The lower one-third of “Sioux Glacier” in south-central Alaska was buried beneath a debris slide during the 27 March 1964 earthquake. Investigations to determine the effect of this cover on the regimen of the glacier revealed that it has increased in thickness by as much as 28 m, primarily as a result of the insulating effect of this debris cover. In areas where debris has continuously veneered the surface, at least since 1938, the ice is also thicker. A longitudinal profile reveals that the area near the upper extent of the slide debris has become intensely crevassed and has been lowered as much as 8 m between 1965 and 1966, while the terminal area is up to 5 m higher and is characterized by thrusting. It is concluded that a kinematic wave passed through this glacier sometime between 1965 and 1966.

The upper zone of debris-veneered ice is moving at 175 m/year while the terminal area is flowing at only 21 m/year. The rate of down-glacier decrease in velocity is about 0.06 m/year per meter of horizontal distance except for an area approximately 1 km from the terminus. Here, the rate of decrease in velocity is 0.1 m/year per meter. The change in rate is presumed to be related to topographic control caused by the recent thinning of the ice here.

Following construction of a glacial ice runway on the Ross Ice Shelf, Antarctica, and prior to flight operations, the runway was proof-rolled. The proof exercise was designed to simulate typical heavy aircraft. Initial testing produced numerous brittle surface failures in the runway ice. Thin sections of ice cores taken from the failed areas showed large crystals (с axis vertical) of clear, blue ice with long, vertical bubbles, indicative of ice formed directly from meltwater. Uniaxial unconfined compression tests on core samples were used to compare runway ice strength with published data for polycrystalline laboratory ice. Since the frequent failure of surface ice had not been expected, it was critical to understand the formation and mechanical properties of the weak ice to prevent its occurrence in the future and to strengthen the existing problem areas. We discuss the likely scenarios for development of weak ice on the airstrip and the physical properties of this type of ice. Also, the procedure used to repair successfully the runway surface is described, which culminated in test flights, followed by full flight operations.

An ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is at most 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar grained ice when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

The study indicates that no significant difference in snow densities is found when using either the CRREL tube or the ILTS box cutters. However, inexperienced workers tend to overestimate snow densities in light snow and depth hoar by 6 and 4% respectively.

A study of Hoseason Glacier was made to test whether photogrammetry could yield meaningful glaciological information from repeated series of air photographs without ground control. Three maps indicate that large time differences, different camera systems, and the use of sea ice as a level datum do not present insurmountable difficulties in photogrammetric reduction. Surface horizontal movement was determined and level profiles were compiled. Hoseason Glacier is probably in equilibrium.

The structure of some moraines in and around two glaciers in northern Norway was studied by the method of fabric analysis. It was found that englacial material tends to lie parallel to the direction of movement of the ice, and material in lateral and terminal moraines shows orientations which appear to be related to the conditions under which it was deposited.

Engabreen is an outlet glacier of the Svartisen Ice Cap located in Northern Norway. It is a unique glacier due to the Svartisen Subglacial Laboratory which allows direct access to the glacier bed. In this study, we combine both sub- and supraglacial observations with ice-flow modelling in order to investigate conditions at the bed of Engabreen both spatially and temporally. We use the full-Stokes model Elmer/Ice and satellite-based surface-velocity maps from 2010 and 2014 to infer patterns of basal friction. Direct measurements of basal sliding and deformation of lower layers of the ice are used to adjust the ice viscosity and provide essential input to the setup of our model and influence the interpretation of the results. We find a clear seasonal cycle in the subglacial conditions at the higher elevation region of the study area and discuss this in relation to the subglacial hydrological system. Our results also reveal an area with an overdeepening where basal friction is significantly lower than elsewhere on the glacier all year round. We attribute this to either water pooling at the base, or saturated sediments and increased strain heating at this location which softens the ice further.

Scheuchzer’s dilatation theory and Altmann’s rigid sliding theory were the first glacier-flow theories to receive serious scientific attention. When Agassiz began a research program at Unteraargletscher in 1839, he held several incorrect notions about glacier flow. Forbes understood the difficulties with the existing theories, and in the early 1840s he and Agassiz acquired motion, temperature, and structural data that were incompatible with the dilation and sliding theories but were suggestive of flow analogous to that of a viscous fluid. How an apparently brittle rigid solid like ice could flow became the central paradox requiring explanation. Some of the most able physicists of the mid-nineteenth century went through contortions in their largely misguided efforts to explain the viscous behaviour in terms of the known physics of rigid solids. Personality and speculation played a far larger part in their debates than we see in scientific discussions today.

It is shown that when the elastic properties of sea-ice sheets are taken into account, wind-induced tilt is insufficient to cause cracking. These results are contrary to those of Weber and Erdelyi (1976) who considered the ice to be rigid.

