Ogives form beneath active ice falls whose heads are situated near or below the firn line. They consist of curved bands of alternating white, bubbly, less dense ice and darker, denser ice with fewer bubbles, extending throughout the thickness of the glacier. The difference in character is held to be due to the different conditions in the upper ice fall, through which the ice passes in one year at high speed. In summer the thin and shattered ice is exposed to high temperatures and melt water, while in winter the conditions are of Arctic-type throughout the thickness of the attenuated ice. A lane of ice on the Gornergletscher, originating as cold, dry snow with no melt water present, illustrates the character and origin of the white bubbly ice. The greater elevation of this cold-snow ice and the waves formed beneath the ice falls are considered to be the result of the lesser thermal conductivity and greater albedo of the white bubbly ice.

Laboratory studies of the supercooling and freezing of baths of sea-water are described and compared with features of natural sea ice. By using dyes the convection cells in the sea-water test baths could be studied. and the growth of crystals relative to this cell structure could be observed. Brine expelled by the separation of ice from the system commonly followed the pre-existing convection channels. Sections of sea ice are interpreted in the light of these observations, and sea ice is shown to inherit drainage channels and banding features from the characteristics of the parent liquid system.

The Antarctic Ice Sheet responds quickly to regime changes, and time lags in its fluctuations are relatively small. During the Pleistocene glacial stages of the Northern Hemisphere, world-wide temperature reductions reduced the plasticity of the ice sheet and made it thicker. The amount of thickening depended on the conditions at the ice base but it was small, for mechanical and thermal reasons. Also, during the northern stages, accumulation over Antarctica was probably less than now, but this too had little effect on the thickness of the ice sheet. The mass budget of the ice sheet alone, without the ice shelves, probably remained strongly positive; the ice sheet probably existed throughout the Pleistocene and is unlikely to disappear in the future. The area of the ice sheet is determined chiefly by the elevation of the “grounding line”, where the peripheral ice cliffs and ice shelves begin to float. During the northern stages, world-wide lowerings of sea-level displaced the grounding line downwards and northwards, and allowed the ice sheet to advance by amounts which account for nearly all the evidence for previous greater glaciations. In summary, the glacial history of most ice-free areas is governed not so much by climatic as by sea-level changes. Therefore, Antarctic glacial fluctuations were dependent on and in phase with those of the Northern Hemisphere. The field evidence from Antarctica has little bearing on the ultimate causes of glacial fluctuations, which might however be determined by field work on the planet Mars.

The age hardening of artificially and naturally compacted snow has been investigated at the South Pole. Results show that the age-hardening process is greatly retarded at low temperatures. Artificially compacted samples of density 0.55 g./cm.3 attained a compressive strength of less than 3.0 kg./cm.2 after one year’s ageing at −49° C. Exposure to solar radiation accelerated the age hardening. Irradiated samples attained a strength of 6.0 kg./cm.2 after 100 hr., increasing to a virtual maximum of 8.0 kg./cm.2 at the end of 600 hr. Compressive strengths increased with decrease in snow-particle size and with increasing angularity of the particles. Below 3 m. the strength of naturally compacted snow was found to increase rapidly with increase in density. Naturally compacted snow of density 0.55 g./cm.3 possessed considerably greater strength than any of the age-hardened samples of artificially compacted snow of the same density. Thin-section studies show that age hardening can be correlated with the formation and growth of intergranular bonds, and that bond growth falls off rapidly with decreasing temperature. In view of the low strengths found in both naturally compacted snows near the surface and in artificially compacted snow at the South Pole, “cut-and-cover” under-snow camp construction may not prove too practical at the South Pole.

Steensby Gletscher, located between Nyeboes Land and Warming Land, is one of the few Arctic ice streams with a floating tongue. It differs from other floating glaciers of the Arctic in that it discharges into a fjord with open water in the summer, in the presence of crevasses on its floating tongue, and in the way its terminus disintegrates areally into sublobes rather than shedding “Arctic” type icebergs by simple calving.

The glacier’s terminal disintegration is ascribed to a slight northward bend of the fjord stretch which contains the floating tongue. The tongue, moving into the bend along a straight path, runs marginally aground near the shore at the outside of the bend, while the still-floating central part of the tongue continues to move forward. This leads to rotational movement of parts of the tongue which split off from the main ice mass along major crevasses to form sublobes separated from each other by wide gaps, and connected with the main ice mass only at their roots.

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.

