bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Quaternary Rock Glaciers, Mount Kenya, Kenya
Authors: Mahaney W. C.
Published: September 2017

Rock glaciers in Teleki Valley on Mount Kenya exist above 4 000 m below steep valley walls where they are supplied with debris from avalanche couloirs. These valley-side rock glaciers consist of three or four lobes of rubble bounded by transverse furrows resulting from differential movement. No ice cores were observed in these rubble sheets, but “drunken forest” stands of Senecio keniodendron indicate the probable presence of interstitial ice resulting either from the metamorphism of snow buried under rockfall and slide-rock debris, or from freezing of water beneath the rock mantle. A geological survey of Mount Kenya in 1976 revealed that rock glaciers are anomalous in the Mount Kenya Afroalpine zone above 3 300 m. Analysis of weathering rinds indicates that several rock-glacier lobes were built up over a short interval of time at or near the end of the last glacial maximum (Würm). Oversteepened fronts on the westernmost lobes may have resulted from re-activation coinciding with the advance of glaciers during late Holocene time (<1 000 B.P.). Soils mantle 20% of the rock-glacier surface and have morphological characteristics comparable with soils forming on moraines of late Würm age in upper Teleki, Hausberg, and Mackinder Valleys.
On the Deterioration of a Grounded Iceberg
Authors: Venkatesh S.
Published: September 2017

This paper examines the deterioration of an iceberg grounded outside St. John’s Harbour, Newfoundland, Canada, in terms of its initial velocity prior to grounding. Theoretical expressions for the lifting of the iceberg and hence its buoyancy loss during grounding are derived as a function of initial iceberg velocity and ocean-bottom slope. Wave erosion and calving are two of the most significant mechanisms for iceberg deterioration. With wave erosion occurring on the seaward side of the grounded iceberg, model simulations are compared with observational data from a field study conducted on the grounded iceberg between 10 and 17 June 1983. Model–simulated time of re-flotation of the iceberg agrees with observations, for initial iceberg velocity of 0.3–0.5 m/s. Model simulations of the deterioration of the iceberg beyond the point of re-flotation are also compared with observations. Allowing for a 10% error in the observed above-water volume of the iceberg on 10 June, the model-simulated mass losses are in good agreement with observations. Best results are obtained for the model initialized with data observed on 14 June 1983, the first day for which detailed observational data are available following re-flotation of the iceberg.
Mass Balance of Four Cirque Glaciers in the Torngat Mountains of Northern Labrador, Canada
Authors: Rogerson Robert J.
Published: September 2017

The net mass balance of four small cirque glaciers (0.7–1.4 km2) in the Torngat Mountains of northern Labrador was measured for 1981–84, allowing three complete mass-balance years to be calculated. The two largest glaciers experienced positive mass-balance conditions in 1982 while all the glaciers were negative in 1983. The temporal pattern relates directly to general climatic conditions, in particular winter snowfall. Spatial variations of mass balance on the glaciers are the result of several factors including altitude, extent of supraglacial debris cover, slope, proximity to side and backwalls of the enclosing cirque, and the height of the backwall above the ice surface. Abraham Glacier, the smallest studied and with consistently the largest negative mass balance (–1.28 m in 1983), re-advanced an average of 1.2 m each year between 1981 and 1984. Mean equilibrium-line altitude (ELA) for the four glaciers is 1050 m, varying substantially from one glacier to another (+240 to –140 m) and from year to year (+60 to –30 m).
Debris-Influenced Sliding Laws and Basal Debris Balance
Authors: Shoemaker E.M.
Published: September 2017

In order to determine the effect of basal debris drag as a component in a sliding law, it is necessary to know the basal debris concentration. Does, for example, this debris concentration exhibit uniformity, in an average sense, across a valley? What effect does a localized region of high quarryability have on basal debris concentration down-stream? The analysis presented here suggests that, for the case of sparse debris, debris concentration tends to be uniform over the entire bed. Consequently, the debris-drag term in a sliding law will also tend to be uniform.

In order to reach the above conclusions, it is necessary to consider debris balance, the balance of the quarrying, abrasion, and debris-flushing rates. This entails proposing and testing quarrying and flushing laws, since these laws have not been previously proposed. It is concluded that the quarrying, flushing, and erosion rates depend weakly on the sliding velocity. Furthermore, the abrasion rate is negligible compared to the quarrying rate. (This conclusion depends partially on the definition of abrasion.) The quarrying rate also depends on other factors such as the effective pressure_pressure-fluctuation mechanism; the cross-valley dependency of this mechanism is investigated. The flushing rate is found to depend on the ratio, N-channel area/bed area, and on average N-channel diameter.
Antarctic Iceberg Distribution and Dissolution
Authors: Hamley T. C. , Budd W. F.
Published: September 2017

