bluuebunny/crossref_metadata_2025 huggingface dataset:
Note on Model Studies of Folding of Moraines in Piedmont Glaciers
Authors: Ramberg Hans
Published: September 2017

The pattern of flow of moraine-carrying glaciers is studied by models whirled in a centrifuge. Because of the rather high centrifugal force (1,000 g), substances with high viscosity, such as bouncing putty and stitching wax (viscosity around 106–107 poises), can be used as glacier-imitation materials. As moraine-imitation material powdered hard wax is used. The strength and high viscosity of the model materials permit detailed structures to be studied without the disturbing effects of sagging after being run to the chosen stage in the centrifuge. Stroboscopic light makes it possible to follow the evolution of the flow and to stop the centrifuge and thus the flow at any stage.

Rather realistic-looking fold structures of the kind seen in some piedmont ice sheets develop readily after a few minutes’ run in the centrifuge.

The mechanism of fold evolution is discussed.

No slip (or shear) has taken place along a “foliation” which sometimes develops parallel to the axial planes of the folds.
Dust-Induced Albedo Changes of Polar Ice Sheets and Glacierization
Authors: Bloch M. R.
Published: September 2017

The custatic changes of the ocean in prehistoric and historical times are linked with the fate of the ocean-based salt industry, and are recognized as erratic. An hypothesis is proposed to explain these erratic changes with albedo changes of the polar ice sheets, caused in turn by erratic volcanic dust fall-out. Ash layers in Antarctic ice cores are connected with historical dislocations of maritime civilizations.

Albedo changes associated with the dusting of ice sheets are considered to be the cause of the decline of periods of glacierization generally. Such albedo changes are connected with volcanic activity on the one hand, and loess formation on the other, caused in turn by the growth of the ice sheets.
Theoretical Gravity Anomalies of Glaciers Having Parabolic Cross-Sections
Authors: Corbató Charles E.
Published: September 2017

Equations and a graph are presented for calculating gravity anomalies on a two-dimensional glacier model having a horizontal upper boundary and a lower boundary which is a parabola with a vertical axis of symmetry.
The Theory of Glacier Sliding
Authors: Weertman J.
Published: September 2017

The theory of the sliding of glaciers presented by the author in earlier papers has been generalized (1) by taking into account the resistance to sliding offered by obstacles both smaller and larger than the controlling obstacles and (2) by relaxing the assumption that ice is always in intimate contact with the bed at the down-stream side of an obstacle. The sliding velocities and controlling obstacle sizes which are found from the generalized theory are approximately the same as those found from the earlier theory. A new result obtained from the present theory is that a water layer an order of magnitude smaller in thickness than the height of the controlling obstacles can cause an appreciable increase in the sliding velocity. The generalized theory contains Lliboutry’s sliding theory as an extreme limiting case. For certain thicknesses of a glacier the sliding velocity is a double-valued function of the shear stress exerted at the bed.
Unconfined Creep of Polar Snow
Authors: O. Ramseier René , L. Pavlak Thomas
Published: September 2017

Snow samples from the Amundsen-Scott South Pole station and “Byrd” station, Antarctica, and “Camp Century”, Greenland were tested for creep under low stresses for various periods of time up to two years. Creep was analyzed as a function of density. Comparisons of compressive viscosities plotted against densities for all three sites showed three distinct regions representing three different mechanisms of densification.
Effects of crystallization and plastic flow on the thermoluminescence of ice
Authors: Ronca L. B. , Zeller E. J.
Published: September 2017

Glow-curves of ice, made in the laboratory, have a distribution of peak-height ratios, with the maximum at approximately 0.75. The distribution was probably caused by varying conditions of crystallization, impossible to control with the present equipment. Glow-curves of ice which has been made to flow have a distribution of peak ratios with the maximum at approximately 1.75.

It is concluded that dislocations in the crystal lattice effect the peak ratio. Dislocations are produced during crystallization by internal stresses, and to a greater extent, by external forces during the flow.
Drumlin Formation Related to Inverted Melt-Water Erosional Marks
Authors: Shaw John
Published: September 2017

Drumlin forms are described from maps and air photographs of a part of the Athabasca Plains, northern Saskatchewan. Three major forms, spindle, parabolic and transverse asymmetrical are recognized. These forms, which may show superimposed minor elements, depart from classical descriptions of drumlins, but are similar to moulds of erosional marks created by separated fluid flows. Assemblages of drumlins also show characteristics similar to those of erosional marks. The form analogy between drumlins and moulds of erosional marks is carried to a conclusion that drumlins may be formed by the infilling of erosional marks created on the under-side of glaciers by separated, subglacial melt-water flows. Estimates of specific discharge are obtained by means of an expected range of Reynolds number. Geomorphological evidence is given for large-scale erosion by subglacial melt water. A discussion of the sedimentology, stratigraphy, and deformational structure of the interiors of drumlins shows that they may be explained by the erosional-mark hypothesis. This paper emphasizes the importance of melt water as a geomorphic agent and may have broad implications for ice-sheet dynamics and profiles, rates of deglaciation, and the occurrence of bedrock thrusting by ice.
Early Discoverers XXXIII: John Hardcastle on Glacier Motion and glacial Loess
Authors: Smalley Ian J.
Published: September 2017

