bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical drill for deep coring in temperate ice
Authors: Árnason Bragi , Björnsson Helgi , Theodórsson Páll
Published: September 2017

A rotary drill for deep coring in temperate ice has been constructed and tested. The total length of the drill is 6 m and its weight is 100 kg. A steel armoured cable carries power to the 2 h.p, electric motor of the drill. The diameter of the core is 90 mm and the maximum length of core is 2 m. An antifreeze mixture at the bottom of the hole was necessary to prevent refreezing of ice chips on the cutting bits.

A 415 m deep hole was drilled during the summer of 1972 into the temperate accumulation area of Vatnajökull. Core recovery was 99%. Because of a fault in the cable the bottom was not reached.
The local distribution of stress near a point of zero shear stress in a rectilinear flow field
Authors: Raymond Charles F.
Published: September 2017

The distribution of stress in the vicinity of a point at which shear stress magnitude is zero is investigated analytically for rectilinear flow of a fluid in a channel or pipe. For a fluid with non-linear power-law properties the contours of constant stress and velocity either approach circular or flat shapes near such a point, irrespective of the particular boundary conditions. There are no intermediate cases, although such intermediate behavior exists for linear fluids.
A Slip-Line Field Analysis of the Deformation at the Confluence of two Glacier Streams
Authors: Collins I. F.
Published: September 2017

The deformation and state of stress at the confluence of two glacier streams are analysed using the techniques of slip-line theory. The valley walls are taken to be vertical parallel planes and the deformation is supposed independent of depth. The mechanical behavior of ice is modeled by the ideal rigid/perfectly plastic material.

Detailed solutions are presented for the deformation at the confluence of one or more tributaries with a main stream and of two main streams. Attention is concentrated on predicting the number, position and magnitude of the bands of intense shear which emanate from some of the junction corners. The predictions of this idealized theory are compared with field data from a confluence on the Kaskawulsh Glacier, Yukon Territory, Canada.
Changes in the Behaviour of the Unteraargletscher in the Last 125 Years
Authors: Haefeli R.
Published: September 2017

All the measurements involved concern the glacier tongue between its end and 2 600 m a.s.l. The total loss of volume of the Unteraargletscher since its last maximum advance (1871) is estimated to be 2.4 km3, which corresponds to a mean surface lowering of 0.67 m/year (referred to a total glacierized area of c. 40 km2 on average). The considerable slowing down of the glacier flow velocity over the 125 years is primarily attributable to the marked decrease in the sliding component, whereas the shear component has only changed slightly. This behaviour is connected with the fact that the decrease in ice thickness has been accompanied by an increase in surface slope, so that the two effects on the shear component partially compensate each other. The seasonal variations in surface velocity were measured simultaneously at two profiles by Agassiz and his team in 1845/46. These variations are due to the variable amount of melt water and the resulting variations in hydrostatic pressure in the contact zone between ice and bedrock, in which the plastic contraction of the water channels plays a decisive role. This leads to the problem of water circulation in the interior of a glacier and its importance in the sliding process. Finally a simple method for the approximate calculation of the longitudinal profile of the surface of a glacier tongue in a steady state and with constant ablation is indicated.
The Location and Timing of Deep Slab Avalanches
Authors: Bradley Charles C.
Published: September 2017

Winter observations in the northern Rocky Mountains of Montana show two periods during which one may expect a collapsing snowpack and accompanying avalanches: (1) shaded and sheltered areas: December-February; (2) sunny and exposed areas: March-May. These periods appear to be linked in part to the cyclic rise and fall of strength in the basal snow layer. It is suggested that sheltered slopes are often about a half-cycle ahead of sunny slopes because sheltered slopes tend to retain the early snows which later become the critically weak basal layer on these slopes.
The Pleistocene Epoch in East Anglia
Authors: West R. G.
Published: September 2017

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

The evidence for the existence of small glaciers in the cwms of the Caernarvonshire mountains during the Late-glacial Period is presented, and by an analysis of their distribution some of the factors responsible for their formation are deduced. These were primarily protection from insolation, drifting of snow into the cirques by wind and the distribution of precipitation.
Origin of Potholes in Glaciated Regions
Authors: Higgins C. G.
Published: September 2017