Shipboard observations (in accordance with Norsk Polar-Institutt guidelines) from 6 years of Australian National Antarctic Research Expeditions (ANARE) voyages have provided data giving a detailed knowledge of iceberg sizes and concentrations in the Southern Ocean between long. 60° and 140° E. The resulting size–frequency distributions are examined in conjunction with a knowledge of water movement along known drift tracks in a selected study area (between lat. 59° and 64° S., and long. 90° and 120° E.) to determine iceberg-dissolution rates. The “median life” (before breaking) of icebergs less than 1000 m in horizontal dimension is estimated to be 0.2 a, which is significantly lower than was previously thought. The mean melt rate is estimated to be 0.12 m d–1, which agrees broadly with previous laboratory studies. The relative contributions of melt, calving, and breakage, plus the enhancement effect of roll-over, are examined in estimating the natural dissolution rate. Breakage appears to be the dominant mechanism for larger icebergs with melt and calving able to explain the disappearance of icebergs in the smallest categories only (within the mean “median-life” period). Examination of the historical records of Captain Cook indicates that iceberg concentrations, as well as the northerly extent in this region 200 years ago, were compatible with the present data.
Role of Debris Cover in the Thermal Physics of Glaciers
Authors: Bozhinskiy A. N. , Krass M. S. , Popovnin V. V.
Published: September 2017

A mathematical model is presented of non-stationary melting processes of ice including particles of morainic material. The problem is treated as a Stephen-type one with the phase boundary of ice melting being located under the debris cover. The main terms of the heat-balance equation for a glacier surface are solar radiation and convective heat transfer. The quantitative relationships characterizing the effect of glacier run-off augmentation from under a thin layer of debris cover are obtained for different bulk moraine concentrations inside the ice. The concept of equivalent time is introduced. It is defined as the time elapsed until the moment the sub-moraine ice-ablation rate becomes equal to the ablation rate of clean ice. This moment signifies the beginning of the shielding stage. Thus, a glacier can be considered as a self-controlling system with respect to its summer run-off. A series of numerical tests for Djankuat glacier, Central Caucasus, has been carried out. The dynamics of moraine-cover growth and alterations of seasonal ablation rate under debris show perfect agreement between the computed data and the results of 14 years of direct observations. Some practical recommendations concerning artificial blackening of a glacier surface for augmentation of liquid run-off are presented. Conditions promoting increase of run-off are: relatively high albedo, relatively low summer air temperature, and relatively small convective heat transfer between the air and the ice surface. The method of artificially blackening a glacier surface is by means of a durable thin dark polymer film. In conclusion, some further aspects of the problem are discussed.
A tutorial on the use of control methods in ice-sheet modeling
Authors: MacAyeal Douglas R.
Published: September 2017

Control methods are recommended as an efficient means to estimate undetermined physical parameters and boundary conditions and, in so doing, to improve the fidelity of a given ice-sheet flow model to specific ice-sheet velocity observations. To accomplish this task, the underlying dynamics of the model are inverted. This permits model-tuning adjustments to be represented explicitly in terms of model/observation misfit. Advantages of the control method over trial-and-error techniques in common use are: (1) it is readily automated with little additional programming effort, (2) the tuning parameters and boundary conditions it achieves are assured to give the best possible fit between model and observation, and (3) it quantifies the uncertainty of tuning parameters and boundary conditions in situations where they are not uniquely determined.
TV-video observations of bed and basal sliding on Storglaciären, Sweden
Authors: Pohjola Veijo Allan
Published: September 2017

Four boreholes in Storglaciären, a small valley glacier in northern Sweden, were inspected with a video camera. In two of the boreholes, the apparent glacier bed was filmed. In one borehole, the bed was found to be composed of soft sediment, but in the other it consisted of bedrock. In the latter, the camera moved 5.6 mm relative to the bed during an 80 min period. The recorded camera movement showed a background motion which is in the expected range of basal sliding. Superimposed on the background motion, a jerky motion of a high-speed spike was found. The jerky motion is interpreted as a stress release induced by local topography at the ice–bed interface.
A new ice mill allows precise concentration determination of methane and most probably also other trace gases in the bubble air of very small ice samples
Authors: Fuchs Andreas , Schwander Jakob , Stauffer Bernhard
Published: September 2017

A new extraction system has been constructed and tested which allows the extraction of gases from air bubbles in ice without melting it. An ice sample of up to 20 g is crushed in a sealed container by a milling cutter and the gas escaping from the opened bubbles is flushed with helium to a Porapak column where it is stored until its injection into the gas Chromatograph. To avoid any contamination with CH4 produced by friction in the gear section, a helium-flushed rotary feed-through is used. CH4 analyses on ice samples of about 10 g from the last 1000 years give precise and reproducible results. In the future, it is planned to measure also the CO2 and N2O concentrations on the same sample.
Temperate glacier time response from field data
Authors: McClung D. M. , Armstrong Richard L.
Published: September 2017

The relationship of glacier response due to mass-balance changes is of fundamental importance when climate variations are to be understood. In this paper, two aspects of the problem are analyzed from field data: (1) advance/retreat of the glacier terminus due to changes in mass balance, and (2) cross-correlation of mass-balance data from two glaciers in the same climate zone. The results show: (1) the terminus can respond quickly in accordance with expected minimum time-scale, and (2) two glaciers in the same general climate zone may have very different yearly mass balance and advance/retreat behaviour. This latter result indicates the importance of local climate variations.
Estimation of subglacial hydraulic properties from induced changes in basal water pressure: a theoretical framework for borehole-response tests
Authors: Stone Dan B. , Clarke Garry K.C.
Published: September 2017