A descriptive account of the glaciers of Jan Mayen is given, based on the results of two recent University of London expeditions. The positions of most of the glacier snouts are compared with previous records and a general advance of the ice margin is reported. The discovery of massive tillite deposits low down in the volcanic sequence is thought to confirm the post-Pleistocene origin of the present Beerenberg mountain. An outline of the geological and topographical evolution of the mountain is related to the history of its glaciation. Three major advances of the ice margin are described, the most recent having taken place within the last 350 years. The transient nature of high-altitude rime structures is demonstrated.

Studies of the geomorphology and rock lichen development north of the Barnes Ice Cap prompt the conclusion that 70 per cent of this extensive, interior region was covered by permanent ice some 300 to 400 yr. ago. Contemporaneously the northern Barnes Ice Cap was significantly larger than today; it dammed up a lake in the upper Isortoq valley, over 80 km. long and up to 300 m. deep. Excluding the ice cap less than 2 per cent of the area is glacierized today; this represents a dramatic reduction in surface area of the former ice cover. Similarly, significant recession of the ice cap implies that glaciers of the “Baffin type” are in a less healthy budgetary state than hitherto has been assumed.

Proof of former extensive ice cover rests largely upon restricted rock lichen development. When sufficient time has elapsed for complete colonization, few indications of the former existence of an ice cover will remain. This type of glacierization may have affected large areas in the high Arctic. Absence of evidence of glaciation, therefore, cannot be relied upon to delimit nunatak areas (plant refugia) during the last glaciation.

In the coastal mountain chain of southern Victoria Land approximately 4,000 km.2 of glacier-cut valleys and dividing ranges are almost completely ice-free, while the surrounding areas are fully glacierized.

In the ice-free Wright Valley and Victoria Valley systems evidence of four glaciations is recognized. The earliest two glaciations were the most extensive; glaciers flowed eastwards from the ice plateau through the coastal ranges and cut broad valleys extending to McMurdo Sound and the Ross Sea. The moraines of these glaciations are thin and highly weathered. The third glaciation was less extensive, consisting of advances by smaller glaciers derived from the inland ice plateau, the Wilson Piedmont Glacier and névé fields in the dividing ranges. The surfaces of moraines of this glaciation are now partly covered by saline lakes, evaporite deposits and extensive areas of desert pavements strewn with ventifacts. The fourth and youngest glaciation comprised small advances by remnants of the plateau-fed valley glaciers. Thick boulder moraines of this glaciation overlie earlier deposits.

During each glaciation the greatest volume of ice was derived from the inland ice plateau. The volume of ice entering the valleys was dependent on the difference in altitude between the plateau surface and subglacial rock thresholds at the valley heads. Decrease in the surface level of the inland ice plateau caused the rock thresholds to increasingly hinder the eastward flow of plateau ice until practically no ice could flow down into the valleys, thereby terminating the glaciation. Such a condition exists at the present time.

In this paper a study of lake ice at Peters Lake with respect to crystallographic nature and impurity in crystal grain boundaries is described. The appearance of the ice structure in 1962 was quite uniform over the whole area of the lake; it showed predominantly horizontal c-axes. Another type of ice with predominantly vertical c-axes could not be found even in the surface layer of the ice. The cause of these two types of ice is explained as being due to wind action. A correlation between the grain-size and the depth of ice is expressed in exponential form down to a depth of 100 cm. A linear relationship between the thickness of ice and the depth of snow cover was obtained. Impurity in grain boundaries measured as specific electrical conductivity was hard to detect in such a pure ice as that at the lake whose purity was about 1 micromho/cm. Supplementary data from Lake Nukabira, Hokkaido, are summarized and compared with the data from Peters Lake.

It is suggested that the dark and light bands associated with a wave ogive system are the result of preferential adsorption of wind-blown dust by interstitial water held in narrow coarsely crystalline bands, which are more frequent in the dark bands. These narrow bands are presumed to be produced by regelation on the closure of extensive crevasses in the cwm zone above the ice fall and that, although originally uniformly distributed, there is a bunching effect caused by velocity fluctuations in the glacier at the top of the ice fall. These velocity fluctuations, which are attenuated by irregularities in the glacier’s bed, produce waves at these points, multiple irregularities producing multiple wave systems.