A review of the inadequacies of the glacial moulin hypothesis for the origin of potholes.
Ice Recession in Dronning Louise Land, North-East Greenland
Authors: Wyllie P. J.
Published: September 2017

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

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

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

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

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

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

Two neighboring Patagonian glaciers are described. They are fed from the same ice field but one is advancing and the other retreating. Various possible causes of this phenomenon are described.
Variations in the Glacier Mass of Jostedalsbreen
Authors: Rogstad Olaf
Published: September 2017

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

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

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

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

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

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

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

The Burroughs Glacier, south-east Alaska, is a slow-moving remnant (14×3km.) of a much more extensive glacier. It is now entirely below the firn line; ablation has revealed ice structures and fabric once 300 m. or more below the glacier surface.

At the present glacier surface three kinds of ice are identified—foliated ice, coarse-grained border ice and very coarse-grained basal ice.

Two systems of fine-grained foliation are present. Differential movement in the glacier has caused recrystallization along closely spaced planes. At the glacier surface this produces a steeply dipping longitudinal foliation. A gently dipping foliation, having a regional trough-like structure, may be associated with former stratification planes or with former spoon-shaped shear surfaces.

The optic orientation of crystals in the coarser layers of the foliated ice shows three weak maxima, and in the finer layers a single weak maximum, corresponding to one of the coarse layer maxima, and normal to the gently dipping foliation plane. The other maxima in the coarse layers are orientated close to the poles of principal fracture planes.

In the coarse ice the fabric shows a pattern with three maxima similar to that obtained in torsion shear experiments. In the glacier the pattern may be formed by shear near the glacier bottom or along gently dipping foliation planes. Grain-size increases towards the glacier terminus, especially in the stagnant ice zone.

Structural evidence suggests that in the early stages of the Little Ice Age the ice flow was from west to east. Later it was to east and west from an ice crest in the upper Burroughs Glacier. Structures produced by present movement have been superimposed on older structures.
Some Physical and Mechanical Properties of Polar Snow
Authors: Ramseier René O.
Published: September 2017

Specimens of polar snow from the South Pole, Antarctica, were tested to investigate air permeability K (cm.sec.−1), ultimate compressive strength σc (g.cm.−2) and dynamic Young’s modulus E (g.cm.−2) as a function of density. Anisotropy in a single layer of snow (snow between two summer crusts) was found in all three properties. Comparison with data for snow from Site 2, Greenland showed an empirical relation for both areas:

Air permeabilities are different at the two sites because of time and meteorological effects.
Correction Factor for Accumulation Measured by the Thickness of the Annual Layers in an Ice Sheet
Authors: Nye J. F.
Published: September 2017

The annual layers in an ice sheet become thinner by plastic deformation, and measurements of annual accumulation by the examination of cores therefore need correction. A simple correction factor is derived.
Glaciological Reconnaissance of the Sukkertoppen Ice Cap, South-West Greenland
Authors: Bull C.
Published: September 2017

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

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

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

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

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

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

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

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

An analysis is made of the rate of bubble coalescence in an ice mass that is deforming. A total strain of at least 8 is required before appreciable coalescence occurs. The analysis has been applied to deforming ice shelves and ice sheets. No appreciable coalescence is expected in ice shelves but coalescence should occur in ice sheets (or glaciers) if the shear strain-rate at the bottom surface is of the order of 0·075/year or larger. Measurements of bubble concentration are capable of setting limits on paleo-strain-rates of the present ice sheets. Bubble migration down temperature gradients presents complications to the study of bubble coalescence.
Computations of the Possible Future Behaviour of Berendon Glacier, Canada
Authors: Untersteiner N. , Nye J. F.
Published: September 2017

If the surface of Berendon Glacier, British Columbia, Canada, rose by 19 m above its 1963 level at a certain point near the terminus it would reach the entrance to a mining tunnel. Computations are made to see whether this is likely in the near future.

