints and Ice Action
Authors: Harland W. B.
Published: September 2017

Some generally accepted views on joints in rocks, particularly exfoliation joints, are summarized. Lewis’ pressure release hypothesis is assessed in relation thereto. An additional hypothesis is suggested whereby the existing stress system in rocks due to the removal of overburden which would favour exfoliation, would be augmented by freezing of the saturated rock when the ice retreats, so triggering this type of extension joint.
Banding and Volcanic Ash on Patagonian Glaciers
Authors: Lliboutry Louis
Published: September 2017

On aerial photographs of the Patagonian ice fields several types of bands can be identified; (1) fine ogives similar to Lüder’s lines in metals; (2) dirt bands which are both the outcrop of the annual debris strata of the névé and melt borders (the Schmelzrände of von Klebelsberg); (3) annual wave ogives below some ice falls; (4) annual ogives in regenerated glaciers, the formation of which is studied; (5) large melt borders which occur at longer intervals as a result of volcanic eruptions. These latter give evidence on the volcanic activity in the middle of the Patagonian ice fields.
Ablation Polygons on Snow—Further Observations and Theories
Authors: Richardson W. E. , Harper R. D. M.
Published: September 2017

A general description of ablation polygons is given and variations from widely distributed regions are examined. After discussion of the conditions in which they most frequently develop, possible explanations are considered, leading to the conclusion that the polygons result from ablation by turbulence in the surrounding air, and that the dirt fringes to the polygons may be explained by the “normal trajectory” theory.
The Old Moraines of Pangnirtung Pass, Baffin Island
Authors: Thompson H. R.
Published: September 2017

The “old moraines” of Pangnirtung Pass were constructed by trunk glaciers, tributary glaciers, glacial streams, rockfalls, talus-creep and other agents and processes. Rivers have since reworked or removed the deposits lying along the axis of the Pass and have begun to dissect the remainder. The old moraines have ice cores, which have tended to melt, collapse and flow downhill, thus further complicating the drift topography. The freshness of many old-moraine fronts implies a recent warming up of the climate, which is also reflected in the decay of the modern giaciers; but erosional undermining may also cause fresh fronts. Although no accurate date can be assigned to the disappearance of the trunk glaciers, A.D. 500 is given as a tentative estimate. There have since been at least two main advances of the tributary glaciers, of which the first followed close on the disappearance of the trunk glaciers and the second occurred not later than 1850.
Glacier Observations in North-West Spitsbergen
Authors: Mellor M.
Published: September 2017

Results of observations on several glaciers in the Kongsfjord area are described, and comments are made concerning accumulation and ablation, glacier flow and the variation of glacier fronts. The findings are compared with those of previous workers in this district and, in particular, with those of H. W. Ahlmann. A history of the fluctuation of several ice fronts during the present century has been compiled from various sources, and some observations dating back to 1837 are mentioned.
Preliminary Results of Research on Snow and Avalanches in Czechoslovakia
Authors: Vrba Miloš , Urbánek Bedřich
Published: September 2017

This paper gives a brief account of the results so far obtained in research in Czechoslovakia on the crystallographic, stratigraphical and thermal properties of snow cover, and the use of these data in avalanche investigations. Avalanche danger is predicted by comparing the penetration resistance of snow layers, measured with a rammsonde, with resistance graphs of typical avalanche situations.
The Use of the Rammsonde as an Instrument for Determining the Density of Firn
Authors: Bull C.
Published: September 2017

It has been found that in the cold firn of the Greenland Ice Sheet a direct relationship exists between the specific gravity of a layer and its “resistance to penetration” as measured with a Rammsonde. Corrections which should be applied to the measured “resistance” to allow for the frictional resistance of the walls of the hole on the Rammsonde tube are discussed. In certain circumstances these corrections can be estimated with reasonable accuracy for tube lengths up to three metres. The statistical method of obtaining the relationships between “resistance” and specific gravity is briefly outlined, and the effect of the size of the snow grains is also considered. It is shown that under these particular conditions it is possible, from measurements of “resistance”, to estimate the specific gravity of a firn layer with a standard error of 0.04, when the specific gravity of the sample is in the range 0.3 to 0.57.