Following pioneering work in Norway, cirque glaciers have widely been viewed as rigidly rotating bodies. This model is incorrect for basin-filling cirque glaciers, as we have demonstrated at West Washmawapta Glacier, a small glacier in the Canadian Rocky Mountains. Here we report observations at the same glacier that assess whether complex temporal variations of flow also occur. For parts of three summers, we measured daily displacements of the glacier surface. In one year, four short-duration speed-up events were recorded. Three of the events occurred during the intervals of warmest weather, when melt was most rapid; the fourth event occurred immediately following heavy rain. We interpret the speed-up events as manifestations of enhanced water inputs to the glacier bed and associated slip lubrication by increased water volumes and pressures. No further speed-ups occurred in the final month of the melt season, despite warm temperatures and several rainstorms; the dominant subglacial water system likely transformed from one of poorly connected cavities to one with an efficient channel network. The seasonal evolution of hydrology and flow resembles behaviors documented at other, larger temperate glaciers and indicates that analyses of cirque erosion cannot rely on simple assumptions about ice dynamics.

A currently active rock glacier with a snout elevation of 4055 m was observed in the Jammu and Kashmir Himalaya. Its formation is ascribed to stagnation of the terminal area of a true glacier.

Studies in the south-eastern part of the Drakensberg mountains and the Basutoland uplands, above the 6,000 ft. (1,830 m.) level, of Southern Africa have yielded evidence for a periglacial regime during the Pleistocene. The limited earlier work in Southern Africa suggested that the Pleistocene climate was too dry for glaciation to have occurred, but the existence of oversteepened slopes, solifluction slumps and cirques is indicative of a periglacial environment. There is some correlation between the respective altitudes and latitudes of these periglacial features.

A method is described of determining the thickness of a valley glacier from measurements of gravity. On a Norwegian glacier approximately 4 km. long and km. wide values of gravity were measured at points on four transverse lines. For comparison, values were measured at points on three lines in the valley below the snout of the glacier. The positions and altitudes of these gravity stations were determined by triangulation. After making corrections for the altitudes of stations and for the effect of the valley walls, the differences between the gravity values obtained on the glacier and those obtained in the valley below the glacier are attributed to the thickness of the ice. Four transverse sections of the glacier, obtained in this way, are given. Errors in the estimates of ice thickness should not exceed 20 per cent on the two lower cross-sections, nor 40 per cent on the upper two.

Uniaxial compressive creep tests on fine-grained polycrystalline ice indicate that secondary strain-rate is proportional to σ1.8, where σ is applied stress, for the range 0.1 < σ < 0.5 kgf/cm2 (10 < σ < 50 kN/m2). On the basis of the present tests, earlier results suggesting linear viscous behaviour at low stress are believed to be invalid.

A contradiction has existed in the literature as to the conditions favoring formation of “ablation hollows” (“suncups”) on a melting snow surface. Some experiments find that these features grow under direct sunlight and decay in overcast, windy weather; whereas others find just the opposite result, that they grow best under cloudy, windy conditions and decay if exposed to direct sunlight. We find that the hidden variable in past experiments, which acts as a switch to determine which mode of formation can operate, is the absence or abundance of dark insoluble impurities in the snow. Direct sunlight causes ablation hollows to grow in clean snow and to decay in dirty snow (for dirt content below a critical value), because the dirt migrates to the ridges between the hollows, lowering the albedo at the ridges. By contrast, when ablation is dominated by turbulent heat exchange, the presence of dirt favours development of ablation hollows because the dirt migrates to the ridges and insulates them; albedo reduction has a negligible effect on ablation.

This hypothesis is supported by an experiment which showed that the presence of a thin layer of volcanic ash on the snow inhibited formation of ablation hollows under direct sunlight.

Application of the gravity flow theory to the percolation of melt water through the firn in the accumulation area of a temperate glacier explains the occurrence of shock fronts in the melt-water flux. The time of propagation of a shock front moving from the surface through the entire firn was calculated under various assumptions. Various time input functions of melt-water flux at the surface with constant total input volumes yield only slight differences in the time of propagation of the shock front at greater depths. The dependence of the time of propagation of a shock front on the input volume, on snow parameters, and on the total thickness of the firn was calculated. An approximately linear relation was found to exist between the time of propagation of a shock front moving through the firn and the total thickness of the firn. The drainage of melt water from the firn after the summer ablation period is also quantitatively explained by the gravity flow theory. All results are in good agreement with experimental data.