We calculate the changes in mass balance that would be necessary to make the glacier, which is now retreating, start to advance and reach the tunnel in 40 years and 20 years respectively. The method fits polynomials to the advance—retreat data and then uses the λ coefficients of Nye (1963[b]) to infer the corresponding mass balance behaviour. It is concluded that if the mean mass balance should increase smoothly to +70 cm/year, which is a high but possible value, by the year 2003, the ice would reach the tunnel portal in 2003. But, even assuming a rather drastic deterioration in the climate in the future and a concomitant increase of the mean mass balance, the ice will not reach the tunnel portal within the next 20 years.
Investigations Into the Mechanical Properties of Alpine Snow-Packs
Authors: Keeler C. M. , Weeks W. F.
Published: September 2017

Data on the physical properties of seasonal alpine snow have been collected from the Beartooth Mountains near Cooke City, Montana (elevation ≈3000 m) and the Bridger Range near Bozeman, Montana (elevation ≈2200 m). Systematic measurements of snow density, temperature, structure, ram and Canadian hardness, centrifugal tensile strength and shear strength measured with a shear box and several types of shear vanes are included. Test results were grouped according to gross snow types (cohesive fine-grained “winter” snow. depth hoar, new snow, etc.) and whether the snow was wet or dry. Then interrelations between the different test parameters were studied. A plot of ram number versus density for winter snow gave a log-linear relation similar to that suggested for polar snows. Both shear-vane and centrifugal-tensile results when plotted as a function of porosity are well described by the negative exponential relation suggested by Ballard and Feldt. Depth hoar and wet snow invariably have lower strength values at any given density. There is an excellent one-to-one agreement between values obtained with the shear vane and the shear box.

Several field experiments were performed to study the sources of error in making in-situ mechanical tests on snow without utilizing a pit wall. Statistical analysis of the results shows that the main factor contributing to the experimental scatter is lateral inhomogeneity in the snow cover. There was no significant difference between the results of different operators. The standard deviation of a group of strength tests is shown to be directly proportional to the mean value of the group. This indicates that a logarithmic transformation should be made in handling snow strength results in order to stabilize the variance. It is emphasized that the systematic relations between snow properties invariably become obscured when different snow “types” are indiscriminately grouped together.
Determination of the Rate of Snow Accumulation at the Pole of Relative Inaccessibility, Eastern Antarctica: A Comparison of Glaciological and Isotopic Methods
Authors: Picciotto E. , Cameron R. , Crozaz G. , Deutsch S. , Wiloain S.
Published: September 2017

The rate of snow accumulation has been measured at the U.S.S.R. station situated at the Pole of Relative Inaccessibility (eastern Antarctic plateau). Five independent methods were used. The results, expressed in g cm−2 year−1, are as follows:

(1)

Accumulation-stake measurements show an accumulation of 3·1±0·5 in 1965. A maximum value of 3·6 for the 6–year interval 1959–65 is derived from snow-thickness measurements.

(2)

Firn stratigraphy was found difficult to interpret in terms of annual layers. An upper limit of 12 g cm−2 year−1 is suggested.

(3)

18O/16O ratios were measured along the upper 235 cm. Assuming that each maximum in the isotope profile corresponds to a summer season, the accumulation would be 8·6±0·9.

(4)

Gross β radioactivity as a function of depth was measured on three firn sections. The 1955 radioactive fall-out horizon is clearly marked, enabling the derivation of an average accumulation of 3·0±0·3.

(5)

The average accumulation over the last 80 years, derived from the 210Pb distribution with depth, is 3·1±0·3.

A multi-annual average accumulation rate of (3·0±0·3) is thus firmly established, as well as the validity of both the 210Pb method and the 1955 radioactive fall-out horizon method. Stratigraphie studies lead to uncertain results. Oxygen isotope variations give accumulation values which are too high by a factor of two at least.

