The temperature in the ablation area of Athabasca Glacier is about —0.5°C at a depth of 10 m. Below 17 m the temperature is slightly below the calculated pressure melting point (average difference 0.01 deg) in some places. Heat produced by ice deformation is calculated as a function of depth in two bore holes. Only in about the lower half of the glacier thickness is this heat sufficient to maintain the ice at the observed temperature as the hydrostatic pressure is reduced by ablation. Freezing of water within the ice must provide heat for this purpose elsewhere in the glacier; it must also provide heat to maintain the deeper ice close to the melting point even though the 10 m temperature is negative. The minimum water content needed is estimated to be between 0.5 and 1%. It is argued that most of this water must be water trapped between grains when the ice formed from firn. The small difference from the pressure melting temperature measured below 17 m probably arises either from impurities or because, as a result of heat supplied for pressure-melting of ice around air bubbles, the ice is at the melting point corresponding to the bubble pressure rather than to the hydrostatic pressure.

Testing of a water-balance equation for the Summit Lake basin in July and August 1968 indicated that, 2½ months before its fourth known draining, there existed a leak through or under the damming glacier that may have been as large as 3–5 m3/s. Lake temperatures recorded during the same period indicate water at 0.5–0.8°C near the ice dam and up to 2.6°C 4–5 km from the dam. These observations support the proposal of Liestøl (1956) and Mathews (in press) of tunnel enlargement by melting. It is calculated that lake water temperatures of 0.25, 0.9 and 0.15°C are required to account for the November 1965, September 1967 and November 1968 drainings, respectively.

“Weakest link” theories predict that the brittle fracture of snow is inherently a statistical problem. The probability of failure of snow in centrifugal tensile tests is shown to be a function of σ/σm where σ is the applied stress and σm is a characteristic strength (a maximum strength) which is a function of density ρ alone. Similar probabilities of failure are obtained for measurements at Alta, Utah, and Berthoud Pass, Colorado where the characteristic strength is obtained from the relationship .

A record of sedimentation from pro-glacial sandur deposits through pro-glacial lake deposits to final deposition of till is used to interpret changing environmental conditions, and depositional processes, during the development of the “Little Welsh Advance” in the Shrewsbury area, England. The relationship between lacustrine sediments and till establishes till deposition by flowage. However, the most important conclusions are derived from the deduction that lacustrine sediments were incorporated into the basal part of the ice sheet and transported across previously deposited end moraines. A discussion of this deduction, based on the findings of Weertman (1961), establishes that during the advancing phase the ice sheet was of the polar type. Final melting is thought to have occurred by both top-melt and under-melt as a result of climatic amelioration.

Measurements of widths, diameters and boulder sizes of patterned ground in the Cairngorm Mountains indicate two sorts of stripes and polygons (fine and coarse). Pipkrake and boulder-inclination observations and measurements suggest that fine polygons are produced by heave and their sizes are dependent upon the frequency of boulders large enough to be resistant to heave, which in turn depends upon climatic severity. The lack of orientation, angle of boulder inclination, hemispherical shape, high relative size dispersion and lithological dependence of coarse polygons indicate a selective weathering origin. The frequency of low inclination of boulders in stripes suggests an origin due to solifluction, whereby large immobile or relatively slower-moving boulders impede soil (and smaller boulder) movements and control stripe spacing. Movement observation and lichenometry indicate that fine polygons and stripes and bare coarse polygons are active at the present time and that coarse stripes and vegetated coarse polygons probably date from the Little Ice Age.

A further development of the Howorka steam-operated ice drill is given. It is mounted on a pack frame for easy transportation in rugged terrain. A propane flame is used to vaporize water in a single-pass fire-tube boiler. The steam is delivered to the ice through a double-walled flexible hose and a straight guide tube with an exchangeable nozzle at the end. One hole, 25 mm in diameter and 8 m deep, can be drilled in 15 min; four such holes can be drilled with one tank of water and 10 with one tank of propane. Holes deeper than 16 m are impractical as heat losses in the hose become too large. Sturdy construction has been used and the drill has been tested and found to work satisfactorily under both temperate and arctic conditions.

A light-weight solid-state electronic distance meter was used to measure short-term ice velocities during a two-day interval on the Coleman Glacier at Mt Baker, Washington, U.S.A. The velocities fluctuated rapidly from zero or almost zero to a large fraction of a meter per day. There was little or no correlation between the movement at different stations and the fluctuations masked any diurnal variation if such existed. The ease of obtaining the results demonstrates the utility of the new equipment for extending the possibilities of glaciological research.

The elastic stresses have been determined, in a single-layer homogeneous snowpack on a realistic avalanche slope, by a two-dimensional finite-element analysis. Calculation of the state of stress throughout the 0.96 m snow layer on a slope approximately that of the Lift Gully at Berthoud Pass, Colorado, resulted in reasonable stress values. In particular, both field experience and the calculated shear stresses predict avalanching in the lower-density snows. Also, tensile stresses were present only in the area of the observed fracture line.