Instead of starting with an initially dry, below sea-level basin undergoing glacierization, as was done in an earlier. model, the present computations are based on the existence of an open channel connecting the Ross and Bellingshausen Seas. The period of glacierization begins as the sea in the channel freezes permanently and acquires accumulation, both from local precipitation and transport from the adjacent mountains. Times of growth of the ice shelf, by combined freezing from below and accumulation of 10 and 20 cm. yr.−1, respectively, are determined for the case of a linear temperature profile in the ice. After the ice shelf becomes grounded further growth is by accumulation only. Steady-state temperature profiles for ice sheets 2,300 and 4,300 m. thick are computed under assumption of constant geothermal heat flux of 10−6 cal. cm.−1 sec.−1 and compared with observed temperatures in the 300 m. drill hole at Byrd Station. Basal melting of the 4,300 m. thick ice is found to exist only for the smaller accumulation rate.

The effect of down-slope motion and sinking of ice strata on the vertical temperature profile of the surface layer is studied with aid of the Benfield-Radok formula. Assuming no climatic temperature change and an initial temperature gradient at the ice crest of 1° C. increase per 100 m. increase in depth, the curve of best fit of all those tried is for a sinking rate of 20 cm. yr.−1 and a down-slope speed of 85 m. yr.−1 (2,130 yr. of motion from the crest).

Due to the abnormally warm summers of 1955 and 1956 the glaciers of Mount Ruapehu deteriorated to such an extent that the ash layer of the eruption of 1945 was exposed everywhere. This caused a development of ice cones similar to those occurring in Iceland. Various factors, especially heavy crevassing, which took place at the same time, are responsible for the different ways of development of dirt cones on Ruapehu.

A summary of the techniques used and results obtained from three oversnow traverses in Marie Byrd Land and the Ellsworth Highland between January 1957 and January 1959 is presented. Seismic reflection shooting at 30 nautical mile (55.5 km.) intervals was combined with gravity, magnetic and altimetric measurements to determine the glacial and subglacial topography. It was found that a vast portion of West Antarctica has an ice–rock interface well below sea-level. A major connecting channel with a maximum depth of more than 2,500 m. below sea-level exists between the Ross and Bellingshausen–Amundsen Seas, whereas there is no major topographic connection between the Ross and Weddell Seas. This channel divides West Antarctica into two provinces with granite and rocks of sedimentary origin to the east and south, and a volcanic region to the north-west. Present ice flow is outward from two high areas, centred over mountainous regions on either side of the channel. It is concluded that the present ice sheet has grown from the convergence of the two smaller ice sheets which formed in the mountainous areas and joined across the intervening open water.

In a 300 m. deep hole drilled in the 3000 m. thick ice at Byrd Station (lat. 80° S. long. 120° W., 1513 m. above sea-level), the temperature was observed to decline with depth below 45 m. This profile was extended to the bottom of the ice with the aid of heat conduction theory under these assumptions:

• i. that as the ice was deposited the climate became warmer at the rate of 045° C. per 1000 years;

• ii. The conduction of geothermal heat is 31.6 cal. cm.−2 yr.−1.

It is estimated that the first 2000 years of geothermal heat conducted to this ice, whose annual accumulation is 30 cm., is dissipated to the atmosphere and space. When the ice becomes thicker, it retains all the geothermal heat given to it for a long time.

An alternative, non-climatic change explanation of the decreasing temperature in the Byrd Station hole is based on colder ice from higher elevations moving under the warmer ice accumulated locally. However, an examination of the topography of the Marie Byrd Land ice does not appear to support this explanation.

Observations were carried out on each significant layer of the snow cover at Ottawa (lat. 45° 24′ N., long. 75° 43′ W.) on the thickness of the layer, and the density, grain size distribution and degree of bonding of the snow in each layer. A logarithmic dependence on time was found for the layer thickness, and the density and grain size distribution. The product of layer thickness times the corresponding snow density was found to be constant when no melting occurred.

A newly discovered pothole field in the White Mountains, N.H., is described, and is attributed to action of melt water from the last continental glacier. Discordance of pothole orientation with slope direction is explained by inferring the presence of a retaining wall of ice which controlled stream flow direction during the period of pothole formation. The potholes constitute the highest evidence of continental glacial drainage yet known in New England.

The seasonal precipitation of Ruwenzori is examined and the height of the climatic snowline determined. Two distinct periods of surplus accumulation and two ablation seasons can be recognized and give rise to a somewhat complex stratification. Precipitation diminishes with altitude above about 10,000 feet (3,050 m.). The water equivalent of the annual accumulation on the highest peak is thought to lie between 25 and 30 inches (635–762 mm.). Twelve months’ synoptic charts have been analysed and an attempt is made to relate the seasonal variations of accumulation and ablation to the meteorological factors accompanying the oscillations of the Inter-Tropical Convergence Zone.

