Nye’s theory of the equilibrium profile of two-dimensional ice caps is modified to include longitudinal stress and creep rate effects. A more generalized law for the sliding velocity of a glacier over its bed is introduced into the analysis in order to permit the inclusion of these additional complications. It is found that in the case of small ice caps (of the order of 30 km. in width), it is important to include the longitudinal stress. A somewhat “flatter” profile than that calculated by Nye is obtained. For ice sheets of the dimensions of the Greenland or Antarctic Ice Sheets, the additional stress causes essentially no modification in Nye’s theory. Nye’s theory also has been extended to include an isostatic sinking under the weight of the ice of the bedrock below an ice cap.

A new mechanism is described which explains the formation of moraines in the ablation areas of cold ice sheets. The mechanism involves the freezing of water onto the bottom surface of an ice sheet. This water comes from regions of the bottom surface where the combination of the geothermal heat and the heat produced by the sliding of ice over the bed is sufficient to melt ice. A number of criticisms are made of the shear hypothesis, which has been advanced to explain moraines occurring on Baffin Island and near Thule, Greenland. It is concluded that this older hypothesis may be inadequate to account for these moraines.

Although in theory the mechanism proposed in this paper undoubtedly will lead to the formation of moraines, the existing field data are insufficient to prove conclusively that actual moraines have originated by means of this mechanism.

During the summer of 1955, 53 thermocouples were installed in the ice mass near a crevasse in a glacier in the ice sheet of northern Greenland. Temperatures were observed in 1955 and 1956. The accumulated data were sufficient to prepare a description of the transient thermal behavior of the ice body adjacent to the crevasse. The isotherm maps have provided a base for the computation of heat flux vectors.

Accumulation along the route of the 1959–60 Victoria Land traverse, derived from 19 snow pits, was found to be 16 cm. of water equivalent. Sastrugi, reflecting prevailing surface wind directions, indicate that the surface winds in Victoria Land are katabatic. Movement points on the Ross Ice Shelf show a maximum rate of about 844 m./yr. with Iesser rates obtaining in more marginal areas. Stake measurements of accumulation on the Ross Ice Shelf indicate an average of 20 cm. of water equivalent/yr. A large glacier, about 300 km. long and up to 30 km. wide and draining into Rennick Bay, was discovered.

When ice is kept in saturated air, thermal etching occurs. This has been applied in the study of grain boundary migration, sub-boundary and slip line formation. A few of the interesting results are reported to illustrate the usefulness of the method.

During the monsoon of 1956 the Geological Survey of India sponsored an expedition to the Bara Shigri Glacier (lat. 32° 16′N., long. 77° 40′E), Kangra District, in the great Himalayan ranges of the Punjab, as part of the Indian programme for the International Geophysical Year 1956–57. Topographical maps of the terminal 3 miles of the glacier, on scales of 1:63.360 and 1:10,000, were prepared for comparison of morphological changes since it was last surveyed 50 years ago. The glacier appears to have shrunk considerably but its full extent could not be assessed because of insufficient earlier data. The Shigri Stream now emerges from a different part of the glacier snout. In order to assist future surveys three photographic stations were established.

Twelve deep pits (5 to 5.5 m.) revealed between 6 and 13 years of snow accumulation. The results show an average net accumulation of 18.5 g./cm.2 per year. Accumulation decreases inland at a mean rate of 1.5 g./cm.2 per 100 m. rise in elevation. Temperature measurements at 100 m. in all pits give a mean temperature-altitude gradient of 0.77° C. per 100 m. Evidence of melt was observed in all pits, the most pronounced melt occurring in 1954. The mean density reflects the local climate. Other empirical correlations of these data show linear trends that vary systematically with surface slope and local climate.

Data are supplied to show that the “blue” surface ice zone encountered in the Skelton Glacier, Antarctica, results from horizontal compressive forces. Examples of the densification of surface snows of the Ross Ice Shelf by this means are also given. Such density changes should be expected in any area where either of the principal horizontal strain-rates is negative.

Melting at the bottom of floating ice shelves may represent an important item in the mass economy of ice sheets. Some earlier studies of the behaviour of fresh-water ice in sea-water at a temperature below 0° C. are quoted.

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.

