Model calculations are made of the magnitude of the shift of the portion of an ice divide on a two dimensional ice sheet and of the “center” (the position of highest elevation) of a circular ice sheet when the rate of accumulation is different on different sides or in different sectors of an ice sheet. It is concluded that gross changes in the accumulation pattern are required to cause an appreciable shift of the position of ice divides or ice centers if the positions of the edge of the ice sheet are fixed.

A numerical model for three-dimensional, time-dependent glacier flow (Campbell and Rasmussen, 1970) treated the ice as a Newtonian viscous fluid and related its dynamics to two large-scale bulk parameters: the viscosity v determining the ice-to-ice friction, and a basal friction parameter A determining the ice-to-rock friction. The equations were solved using the relatively simple flow law of Bodvarsson (1955) in which the basal shear stress is proportional to volume transport. Recent research suggests that a more realistic basal flow law is one in which the basal shear stress to some lower power (1–3) is either proportional to the vertically averaged velocity (Glen, 1958; Nye, 1960, 1963[a], [b], [c], 1965[a], [b], [c]) or to the ratio of the vertically averaged velocity to glacier thickness (Budd and Jenssen, in press).

In the present study a generalized flow law incorporating all of the above bulk basal flow laws is applied to the Campbell–Rasmussen momentum equation to form a generalized two-dimensional transport equation, which, when combined with the continuity equation, yields a numerically tractable set of equations for three-dimensional, time-dependent glacier flow. Solutions of the model are shown for steady-state flow and surge advance and recovery for a typical valley glacier bed for powers 1, 2, and 3 for each of the basal flow laws for a steady-state climate input and a given ice-to-ice viscosity parameter.

The determination of glacial ice thickness by vertical resistivity depth soundings relies upon the use of theoretical curves which neglect the effect of valley walls. To improve the utility of glacial resistivity measurements an analytical expression is derived for the apparent resistivity determined by a Wenner array oriented parallel to the strike of a layered trough embedded in a perfectly conducting half space. Numerical evaluation of this expression allows the effects of glacial cross-section to be determined. It is shown that the presence of valley walls and layering within the glacier can strongly effect the determination of total ice thickness, and a criterion for the reliable use of plane-layered master curves in the interpretation of field data is established. An apparent resistivity curve calculated for a layered trough is shown to give an excellent fit to field data published by Röthlisberger and Vögtli (1967).

Radio echo-sounding surveys of Antarctica and Greenland have revealed extensive layering within the ice. Formulae for the effective reflection coefficient, when viewed by a pulsed radar, are derived for isolated or multiple randomly spaced layers. In the latter case the variation in dielectric constant with depth is described by a vertical autocorrelation function and a standard deviation. Some measurements of the reflection coefficient of layers, and the dielectric absorption of ice are given. The significance of the fading of layer echoes and the possible causes of variations in the dielectric constant are considered and some further investigations are suggested.

It is concluded that the echo strengths found in the Antarctic may be explained by multiple layering, and that the necessary fractional change in the dielectric constant may be as small as 10−4. It is suggested that this change in dielectric constant may be due to differences in orientation of anisotropic ice crystals.

In the summer of 1972, the amount of ice melt obtained by stake measurements on the McCall Glacier, Brooks Range, was compared with the discharge of a small controlled run-off site, and with heat balance calculations. For daily values the agreement was not always good; however, for the 11 d period for which the study was carried out, the agreement can be considered as excellent. The amount of ice melt calculated from run-off and heat balance gave 3.5 and 1.2% higher values, respectively, than the direct measurements. This is encouraging, insofar as it suggests that it may be possible to calculate the combined ice, water, and heat balance for the glacier as a whole.

32Si dating of glacier ice has hitherto been complicated by the poor knowledge of the half life. Furthermore, fall-out of bomb-produced 32Si impedes the determination of the specific activity of cosmic-ray produced 32Si in recent precipitation. Measurements on well-dated pre-bomb samples from the Greenland ice sheet establish a calibration for 32Si dating of up to 1 000 year old polar ice samples of the magnitude of 1 metric ton. If the technique is used on temperate glaciers, samples of pre-bomb deposits (or from after 1970) must be collected for comparison with samples of old ice, using an apparent half life of 295±25 years. Due to secular cosmic-ray flux variations, the true half life of 32Si is estimated at the slightly higher value of 330±40 years.