The nature of candle ice, stratified ice and ice of radial structure observable on ice island t-3 was investigated. Cores were drilled through the ice island at two sites. Crystallographic examination, and visco-clastic and chlorinity measurements, were made all along the cores. Results indicate that the ice body of t-3 is composed of three strata; the stratum above a heavy dirt layer is composed of iced firn which shows a granular nature with crystalline facets; that below the dirt layer is “basement ice”; and at the bottom is a sea-ice layer 1.8 m. thick. The basement ice is subdivided into four strata. Petrographic studies of dirt samples obtained from the surface and from the ice cores were carried out by an X-ray diffraction method; from the results, the dirt is thought to be dust of Precambrian granite or gneiss, which are the prevailing rocks in Ellesmere Island. The structure of t-3 was inferred from assumptions based on the data obtained from the core drillings at the two sites.

Observations were made on the density of naturally and artificially formed lake and river ice. The effect of initial snow density, size and shape of snow crystals, rate of water spread and rate of freezing on the density of snow-ice obtained was studied in the laboratory and is presented in graphical form. The observations indicate that snow-ice formed under natural conditions will probably have a density between 0.85 and 0.90 g./cm.3. The classification of snow-ice is discussed briefly.

This paper is a synthesis of glaciological investigations conducted in Terre Adélie, mainly during the LG.Y. The surface and bedrock profiles have been obtained along a 500 km. line roughly perpendicular to the coast; the mean annual temperature has been studied as a finnction of altitude, and mean accumulation has been related to distance from the coast and surface slope. Stratigraphic studies made at Station Charcot again raise the problem of the determination of mean accumulation in certain parts of the Antarctic plateau; they provide a quadratic relationship between density and depth. The snow-drift studies lead to the Mowing conclusions: wind velocity and density of drifting snow are functions of height above the surface, and the total transport depends on wind velocity. Lastly, measurements have been made of glacier flow near the coast. The paper ends with a schematic study of the mass balance in Terre Adélie; accumulation seems to be slightly larger than ablation, a result that is to be contrasted with the obtervrd coastal retreat near Dumont d’Urille base.

A series of glow-curve measurements were made to determine the general nature of the thermoluminescence of natural ice. The curves were made by subjecting the samples to ultraviolet radiation from a quartz-envelope mercury arc lamp while keeping the samples at liquid air temperature. The samples were then heated by passing a stream of air over the sample container. The resultant rise in temperature is non-linear but is nearly uniform from run to run. The light emitted was measured by the microphotometric portion of the standard apparatus for determination of mineral thermoluminescence.

Curves were obtained on samples collected from the ice tunnel in the ice cap at Jungfraujoch and from freshly fallen and old snow at Bern in Switzerland. A systematic variation in glow-curve shape was found. This variation appears to be directly related to the stress history of the ice. Ice which has been subjected to high shearing stress can he readily distinguished from ice which has not.

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.

During the I.G.Y. seven geophysical stations were occupied on the semi-permanent sea ice of inner McMurdo Sound, Antarctica. Three more were occupied on the floating tongue of the Koettlitz Glacier. Seismic refraction, reflection and S-wave propagation studies yielded preliminary data on the configurations of the ice cover and a profile of the bottom of the sound. The bottom slopes smoothly to a depth of 627 m. at the center of the sound. Secondary reflections indicate the presence of an unconsolidated layer on the bottom at some points. The glacier tongue near its seaward edge has a fairly uniform thickness of about 45 m.

The Burroughs Glacier, south-east Alaska, is a slow-moving remnant (14×3km.) of a much more extensive glacier. It is now entirely below the firn line; ablation has revealed ice structures and fabric once 300 m. or more below the glacier surface.

At the present glacier surface three kinds of ice are identified—foliated ice, coarse-grained border ice and very coarse-grained basal ice.

Two systems of fine-grained foliation are present. Differential movement in the glacier has caused recrystallization along closely spaced planes. At the glacier surface this produces a steeply dipping longitudinal foliation. A gently dipping foliation, having a regional trough-like structure, may be associated with former stratification planes or with former spoon-shaped shear surfaces.

The optic orientation of crystals in the coarser layers of the foliated ice shows three weak maxima, and in the finer layers a single weak maximum, corresponding to one of the coarse layer maxima, and normal to the gently dipping foliation plane. The other maxima in the coarse layers are orientated close to the poles of principal fracture planes.

In the coarse ice the fabric shows a pattern with three maxima similar to that obtained in torsion shear experiments. In the glacier the pattern may be formed by shear near the glacier bottom or along gently dipping foliation planes. Grain-size increases towards the glacier terminus, especially in the stagnant ice zone.

Structural evidence suggests that in the early stages of the Little Ice Age the ice flow was from west to east. Later it was to east and west from an ice crest in the upper Burroughs Glacier. Structures produced by present movement have been superimposed on older structures.