A set of internally consistent mass budget terms is proposed for consideration. Vertically measured, water-equivalent components of accumulation, ablation, and net budget are defined for points on a glacier (specific quantities) or as area-integrated totals for the whole glacier (total quantities). The budget year is defined as the time between two minima of net budget. Additional terms involving specific and total rates of accumulation, ablation, net budget, and various subdivisions of the glacier area are developed. Mass budget quantities can be separated into steady-state and budget imbalance terms. Net budgets can be calculated by simplified means when the variation of budget with altitude is known. It is suggested that the term “firn” be applied to layers which have survived one summer’s ablation season.

Investigations of the mass balance of the Hintereisferner are dealt with for the period 1952–61. Ablation of ice was measured with stakes, ten of which per square kilometre were considered as a sufficient number. The area of ice ablation terminates in the “zero-line of ice ablation”. The net accumulation was studied in pits, and by mapping of enduring accumulation patterns. In order to avoid errors it is proposed that the term “firn line” be replaced by the term “old snow line”. This would more clearly emphasize that only the net accumulation of old snow from the current budget year is a gain of mass for the glacier. The term “firn”, in accordance: with Flint’s [1957] definition should be used only for snow more than one year old. Between the old snow line and the zero-line of ice ablation in some years an appreciable firn ablation takes place. The mass balance reveals a large variation between +0 77×106m.3 of water in the most favourable budget year 1954–55, and −9.83×106m.3 of water in the most unfavourable budget year 1957–58. The average annual mass balance was −3.60×106m3 of water, with an estimated maximum possible error of about ±0.54×106m3 of water.

The mass balance of Storglaciären in Kebnekajse, Swedish Lappland, has been studied in some detail sine 1946. Out of sixteen budget years, fourteen have given a deficit, one a surplus and one has been balanced. It is emphasized that more attention should be paid to the accuracy needed for significant mass balance studies. At present the density of the observation network on Storglaciären is 120 observations per km.2 for accumulation and 13 observations per km.2 for ablation measurements. The net loss during the sixteen years of observation amounts to nearly 10 per cent of the total glacier volume, and it is suggested that the principal cause of this loss is the increase in the mean summer temperature.

Glacier reconnaissance in North America depends largely on aerial photography. Qualitative interpretation of such photography presently yields information on extent and yearly variations of existing glaciers, vigor of their activity, formation of kinematic waves, snow-line altitudes, residual annual snow accumulation, and recent climatic changes. Methods are proposed whereby such data can be combined with limited ground observations to obtain quantitative mass budget data.

Mass budget studies on the glaciers of Axel Heiberg Island, Canadian Arctic Archipelago, during the summers of 1959–61, resulted in recognition of five distinct zones in the accumulation area. The 1961 data from these zones of the main glacier investigated are presented. The implication is made that the long-term changes in size, elevation and net accumulation of these zones can be utilized as climatic indicators.

Discussions of possible causes of preferred crystal orientations in fresh-water ice are presented, with data on ice orientations from several Arctic lakes. Evidently, initial ice orientations are determined by wind conditions. Orientation selection during growth at the bottom of the ice also takes place, but in the lake ice examined it is apparently largely unsystematic. Constitutional supercooling can cause c-axis-horizontal orientations, but it is not of sufficient magnitude in the lakes examined to have much effect. Striations are locally significant but erratic.

An examination of rates of ice growth, actual ice thickness and the quality of the lake ice profile on Knob Lake, central Labrador—Ungava, showed that all these factors were extremely variable. Three sites were established on Knob Lake from 1957 to 1961, and a similar sequence of sites was established on a neighbouring lake, Maryjo Lake, from 1959 to 1961. Significant variations occurred within a single lake body from site to site, though it was noted that certain patterns of ice growth and quality did occur throughout most years and could be directly related to patterns of snow accumulation on the lake. Variations from lake to lake were found to be least at the centre lake sites, probably because snow cover was always least at these sites and would not affect heat loss so greatly as at the marginal sites. It is suggested that the majority of empirical formulae proposed for lake ice growth are unrealistic for short-term forecasting of ice thickness and growth, and even long-term forecasting, using accumulated degree-days of frost, only gives average values. The only answer is repeated samplings on any lake, until such time that sufficient data are gathered for a full statistical approach based on probability analysis.

The occurrence of ice mounds, which were observed in the western part of the Sør-Rondane by a geological and gravity reconnaissance party of the 1960 Expédition Antarctique Belge, is described. An explanation of the origin of these mounds could be the refreezing of an accumulated pocket of melt water within the ice. The possibility of the formation of pockets of melt water, despite the severity of the climate, is discussed in relation to several examples of the melting of snow and ice. It seems that such a pocket could form above the higher mounds of the underlying moraine by the hot-house effect.

A new advance since about 1954 of the glaciers descending on all sides of the great volcanic mountain Beerenberg (2,277 m.) on the island of Jan Mayen (lat. 71° N., long. 8° W.) has been reported. Annual precipitation in the area appears to have risen fairly steadily and in the 1950’s had almost doubled as compared with the 1920’s. Other places around the Greenland Sea show substantial increases of precipitation after 1920 as compared with the 1910–20 rate, but mostly attained a maximum in the 1930’s or around 1940. Periodicities are briefly discussed as well as secular change. Temperatures at Jan Mayen have fallen somewhat since the 1930’s but they have not altered much since the 1940’s. The likely causes in terms of changes of the atmospheric circulation and other circumstances, including lag in the glaciers’ response, are briefly discussed. The increase of precipitation seems to be the main, almost the sole, causative factor in the glacial advance.

Laboratory experiments and field observations permit an explanation of the varying crystallographic orientations observed in lake ice in terms of four factors: (1) coincidence of the plane of most rapid growth in ice (the basal plane) with the vector of thermal flux, (2) mechanical fragmentation of early-formed dendrites and plates by winds above a critical velocity (approximately 2.7 m./sec.), (3) the presence of a sufficiently thick layer of supercooled water to permit vertical crystal growth, and (4) the operation of geometric factors, first pointed out by Perey and Pounder, which result in the gradual elimination of the flatter plates of growing ice by the steeper ones.