From data taken on the British Trans-Arctic Expedition it is calculated that 9% of the Arctic Ocean surface between the North Pole and Spitsbergen was hummocked or ridged ice, 17% was unridged ice less than a year old, 73% was unridged old ice and 0.6% was ice-free. The mode of 250 thickness measurements taken through level areas of old floes along the entire traverse lies between 2.25 and 2.75 m. The mean end-of-winter thickness of the ice is calculated to be 4.6 m in the Pacific Gyral and 3.9 m in the Trans-Polar Drift Stream. From measurements of the percentage coverage and thickness of the various ice forms, it is calculated that the total annual ice accumulation in the Arctic Ocean is equivalent to a continuous layer of ice 1.1 m thick. 47% of this accumulation occurs in ice-free areas and under ice less than 1 year old. 20% of the total ice production is either directly or indirectly related to ridging or hummocking. An ice-ablation rate of 500 kg m−2 measured on a level area of a multi-year floe is compared with the rate on deformed and ponded ice. Greatest melting occurs on new hummocks and least on old smooth hummocks. The annual balance of ice older than 1 year but younger than multi-year ice is calculated from a knowledge of ice-drift patterns and the percentage coverage of first-year ice. The same calculations give a mean-maximum drift period of 5 years for ice in the Trans-Polar Drift Stream and 16 years in the Pacific Gyral. It is calculated that for the period February 1968 to May 1969 the annual ice export was 5 580 km3.

The deformation of a strain triangle (≈6 km × 8 km × 11 km) located on first-year ice in the Beaufort Sea was observed over a two-week period in March 1971. Significant strain events (≈ 1.5%) were observed to occur during short (≈6 h) time periods. The long-term (one day or more) divergence rate varied between 0.04 and 0.08 × 10−3 h−1. Short-term divergence rates showed values as high as 0.29 × 10−3 h−1. The observed shearing motion indicated that the floes to the east were moving to the south relative to the floes to the west. This agrees with the shear pattern that might be expected considering the location of the station in the Pacific Gyre. Studies of fracture (lead and crack) orientations in the vicinity of the strain triangle indicate reasonable correlations with the orientation of the strain-rate ellipse. A qualitative relation is suggested between the fracture density and the long-term divergence rate. Correlations were also observed between the divergence of the wind field as computed from the surface pressure field and the ice divergence.

A history of the idea of transporting large icebergs to arid regions to provide a fresh-water source is presented and the problem is considered in four main parts: (1) Location of a supply of icebergs. Only in the Antarctic are supplies of large tabular icebergs available. Data on the size distribution of these icebergs are reviewed and it is concluded that icebergs of almost any desired size can readily be located. (2) Towing. Steady-state towing velocities of different sized icebergs are calculated based on estimates of the drag of the icebergs and the bollard pull of tugs. Because drag increases with velocity squared, large icebergs can only be towed at very slow velocities (<c. 0.5 m/s). However, tugs that can be built within the capabilities of current technology are capable of towing extremely large icebergs. (3) Melting in transit. Calculations of melting indicate that, although melting losses are significant and may be excessive for small icebergs, when large icebergs are towed, large amounts of ice are left when the iceberg arrives at its destination. Towing trajectories, travel times, and ice delivery rates are calculated for optimum routes between the Amery Ice Shelf and Western Australia (A–A) and the Ross Ice Shelf and the Atacama Desert (R–A). Forces included in these calculations are towing, air, water, gradient current and Coriolis. Transit times exceed 107 d (A–A) and 145 d (R–A) with over 50% of the initial ice delivered. (4) Economic feasibility. After total towing charges are paid, it is possible to deliver ice to Western Australia for 1.3 mills/m3 of water and to the Atacama Desert region for 1.9 mills/m3. These costs are appreciably less than the expected price of water delivered at these locations (8 mills/m3). The water delivered by the operation of one super-tug alone would irrigate 16 000 km2. Problems related to both iceberg transport and processing are reviewed and although substantial problems do exist, they appear to be within the capabilities of current technology.

It is suggested that the overall idea is indeed feasible and should be explored further by specific groups of experts.

The morphology of the Barnes Ice Cap margin at the proglacial Generator Lake is described. Types of calving that take place into the lake are discussed, particularly an observed calving in July 1970 when an ice-ramp of about 0.4 × 106 m3 volume broke off due to a rise in lake level. Bending analyses which throw some light on the calving mechanism are presented.

Friction on the bed is assumed to obey Coulomb’s law of solid friction in the presence of interstitial pressure (Lliboutry, 1968). According to this, the friction is a maximum at certain places in the bottom of the valley. Assuming Glen’s non-linear creep law, the steady-state flow of ice along a regular cylindrical channel of parabolic section has been calculated. The results reproduce to high accuracy the distribution of velocity measured on the Athabasca Glacier (Raymond, 1971).

Unusual seismic signals with weak P phases and well-developed monochromatic shear-wave trains have been recorded and their sources located near College Fiord, Alaska. Epicentral determinations show that they originate on or near glaciers. Some of the events have equivalent earthquake magnitudes of 2.0 to 2.5. These energy sources seem to be compatible with spasmodic glacier movement. Smaller events occur often—as many as 60 per day.

This paper puts forward an explanation of the origin of small marginal lakes (superglacial or moat lakes) occasionally found on the edges of valley glaciers. The explanation departs from earlier theories. On the basis of observations made on the Juneau Icefield in south-eastern Alaska, I have come to the conclusion that the lake basins are primarily blow-outs formed as a result of wind erosion.

The daily snow melt calculated from meteorological observations is compared with detailed mass-balance measurements taking into account internal changes in density and free water content in the surface layers of a glacier snow-pack. The energy balance is calculated from measurements obtained by a meteorological station at the experimental site. In addition to the standard ablation measurements the run-off from the melting snow-pack was obtained for a few days. The snow-density profiles were measured with a portable gamma-transmission probe and the liquid-water content of snow was determined by a calorimetric method.

Agreement between the melt calculated by the heat-balance method and the mass changes observed in the mass-balance measurements is fair for daily periods. It appears that about 20% of the daily snow melt takes place internally as a result of penetration of solar radiation.

Snow fences built up-wind of natural snowdrifts at four alpine sites in the Colorado Rocky Mountains changed snow accumulation appreciably. The 3 m tall fences increased the amount of snow at three sites but decreased it at the fourth. At two of the three sites where snow was increased, there was no change in melt rate, so the additional snow prolonged the melt period 1–3 weeks. Fences most successfully augmented natural snow accumulation at sites with level or gently sloping terrain down-wind from the accumulation site. Between 15 and 30 m of fence was needed to produce an extra 1000 m3 of water equivalent in the snowfields at the beginning of the melt season. Fences of the type described here, if properly located, are a means of increasing summer stream flow from alpine areas.

Abundant specimens of lichens, including Rhizocarpon geographicum, are reported from an active medial moraine on Storbreen, southern Norway. The size and distribution of two crustose and two foliose species are described. Inferences are made regarding the age, origin and population dynamics of the lichens. Some implications of the observations for lichenometric dating and use of lichens as indicators of moraine stability are discussed.

Comparative tests of the snow resistograph with the ram penetrometer indicate that there is a high degree of correlation between the two instruments despite fundamental differences in operation. It is probable therefore that the two instruments are measuring essentially the same parameters and may be used interchangeably. The resistograph has a large advantage over the ram penetrometer, in terms of speed and ease of operation, and in its capacity to measure the strength of very weak snow.