A reconnaissance was made of one of two small ice caps near the Robeson Channel coast of northern Ellesmere Island. It is shown that, after a period of net wastage, this ice cap is now thickening slightly and extending its margins. The present regime of the ice cap is a direct result of generally cooler summers in the last decade.

The structure and flow field in the margin of the Barnes Ice Cap was determined through observations on the ice-cap surface, in four bore holes, and in a 125 m ice tunnel. A band of fine bubbly white ice with a single maximum fabric appears at the glacier surface about 160 m from the margin. This band is overlain by coarse blue ice with a four-maximum fabric, and underlain by alternating bands of fine ice with a single-maximum fabric and moderately coarse ice with a two or three-maximum fabric.

The effective strain rate was determined from the bore-hole and tunnel deformation data, and possible variations in the other three parameters in Glen’s flow law, , were studied. It appears that τxy is independent of depth near the surface, and that relative to the coarse blue ice, A is 40 to 50% lower in the white ice and possibly 10% lower in the fine blue ice.

Dips of foliation planes decrease rapidly with increasing depth and distance from the margin. This foliation is assumed to have developed near and parallel to the bed some distance from the margin. An analysis based on this assumption predicts the observed change in dip, but suggests that it did not develop under the present flow field. The ice cap was probably thicker a few tens of years ago, and the observed foliation pattern may be a relict from that time.

The works undertaken on the Glacier d’Argentière in order to divert the subglacial stream, have allowed access to several natural cavities which correspond to places where the glacier loses contact with its rock bed. These cavities show a certain number of original phenomena both on the rock bed and also on the ice arch. Studies of the basal ice layer reveal peculiar characteristics which distinguish it from the rest of the ice mass: lamination, interstratification of ice containing sand with pure ice, crystallographic composition, and specific chemical composition.

The sliding speeds of the glacier are variable, and an increase in the friction below these cavitations is at the origin of a form of regressive glacial cavitation. The subglacial cavities are grouped together in a network transverse to the direction of glacier flow; they are interconnected by channels which are more or less open which allow proper thermal exchanges to be established and favour sliding.

With the aid of an atomic absorption spectrophotometer (Perkin Elmer 303), chemical analyses were performed on different types of ice collected in an enclosed natural subglacial cavity of the Glacier d’Argentière (French Alps). Contamination was reduced to background noise level of the instrument at each step of the procedure which was developed. One of the main problems encountered during the processing was the desorption of cations adsorbed on the surface of particles dispersed in the ice.

The mean composition in Na, K, Ca and Mg was established for glacier ice and for ice accretions hanging from the ceiling of the cavity or at the bedrock–glacier contact. The mean composition and the ratio (Na+K)/(Ca + Mg) of the ice accretions are higher than those of the glacier ice. This implies a refreezing of interstitial water which was enriched by desorption when, before refreezing, it was forced through the mud layer plastered at the base of the glacier.

Striated ground was found above 3 600 m elevation in the Páramo de La Culata, Pico Espejo and Pico Bolívar areas of the central Venezuelan Andes. This ground, formed by nocturnal freezing and diurnal thawing of the contained water, consisted of aligned lumps of fine to coarse sand, separated by small discontinuous channels (1–3 cm wide). Sorting was observed in the form of pebble-rich and pebble-poor zones. Striated ground in the process of formation showed that needle ice filled the channels before thawing. Lack of sorting is an indication of very recent formation, probably the previous night. The orientation of the striae is compared with the wind direction. This indicates that the formation of needle ice in the ground reflects the direction of the freezing wind, producing striae orientated in that direction, thus supporting Troll’s (1944) original observations.