In 1890–91 John Hardcastle presented his views on glacier motion and the climatic significance of loess deposits. He should be recognized as a significant pioneer in the study of glacier-flow mechanisms, and more particularly, as the initiator of the study of loess stratigraphy and the multiple-event approach to the formation of loess deposits, especially glacial loess.
Experience with Shear Frames
Authors: Perla R. , Beck T. M. H.
Published: September 2017

The shear frame is a simple in situ device for indexing the shear strength of thin weak layers. The index is sensitive to shear-frame geometry, rate-of-pull, and shear-frame mass. It is time-consuming to carefully align the device on the Gleitschicht (shear failure plane) in a slab avalanche zone. The ratio shear frame index/shear stress of the Gleitschicht has a high variance, and may not be a fundamental measure of slab avalanche stability. Corrections for the normal stress on the Gleitschicht reduce the variance only slightly. Despite these limitations, the shear frame is a useful tool for gathering statistical data on strength distributions and anisotropies of the Gleitschicht until a more fundamental technique is developed.
Theory of glacial erosion, transport and deposition as a consequence of subglacial sediment deformation
Authors: Boulton G.S.
Published: September 2017

A theory of erosion, transport and deposition of unlithified sediments by glaciers is presented. It predicts the large-scale areal distribution of zones and rates of erosion and deposition in time and space through a complete glacial cycle, together with the resultant intensity of large-scale lineations (drumlins) which will be incised in the landscape. The theory also predicts the dispersal patterns of subglacial lithologies, together with the form of dispersal trains derived from distinctive sources and the vertical and horizontal distribution of lithologies within a till. It predicts major erosional discontinuities within tills and the formation of boulder pavements. It suggests that the dominant proportion of the lowland tills produced by Pleistocene mid-latitude ice sheets was generated by subglacial deformation and explains why they are predominantly fine-grained.

The theory is based on an analysis of glacier-dynamic processes and therefore can be used to infer the dynamic behaviour of former ice sheets from the distribution of tills and their lithologic composition.
Microwave emission from density-stratified Antarctic firn at 6 cm wavelength
Authors: West Richard D. , Winebrenner Dale P. , Tsang Leung , Rott Helmut
Published: September 2017

Previous observations have shown spatial covariances between microwave emission from Antarctic firn at 6 cm wavelength, physical firn temperature and firn-density stratification. Such observations motivate us to understand the physics underlying such covariances and, based on that understanding, to develop estimation methods for firn in which density, and therefore dielectric permittivity, varies randomly in discrete layers with mean thicknesses on the order of centimeters. The model accounts for depth profiles of the physical temperature, mean density and variance of random density fluctuations from layer to layer. We also present a procedure to estimate emission-model input parameters objectively from in situ density-profile observations, as well as uncertainties in the input parameters and corresponding uncertainties in theoretical brightness-temperature predictions. We compare emission-model predictions with ground-based observations at four diverse sites in Antarctica which span a range of accumulation rates and other parameters. We use coincident characterization data to estimate model inputs. At two sites, layered-medium emission-model predictions based on the most probable input parameters (i.e. with no model tuning) agree with observations to within 3.5% for incidence angles≤50°. Corresponding figures for the other two sites are 7.5% and 10%. However, uncertainties in the input parameters are substantial due to the limited length and depth resolution of the characterization data. Uncertainties in brightness-temperature predictions are correspondingly substantial. Thus brightness-temperature predictions for the last-mentioned sites based on only slightly less probable input parameters are also in close agreement with observations. The significance of agreements and discrepancies could be clarified using characterization measurements with finer depth resolution.
Internal and basal ice changes near the grounding line derived from radio-echo sounding
Authors: Uratsuka Seiho , Nishio Fumihiko , Mae Shinji
Published: September 2017

Evidence of changing basal and internal ice properties near the grounding line was derived from airborne radio-echo-sounder observations of the ice sheet around the Sør Rondane Mountains, Antarctica. From the trailing figure of the bottom-echo signal, the roughness of the ice bottom near the grounding line was inferred. Results show that the specular components of scattering begin to appear on the ice-shelf side of the grounding line. Furthermore, double-trip echoes were observed with a strong scattering in the shelf area, and their boundary of occurrence was very close to the grounding line. This is evidence of interaction between ice and sea water at the bottom of the ice shelf. We also examined the occurrence of internal layered echoes. In most of the area around the mountains, internal echoes were observed continously, but they were not found at or close to the ice shelf. The boundary between the appearance and disappearance of internal-layer echoes is distinct, and occurs 20–30 km inland from the grounding line. These results suggest that some major change may occur in the internal ice on the inland side of the grounding line.
Quiescent-phase evolution of a surge-type glacier: Black Rapids Glacier, Alaska, U.S.A.
Authors: Heinrichs T.A. , Mayo L.R. , Echelmeyer K.A. , Harrison W.D.
Published: September 2017