Accumulation values of the same order of magnitude (2·8±0·2) were derived from radioactive fall-out measurements at the U.S. “Plateau” station.
A Flow Model and a Time Scale for the Ice Core from Camp Century, Greenland
Authors: Dansgaard W. , Johnsen S. J.
Published: September 2017

A flow model is described for the Camp Century area in Greenland. The horizontal velocity profile along the core is assumed to be uniform from the surface down to y = 400 m above the bottom. Below this level, the horizontal velocity vx, is assumed to decrease proportionally to y. Furthermore, at a given y, vx is assumed to be proportional to the distance x from the ice divide. The resulting vertical strain-rate under steady-state conditions gives the age of the ice as a function of y. The flow model has explained the measured temperature profile, and the time scale has been verified by comparison between observed stable isotope variations and past climatic changes (at least 70 000 years back in time) estimated by other methods.
Position of Ice Divides and Ice Centers on Ice Sheets
Authors: Weertman J.
Published: September 2017

Model calculations are made of the magnitude of the shift of the portion of an ice divide on a two dimensional ice sheet and of the “center” (the position of highest elevation) of a circular ice sheet when the rate of accumulation is different on different sides or in different sectors of an ice sheet. It is concluded that gross changes in the accumulation pattern are required to cause an appreciable shift of the position of ice divides or ice centers if the positions of the edge of the ice sheet are fixed.
Comparison of Three Contemporary Flow Laws in a Three-Dimensional, Time-Dependent Glacier Model
Authors: Rasmussen L. A. , Campbell W. J.
Published: September 2017

A numerical model for three-dimensional, time-dependent glacier flow (Campbell and Rasmussen, 1970) treated the ice as a Newtonian viscous fluid and related its dynamics to two large-scale bulk parameters: the viscosityvdetermining the ice-to-ice friction, and a basal friction parameterAdetermining the ice-to-rock friction. The equations were solved using the relatively simple flow law of Bodvarsson (1955) in which the basal shear stress is proportional to volume transport. Recent research suggests that a more realistic basal flow law is one in which the basal shear stress to some lower power (1–3) is either proportional to the vertically averaged velocity (Glen, 1958; Nye, 1960, 1963[a], [b], [c], 1965[a], [b], [c]) or to the ratio of the vertically averaged velocity to glacier thickness (Budd and Jenssen, in press).

In the present study a generalized flow law incorporating all of the above bulk basal flow laws is applied to the Campbell–Rasmussen momentum equation to form a generalized two-dimensional transport equation, which, when combined with the continuity equation, yields a numerically tractable set of equations for three-dimensional, time-dependent glacier flow. Solutions of the model are shown for steady-state flow and surge advance and recovery for a typical valley glacier bed for powers 1, 2, and 3 for each of the basal flow laws for a steady-state climate input and a given ice-to-ice viscosity parameter.
Refreezing of Interstitial Water in a Subglacial Cavity of an Alpine Glacier as Indicated By The Chemical Composition Of Ice
Authors: Souchez R. A. , Lorrain R. D. , Lemmens M. M.
Published: September 2017

With the aid of an atomic absorption spectrophotometer (Perkin Elmer 303), chemical analyses were performed on different types of ice collected in an enclosed natural subglacial cavity of the Glacier d’Argentière (French Alps). Contamination was reduced to background noise level of the instrument at each step of the procedure which was developed. One of the main problems encountered during the processing was the desorption of cations adsorbed on the surface of particles dispersed in the ice.

The mean composition in Na, K, Ca and Mg was established for glacier ice and for ice accretions hanging from the ceiling of the cavity or at the bedrock–glacier contact. The mean composition and the ratio (Na+K)/(Ca + Mg) of the ice accretions are higher than those of the glacier ice. This implies a refreezing of interstitial water which was enriched by desorption when, before refreezing, it was forced through the mud layer plastered at the base of the glacier.
Striated Ground in the Venezuelan Andes
Authors: Schubert Carlos
Published: September 2017