This paper is a summary of the more important results of glaciological investigations carried out in Trinity Peninsula, Graham Land during 1958–60, and which will be published at length in Falkland Islands Dependencies Survey Scientific Report No. 42. The budgets for Depot Glacier and the ice piedmont between Hope Bay and Trepassey Bay are given and it is concluded that in a normal year they are in a state of near equilibrium. The state of the glaciers of southern Trinity Peninsula is discussed in a consideration of the importance of rime ice formation on the west coast of the peninsula. Movement and accumulation studies in Trinity Peninsula and the islands of the James Ross Island group demonstrate a decrease in glacierization south-eastwards from the central plateau area. The recent glacial history of the area is also briefly reviewed.

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 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.

The failure to detect experimentally a glide direction in the ice crystal is satisfactorily explained by assuming that the crystal glides simultaneously in three symmetry-equivalent directions with a response to the shear stress component in each direction that is the same as that observed for the crystal as a whole or for polycrystalline aggregates—the typical non-linear, power-type flow law. A hexagonal crystal responding to stress by this type of “non-linear crystal viscosity” behaves very differently from a tetragonal one. For a tetragonal crystal, the glide directions are well defined in the response of the crystal if the power-flow-law exponent n exceeds n ~ 1·5, whereas for a hexagonal crystal a well-defined glide direction can be observed only if n > c. 5. The response of a hexagonal crystal is entirely independent of a-axis orientation if n = 3 exactly. For 3 < n < c. 5 the true glide direction should be weakly apparent, whereas for 1 < n < 3 the crystal should show a response weakly suggestive of preferred glide in a direction perpendicular to the true glide direction. In the observed range of n values for ice, 2 < n < 4, the expected response to simultaneous glide differs so slightly from the hitherto-postulated a-axis-independent, “non-crystallographic” glide as to be practically undetectable experimentally. This circumstance makes it possible to identify <>as the glide direction, from structural considerations alone, and to accommodate the plastic properties of the ice crystal into the modern concepts of crystal plasticity. It may be expected that hexagonal close packed and face-centred cubic metals at high temperatures, in steady state creep, will show translation gliding without well-defined glide directions.

Measurements have been made using two different methods of the rate at which the glacier Austerdalsbreen is slipping past its side wall at four sites. The rate of slipping varies from site to site in a way which seems to be connected with the details of glacier flow in the neighbourhood, and in all cases is less than the slip previously measured further up-glacier at the foot of one of the ice falls, and is also a smaller fraction (about one sixth) of the flow rate in the centre of the glacier. One of the methods measured the velocity of the last metre of ice, and this method gave movements which were more erratic than the other method, which measured velocity a few metres from the edge. This suggests that protuberances of rock and boulders lodged between the ice and the rock wall cause local variations in flow which are smoothed out in a few metres. The results are discussed in connection with the process of glacial erosion.

The paper describes the expedition’s work on the north fork of the Eldridge Glacier, which is found to be of the temperate alpine type. Velocity profiles show both slip at the glacier’s edge and shear in the adjacent layers. A summer accumulation pattern is demonstrated which makes the glacial balance unusually delicate. It is concluded that glaciers in this region are near their recent maxima because the high altitude accumulation offsets the shrinking of the lower tributary glaciers. Examination of an ice-dammed lake shows the main Eldridge Glacier to be near the maximum of the last major advance which raised the level of the ice at least 60 m.

Starting from Glen’s flow law for ice and from a series of assumptions based in part on observations in Greenland and in the Jungfraujoch, the velocity distribution (horizontal velocity component) and surface configuration is derived for a strip-shaped ice sheet in a stationary state. For the choice n = 3 − 4 of the exponent in the power-law flow relation, there is extensive agreement between the theoretically calculated surface profile and the east-west profile measured through “Station Centrale” by Expéditions Polaires Françaises. The corresponding theoretical solution for a circular ice sheet is also given. As a first application of this theory, an attempt is made to calculate the average rate of accumulation in Antarctica from its surface profile (assumed circular in plan) and from the flow-law parameters derived from the Greenland Ice Sheet. It is also shown that a change in accumulation has only a small influence on the total ice thickness of an ice sheet. A method of calculating approximately the age of ice in an ice sheet, based on the foregoing theory, is illustrated by applying it to the Greenland Ice Sheet. After comparing the present theory with that of Nye, a general expression for the surface profile of an ice sheet with constant accumulation is set up and discussed by means of comparison with two profiles through Antarctica.