Black Rapids Glacier, a surge-type glacier in the Alaska Range, most recently surged in 1936–37 and is currently in its quiescent phase. Mass balance, ice velocity and thickness change have been measured at three to ten sites from 1972 to 1994. The annual speed has undergone cyclical fluctuations of as much as 45% about the mean speed. Ice thickness and surface slope did not change enough to cause the speed fluctuations through changes in ice deformation, which indicates that they are being drinven by changes in basal motion. The behavior of Black Rapids Glacier during this quiescent phase is significantly different from that of Variegated Glacier, another well-studied surge-type glacier in Alaska. The present medial-moraine configuration of Black Rapids Glacier indicates that a surge could occur at any time. However, ice velocity data indicate that the next surge may not be imminent. We belive that there is little chance that the next surge will cross and dam the Delta River.
Surface morphology and backscattering of ice-ridge sails in the Baltic Sea
Authors: Manninen A. T.
Published: September 2017

The triangular shape of an ice-ridge sail in the Baltic Sea was studied statistically. The dimensions and orientation of individual ice blocks were measured in several ridges. All measurements were carried out from the standpoint of backscattering research. The results confirm that given geometrical properties of the two sides of ice ridges are in general not equal. A slight negative correlation was found between the slope angle and width of the sail. All three orientations and all three size parameters of ice blocks on both sides of the ridges studied can be considered as normally distributed. A log-normal distribution, however, fits slightly better the dimensions of the orientationally best rectangular approximations of the polygonal main facets of flat ice blocks. Three-dimensional modelling of ice ridges is essential, since the total side-facet area visible is typically at least as large as the total main-facet area. Calculated incidence-angle distrubutions show that the broad distributions of orientations and dimensions make different redges appear very similar on radar images.
Observations of pressure effects on the creep of ice single crystals
Authors: Cole David M.
Published: September 2017

Experiments performed on ice single crystals oriented for basal slip indicate that the steady-state creep rate is only marginally affected by confining pressure up to 19 MPa, at a constant absolute temperature of 263 K. The observations Contradict earlier work at similar pressures and the disparity is examined in terms of experimental errors.
Sampling-rate effects on the properties of dye breakthrough curves from glaciers
Authors: Nienow Peter W. , Sharp Martin , Willis Ian С.
Published: September 2017

Dye-tracer techniques are widely used in infer the character of subglacial drainage systems. Quantitative analysis of dye breakthrough curves focuses on the determination of the water through flow velocity (u), the dispersion coefficient (D) and the dispersivity parameter (d = D/u). Together, these parameters describe the rate of passage of tracer through the drainage system and the extent to which the dye cloud becomes spread out during passage. They have been used to infer the nature of flow conditions within a drainage system and temporal changes in system morphology. Estimates of all three parameters, however, are dependent upon the sampling interval at which measurements of dye concentration used to define breakthrough curves are made. For a given breakthrough curve, the dispersion coefficient increases with the sampling interval, while the through flow velocity shows no systematic variation. As a result, the dispersivity also tends to increase with the sampling interval. Investigations of the sensitivity of parameter estimates to the sampling interval reveal that reliable estimates can be obtained only if the sampling interval is less than 1/16 of the time from dye injection to peak dye concentration. As a general guide, we Suggest that, ideally, quantitative analyses of dye breakthrough curves should therefore be conducted only when this criterion can be met.
A Further Comparison of Glacier Velocities Measured by Radio-echo and Survey Methods
Authors: Doake C. S. M. , Gorman M. , Paterson W. S. B.
Published: September 2017

A comparison has been mager between ice velocities that were measured by the radio-echo technique and by a survey method on the Devon Island ice cap, Arctic Canada (lat. 75° 23' N., long. 82° 23'W.). Results were 2.58±0.11 ma1 by radar and 2.17±0.20 m a–1 by survey. The discrepancy between the two measurements is within the limits of statistical significance, and the methods are consigerred to give comparable results.
Ice and Ocean Tilt Measurements in the Beaufort Sea
Authors: Weber J.R. , Erdelyi M.
Published: September 2017

During the AIDJEX pilot study 1972 in the Beaufort Sea, the tilt changes of the fluid ocean surface and of the sea ice were measured with a hydrostatic level. Preliminary results indicate a tilt range of ± 5 μrad for the water surface and of ± 30 (μrad for the sea ice. The tilt change of the sea ice Δ δ appears to be directly proportional to the component of the velocity change of the ice drift parallel to the hydrostatic level ΔUd, according to the relationship Δ δ = 180ΔUdμrad m-1 s. It is conclugerd that the ice tilt is wind induced, and that the ice sheet tilts downward in the drift direction as a result of the moment exerted on it by wind and water drag. It is postulated that this tilt causes the ice to break at right angles to the drift direction. The tilt is a function of the length of an ice floe (or of the unbroken distance between two cracks), of the average ice thickness, of the average drag coefficients, and of wind and current velocities. Calculation of the ice tilt using a simple mogerl of a floating, rigid ice slab gives values which are very much smaller than the observed tilts. If the discrepancy between theory and observation can be resolved, or if an empirical formula between wind velocity and tilt angle can be gerduced freom continuous tilt observations which will be carried out during the AIDJEX main experiment, it will be possible, for a given wind, to estimate the maximum length of an unbroken ice sheet freom its estimated thickness, drag coefficients, and tensile strength. It should also be possible to calculate the average drag coefficients of a freee-floating ice pan, or of an ice island, freom tilt, wind, and current measurements. The curious relationship between tilt angle and atmospheric pressure gradient that Browne and Crary observed on the ice island T-3 in 1952 is explained as being the wind-induced tilt of the ice island rather than that of the fluid ocean surface.
The Maximum Extent of Glaciers in Part of West Falkland
Authors: Clapperton C. M. , Suggern D. E.
Published: September 2017