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.

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.

Snow-pit analysis in the tow-accumulation region in northeast Greenland indicated a mean annual accumulation of 12 ± 1.6 cm. It also revealed numerous faceted layers that were not related to the summer horizon of previous years. In general, the faceted crystals were found under a wind crust. These crusts appear to originate during the winter. Snow- and air-temperature data from automatic weather stations suggest that the katabatic storms are responsible for the formation of the wind crusts and the faceted layers. Frequent, abrupt temperature changes up to 30°C were observed within two days, due to turbulent mixing of cold-air inversions. The near-surface air-temperature variations are correlated with wind speed, the latter leading the former by 6–9 hours for increasing wind, and 1–4 hours for decreasing wind. Because of low accumulation, katabatic storms affect the same snow surface for several months, causing repealed air-temperature fluctuations. This leads to strong vapor-pressure gradients and faceted crystal growth in the top snow layer. On average we found two faceted layers (in addition to the summer layer) per year for a 4 year record. In addition to its climatological significance in the snow record, the formation of these layers is especially important to understand for the interpretation of microwave satellite observations of the firn.

An examination of both experiments and computer models of polycrystalline ice undergoing a simple shear suggests that there is good agreement. The model has correctly reproduced the deformational and microstructural features caused by glide on (0001) in the ice aggregates. This success is particularly prominent for those ice grains with a lattice orientation suitable for hard or easy glide or kinking, and where there is a sub-horizontal с axis and a larger grain-size. A limitation may be that the model cannot explicitly simulate recrystallization and grain-boundary migration, which are two other important processes operating jointly with glide in experimentally deformed ice. However, through the use of the models, it is possible to show how kinematic factors can control the processes of recrystallization. The localization of recrystallization in the polycrystalline ice aggregate is determined by the stress and strain variations between neighbouring grains.

Supraglacial debris is significant in many regions and complicates modeling of glacier melt, which is required for predicting glacier change and its influences on hydrology and sea-level rise. Temperature-index models are a popular alternative to energy-balance models when forcing data are limited, but their transferability among glaciers and inherent uncertainty have not been documented in application to debris-covered glaciers. Here, melt factors were compiled directly from published studies or computed from reported melt and MERRA-2 air temperature for 27 debris-covered glaciers around the world. Linear mixed-effects models were fit to predict melt factors from debris thickness and variables including debris lithology and MERRA-2 radiative exchange. The models were tested by leave-one-site-out cross-validation based on predicted melt rates. The best model included debris thickness (fixed effect) and glacier and year (random effects). Predictions were more accurate using MERRA-2 than on-site air temperature data, and pooling MERRA-2-derived and reported melt factors improved cross-validation accuracy more than including additional predictors such as shortwave or longwave radiation. At one glacier where monthly ablation was measured over 4 years, seasonal variation of melt factors suggested that heat storage significantly affected the relation between melt and energy exchange at the debris surface.

The surface condition of the North Water was investigated during two winters (i.e. the three polynyas: Smith Sound polynya, Lady Ann Strait polynya, and Barrow Strait polynya). Since no detailed information was available on ice conditions and the extent of open water during winter, radiometric temperature measurements of the sea surface had to be taken along a flight line of 2650 km from an altitude of 300 m. From November to March 1978-79 and 1980-81, 14 remote-sensing flights were carried out. On the basis of the radiometric measurements, the following ice types were identified: ice-free, dark nilas, light nilas, grey ice, grey-white ice, and white ice. A comparison between the thermal and the visual ice classification (the latter being based on grey tones of the aerial images) showed a deviation of 3%. The analysis showed that in November, December, and January more than 50% of the Smith Sound polynya was covered by young ice, nilas, and ice-free, whereas in February and March white ice was dominant. Moreover, it was found that the two polynyas in Smith Sound and Lady Ann Strait were much smaller than previously believed. In Barrow Strait, a semi-permanent polynya was observed in the winter of 1980-81. The occurrence of polynyas in Barrow Strait seems to be connected with the location of the fast-ice edge. On the basis of the calculated ice-type distribution and heat-flux rates for different ice types, an energy loss of 178 W m-2 was found on the surface of the Smith Sound polynya due to open water and thin ice for the winter months November to March. Compared with other ice-covered sea surfaces in the Arctic, the heat release by the sea-water in the Smith Sound polynya is about 100 W m-2 larger.