In this paper we develop a theoretical model describing water motion in a coupled borehole-subglacial flow system. The theory applies to basal drainage systems having multiple and extensive interconnected flow paths. Within this domain it encompasses a broad range of flow regimes, from laminar Darcian flow in a thick permeable unit to turbulent sheet flow in a very thin layer. Important terms in the model are highlighted by recasting the problem in dimensionless form. The non-dimensional formulation indicates that there are four free parameters in the coupled system. These parameters characterize skin friction in the borehole, and diffusion, transmissivity and turbulent transport in the subglacial flow layer. Dimensionless results show that, under most circumstances, the effects of skin friction in the borehole are negligible. Diffusion, transmissivity and especially turbulent transport in the basal layer are found to influence subglacial water flow strongly. We use our model to predict fluctuations of borehole-water levels that result from different types of disturbances. We show how this framework can be used to estimate subglacial hydraulic properties by comparing model results with data collected during field experiments on Trapridge Glacier, Yukon Territory, Canada in 1989 and 1990.
Determination of ice-shelf bottom melting by time-domain reflectometry
Authors: Grosfeld K. , Blindow N.
Published: September 2017

For our work in the Filchner-Ronne Ice Shelf Programme (FRISP), we have developed a new technique for measuring the bottom-melting rate with high reliability. The method is based on time-domain reflectometry (TDR) measurements of transmission lines inserted into melt holes. The TDR-data are digitally recorded on magnetic tape. System resolution has been estimated at 0.2 m. Hence, re-measuring after 1 year gives an accuracy of 10% for melting rates of 2m a-1. Two transmission lines for TDR measurements were installed during the German FRIS Expedition 1989–90. This paper describes the design of the system. Examples of recorded wave forms are given.
Subglacial measurement of turbidity and electrical conductivity
Authors: Stone Dan B. , Clarke Garry K. C. , Blake Erik W.
Published: September 2017

Direct measurements of the properties of subglacial water are necessary for understanding water flow beneath glaciers. In this paper we describe the construction, calibration and field usage of two instruments—one that measures turbidity and the other that measures electrical conductivity of subglacial water. The sensors are inexpensive and reliable. To demonstrate the potential usefulness of these devices, we present samples of data obtained from beneath Trapridge Glacier, Yukon Territory, Canada.
Compressive Strength Properties of Snow
Authors: Jellinek H. H. G.
Published: September 2017

The compressive strength of snow cylinders was investigated as a function of the age of the snow from which the cylinders were made, the snow particle size and the age of the cylinders. The results show that the compressive strength is reduced if the snow is older, if the particle size is smaller, or if the cylinders are younger. The variation with age of the cylinders can be represented by an equation similar to that for a first-order chemical reaction. The effect of adding small quantities of various gases to the atmosphere in which the cylinders were kept was also investigated; carbon dioxide and methane had no measurable effect, but ammonia lowered the strength of the cylinders. All the strength measurements were carried out at −10° C.
Ice Flow in Antarctica
Authors: Mellor Malcolm
Published: September 2017

A number of measurements of ice flow in the coastal regions of Antarctica are given. Observations show that the general outward movement of the continental ice, termed “sheet flow”, is locally accelerated where “ice streams” are formed. Estimates indicate that ice streams, which only occupy a small fraction of the total length of coast, are responsible for the removal of more ice from the continent than the “sheet flow” over the remaining length of coast. Further estimates suggest that the great bulk of Antarctic icebergs are produced by ice shelves, but that data on ice shelf movement are inadequate at the time of writing.
A Method of Determining the Strain-Rate Tensor at the Surface of a Glacier
Authors: Nye J. F.
Published: September 2017

The rate of strain tensor at a point on the surface of a glacier may be determined by setting up a number of stakes in a pattern and measuring the rate of change of the distances between them. A suitable pattern consists of four stakes at the corners of a square with one stake at the center. Five such patterns were used on Austerdalsbreen, Norway, in August 1956. The problem is to deduce the best values of the 3 independent components of the strain-rate tensor from the 8 measured quantities, and, for this purpose, a least-squares method, invented by Bond for the analogous problem in crystal physics, is used. The principal strain-rates are found to within about ±0.005 yr.−1 and their directions relative to the stake system to within about ±0.5°. The directions and magnitudes of the principal stresses are then deduced from Glen’s flow law and a suitable general theory. The directions of the principal strain-rates are in good agreement with the directions of the crevasses, but the experiment is inconclusive on the question of the magnitude of the stress needed to form a crevasse.
Some Preliminary Observations on the Plasticity of Greenland Glaciers
Authors: Landauer Joseph K.
Published: September 2017

A series of deformation measurements have been selected for preliminary studies on the plasticity of Greenland glacier ice. The measurements to be reported on were obtained in the Red Rock and TUTO tunnels in north-west Greenland. Both tunnels were excavated during the summer of 1955 with some additional work done during the summer of 1956. Deformation measurements made up to the end of the 1956 summer season, therefore, are of limited reliability, but certain trends appearing in these data seem worth reporting. The topics discussed are (1) the shearing of an initially vertical peg system at Red Rock, (2) the deformation of core holes at TUTO, and (3) tunnel closure at both sites. These data are analysed on the basis of laminar flow of the Nye type and certain conclusions are derived.
Early Discoverers XII: Some Notes on Sea Ice Observed By Captain James Cook, R.N., During his Circumnavigation of Antarctica, 1772–75
Authors: Herdman H. F. P.
Published: September 2017