Although it is known that cirque glaciers once existed in the Falkland Islands, it has remained in doubt whether or not the islands were ever covered by ice caps or an ice sheet during the Cainozoic. This paper scrutinizes geomorphological evigernce on the south-eastern flank of a high massif in West Falkland. It is suggested that, at the time of their maximum extent in the Cainozoic, the largest glaciers were no more than 2.7 km long.
The Freeezing behaviour of Supercooled Water Drops
Authors: Gay M. J. , Latham J.
Published: September 2017

An electrodynamic containment system has been used to study the freeezing behaviour of supercooled water drops, of radius range 25 to 90 μm. The drops were freozen at temperatures between 0 and — 29°C in an environment whose relative humidity was approximately 90% with respect to ice. Freezing events were observed visually and photographically, and measurements were mager of the accompanying freactional mass loss Δm/m.

The most common moger of freeezing (70% of the drops studied) resulted in an apparently spherical ice particle. However, 18% exhibited spikes or other protuberances and the freeezing of 3% was accompanied by the ejection of numerous ice particles. In each of these situations values of Δm/m ranged freom about 5 to 15%. A further 9% of the drops exhibited one or more secondary mass-loss events, occurring several seconds after the freeezing process was complete; these were thus indicative of the ejection of ice particles.

Almost all of the values of Δm/m were significantly in excess of those predicted on the basis of evaporation during freeezing, suggesting that an additional mechanism of mass loss was also present. The measured freeezing times were consigerrably shorter than the classical values—at least, for the larger drops freeezing at warmer temperatures. Some visual observations were consistent with the “supersaturation wave” around a freeezing drop, which has been predicted by Nix and Fukuta (1974).
The Freeezing of Small Tyndall Figures in Ice
Authors: Mae Shinji
Published: September 2017

Tyndall figures, small thin discs of liquid water containing a vapour cavity, were formed in the centres of grains of pure, polycrystalline ice and observed while freeezing and growing. The freeezing experiments showed that the rate of gercrease in the radius of a Tyndall figure does not gerpend upon the radius of the figure, but does gerpend upon the thickness, h. Below a transition thickness, h = 12 μm, the rate of gercrease of the radius varied with h−2; above ht, with h−1. For growing figures the transition thickness was htg ≈ μm and was defined in such a way that when h > tg perturbations with wavelengths greater than 102 μm formed on the siger faces of the Tyndall figures.
Extraction of Trace Components from Large Quantities of Ice in Bore Holes
Authors: Oeschger H. , Stauffer P. , Bucher P. , Moell M.
Published: September 2017

A melting probe system has been gerveloped which can be lowered down to 400 m in an ice bore hole of 135-165 mm diameter. At the gersired gerpth, a section of the bore hole is isolated and evacuated. Afterwards several tons of ice are melted under vacuum with an electrical heater. The inclusions which are principally gaseous, may be collected both during or after the melting procedure. The application of this system is mainly in the field of dating polar ice by radio-active isotope analysis.
A Method of Concentrating the Major Impurities Contained in Ice by Ion Exchange
Authors: Ricq-de Bouard M.
Published: September 2017

This note gerscribes a method for concentrating Na, K, Ca, and Mg impurities in samples of snow and ice for analysis by atomic absorption in flame photometry. The cations are fixed on a Dowex 50 ion-exchange resin then selectively released and separately analysed by atomic absorption. This method allows the simultaneous treatment of a large number of specimens with concentration factors which can reach 60 to 75 and with very low risk of contamination or loss of the specimens.
Diffusion Law for the Dispersion of Hard Particles in an Ice Matrix that Undergoes Simple Shear Deformation
Authors: Weertman J.
Published: September 2017

A diffusion equation is obtained that describes the mechanical dispersion of a dilute mixture of solid particles within an ice matrix that is undergoing deformation. It is shown that within the limits of time intervals and strain-rates appropriate to the movement of glaciers and ice sheets, the dispersal distance usually is no larger than a distance about one order of magnitude greater than the size of the particles themselves.
Stress-Generated Ice Crystals in a Nearly Isothermal Two-Phase System
Authors: LaChapelle E.
Published: September 2017

