An analysis of the margin of the ice sheet in the upper Ferrar Glacier area of south Victoria Land, Antarctica, shows that the shear hypothesis and the theory of Weertman are both of value if an attempt is made to explain the formation of the morainic deposits of this area.

Three types of debris layer have been observed within the glacier:

• i. Silty and sandy layers, with a slight dip towards the interior of the glacier, are separated from one another by white bubbly ice and blue dense ice at the edge of the glacier. They have resulted from a freezing-in process due to the formation of segregation ice and upwarping near the margin of the ice sheet.

• ii. Fault planes in the glacier, filled with slabs and gravel, are the result of shearing which has occurred along and transformed thermal-contraction fissures. The debris has been scraped from the glacier bed, carried into the ice and ultimately transported along these planes.

• iii. Three coarse debris layers of different ages associated with major shear zones at the boundary between stagnant and active ice.

Due to favourable circumstances, the debris layers of Weertman have been observed to be faulted by shear planes of the second type.

The mathematical theory of heat conduction is applied to the analysis of ice segregation processes in soil. A diffusion equation is first employed for the flow of soil moisture. Two new quantities, the rate of ice segregation,σ and the segregation efficiency, E, are introduced. The first is the rate of ice growth measured as mass per area per time. The latter is defined as E = σL/(K1∂T1/∂x−K2∂T2/∂x), where L is the latent heat of fusion of ice, T1and K1are the temperature and thermal conductivity of frozen soil, and T2 and K2 are the temperature and thermal conductivity of unfrozen soil. Three types of soil freezing can be classified in terms of E: freezing of non-frost-susceptible soil (E = 0), perfect segregation (E = 1) and imperfect segregation (0 < E < 1). Finally, the mathematical boundary conditions at an advancing frost line are obtained in freezing, frost-susceptible soil (E ≠ 0). Two parameters related to the structure of soil are pointed out, which seem to be valid criteria of frost susceptibility. The amount of frost-heaving is derived under special conditions.

In South Wales there is evidence for two phases of intense glaciation and an interglacial phase during the Pleistocene. During the closing stages of the earlier glaciation in the west of the Vale of Glamorgan two overflow channels were cut by melt water from an ice lobe off the Glamorgan upland, abutting against ice from the Irish Sea. During retreat, ice from the Irish Sea and local ice deposited material on the Lower Lias outcrop on which two contrasting soils developed. Soils normally associated with a Mediterranean climate developed locally on the outcrop of the Carboniferous Limestone during the interglacial phase.

Salinity profiles of young sea ice are presented which show salinity differences of the order of 2‰ to 3‰ within a ~3 cm. distance, horizontally as well as vertically. This ice is also shown, by use of a penetrating dye, to be very permeable which encumbers any attempt to explain such pronounced salinity variations. Two generations of brine-drainage features are described; the first is inherited from the liquid and the later-generation channels develop from brine-pocket and Tyndall-figure migration.

It is proposed that at least part of the brine contained in the ice mass migrates downward in the following way: cold dense brine cascades from higher levels, causing the more dilute, warmer brine at lower levels to partially freeze. This would also account for some of the local variations in salinity.

When a surface layer of the soil freezes, both heat and water diffuse from the unfrozen soil beneath to the frozen region. Often the soil does not freeze homogeneously but distinct ice lenses form. An analysis of the diffusion and ice nucleation processes suggests conditions under which ice lensing can be expected; in particular, it is shown that multiple ice lenses cannot form unless the soil thermal diffusivity is greater than the water diffusion coefficient. Analysis of a simple one-dimensional case (a semi-infinite mass of homogeneous soil whose surface temperature is suddenly lowered) gives the temperature and water-content fields as functions of time; these agree with those observed in an experimental study of freezing clay.

Nuclear magnetic properties of hydrogen are used for the quantitative analysis of the water content of sea ice from 0° C. to −40° C. The data on water content are utilized to calculate the brine volume and brine weight content of the samples. Over a range of water contents of 2% to 96% the standard deviation of the nuclear magnetic resonance data from chemical analysis data is ±0.6%, An estimate of water content in a sample of sea ice at −70° C. is given, and the value of nuclear magnetic resonance measurements for field studies is discussed.

The geographical distribution of the drumlins was studied. They are arranged in bands perpendicular to ice pressure with a weaker alignment parallel to ice flow. An hypothesis of drumlin origin is presented. Two ice flows are present, a strong flow from an Irish centre to the north-west, and a weaker flow of Scottish ice from the north.