This paper is derived from notes on ice conditions made during a study of Captain James Cook’s voyage around Antarctica in 1772–75. The original notes comprised a detailed examination of the day-to-day remarks on ice in Cook’s Journal, together with comments in the light of present-day knowledge.
The Estimation of the Regimen and Former Firn Limit of a Glacier
Authors: Mercer J. H.
Published: September 2017

An account is given of how, when accurate topographic maps of a glacier are available, not only the regimen but also the probable response to a change in the firn limit can be calculated from the area distribution. The derivation of the formula used is explained and an account given of its application in suitable areas of Alaska, where recent climatic changes are discussed.
Growth and Thermal Structure of the Deep Ice in Byrd Land, Antarctica
Authors: Wexler H.
Published: September 2017

Instead of starting with an initially dry, below sea-level basin undergoing glacierization, as was done in an earlier. model, the present computations are based on the existence of an open channel connecting the Ross and Bellingshausen Seas. The period of glacierization begins as the sea in the channel freezes permanently and acquires accumulation, both from local precipitation and transport from the adjacent mountains. Times of growth of the ice shelf, by combined freezing from below and accumulation of 10 and 20 cm. yr.−1, respectively, are determined for the case of a linear temperature profile in the ice. After the ice shelf becomes grounded further growth is by accumulation only. Steady-state temperature profiles for ice sheets 2,300 and 4,300 m. thick are computed under assumption of constant geothermal heat flux of 10−6 cal. cm.−1 sec.−1 and compared with observed temperatures in the 300 m. drill hole at Byrd Station. Basal melting of the 4,300 m. thick ice is found to exist only for the smaller accumulation rate.

The effect of down-slope motion and sinking of ice strata on the vertical temperature profile of the surface layer is studied with aid of the Benfield-Radok formula. Assuming no climatic temperature change and an initial temperature gradient at the ice crest of 1° C. increase per 100 m. increase in depth, the curve of best fit of all those tried is for a sinking rate of 20 cm. yr.−1 and a down-slope speed of 85 m. yr.−1 (2,130 yr. of motion from the crest).
The Recent Nature of the Siberian Pole of Cold
Authors: Gerasimov I. P.
Published: September 2017

The Siberian pole of cold is situated in the extreme north-east of Eurasia (in the region of the Cherskiy mountain system, in the upper parts of the basins of the Yana, Indigirka and Kolyma Rivers). Particularly low air and soil temperatures have been observed in the intermontane areas. Among these localities is the famous Oymyakon, where the lowest minimum temperature in the Northern Hemisphere has been recorded. In the climate of this area extreme aridity, connected with the intracontinental position of the territory, is combined with intense cold.

In the two highest massifs (Ulakhan-Chistay and Suntar-Khayata) small centres of recent glacierization (chiefly kars) are developed; there are also distinct traces of a more extensive older mountain glaciation. In the intermontane areas and on the principal level of the dissected hilly peneplain positive indications of a former glaciation are absent. However, the recent cryogenic phenomena represented by fossil ice, permafrost, taryns, as well as thermokarstic, solifluction and congelation features, are very abundant and diverse.

The widespread development of all these features gives this territory a periglacial aspect, and also provides the possibility of using the study of many recent phenomena for palaeogeographical purposes. From this point of view, the processes leading to the formation of loess deposits (cryogenic facies) and the formation of structural and thixotropic soils arc of particular interest.

The recent natural landscapes in this region are represented by a dominant type of larch tundra–forest associated with comparatively typical taiga bog formations in the depressions and xero-cryophile meadow–steppe landscapes on the steeper and warmer southern slopes. Such a unique landscape combination connected with the specific climatic conditions of this region provide a basis for interpreting the recent natural conditions of the Siberian pole of cold as a survival of the “late glacial.” At present these natural conditions are being intensively developed economically.
Thrust Structures in Young Sea Ice
Authors: Dunbar Moira
Published: September 2017

Curious interlocking thrust structures, described in theJournal of Glaciology, Vol. 3, No. 23, 1958, p. 173–75, are shown to be a common and typical deformation feature of young sea ice, and a suggestion is put forward as to their formation.
Solidification of Sea Ice
Authors: Adams Clyde M. , French David N. , Kingery W. David
Published: September 2017

Thermal considerations affecting the rate of formation of sea ice are discussed showing the effects of the major variables. The natural solidification process (freezing downward from contact with cold air) is contrasted with freezing of layers cast on the surface of sea ice. Transient heating and cooling of solid ice during and after flooding are analyzed. Procedures for maximizing the rate of ice formation and minimizing base-ice heating are discussed, along with factors affecting brine segregation.
Temperature Gradients in the Antarctic Ice Sheet
Authors: Mellor Malcolm
Published: September 2017