The use of the two-phase system ice–water to illustrate the effects on equilibrium of both hydrostatic and non-hydrostatic stresses has been a recurrent theme in the history of thermodynamic theory. The effects of hydrostatic pressure on the melting point of ice are firmly established by theory and experiment. Those of non-hydrostatic stress are still a subject of debate today; several theorists have predicted ice re-crystallization under such stress, but the magnitude of any slight melting-point depression is not known with certainty. The recrystallization of ice caused by local variations in hydrostatic stress was predicted and experimentally confirmed over a century ago. Cavities deep within temperate glaciers provide a suitable environment for the occurrence of this latter phenomenon. A water-filled cavity intersected by a tunnel in nearly stagnant ice of the Blue Glacier, Washington State, U.S.A., was lined with large and unusual single ice crystals which apparently owe their origin to the effects of hydrostatic stress. Even the minute differences in pressure melting point around this cavity are adequate to remove the heat of fusion as ice forms within it. There is evidence that interstitial movement of melt water in the surrounding ice also contributes to the heat and mass transfer. The form of these crystals indicates that they grew into slightly supercooled water. It is suggested that this growth pattern is sustained by the existence of oriented stresses at the cavity walls.
On The Use of the Equilibrium Equations and Flow Law in Relating the Surface and Bed Topography of Glaciers and Ice Sheets
Authors: Collins I. F.
Published: September 2017

In a recent paper Robin has developed a method of calculating the relation between bed and surface topography of an ice sheet. He found that by including the effect of longitudinal strains in the equilibrium equation the correlation between theory and observation could be much improved. This paper is concerned with the mathematical justification of the assumption made by Robin.
On The Calving of Ice From Floating Glaciers and Ice Shelves
Authors: Reeh Niels
Published: September 2017

The deformation and the state of stress in the frontal part of a floating glacier is analysed by a method analogous with the beam theory, applied in engineering practice for determining stresses and deflections of a beans of an elastic material. Very rough approximations are made, the most severe being that of assuming the viscosity of the ice constant. Curves showing the progress in time of the deflections and the stresses in the frontal part of the glacier are given for the case of an infinitely wide glacier. The curves show, that the stresses are greatest at a cross-section situated at a distance of about the thickness of the glacier from the front, and that the stresses are of a magnitude which very likely will lead to fracture, resulting in the formation of an iceberg. It is shown that the magnitude of the icebergs as well as the frequency of the calving is a function of the thickness, the density, and the temperature of the glacier. Observations from nature supporting the theory are described. Finally other calving mechanisms for floating glaciers are briefly discussed.
Albedo Measurements of an Arctic Ice Cover From High Towers
Authors: Langleben M. P.
Published: September 2017

Radiometers, suspended at a height of 15 m between two towers anchored to the bottom of the ice cover, have been used to measure the average or integrated albedo of the surface. The work was carried out in May 1967 at Tanquary Fiord, Ellesmere Island (lat. 81° 25′ N., long. 76° 50′ W.) during the period when the surface of the ice cover was undergoing rapid change. The albedo was observed to have a value of almost 1·0, for a fresh snow cover, and about 0·8 for a weathered snow cover. It decreased to 0·6 as the wind partially cleared the surface of snow and gradually to 0·5 with further deterioration of the snow. The onset of melting, produced when the daily mean temperature exceeded 0°C, rapidly lowered the albedo to a value of about 0·3.
The Quantity of Melt Water in the Marble Point–Gneiss Point Area McMurdo Sound, Antarctica
Authors: Davis John R. , Nichols Robert L.
Published: September 2017

Among the important factors in the formation of melt water are: (1) The air and soil temperatures. (2) The presence or absence of debris on snow and ice. (3) The surface gradients of the glaciers. These gradients determine the areas of snow and ice in the zone where melting can occur as well as the amount of insolation. (4.) The orientation of snow and ice slopes. In general, in the Southern Hemisphere north-facing slopes receive more insolation than south-facing slopes.

The main source of the melt water is Wilson Piedmont Glacier, and the snowdrift-ice slabs are next in importance. The seasonal snowfall is not an important source, nor is the ice in the active zone. As no rain has ever been reported, all run-off is melt water.

The seasonal discharge of the Surko and Scheuren Rivers was roughly measured in 1957–58. It was found to be approximately 13 m3 s−1 d for the Surko River and approximately 19 m3 s−1 d for the Scheuren River, and it seems likely that the total seasonal discharge of all streams in the area was not far from 50 m3 s−1 d.
Determination of Temperature on Ice Caps by Seismic Methods
Authors: Thyssen F.
Published: September 2017

An empirical formula, derived by the author for the seismic velocities of P waves in glaciers and ice caps, is used to determine the temperatures which can be deduced from the maximum and the mean vertical velocities. With the aid of several examples from previous publications, these temperatures are discussed and, as far as they are available, direct temperature measurements are compared with the derived temperatures.
Distribution of Surging Glaciers in Western North America
Authors: Post Austin
Published: September 2017