Studies in the south-eastern part of the Drakensberg mountains and the Basutoland uplands, above the 6,000 ft. (1,830 m.) level, of Southern Africa have yielded evidence for a periglacial regime during the Pleistocene. The limited earlier work in Southern Africa suggested that the Pleistocene climate was too dry for glaciation to have occurred, but the existence of oversteepened slopes, solifluction slumps and cirques is indicative of a periglacial environment. There is some correlation between the respective altitudes and latitudes of these periglacial features.

Meteorological observations were made on Lewis Glacier, Mount Kenya, during the “long rains” in April 1960. General meteorological observations indicated rather similar conditions to those found in other months. Ablation occurred on each day but amounts were generally small. Rather more accumulation occurred than is expected during the dry season, but again amounts were small. The net accumulation over a to day period was only 0.38 cm. water-equivalent, although about 30 cm. new snow (about 10 cm. water-equivalent) was lying when the expedition arrived. Detailed observations of short-wave radiation, temperature, wind and humidity with estimates of long-wave radiation were used to calculate the heat balance at the surface of the upper ablation region. Agreement between calculated and measured ablation was reasonably good. Over the periods considered, radiation accounted for 89.5 per cent of ablation, turbulent exchange from the air for 8.0 per cent and evaporation for 2.5 per cent. Subsurface melting was taken into account and the formation of ice bands in terms of such melting is discussed.

The rate of grain growth in thin sections of polycrystalline ice was found to be practically the same at temperatures between 0°C. and −1°C. and not to depend to a great extent upon initial average grain size. In general, several hundred hours of annealing at 0°C. reduced the number of grains by a factor of about 3. The growth rate of certain grains was much greater than the average and these increased about a hundredfold in area. The rate of change of the average diameter was approximately inversely proportional to the annealing time. Grain boundary angles tended to average 120° irrespective of the number of sides per grain. Both grain shapes and crystallographic orientations were found to influence boundary migration rates. After long periods of annealing there was a strong tendency for the surviving grains to have their c -axes oriented parallel to the plane of the ice surface.

The flow near the end of a glacier in a steady state is investigated by using a theoretical model: a plastic–rigid material with a constant flow stress resting on a rough horizontal bed. Starting from an appropriately chosen slip-line far from the end, the slip-line field is constructed numerically and continued to the end of the glacier. The field rapidly settles down to a form independent of the precise starting conditions. In the region of small surface slope it agrees with the approximate analytical solution reported earlier (Nye, 1951). To avoid a breakdown in the method it is found necessary to modify the bed by a trivial amount over the final 3 m. In practice the ice can lose contact with the bed very near the end, and the effect of this on the solution is discussed.

The velocity field is computed for a uniform ablation-rate. Other distributions of ablation-rate could be accommodated, but there appears to be a critical gradient of ablation-rate beyond which the slip-line field fails.

The laws of wind-speed variation with height and their modification with stability are discussed and applied to observations in the first 2 m. over various cold surfaces. An exponential law is superior save in frequent, near-neutral conditions, but the logarithmic law is superior in neutral and again in really stable conditions. A power law and a logarithmic-plus-linear law give the best fit with the data only at moderate stabilities. A logarithmic-plus-cubic law of wind speed is evolved that permits suppression of linear additions to the logarithmic law at two distinct stabilities. A power form of variation of Richardson number with height is found and compared with a linear form. The former is applied with the logarithmicplus-cubic law to the observed data, though with limited success. Eddy-viscosity coefficients for the different laws are compared.

Ice temperatures were measured on the ice plateau at Mawson, Antarctica, for one year down to depths of 11 m. and through a floating sea-ice cover for six months. The plateau data were examined by harmonic analysis and the thermal diffusivity of the ice was obtained from the classical model of heat diffusion. An improved model of heat diffusion proposed by Lettau (1954) was also used to derive the diffusivity. The results show that absorbed radiation affects the computed diffusivity values down to 6–8 in. depth and a model is put forward to explain these apparent changes with depth. Data on the extinction of radiation in the ice have been published elsewhere (Weller and Schwerdtfeger, in press). The diffusivity of the ice is determined for periods with no radiation in winter and the value of 0.011 cm2. sec−1 agrees well with values at 8 m. depth where the effect of radiation becomes negligible.

Heat-flux plates embedded in the ice were used to determine the diffusivity independently and also to give numerical values of the heat flux at any moment. The geometry and characteristics of these flux plates are discussed elsewhere (Schwerdtfeger and Weller, 1967). They are also used to derive the diffusivity of sea ice and enable a detailed analysis of the diurnal heat flux in such complex substances as sea ice to be made.