Measurements of ice temperature to depths of 30–40 m. are given for a number of points on the ice sheet in MacRobertson Land. Variations of mean surface temperature with elevation and with latitude, and the temperature gradients below a depth of 15 m. are compared with results from other parts of Antarctica and from Greenland. Explanations of negative temperature gradients near the surface of ice sheets are reviewed, and an equation derived by Robin is checked against the measurements following its recent justification from conduction theory. Surface ice velocities necessary for development of the observed temperature gradients are computed, and these values are then compared with ice velocities estimated independently from flow measurements at the coast and continuity considerations. It is found that, if negative gradients are attributed solely to the Robin effect, improbably high ice velocities are called for, and so climatic change is reconsidered. Some evidence of secular warming in Antarctica is mentioned and a recent numerical solution of the conduction equation for the surface-warming case is described. It is concluded that the measured temperature profiles can be explained reasonably by climatic amelioration.
The United States Glaciological Researches during the International Geophysical Year
Authors: Crary A. P. , Field W. O. , Meier M. F.
Published: September 2017

The U.S. IGY program in glaciology is reviewed in two parts: Antarctica and northern latitudes. The objectives of the program are outlined and the results of each investigation are briefly summarized. A separate discussion of observations related to changes in the Earth’s ice cover is included.
Tensile Strength of NaCl Ice
Authors: Weeks W. F.
Published: September 2017

To resolve some of the factors causing strength variation in natural sea ice, fresh water and five different NaCl–H2O solutions were frozen in a tank designed to simulate the one-dimensional cooling of natural bodies of water. The resulting ice was structurally similar to lake and sea ice. The salinity of the salt ice varied from 1‰ to 22‰. Tables of brine volumes and densities were computed for these salinities in the temperature range 0° to −35° C. The ring-tensile strength σ of fresh-water ice was found to be essentially temperature independent from −10° to −30°C., with an average value of 29.6±8.5 kg./cm.2at −10° C. The strength of salt ice at temperatures above the eutectic point (–21.2° C.) significantly decreases with brine volumev;. The σ–axis intercept of this line is comparable to the a values determined for fresh ice indicating that there is little, if any, difference in stress concentration between sea and lake ice as a result of the presence of brine pockets. The strength of ice containing NaCl.2H2O is slightly less than the strength of freshwater ice and is independent of the volume of solid salt and the ice temperature. No evidence was found for the existence of either phase or geometric hysteresis in NaCl ice. The strength of ice at sub-eutectic temperatures, however, is decreased appreciably if the ice has been subjected to temperatures above the eutectic point; this is the result of the redistribution of brine during the warm-temperature period. Short-term cooling produces an appreciable (20 per cent) decrease in strength, in fresh-water and NaCl.2H2O ice. The present results are compared with tests on natural sea ice and it is suggested that the strength of freshwater ice is a limit which is approached but not exceeded by cold sea ice and that the reinforcement of brine pockets by Na2SO4.10H2O is either lacking or much less than previously assumed.
Antarctic Interglacial Features
Authors: Nichols Robert L.
Published: September 2017

The upper 180 ft. (55 m.) of Lake Vanda in Wright Valley, south Victoria Land, is essentially potable, whereas that part below 200 ft. (61 m.) is more than three times as saline as sea-water. The salinity below 200 ft. (61 in.) resulted from the evaporation and freezing, mainly during interglacial (Loop-Trilogy) time, of a larger, less saline body of water.

An alluvial fan in Wright Valley has been dated as interglacial on the basis of (1) ice-marginal channels formed in Loop time that cut across it, and (2) the fjord-like longitudinal cross-section of the valley formed by the ice of the oldest glaciation or glaciations.

Fossils found in till and glacio-fluvial deposits in the McMurdo Sound region, south Victoria Land, date from both early and late Pleistocene interglacial time.

An ocean-bottom core sample obtained in the Ross Sea contained interglacial material. The presence in the sample of glacial marine sediments deposited in interglacial time suggests that the Antarctic Ice Sheet maintained itself throughout the Pleistocene.

Sub-surface efflorescences consisting of a layer of pure salts as much as 3 in, (7.6 cm.) thick are found 2−5 in. (5−13 cm.) below the surface in Loop deposits in Wright Valley. The absence of similar thick occurrences in Trilogy deposits indicates that the efflorescences are, in part at least, interglacial.

Interglacial cinder cones and lava flows are found in the McMurdo Sound area, and some of the widespread scoria present in moraines, glacio-fluvial deposits and beaches dates from interglacial time.
Instruments and Methods: A Steam-Operated Ice Drill for the Installation of Ablation Stakes on Glaciers
Authors: Howorka F.
Published: September 2017

An easily portably thermal ice drill was designed and constructed, with water vapour being used for melting the ice. A lore hole, 8 m. deep, can be drilled within about 30 min., depending on the ice properties. The energy for boiling the water is supplied by butane cartridges similar to those used for camping purposes. One cartridge lasts for drilling about three holes 8 m. deep. The weight of the whole equipment is 12.5 kg.
Earthquake-Induced Changes in Alaskan Glaciers
Authors: Nielsen Lawrence E.
Published: September 2017