In western North America 204 surging glaciers have been identified by aerial photographic observations. These glaciers exhibit either intense crevassing and rapid ice displacements during surges or distinctive surface features which have resulted from past surges. Distribution of these unusual glaciers is not random throughout the glacierized areas, as they occur only in the Alaska Range, eastern Wrangell Mountains, eastern Chugach Mountains, Icefield Ranges, and the St Elias Mountains near Yakutat and Glacier Bay. No surging glaciers have been identified in the Brooks Range, Kenai Mountains, west and central Chugach Mountains, west and central Wrangell Mountains, Coast Mountains, Rocky Mountains, Cascade Range, Olympic Mountains, or Sierra Nevada. No definite reason for this restricted distribution is apparent. Surging glaciers are found in maritime to continental and temperate to subpolar environments. Practically all physical forms of glaciers are represented. The restricted distribution does not relate to topography, bedrock type, altitude, orientation, or size of glacier. Some surging glaciers are associated with fault-related valleys, but neither recent faulting nor earthquakes have initiated surge activity. Possible causes for the limited distribution of surges are unusual bedrock roughness or permeability in certain areas, anomalously high ground-water temperatures, and/or abnormal geothermal heat flow.
On the Rates of Growth of Grains and Crystals in South Polar Firn
Authors: Gow Anthony J.
Published: September 2017

The size of firn crystals as a function of age has been investigated in thin sections to a depth of 49 m at the South Pole. Grain cross-sections increased in size from 0.24 mm2 at 0.1 m depth to 0.63 mm2 at 10 m. Crystals, as distinct from grains, increased in size from 0.18 to 0.43 mm2 over the same interval, implying that grains are generally composed of just one or two crystals rather than several as is frequently contended. The mean crystal cross-section increased linearly with the age of the firn at a rate of 0.0006 mm2 year−1; in 388 year old firn at 49 m the crystal size measured 0.63 mm2. Analysis of crystal-growth data from other locations in Antarctica and Greenland also revealed a strong linear relationship between the mean cross-sectional arcas (D2) of crystals (in mm2) and their ages in years (t), i.e. . The fact that the temperature dependence of the crystal growth rate K can be expressed very satisfactorily in an equation of the form K = K0 exp (E/RT) confirms predictions that crystal growth in firn is essentially analogous to grain growth in metallic and ceramic sinters. An extrapolation of available data indicates that crystal growth rates in dry firn could be expected to vary by two orders of magnitude (0.0003 to 0.03 mm2 year−1) over the temperature range −60° to −15°C. A method of utilizing crystal growth-mean annual temperature data to determine accumulation rates in snow is demonstrated.
Ice-Fabric Study of the Mawson Region, East Antarctica
Authors: Kizaki K.
Published: September 2017

Attempts are made to test the relation predicted by Brace (1960) between strain-rates and the ice-fabric patterns obtained at Mawson station, east Antarctica. These orientation fabrics not only are hardly related to the prediction by Brace (1960) or Kamb (1959) but also change easily within a strain grid with 100m diagonals.

Stable patterns of two- and three-maximum fabrics are confirmed. The latter is common and stable in the coarse ice at the surface of the ice sheet. It is apparent that the fabric patterns are generally related to the grain-size. The single-maximum fabric always occurs in fine-grained ice, then more maxima are formed in the course of grain growth.

It appears that syntectonic-secondary recrystallization is effective in producing the orientation fabrics with two, three and multiple maxima. Also, the maxima always shift away from the pole of foliation as grain-size increases and there are several stable positions of maximum such as 0°, 17°, 23° and 30°. It is expected that further stable angles would occur with coarser crystals as found in temperate glaciers.
On the Use of Asymptotic Solutions to Plane Ice—Water Problems
Authors: Lock G. S. H.
Published: September 2017

The paper considers one-dimensional freezing and thawing of ice–water systems for the conditions first examined by Stefan. An order-of-magnitude analysis applied to the governing equations and boundary conditions quantifies the error resulting from the neglect of various factors. Principal among these are density difference, initial superheat and variable properties.

Asymptotic solutions for the temperature distribution and interface history are developed for a wide range of boundary conditions: prescribed temperature or heat flux, prescribed convection and prescribed radiation. Comparison with known results reveals the general adequacy of the asymptotic solutions and an estimate of the error incurred.
Pressures Inside Freezing Water Drops
Authors: Visagie P. J.
Published: September 2017

A small quartz Bourdon tube was employed to measure the pressures that develop inside 7 and 10 mm diameter water drops freezing in stirred cold liquid baths. In general, the pressure repeatedly rose and then was relieved by cracks in the ice shell as freezing proceeded. The cracking pressure tended to increase with the shell thickness and was dependent on the freezing rate. Pressures up to 76 bar were observed. The effect of the concentration of dissolved gas was investigated. Empirical relationships were found relating cracking pressure to the internal radius of an ice shell and to the average temperature gradient across its thickness.
Radio Echo Sounding of Horizontal Layers in Ice
Authors: Harrison C. H.
Published: September 2017

Radio echo-sounding surveys of Antarctica and Greenland have revealed extensive layering within the ice. Formulae for the effective reflection coefficient, when viewed by a pulsed radar, are derived for isolated or multiple randomly spaced layers. In the latter case the variation in dielectric constant with depth is described by a vertical autocorrelation function and a standard deviation. Some measurements of the reflection coefficient of layers, and the dielectric absorption of ice are given. The significance of the fading of layer echoes and the possible causes of variations in the dielectric constant are considered and some further investigations are suggested.