Inexpensive add-on boards are currently available that enable personal computers to be used as digital image-processing systems. The capabilities of one such system are illustrated by two specific cases examining the surface characterization of a sea-ice cover and the statistical description of sea-ice structure. The unit discussed digitizes video input into a 512 × 512 array of pixels, assigning each a gray shade from 0 to 255. A key feature of the system is that the primitive commands of the board can be accessed through higher-level programming languages. This allows users to customize easily the system for their own needs.

The speed of Ice Stream B, Antarctica, was measured twice a day-over a 1 month study period, and found to be steady at about the ±3½% level, the sensitivity of the measurements. The vertical strain was measured at three sites over a 1 year period at 1 h intervals with sensitivities of 2 or 0.2 ppm. The strain rate varied on all time-scales. Events of high strain rate were observed, but never at more than one site at a time. They can probably be understood in terms of local modification of the strain field associated with crevassing. Diurnal variation in strain rate was observed at one and possibly two sites during two summers. The seismicity was measured at all three sites, and diurnal and seasonal variations were prominent at all, the seismicity being much more intense in winter. Several possible causes of the diurnal variations in strain and seismicity are considered: thermal and atmospheric effects, and the effects of tides in the Ross Sea.

Petrologic analysis was performed on ice-wedge ice in order to investigate changes in fabric across wedges in relation to the growth mechanism. Crystal size increased from the centre outward and strongly preferred dimensional orientations developed parallel to the sides of wedges. c-axis orientations changed from a horizontal girdle at the wedge centre to a point maximum normal to the foliation at the boundary. These changes are related to recrystallization and grain growth associated with the horizontal stress field. In massive ice penetrated by an ice wedge, crystal size and complexity of crystal shape decreased toward the wedge, dimensional orientations tended to become parallel to the wedge, and c-axes formed a point maximum normal to the wedge boundary.

Glaciological mass-balance measurements have been the backbone of internationally coordinated glacier monitoring. The resulting annual observations have been used to understand glacier reactions to climate change, and to assess both regional and global glacier mass changes and related contributions to runoff and sea-level rise. However, the comparability of annual observations is hampered by differences in survey periods and mass-balance amplitudes between glaciers, regions and hemispheres. This study presents a simple approach to temporally downscale glaciological mass balance using seasonal observations and sine functions. The proposed analytical model allows reconstruction of the seasonal course of glacier mass balance at weekly to monthly resolution from only annual or seasonal observations. Strengths and limitations of this analytical approach are discussed and compared with results from numerical mass-balance modelling. Potential applications include seasonal corrections of glaciological and geodetic observations and comparisons to monthly results from spaceborne gravimetry and altimetry.

Many authors have used propagation of ultrasonic waves in ice for glaciological studies. This propagation is characterized by the velocity of sound and by the attenuation of stress waves. In crystalline materials, these two characteristics depend on structural slate. In particular plastic deformation gives velocity and attenuation variations.

We have measured the sound velocity and attenuation of ultrasonic waves in strained specimens of ice (single crystals and polycrystals). These measurements done between 100 and 273 K at a frequency of 5 MHz show that plastic deformation leads to an increase of attenuation arid an increase of velocity. Annealing treatments at 271 K cause recovery of propagation characteristics. The variation in attenuation can be interpreted by the theory of dislocations and this interpretation is supported by our data on the influence of frequency on this increase of attenuation induced by plastic deformation, but the theory of dislocations implies a decrease of modulus, i.e. of velocity, hence we must postulate that an added phenomenon screens the effect of dislocations. That phenomenon could be connected with ageing effects observed on different physical properties of ire and may be due to modification of protonic arrangement or creation of interstitials during plastic deformation. Thus our experiments show that it is necessary to be careful in using results determined from the propagation of ultrasonic waves in ice.

The ground in Spitsbergen is frozen to a depth of about 320 m., as can be seen from observations in the collieries. At a mean surface temperature of −8° C. this corresponds to a geothermal gradient of 1°/40 m. The temperature of the sea water is almost 0° C. Along the coast the land lies very little above the sea level, and here the sea is shallow. One assumes that the land as well as the sea bed is horizontal. Thus the temperature on the land is –8° C., in the sea 0° C. On the coast the temperature must suddenly change. One must also take into account the fact that the temperature rises with depth. A simple calculation leads to the conclusion that the frozen ground below the sea bed must extend about 100 m. from the coast. Investigations near a Swedish colliery have shown this to be the case.

This result also applies to the conditions underneath a glacier. On the same assumptions one can conclude that if the glacier is less than 400 m. wide the frozen ground underneath forms one coherent layer and that this is not the case if the glacier is wider. The same applies to a shallow fjord.