Striated ground was found above 3 600 m elevation in the Páramo de La Culata, Pico Espejo and Pico Bolívar areas of the central Venezuelan Andes. This ground, formed by nocturnal freezing and diurnal thawing of the contained water, consisted of aligned lumps of fine to coarse sand, separated by small discontinuous channels (1–3 cm wide). Sorting was observed in the form of pebble-rich and pebble-poor zones. Striated ground in the process of formation showed that needle ice filled the channels before thawing. Lack of sorting is an indication of very recent formation, probably the previous night. The orientation of the striae is compared with the wind direction. This indicates that the formation of needle ice in the ground reflects the direction of the freezing wind, producing striae orientated in that direction, thus supporting Troll’s (1944) original observations.
The Effect of Confining Pressure on the Mechanical Properties of Sand–Ice Materials
Authors: Alkire Bernard D. , Andersland Orlando B.
Published: September 2017

Cylindrical samples containing 0.59 mm to 0.84 mm diameter silica sand at about 97% and 55% ice saturation (the ratio of ice volume to sand pore volume) were tested at a temperature of −12° C in triaxial compression. Both constant axial strain-rate tests and step-stress creep tests provide information on the influence of confining pressure on the shear strength and creep behavior of the sand–ice material. Changes in the degree of ice saturation help show the influence of the ice matrix versus the sand material on the mechanical behavior. Data are discussed in terms of the Mohr–Coulomb failure law and creep theories. It is shown that the cohesive component of strength depends on response of the ice matrix, whereas the frictional component of strength responds in a manner very similar to unfrozen sand tested at high confining pressures. Experimental data show that creep rates decrease exponentially and creep strength increases with an increase in confining pressure.
Icebergs as a Fresh-Water Source: An Appraisal
Authors: Weeks W. F. , Campbell W. J.
Published: September 2017

A history of the idea of transporting large icebergs to arid regions to provide a fresh-water source is presented and the problem is considered in four main parts: (1) Location of a supply of icebergs. Only in the Antarctic are supplies of large tabular icebergs available. Data on the size distribution of these icebergs are reviewed and it is concluded that icebergs of almost any desired size can readily be located. (2) Towing. Steady-state towing velocities of different sized icebergs are calculated based on estimates of the drag of the icebergs and the bollard pull of tugs. Because drag increases with velocity squared, large icebergs can only be towed at very slow velocities (<c. 0.5 m/s). However, tugs that can be built within the capabilities of current technology are capable of towing extremely large icebergs. (3) Melting in transit. Calculations of melting indicate that, although melting losses are significant and may be excessive for small icebergs, when large icebergs are towed, large amounts of ice are left when the iceberg arrives at its destination. Towing trajectories, travel times, and ice delivery rates are calculated for optimum routes between the Amery Ice Shelf and Western Australia (A–A) and the Ross Ice Shelf and the Atacama Desert (R–A). Forces included in these calculations are towing, air, water, gradient current and Coriolis. Transit times exceed 107 d (A–A) and 145 d (R–A) with over 50% of the initial ice delivered. (4) Economic feasibility. After total towing charges are paid, it is possible to deliver ice to Western Australia for 1.3 mills/m3 of water and to the Atacama Desert region for 1.9 mills/m3. These costs are appreciably less than the expected price of water delivered at these locations (8 mills/m3). The water delivered by the operation of one super-tug alone would irrigate 16 000 km2. Problems related to both iceberg transport and processing are reviewed and although substantial problems do exist, they appear to be within the capabilities of current technology.

It is suggested that the overall idea is indeed feasible and should be explored further by specific groups of experts.
Seismic Evidence for Glacier Motion
Authors: VanWormer Douglas , Berg Eduard
Published: September 2017

Unusual seismic signals with weak P phases and well-developed monochromatic shear-wave trains have been recorded and their sources located near College Fiord, Alaska. Epicentral determinations show that they originate on or near glaciers. Some of the events have equivalent earthquake magnitudes of 2.0 to 2.5. These energy sources seem to be compatible with spasmodic glacier movement. Smaller events occur often—as many as 60 per day.
Resurvey of Bore Hole at Dye 3, South Greenland
Authors: Lyle Hansen B. , Gundestrup N. S.
Published: September 2017