It is concluded that the echo strengths found in the Antarctic may be explained by multiple layering, and that the necessary fractional change in the dielectric constant may be as small as 10−4. It is suggested that this change in dielectric constant may be due to differences in orientation of anisotropic ice crystals.
Dating of Polar Ice By 32Si
Authors: Clausen Henrik B.
Published: September 2017

32Si dating of glacier ice has hitherto been complicated by the poor knowledge of the half life. Furthermore, fall-out of bomb-produced 32Si impedes the determination of the specific activity of cosmic-ray produced 32Si in recent precipitation. Measurements on well-dated pre-bomb samples from the Greenland ice sheet establish a calibration for 32Si dating of up to 1 000 year old polar ice samples of the magnitude of 1 metric ton. If the technique is used on temperate glaciers, samples of pre-bomb deposits (or from after 1970) must be collected for comparison with samples of old ice, using an apparent half life of 295±25 years. Due to secular cosmic-ray flux variations, the true half life of 32Si is estimated at the slightly higher value of 330±40 years.
Subglacial Cavitation Phenomena Under the Glacier D’Argentière, Mont Blanc, France
Authors: Vivian Robert , Bocquet Gerard
Published: September 2017

The works undertaken on the Glacier d’Argentière in order to divert the subglacial stream, have allowed access to several natural cavities which correspond to places where the glacier loses contact with its rock bed. These cavities show a certain number of original phenomena both on the rock bed and also on the ice arch. Studies of the basal ice layer reveal peculiar characteristics which distinguish it from the rest of the ice mass: lamination, interstratification of ice containing sand with pure ice, crystallographic composition, and specific chemical composition.

The sliding speeds of the glacier are variable, and an increase in the friction below these cavitations is at the origin of a form of regressive glacial cavitation. The subglacial cavities are grouped together in a network transverse to the direction of glacier flow; they are interconnected by channels which are more or less open which allow proper thermal exchanges to be established and favour sliding.
Freezing Potentials and Currents in Potassium Fluoride Solutions at Constant Growth Rates
Authors: Hanley T. O’D. , Weber A. H.
Published: September 2017

The Workman–Reynolds effect was studied in the growth of ice on a monocrystalline seed, at constant growth rates and under steady-state conditions, from KF solutions at concentrations from 2 × 10−5 to 10 × 10−5 Normal. Freezing potentials increased with growth rate to a maximum of 12 V at 11.2 μm/s. Discharge currents through a 105 Ω shunt generally increased with freezing rate until a maximum of 1.5 μA at 11.2 μm/s. The charge transfer decreased with growth rate to 200 μC at 10.3 μm/s and then reached a maximum of 850 μC at 11.2 μm/s. Apparent diffusion coefficients of about 2 × 10−3 mm2/s increased slowly with growth rate until a rapid increase began, apparently associated with interface breakdown. Distribution coefficients of the order of 10−3, calculated from a criterion for constitutional supercooling, increased with concentration. Parameters for LeFebre’s model of the interface showed an interface thickness of about 6 mm, an interface capacitance near one-half pF/mm2, and an interface resistance of about 6 × 104 Ω/mm2. Several empirical relations between these quantities were disclosed. Comparison with values obtained for KC1 solutions with the same freezing cell shows that the KF solutions yielded higher values of freezing potential, charge transfer, and distribution coefficient, and lower values of diffusion coefficient, interface capacitance, and interface resistance.
The Magnitude of Jökulhlaups
Authors: Clague J. J. , Mathews W. H.
Published: September 2017

A review of available information on six self-dumping glacier-dammed lakes indicates that instantaneous discharge during a jökulhlaup is proportional to some power of the cumulative volume of water released rather than being a direct function of time. Information on these and four other self-dumping lakes, moreover, indicates that the peak discharge at the end of each jökulhlaup is approximately proportional to the two-thirds power of the total volume of water released during the flood.
Some Further Observations on the Behavior of an Ice-Dammed Self-Draining Lake, Glacier Bay, Alaska, U.S.A.
Authors: Moravek John R.
Published: September 2017

In an effort to ascertain the drainage mechanism of ice-dammed self-draining lakes, the author made observations on the behavior of the small Casement Glacier Lake in 1967. On 22 July when the first outburst of the lake occurred the water level dropped 31.92 m, leaving approximately 35 m of water remaining. Then, following a 2 week period of stability, the lake level fell gradually but steadily during the rest of the summer. Whereas a second rapid discharge occurred in 1965, one never did in 1967. The initial discharge was subglacial and resulted from flotation of the dam; the slow late-summer drainage, however, cannot be attributed to that mechanism and thus remains to be explained.
Anthropogenic Ice: Notes on a Dramatic Ephemeral Cryergic Landform
Authors: Barnett D. M.
Published: September 2017

A brief photographic history of a man-induced ice cone is given. This ephemeral feature created around a gas well on Melville Island, N.W.T., Canada, indicates that the present climate is not capable of sustaining a natural ice mass. Disappearance of the ice is projected by 1974 without intervention of man.
On the Formation of Small Marginal Lakes on the Juneau Icefield, South-Eastern Alaska, U.S.A.
Authors: Seppälä Matti
Published: September 2017