The earthquake of 27 March 1964 in Alaska created a great number of rock avalanches which discharged onto the glaciers from the surrounding mountains. The ice falls became much more broken up than normal but the remainder of the surface of the glaciers was largely unchanged except for more open crevasses than before the earthquake.
Instruments and Methods: An Effective Pressure Room Seal in Ice
Authors: Ballard G. E. H. , Ramseier R. O.
Published: September 2017

Several methods were tried to seal a room in ice which could be pressurized to the overburden pressure of the ice. We found that a keyed bulkhead consisting of two ice walls with an in-place frozen mixture of water, clay and styrofoam pellets between them produced an effective seal.
The Distribution of 10 Meter snow Temperatures on the Greenland Ice Sheet
Authors: Mock S. J. , Weeks W. F.
Published: September 2017

All available 10 m. snow temperatures from the Greenland Ice Sheet have been analyzed using multiple regression techniques to develop equations capable of accurately predicting these temperatures. The analysis was carried out for all Greenland and for various sub-areas. The resulting equations show that 10 m. snow temperatures can be accurately predicted from the parameters latitude and elevation. Longitude was found to be a further significant parameter in south Greenland.

Gradients of 10 m. snow temperatures versus elevation for north Greenland are close to the dry adiabatic lapse rate indicating adiabatic warming of katabatic winds as the controlling mechanism in their altitudinal distribution. In both south Greenland and the Thule peninsula, gradients of 10 m. snow temperatures versus elevation are markedly greater than the dry adiabatic lapse rate and are highly dependent upon elevation, indicating downward transfer of latent heat in the snow, largely as a result of percolating melt water.

An isotherm map, showing the distribution of 10 m. snow temperatures on the Greenland Ice Sheet calculated from the prediction equations, was prepared. The map is based upon a revised contour map of the ice sheet made from a compilation of all known elevations.
The Regime of the Western Part of the Ross Ice Shelf Drainage System
Authors: Giovinetto M. , Robinson Edwin S. , Swithinbank C. W. M.
Published: September 2017

The net mass budget is estimated for the western part of the Ross Ice Shelf drainage system. The area of the system is (1.75±0.26) × 106 km.2, and the drainage periphery extends along the eastern flank of the Trans-Antarctic Mountains between lat. 77° 58′ S., long. 164° 37′ E. and lat. 85° 27′ S., long. 147°50′ discharge is estimated from vertical cross-sections and corresponding ice-movement data for eight outlet glaciers. Free-air gravity anomalies, corrected for the effect of terrain above the glacier surface, are used to determine cross-sections of valleys by comparison with theoretical gravity profiles for several two-dimensional valley models. These data provide a basis for estimating the rate of ice discharge from the plateau, which is compared with the estimated rate of net accumulation at the surface, to determine the net budget of the ice sheet in the region. Representative mean rates of ice discharge measured in different types of glaciers are approximately 0.25 × 1015 g. km.−1 yr.−1 in outlet glaciers with large basins, and 0.05 × 1015 g. km.−1 yr.−1 in outlet glaciers with small basins. Taking into account the snowshcd area and the rate of accumulation, the rate of ice discharge in cirque and piedmont glaciers is estimated at about 0.02 × 1015 g. km.−1 yr.−1 The difference ((48±29) × 1015 g. yr.−1) between mass input ((96±25) × 1015 g. yr.−1) and mass output ((48±15) × 1015 g. yr.−1) is large enough relative to the estimated standard error to indicate a probable positive net budget.
Ice-Flow and Thickness Measurements in the Sør-Rondane, Dronning Maud Land, Antarctica
Authors: Van Autenboer T. , Blaiklock K. V.
Published: September 2017

Velocity and ice-thickness profiles were measured un the western glaciers of the Sør-Rondane during the Expéditions Antarctiques Belges of 1959 and 1960 Some of the stations were re-occupied for velocity measurements during the Expédition Antarctique Belgo-Néerlandaise, Campagne d’Été 1964–65.

The profiles, with stations at 1 mile. (1.6 km.) intervals, were generally east-west and at right-angles to the direction of flow of the plateau outlet glaciers. The movement was measured by resection of each station from the main triangulation points over periods ranging from 256 to 1,501 days. Double ties with a Worden geodetic-type gravity meter were measured between the stations. An additional gravity station was occupied on rock at each end of the profile. The ice thickness and the subglacial topography are calculated from the gravity profiles. Combined with the surface velocity, they allow an estimate of the discharge of the glacier. The results indicate a close relationship between the glacier flow and the supply from the Antarctic Ice Sheet, as demonstrated by a study of the aerial photographs.
Certain Effects of Glacial Events in the Vale of Glamorgan, South Wales
Authors: Crampton C. B.
Published: September 2017

In South Wales there is evidence for two phases of intense glaciation and an interglacial phase during the Pleistocene. During the closing stages of the earlier glaciation in the west of the Vale of Glamorgan two overflow channels were cut by melt water from an ice lobe off the Glamorgan upland, abutting against ice from the Irish Sea. During retreat, ice from the Irish Sea and local ice deposited material on the Lower Lias outcrop on which two contrasting soils developed. Soils normally associated with a Mediterranean climate developed locally on the outcrop of the Carboniferous Limestone during the interglacial phase.
Observations on the Level of a Self-Draining Lake on the Casement Glacier, Alaska
Authors: Lindsay John F.
Published: September 2017