The 2037 m deep bore hole at Dye 3 in south Greenland was surveyed in 1981, 1983, 1985, and 1986. The directional surveys show the ice flow is planar with a surface velocity of 12.2m/year at an azimuth of 060°, which agrees with surface velocity measured by navigation satellites. Measurements of hole diameter and inclination are highly correlated with dust content in the ice. The temperature measurements show strong convection in the hole fluid with a cell height of about 20 m and an amplitude of 0.1 K. The calculated mean in-situ ice density is 921.3 ± 1.5kg/m3. Due to ice deformation, the lowest 4 m of the hole were not accessible in 1985 and the lowest 180 m were not accessible in 1986.
Character of the Englacial and Subglacial Drainage System in the Lower Part of the Ablation Area of Storglaciären, Sweden, as Revealed by Dye-Trace Studies
Authors: Seaberg Sheliah Z. , Seaberg John Z. , Hooke Roger Leb. , Wiberg Daniel W.
Published: September 2017

During the 1984 and 1985 melt seasons, flow velocities and dispersive characteristics of the englacial and subglacial hydraulic system on Storglaciären, a small valley glacier in northern Sweden, were studied with the use of dye-trace tests. Similar tests conducted on one of the two principal pro-glacial streams provided a basis for comparison of the combined englacial-subglacial system with the pro-glacial one. Velocities in the two systems were broadly comparable after compensating for the effect of slope differences. However, velocities in the glacial conduits increased almost linearly with discharge. Analysis suggests that this can be explained by an increase in water pressure in the conduits, combined with a decrease in effective sinuosity, as discharge increases. Dispersivity (the ratio of the dispersion coefficient to the water velocity) in the glacial system is high early in the season but decreases progressively during July. This is believed to reflect a change from an extensively braided to a more integrated drainage system. Dispersivity is only slightly lower in the pro-glacial streams than in the late-season glacial conduits, suggesting similar degrees of braiding. However, retardation of dye due to temporary storage is greater in the glacial conduits. This suggests that the glacial streams have a larger number of stable eddies in which dye can be trapped for extended periods of time.
The Glaciological Studies of the Baffin Island Expedition, 1950: Part III: Equipment and Techniques
Authors: Ward W. H.
Published: September 2017

The following items of equipment and glaciological techniques used on the Barnes ice cap are described:

Thermo-electric boring in cold ice.

Mechanical drilling in (a) cold rock, (b) cold ice.

Measurement of temperature in ice and rock.

Snow kit and measurement of ice density.

Crystal rubbings on cold ice.
An Approximate Analysis of Melting and Freezing of a Drill Hole Through an Ice Shelf in Antarctica
Authors: Tien Chi , Yen Yin-Chao
Published: September 2017

An approximate analysis of (he processes of inciting and freezing of a drill hole, 500 m depth and 0.15 m m initial radius, through an ice shelf was made. Results are expressed in graphical form showing the time available for experimentation under the hole as a function of heating duration. It was also found that refreezing has a much slower rate than melting.
Development of a gateway for interoperability in community-based care: An empirical study
Authors: Ota Sakiko , Kudo Ken-Ichi , Taguchi Kenta , Ihori Mikio , Yoshie Satoru , Yamamoto Takuma , Sudoh Osamu , Tsuji Tetsuo , Iijima Katsuya
Published: September 2017

BACKGROUND:

Information and communications technology has attracted attention as a useful way of sharing care records in community-based care. Such information sharing systems, however, imposed the burden of inputting the same records into different information systems due to a lack of interoperability of the systems.

OBJECTIVES:

The purpose of this study was to develop a gateway that links information systems and to investigate the functionality and usability of the gateway through an empirical study.

METHODS:

We developed a gateway with healthcare and welfare professionals in Kashiwa city, Japan. The gateway system consisted of two sub-systems: a data exchange sub-system and a common sub-system. Regarding the security, we used the transport layer security 1.2 and a public key infrastructure. For document formats, we utilized the health level seven international, extensible markup language, and portable document format. In addition, we performed an empirical study with 11 scenarios of four simulated patients and a questionnaire survey to the professionals.

RESULTS:

Professionals of eight occupations participated the empirical study and verified the gateway to link information systems of six vendors. For a questionnaire survey, 32 professionals out of 40 reported that the gateway would eliminate the burden of inputting the same records into different information systems.