Observations have been made of the modification produced by a temperature gradient in the shape of air bubbles in natural snow crystals, and also of the shrinkage of the bubbles with time. The rate of shrinkage is governed by a constant which is strongly temperature dependent with an activation energy of about 15.1 kcal./mole, a value sufficiently similar to the activation energy for diffusion of tritium, dielectric relaxation and mechanical relaxation to suggest that atomic diffusion processes may be responsible for all of these phenomena.

A theoretical expression is derived for the rate of increase in the density of a compact of uniform ice spheres due to volume diffusion in the ice. The diffusion occurs due to the existence of high concentrations of vacancies in the ice just beneath the concave surfaces of the necks which grow between the ice spheres. Accurate measurements on the densification of a compact of ice spheres as a function of time, temperature, and particle size are found to be in excellent agreement with the theory The importance of this process in the metamorphism of dry snow at a uniform temperature is discussed.

The growth of bonds between snow grains or ice spheres has been variously attributed to surface diffusion, volume diffusion, and evaporation–condensation. To distinguish among these possible mechanisms the unconfined compressive strength of two groups of snow samples was determined as a function of time. One group was allowed to sinter under atmospheric conditions while the other group was kept immersed in silicone oil. The much lower rate of strengthening of the latter group suggests that evaporation–condensation must be the major mechanism of mass transport in snow under atmospheric conditions. The possible magnitudes of the various mass transfer coefficients are discussed.

The average yearly net ablation rate on permanently ice-covered Lake Fryxell, Victoria Land, Antarctica, is 30 to 40 cm. This figure was calculated by a novel method utilizing a record of ablation which is incorporated in the ice cover of the lake. These values are higher than those measured on Ross Island 80 km. to the east; the difference in ablation rates for the two areas is attributed to the prevalence of katabatic winds in the climate of Taylor Valley. The Lake Fryxell ablation figure is applied to nearby Canada and Commonwealth Glaciers in the calculation of their ice budgets.

A series of concentric debris bands crop out on the frontal stagnant zone of Sørbreen, Ny Friesland, Vestspitsbergen. The contained debris, which is dominantly sand and silt with some clay and gravel, is well sorted and banded, and it is thought to be derived from subglacial fluvial deposits. These debris bands give rise to a complex series of bedded moraine ridges, and bedded and unbedded sediment sheets on the glacier surface.

The development of a supraglacial hummocky moraine is traced and it is composed of several elements: supraglacial ridges, kettle-holes, and flowed sediment sheets, which are derived from debris bands; supra-glacial fluvial deposits and clay-silt ablation tills; and englacial fluvial deposits. It is also suggested that large areas of the outwash plain are underlain by dead glacier ice.

From the present work there are several possible implications for the interpretation of Pleistocene deposits:

• i. Certain types of “controlled disintegration features” may have formed supraglacially from debris bands. Some bedded features hitherto interpreted as Huvioglacial in origin may be supraglacial moraines.

• ii. Certain types of “kame-and-kettle“moraine may be mainly supraglacial in origin.

• iii. Complex sequences of tills and bedded sediments may have been formed during a single glacier retreat phase rather than by multiple advance and retreat.

Advantages of neutron moisture probes over standard snow sampling tubes include integration of water content over a greater horizontal extent, easier measurement of snow layering, and possible increase in accuracy through elimination of the need to extract a full core. However, the neutron probe is better suited for evaluation of water content changes with time at a fixed location, as in soil moisture studies, than for measurement of the total water content of a variable snow pack. Field tests in the mountains of Idaho, U.S.A., showed statistically significant differences among mean snow densities determined by a neutron probe in closely spaced holes at a single sampling station. Within-station variance was about the same as with a conventional snow tube. There were significant differences in density for a given depth from hole to hole, but statistical interactions make it difficult to interpret these differences. There was a poor correlation between measurements made in the same hole with a neutron probe and with a snow sampling tube.

In metamorphic rocks a sharp distinction between planar structures (e g. in schiste) and layered structures (e.g. in banded gneisses) is generally made. This same distinction has not been maintained in descriptions of analogous structures in glacial ice. At least part of the problem lies with the use of the term foliation, which, unfortunately, has been applied to both types of structures. On historical and etymological grounds, as well as on the basis of widespread acceptance by petrologists and structural geologists, it is argued that foliation should apply to planar structures in both rocks and glacial ice.