This paper puts forward an explanation of the origin of small marginal lakes (superglacial or moat lakes) occasionally found on the edges of valley glaciers. The explanation departs from earlier theories. On the basis of observations made on the Juneau Icefield in south-eastern Alaska, I have come to the conclusion that the lake basins are primarily blow-outs formed as a result of wind erosion.
Short-Term Snow Melt and Ablation Derived from Heat- and Mass-Balance Measurements
Authors: Föhn Paul M. B.
Published: September 2017

The daily snow melt calculated from meteorological observations is compared with detailed mass-balance measurements taking into account internal changes in density and free water content in the surface layers of a glacier snow-pack. The energy balance is calculated from measurements obtained by a meteorological station at the experimental site. In addition to the standard ablation measurements the run-off from the melting snow-pack was obtained for a few days. The snow-density profiles were measured with a portable gamma-transmission probe and the liquid-water content of snow was determined by a calorimetric method.

Agreement between the melt calculated by the heat-balance method and the mass changes observed in the mass-balance measurements is fair for daily periods. It appears that about 20% of the daily snow melt takes place internally as a result of penetration of solar radiation.
Lichen Growth on an Active Medial Moraine, Jotunheimen, Norway
Authors: Matthews J. A.
Published: September 2017

Abundant specimens of lichens, includingRhizocarpon geographicum, are reported from an active medial moraine on Storbreen, southern Norway. The size and distribution of two crustose and two foliose species are described. Inferences are made regarding the age, origin and population dynamics of the lichens. Some implications of the observations for lichenometric dating and use of lichens as indicators of moraine stability are discussed.
Instruments and Methods Comparison of the Snow Resistograph with the Ram Penetrometer
Authors: Lawrence William St. , Bradley Charles C.
Published: September 2017

Comparative tests of the snow resistograph with the ram penetrometer indicate that there is a high degree of correlation between the two instruments despite fundamental differences in operation. It is probable therefore that the two instruments are measuring essentially the same parameters and may be used interchangeably. The resistograph has a large advantage over the ram penetrometer, in terms of speed and ease of operation, and in its capacity to measure the strength of very weak snow.
A Comparison of the Energy-Balance and Bulk-aerodynamic Approaches for Estimating Glacier Melt
Authors: Hay J. E. , Fitzharris B. B.
Published: September 2017

Two models that estimate glacier ablation from simple meteorological observations are described. Both the energy-balance and bulk-aerodynamic approaches are used to determine the bulk-exchange coefficient for transfer of sensible- and latent-heat energy to the melting ice surface from 17 summer days of measurement on Ivory Glacier, New Zealand. The behaviour of the coefficient is examined over progressively increasing time intervals and as a function of wind speed and gradient, and of atmospheric stability. The models are verified with 36 d of independent data from a different summer on the same glacier. The more accurate short-term estimates of ablation are obtained using the energy-balance approach with empirically but independently derived values of the exchange coefficient.
The Annual Balance of North Cascade Glaciers, Washington, U.S.A., Measured and Predicted Using An Activity-Index Method
Authors: Pelto Mauri S.
Published: September 2017

The annual balance has been measured for ten North Cascade glaciers in 1983–84, 1984–85, 1985–86, and 1986–87 (1984, 1985, 1986, and 1987). Based on these data, an annual balance prediction method was designed and tested. Comparison of measured versus predicted annual balances indicates an accuracy of ±0.22–0.30 m. The method is based on annual measurement of the accumulation area ratio (AAR), and determination of the perennially constant activity index and area-altitude distribution on each glacier. The accumulation area ratio is determined from aerial and ground photographs at the end of the ablation season. The activity index is identified from observation of the rise of the snow line with time, compared to measured snow depths above the snow line. The AAR-activity index method was used to calculate the annual balance of 47 North Cascade glaciers in 1984, 1985, 1986, and 1987. The mean balance during the 4 year period was —0.33 m.

From the mass-balance records, it is apparent that North Cascade glaciers can be divided into six climatic sensitivity groups. Each glacier type responds differently to specific climatic conditions. The mass-balance variation for glaciers of the same type is small.

Since 1977, warmer, drier climatic conditions have prevailed in the North Cascades, resulting in the retreat of 42 of the 47 glaciers examined.
Effect of Glaciers on Annual Run-Off, Johan Dahl Land, South Greenland
Authors: Braithwaite R. J. , Olesen Ole B.
Published: September 2017

Run-off data for two basins in south Greenland, one of which contains glaciers, are compared with precipitation at a nearby weather station and with ablation measured in the glacier basin. Seasonal variations of run-off for the two basins are broadly similar while run-off from the glacier basin has smaller year-to-year variations. A simple statistical model shows that this is the result of a negative correlation between ablation and precipitation, which has the effect of reducing run-off variations in basins with a moderate amount of glacier cover although run-off variations may become large again for highly glacierized basins. The model also predicts an increasing run-off with ablation correlation and a decreasing run-off with precipitation correlation as the amount of glacier cover increases. Although there are still too few data sets from other parts of Greenland for final conclusions, there are indications that the present findings may be applicable to other Greenland basins.