Three small Alaskan glaciers with different bed conditions were studied: Exit Glacier had a thin deforming layer and produced subglacial and proglacial glaciotectonic land forms; Childs Glacier also had a thin deforming layer but the upper part was frozen to the ice; Matanuska Glacier had no deforming layer but had subglacial debris-rich ice. Since it has been shown that sediment at the base can account for the majority of ice movement, it is suggested that there is a deforming bed/debris-rich continuum whereby similar processes occur throughout the different subglacial environments. These include: similar longitudinal deformation patterns (compression at the margin, extension and simple shear up-glacier); similar vertical deformation patterns, increase in deformation (and fabric strength) upwards through the sequence (leading to the attenuation of stratified ice into dispersed ice); and similar and interrelated incorporation processes. The major differences were that the processes occurred at a much faster rate within the deforming layer and that probably only the deforming layer will be recorded in the geological record.

Investigations of the mass balance of the Hintereisferner are dealt with for the period 1952–61. Ablation of ice was measured with stakes, ten of which per square kilometre were considered as a sufficient number. The area of ice ablation terminates in the “zero-line of ice ablation”. The net accumulation was studied in pits, and by mapping of enduring accumulation patterns. In order to avoid errors it is proposed that the term “firn line” be replaced by the term “old snow line”. This would more clearly emphasize that only the net accumulation of old snow from the current budget year is a gain of mass for the glacier. The term “firn”, in accordance: with Flint’s [1957] definition should be used only for snow more than one year old. Between the old snow line and the zero-line of ice ablation in some years an appreciable firn ablation takes place. The mass balance reveals a large variation between +0 77×106m.3 of water in the most favourable budget year 1954–55, and −9.83×106m.3 of water in the most unfavourable budget year 1957–58. The average annual mass balance was −3.60×106m3 of water, with an estimated maximum possible error of about ±0.54×106m3 of water.

Hercules Dome, Antarctica, has long been identified as a prospective deep ice core site due to the undisturbed internal layering, climatic setting and potential to obtain proxy records from the Last Interglacial (LIG) period when the West Antarctic ice sheet may have collapsed. We performed a geophysical survey using multiple ice-penetrating radar systems to identify potential locations for a deep ice core at Hercules Dome. The surface topography, as revealed with recent satellite observations, is more complex than previously recognized. The most prominent dome, which we term ‘West Dome’, is the most promising region for a deep ice core for the following reasons: (1) bed-conformal radar reflections indicate minimal layer disturbance and extend to within tens of meters of the ice bottom; (2) the bed is likely frozen, as evidenced by both the shape of the measured vertical ice velocity profiles beneath the divide and modeled ice temperature using three remotely sensed estimates of geothermal flux and (3) models of layer thinning have 132 ka old ice at 45–90 m above the bed with an annual layer thickness of ~1 mm, satisfying the resolution and preservation needed for detailed analysis of the LIG period.

Antarctic lakes with perennial ice covers provide the opportunity to investigate in-lake processes without direct atmospheric interaction, and to study their ice-cover sensitivity to climate conditions. In this study, a numerical model – driven by radiative, atmospheric and turbulent heat fluxes from the water body beneath the ice cover – was implemented to investigate the impact of climate change on the ice covers from two Antarctic lakes: west lobe of Lake Bonney (WLB) and Crooked Lake. Model results agreed well with measured ice thicknesses of both lakes (WLB – RMSE= 0.11 m over 16 years of data; Crooked Lake – RMSE= 0.07 m over 1 year of data), and had acceptable results with measured ablation data at WLB (RMSE= 0.28 m over 6 years). The differences between measured and modeled ablation occurred because the model does not consider interannual variability of the ice optical properties and seasonal changes of the lake's thermal structure. Results indicate that projected summer air temperatures will increase the ice-cover annual melting in WLB by 2050, but that the ice cover will remain perennial through the end of this century. Contrarily, at Crooked Lake the ice cover becomes ephemeral most likely due to the increase in air temperatures.