A small ice-dammed glacial lake beside the Casement Glacier in south-eastern Alaska was observed to drain in two separate pulses during the summer of 1965. The initial discharge appears to have resulted when the ice lobe damming the lake was floated by the increasing depth of water. There is no good explanation for the second rapid discharge but it may have been due to the sudden opening of crevasses.
Observation of Hollows in the Snow Surface of Torv Gletscher, East Greenland
Authors: Rucklidge John
Published: September 2017

Many elongated hollows about 300 m. long, 200 m. wide and 30 m. deep occur on the surface of Torv Gletscher in a region where the flow of the glacier splits in several directions. Their possible origin is discussed.
Creep-Velocity Bounds and Glacier-Flow Problems
Authors: Palmer Andrew C.
Published: September 2017

A general result due to Martin can be used to find upper and lower bounds on velocities in steady-creep problems. This method can be applied to glacier flow if ice can be assumed to satisfy a powerlaw stress–strain-rate relation. Bounds on the mean velocity over the glacier cross-section and on the mean velocity on the surface are determined for a particular example (a uniform parabolic channel, with powerlaw exponent 3) and they are shown to bound quite closely the exact solutions due to Nye. Bounds can be found rapidly by hand calculation. The method can be applied to real glacier cross-sections measured in the field.
Metamorphism of Air Bubbles in a Snow Crystal
Authors: Maeno Norikazu , Kuroiwa Daisuke
Published: September 2017

Observations have been made of the modification produced by a temperature gradient in the shape of air bubbles in natural snow crystals, and also of the shrinkage of the bubbles with time. The rate of shrinkage is governed by a constant which is strongly temperature dependent with an activation energy of about 15.1 kcal./mole, a value sufficiently similar to the activation energy for diffusion of tritium, dielectric relaxation and mechanical relaxation to suggest that atomic diffusion processes may be responsible for all of these phenomena.
Laboratory Measurements of the Resistivity of Ice
Authors: Østrem Gunnar
Published: September 2017

An attempt has been made to measure the D.C. resistivity of ice directly by placing plane–parallel samples between two electrodes with guard rings. Very strong polarization effects were observed which were most pronounced in ice from an ice–cored moraine, lesser in glacier ice, and the least in artificially frozen ice.
Glaciological Notes From Sukkertoppen, West Greenland
Authors: Gribbon P. W. F.
Published: September 2017

The retreat of a glacier front at Sukkertoppen, West Greenland, has been related by lichen size measurements to the lowering of the snow level in the accumulation region of the glacier. The altitudes of two Quaternary marine shell beds near Sukkertoppen have been measured and the shell fauna contained in them has been identified. The behaviour of two adjacent ice-dammed lakes is also discussed.
Recent Glacial History of an Alpine Area in the Colorado Front Range, U.S.A.: I. Establishing a Lichen-Growth Curve
Authors: Benedict James B.
Published: September 2017

A lichen-growth curve has been developed for dating Recent glacial and periglacial deposits in the Indian Peaks area of the Colorado Front Range.Rhizocarpon geographicumwas selected for the study because of its long life span and consistent size-age relationship. The species grows at different rates in different micro-environments, with moisture, stability of substrate and length of snow-free growing season having the greatest effect. Growth rates were determined indirectly, by measuring the maximum diameters of circular or nearly circular thalli growing on surfaces of known exposure age. Measurements were made on 24 historically dated surfaces, ranging in age from 25 to 69 yr., and on three radiocarbon-dated surfaces, including (1) mudflow levees younger than 180 yr., (2) a rock wall built by prehistoric Indians about 970 yr. ago, and (3) ground moraine deposited by a retreating valley glacier about 2,460 radiocarbon years ago.R. geographicurrzgrows very rapidly (14. mm./100 yr.) during the First 100 yr. of its life. Growth then slows to an average rate of 3.3 mm./100 yr. The completed growth curve is believed to be suitable for dating deposits at least as old as 3,000 yr.
The Strength–Density Relationship for Dry Snow
Authors: Radke L. F. , Hobbs P. V.
Published: September 2017

A linear relationship between strength and density is a characteristic feature of deposited snow. This relationship is explained theoretically in the case of old dry snow in ternis of the theory of sintering. The discontinuity in the relationship at a density of about 0.4 g./cm3 is considered to mark a transition point below which the snow densifies primarily by rearranement of the grains and the strength increases by the growth of existing bonds, and above which densification occurs by volume diffusion and the strength increases primarily by the creation of new bonds. Experimental evidence to support these ideas is presented.
Equations for Determining the Brine Volume of Sea Ice from −0.5° to −22.9°C.
Authors: Frankenstein Guenther , Garner Robert
Published: September 2017

Brine volume of sea ice is a function of the salinity and temperature of the ice, and it is related to its strength. This paper gives three equations which can be used to compute the brine volume for three temperature ranges from −0.5° to −22.9°C. A less accurate equation covering the total range is also presented.
Recent Glacial History of an Alpine Area in the Colorado Front Range, U.S.A.: II. Dating the Glacial Deposits
Authors: Benedict James B.
Published: September 2017

