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

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

It appears that syntectonic-secondary recrystallization is effective in producing the orientation fabrics with two, three and multiple maxima. Also, the maxima always shift away from the pole of foliation as grain-size increases and there are several stable positions of maximum such as 0°, 17°, 23° and 30°. It is expected that further stable angles would occur with coarser crystals as found in temperate glaciers.

Detailed observations on a collapsing kame terrace indicate that the terrace is being reshaped by: slumping and sliding of debris into depressions, melt-water erosion on the side of the terrace, debris flows in the gullies, and stagnant-ice bursts, a phenomenon analogous to a glacier burst except in the mode of formation of the water. Temperatures in the gravel over the ice, where the gravel is about 4 m thick, indicate that the rate of melting of the upper surface of the ice due to conduction may be as high as 24 cm year−1. Highest temperatures in the gravel were recorded during periods of heavy rainfall.

Creep tests on homogeneous, isotropic polycrystalline ice gave an apparent activation energy for creep of 16.4 kcal/mol (68.8 kJ/mol) over the temperature range −10° to −60° C. Above −10° C the Arrhenius relation for temperature dependence is invalid, and creep rate becomes progressively more temperature dependent as the melting point is approached. Between −20° and −50° C the apparent activation energy for creep of a single crystal of ice was found to be 16.5 kcal/mol (69.1 kJ/mol). A complete creep curve for a single crystal loaded in uniaxial compression parallel to the basal plane was qualitatively similar to the classical creep curve; creep rate at all stages was very much faster than for polycrystalline ice under the same conditions. Creep tests on polycrystalline ice at 0° C gave a stress/strain-rate relation for that temperature, but its precise meaning is unclear, since recrystallization complicated the results.

The heat-balance components of the faces of snow blocks were measured at “Plateau” station on the Antarctic plateau using micro-meteorological instrumentation. Heat-balance considerations and sublimation observations indicate considerable mass loss from the sloping snow surfaces during summer but little loss from horizontal surfaces. This process tends to level the irregularities of the snow surface. The conclusions are applicable to the snow dunes forming the general accumulation pattern on the Antarctic plateau.

Modified versions of in situ strength tests previously applied to metamorphosed snow were developed to measure the mechanical properties of newly fallen snow during storm periods. A large drop-cone penetrometer, protected from the wind by an aluminum shell, was used to determine snow “hardness”. A lightweight model of the Haefeli ram penetrometer measured “ram numbers”. Shear strengths were obtained from large, light-weight frames. Some preliminary tests were made with a shear vane driven by a torque wrench. A new technique was devised for measuring tensile strength whereby a cantilever beam of snow is undercut until it fails under its own weight. Comparisons between the cantilever test and the shear-frame test show high ratios for tensile to shear strength. Cantilever strength plotted against density shows an order of magnitude variation in strength at all densities.

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

Asymptotic solutions for the temperature distribution and interface history are developed for a wide range of boundary conditions: prescribed temperature or heat flux, prescribed convection and prescribed radiation. Comparison with known results reveals the general adequacy of the asymptotic solutions and an estimate of the error incurred.

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.

The effect of growth velocity υ and solute concentration C on the cellular substructure that develops in NaCl ice is studied in the range 3×10−3 to 10−5 cm s−1 and 1 to 100‰ respectively. The substructure is the result of the formation of a constitutionally super-cooled zone in the liquid ahead of the advancing interface. Unidirectional freezing runs were made by placing a cold plate in contact with the “top” of the solution and using cold-plate temperatures of −20 and −70°C. The growth velocities were determined from a least-squares fit of the growth data to a power series. The average spacings between neighboring substructures a0were measured from photomicrographs of precisely located thin sections. Log-log plots of a0against υ show that the slope n gradually changes as a function of υ. In the run where no convection occurred, n changes from to 1 as υ decreases in agreement with the prediction of Bolling and Tiller. The results of Rohatgi and Adams are also shown to be in good agreement with this prediction. On the other hand when convection occurs, n changes from to approximately o as υ decreases. This is caused by convection reducing the effective value at C at the growing interface. The variation of a0with C is quite complex and shows a minimum in the composition range 9 to 25‰ NaCl.

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

Simultaneous measurements were made of bot the strength and structural properties of a dry, seasonal snow-pack. The densities of the snow studied ranged from 126 to 407 kg m−3. The mechanical strength of this snow as determined by insitu shear-wave test and a centrifugal tensile test increases exponentially with the increase in size of intergranular sands. Bonding increases at a rate substantially greater than that predicted by the classical sintering equations. It is suggested that this is due to the wide variety of stresses present in snow with these relatively low densities.

The USA CRREL drill is an 80-kg, electrothermal unit designed for continuous coring in temperate or polar ice or snow. The drill melts a hole approximately 16.3 cm in diameter and retrieves a core approximately 12.2 cm in diameter at rates from 1.9 m h−1 in −28°C ice to 2.3 m h−1 in temperate ice. The melt water formed is removed by a vacuum system and stored in a tank. Additional equipment includes 450 m of armored electrical cable, a hoist, a 6.7-m tower and a gasoline generator. The minimum time required to drill a 450-m hole is 435 h. All of the equipment has been designed to be assembled and operated by two men and has a gross shipping weight of 1180 kg.

Slab avalanches are shown to be released by brittle fracture. An analogy is drawn in which the snow-pack is considered to be a macroscopic, molecular model of glass. The analogy is examined qualitatively from two viewpoints: the Griffith fracture criterion, and stress concentration theory. The details of fracture propagation in a layered snow-pack are explained by means of stress concentration theory, and many details of slab avalanches are shown to be consistent with the proposed mechanism. The significance of various fracture surface markings is pointed out.

Results obtained from tensile and compressive tests on pure ice single crystals at various temperatures down to −90°C are reported. At −50°C tensile creep tests give a continually increasing creep rate until fracture, as observed at higher temperatures. The stress dependence of the strain-rate is discussed. Fracture stress increases with decreasing temperature. Results from constant strain-rate compressive tests are compared with theoretical curves computed from Johnston’s (1962) theory of dislocation multiplication. A dislocation velocity of the order of 0.5×10−8 m s−1 is deduced for ice at −50°C.

Surface topography of etched ice crystals was examined by a scanning electron microscope in combination with a Formvar replica method. The deep focus of the scanning electron microscope allowed observation of the sharply three-dimensional topography of ice surfaces. Various useful information was obtained from microphotographs of etched basal and prismatic planes, fractured surfaces, and grain boundaries formed between microcrystals of ice.

An alternative origin and significance for kettle holes is considered. Kettles among some kame tracts may be due not to melt of buried ice but rather represent the location of ice pillars or roof pendants among stratified subglacial deposits.