At the inland station “Southice” (at approximately lat. 82° S., long. 29° W.) investigation in firn to 45m. included profiles of temperature, density, granularity and crystal size. Mean annual accumulation and temperature are interpolated and crystal fabric analyses briefly discussed. A study of drifting snow is outlined.

Similar studies, but without crystal observations, were continued across the continent using snow cores to 11 m. depth and supplemented by Rammsonde soundings. These sub-surface observations with the sastrugi forms noted, permit the interpolation of the mean accumulation, temperature and wind direction at different heights across the continent. Radiation flux, wind speed and air and snow temperature profiles were recorded at various halts.

The Siberian pole of cold is situated in the extreme north-east of Eurasia (in the region of the Cherskiy mountain system, in the upper parts of the basins of the Yana, Indigirka and Kolyma Rivers). Particularly low air and soil temperatures have been observed in the intermontane areas. Among these localities is the famous Oymyakon, where the lowest minimum temperature in the Northern Hemisphere has been recorded. In the climate of this area extreme aridity, connected with the intracontinental position of the territory, is combined with intense cold.

In the two highest massifs (Ulakhan-Chistay and Suntar-Khayata) small centres of recent glacierization (chiefly kars) are developed; there are also distinct traces of a more extensive older mountain glaciation. In the intermontane areas and on the principal level of the dissected hilly peneplain positive indications of a former glaciation are absent. However, the recent cryogenic phenomena represented by fossil ice, permafrost, taryns, as well as thermokarstic, solifluction and congelation features, are very abundant and diverse.

The widespread development of all these features gives this territory a periglacial aspect, and also provides the possibility of using the study of many recent phenomena for palaeogeographical purposes. From this point of view, the processes leading to the formation of loess deposits (cryogenic facies) and the formation of structural and thixotropic soils arc of particular interest.

The recent natural landscapes in this region are represented by a dominant type of larch tundra–forest associated with comparatively typical taiga bog formations in the depressions and xero-cryophile meadow–steppe landscapes on the steeper and warmer southern slopes. Such a unique landscape combination connected with the specific climatic conditions of this region provide a basis for interpreting the recent natural conditions of the Siberian pole of cold as a survival of the “late glacial.” At present these natural conditions are being intensively developed economically.

The dark and light bands on glaciers known as ogives are only found beneath ice falls and avalanche fans. They are not to be confused with sedimentary layering, which may appear similar. Vareschi’s pollen studies are considered in relation to the present theory; his evidence is re-interpreted and shown to support the theory put forward.

The Norwegian glacier Austerdalsbreen has a fine double set of ogives, one set on ice from Odinsbreen and the other on ice from Thorsbreen. These ogives are continuous from near the feet of these ice falls down to the end of the main glacier. The ice from the collecting ground of Jostedalsbreen which moves slowly towards the head of these ice falls is normally stratified as seen in the deep crevasses immediately above the ice falls. The high velocity of flow, 2,000 m. per year in the upper part of Odinsbre ice fall, causes the ice to stretch into a thin and heavily crevassed layer which exposes a very high proportion of surface per unit volume to the sun, the rain and the snow. In summer this leads to:(1) crystal changes, primarily of enlargement, (2) an infusion of dirt which blows on to the glacier from the neighbouring snow-free and vegetation-free land surfaces, and (3) water filling the bottom of some of the deeper crevasses, which may later freeze. On the other hand, the ice which passes down the ice falls in winter is largely protected by a mantle of snow; crystal changes then are slow, little dust collects, and less water pours into the crevasses which, instead, are filled with new snow. So the ice reaching the lower part of the ice falls and moving on to form the main glacier, Austerdalsbreen, has been subjected throughout its mass to seasonal differences. These differences seem to be more systematic in the deeper ice, and only when the chaotic surface layers are melted away, do they appear on the surface of Austerdalsbreen as well defined ogives. The greater proportion of blue, bubble-free ice with large crystals in the “summer” ice, is alone sufficient to distinguish it from the lighter-coloured “winter” ice with its more frequent bands of white bubbly ice having very small crystals. But as ablation continues, more and more dust is brought to the surface and this still further darkens the “summer” ice. In addition the darker ice melts more readily and tends to form troughs in the glacier surface which retard stream flow, hold the lingering snows, and trap further dust and dirt. The cracks between large crystals also hold dirt better than the smooth hard white surfaces which occur more frequently in the “winter” ice. Hence the ogives remain distinct throughout their journey down Austerdalsbreen. Near the snout the medial moraine is very abundant along the darker bands deriving from Thorsbreen, and this further supports our view that this darker ice was in the ice fall in summer when most debris falls from the rock walls on to the ice fall.