Recent glacial deposits in the Indian Peaks area of the Colorado Front Range have been dated lichenometricaily, using a growth curve developed locally for Rhizocarpon geographicum. Radiocarbon dates, where available, tend to support the lichen chronology. Three distinct intervals of glaciation, each consisting of several minor pulsations, have occurred in the area during the past 4500 years. The earliest advance (Temple Lake Stade) is dated at 2500–700 b.c. A later advance (Arikaree Stade) began in about a.d. 100 and ended in a.d. 1000. The most recent advance (Gannett Peak Stade) is dated at a.d. 1650–1850. It remains to be seen whether the Arikaree Stade was purely a local development or whether glaciers were advancing elsewhere in the cordilleran region during this interval. Alluviation on the plains east of the Colorado Front Range seems to have occurred during the waning stages of mountain glaciation.
Instruments and Methods: An Automatic Gauge for Measuring Sea-Ice Thickness
Authors: Schwerdtfeger Peter
Published: September 2017

A device is described which automatically measures the thickness of a floating ice cover at regular or any desired times and allows the result to be printed together with the time on a shore-based recorder. This instrument has been proven by a year’s operation near Mawson, Antarctica.
Short Note: Steady Profile of a Finite-Amplitude Kinematic Wave on a Glacier
Authors: Johnson James N.
Published: September 2017

The steady profile of a finite-amplitude kinematic wave on a glacier is calculated with the assumption that the wave velocity varies linearly with h1, the departure of the ice thickness from the datum state. If the flow of ice is due mainly to sliding of the glacier on its bed, the width of the calculated steady profile is several hundred times the datum state ice thickness. The width of an observed kinematic wave front on Nisqually Glacier, Mt. Rainier, Washington is at least an order of magnitude smaller than the calculated steady profile. This indicates that the observed steepening of the wave may be due to effects other than variation of wave velocity with ice thickness.
A Supraglacial Extension of an Ice-Dammed Lake, Tunsbergdalsbreen, Norway
Authors: Howarth Philip J.
Published: September 2017

Observations on Tunsbergdalsbreen show that an ice-dammed lake, Store Brimkjelen, overflowed on to the surface of the glacier. The lake lifted a section of the glacier and formed a long irregular crevasse along the line of dislocation.
Fabric Analysis of a Core from the Meighen Ice cap, Northwest Territories, Canada
Authors: Koerner R. M.
Published: September 2017

Ice samples from a 121 m core, representing the total thickness of the Meighen Ice Cap near its highest point, were studied for ice fabric, firn- and dirt-layer distribution. The absence of a strongly preferred fabric between the surface and the base of the ice cap at the core site suggests an absence of past or present ice movement at this point. From the variations of ice texture, am- and dirt-layer distribution with depth it is concluded that the ice cap post-dates the climatic optimum and has never been much thicker than it is at present. There is a possible relic ablation surface at a depth of 50 m which is estimated to be at least 500–600 years old.
Slip in Single Crystals of Ice
Authors: Readings C. J. , Bartlett J. T.
Published: September 2017

Rectangular specimens of ice (c. 5 cm × 2 cm × 0.5 cm) were cut from large single crystals (c, 10 cm × 5 cm2) grown from pure water by a modified Bridgman technique. When these specimens were deformed under controlled conditions, slip lines which were predominantly parallel to the basal plane became visible. In some cases short. perpendicular segments were also seen which can be interpreted as evidence for cross-slip in ice. Measurements of slip-band spacings were made on silvered “formvar” replicas of some deformed crystals. These measurements showed that “coarse” slip occurred when the resolved shear stress on the basal plane. σ, was greater than about 0.2 bars, and that the average thickness of the slip lamellae, d (cm) was approximately given by Wakahama’s relationship. (σ−0.2) d = 0.45 × 10−3. At lower stresses “fine” slip occurred, and the relationship between the average thickness of the lamellae and the resolved shear stress was more adequately described by Taylor’s formula, σd = 7.2 × 10−5. It is. however, possible that both coarse and fine slip occurred at higher stresses, but that the fine slip was then below the limit of resolution.
Glacial Features of Tanquary Fiord and Adjoining Areas of Northern Ellesmere Island, N.W.T.
Authors: Hattersley-Smith G.
Published: September 2017

The results of the present study support the conclusion that the former ice cover of northern Ellesmere Island was very much more extensive than the present, although the age of maximum glaciation is not known. In the Tanquary Fiord area the conclusion is based on bathymetric data indicating considerable overdeepening of the fiords; morphology of the main valleys; and the presence of moraines, erratics and glacial lake deposits at high levels. Tanquary Fiord became free of glacial ice at least 6 500 years ago and peat was forming in the valleys by this time. A long period of river erosion followed the main retreat of the ice. Subsequently, and within the last 4 000 years, glaciers advanced to re-occupy V-shaped valleys, and at the same time small ice caps were probably regenerated. In the last 900 years, however, there has been little change in the terminal position of most of the major glaciers, which appear to be advancing slightly, although in the last 40 years the side glaciers have receded from well-marked terminal moraines.