Cylindrical samples containing 0.59 mm to 0.84 mm diameter silica sand at about 97% and 55% ice saturation (the ratio of ice volume to sand pore volume) were tested at a temperature of −12° C in triaxial compression. Both constant axial strain-rate tests and step-stress creep tests provide information on the influence of confining pressure on the shear strength and creep behavior of the sand–ice material. Changes in the degree of ice saturation help show the influence of the ice matrix versus the sand material on the mechanical behavior. Data are discussed in terms of the Mohr–Coulomb failure law and creep theories. It is shown that the cohesive component of strength depends on response of the ice matrix, whereas the frictional component of strength responds in a manner very similar to unfrozen sand tested at high confining pressures. Experimental data show that creep rates decrease exponentially and creep strength increases with an increase in confining pressure.

The Workman–Reynolds effect was studied in the growth of ice on a monocrystalline seed, at constant growth rates and under steady-state conditions, from KF solutions at concentrations from 2 × 10−5 to 10 × 10−5 Normal. Freezing potentials increased with growth rate to a maximum of 12 V at 11.2 μm/s. Discharge currents through a 105 Ω shunt generally increased with freezing rate until a maximum of 1.5 μA at 11.2 μm/s. The charge transfer decreased with growth rate to 200 μC at 10.3 μm/s and then reached a maximum of 850 μC at 11.2 μm/s. Apparent diffusion coefficients of about 2 × 10−3 mm2/s increased slowly with growth rate until a rapid increase began, apparently associated with interface breakdown. Distribution coefficients of the order of 10−3, calculated from a criterion for constitutional supercooling, increased with concentration. Parameters for LeFebre’s model of the interface showed an interface thickness of about 6 mm, an interface capacitance near one-half pF/mm2, and an interface resistance of about 6 × 104 Ω/mm2. Several empirical relations between these quantities were disclosed. Comparison with values obtained for KC1 solutions with the same freezing cell shows that the KF solutions yielded higher values of freezing potential, charge transfer, and distribution coefficient, and lower values of diffusion coefficient, interface capacitance, and interface resistance.

A review of available information on six self-dumping glacier-dammed lakes indicates that instantaneous discharge during a jökulhlaup is proportional to some power of the cumulative volume of water released rather than being a direct function of time. Information on these and four other self-dumping lakes, moreover, indicates that the peak discharge at the end of each jökulhlaup is approximately proportional to the two-thirds power of the total volume of water released during the flood.

In an effort to ascertain the drainage mechanism of ice-dammed self-draining lakes, the author made observations on the behavior of the small Casement Glacier Lake in 1967. On 22 July when the first outburst of the lake occurred the water level dropped 31.92 m, leaving approximately 35 m of water remaining. Then, following a 2 week period of stability, the lake level fell gradually but steadily during the rest of the summer. Whereas a second rapid discharge occurred in 1965, one never did in 1967. The initial discharge was subglacial and resulted from flotation of the dam; the slow late-summer drainage, however, cannot be attributed to that mechanism and thus remains to be explained.

A brief photographic history of a man-induced ice cone is given. This ephemeral feature created around a gas well on Melville Island, N.W.T., Canada, indicates that the present climate is not capable of sustaining a natural ice mass. Disappearance of the ice is projected by 1974 without intervention of man.

Using time-domain pulsed radar, the intrastructure of a typical temperate glacier has been studied. Certain features have exhibited a rapid change in structure, and cannot be explained by density or ice characteristics of a stable nature. It is believed these time-dependent structures are related to the internal water system for glaciers.

For the observation of areal snow-depth distribution over a wide area, such as the Ishikari Plain in Hokkaido, Japan, existing telephone poles were used in place of the snow scales. Telephone pole number plates (telephone poles in Japan have number plates) were photographed by a 35 mm camera with zoom lens ranging from 80 mm to 200 mm through the window of the observation vehicle. The snow depth was calculated by the ratios of the length of the number plates to the distance between the lower edge of the number plates and the snow surface. Since measurements by direct sounding using a rod as compared with the values by the above method showed a good coincidence with an accuracy of ± 10 cm, it was considered satisfactory for snow depth observation over a wide area.