Estimates have been made of the mass budget of the total drainage basin of Lambert Glacier. These show a small but significant positive state of balance for the interior basin (the accumulation area up-stream of the major ice streams), and strongly suggest a positive balance for the Lambert Glacier system (the region of major ice streams, between the Amery Ice Shelf and the interior basin). The total mass flux into the interior basin is estimated as 60 Gt a−1. Results are presented from a number of ice movement stations established between 1972 and 1974 around the perimeter of the southern Prince Charles Mountains. These results, together with ice thicknesses from radio echo-sounding in the area, give a total mass outflux through the 2 000 m contour of 30 Gt a−1, implying a budget excess of a further 30 Gt a−1 over the whole interior basin. Results from velocity and ice thickness measurements give a mass discharge through a section near the junction of Lambert Glacier and the Amery Ice Shelf of 11 Gt a−1. Losses within the Lambert Glacier system proper account for a further 7 Gt a−1 and an overall mass excess of 12 Gt a−1 is estimated for the Lambert Glacier system. This present positive state of balance contrasts with geomorphological evidence from the southern Prince Charles Mountains of a large drop in ice level in recent geological time, and the ice surface in the area may now be building up after a major recession.

Electrical resistivity measurements were carried out at station J9 on the Ross Ice Shelf where temperature measurements were available to a depth exceeding three-quarters of the thickness of the shelf. As in a previously published study at a point about 30 km up-steam (Bentley, 1977), the apparent resistivities fit well to a model based upon a steady-state ice shelf with zero bottom balance-rate and an apparent activation energy in the solid ice of 0.15 to 0.25 eV (14–24. kJ mol−1), with preference for the lower end of the range. This model also fits the observed temperature data almost perfectly. Causes of resistivity variation with depth other than the temperature, such as impurity content, metamorphic history, grain size and crystal orientation, probably do not strongly affect the resistivity depth function. Our conclusion is that the true activation energy in the solid ice is less than 0.25 eV (24 kJ mol−1) and perhaps as small as 0.15 eV (14 kJ mol−1), although a reduction by a factor of two or three in the ionic impurity concentration between 50 and 250 m depth cannot be entirely ruled out as a cause of the low apparent temperature effect. A note added in proof indicates that Herron and Langway (in press) have, in fact, reported a decrease in Na+ concentration with increasing depth by a factor of two or three.

Subtle rhombus and rhomboid parallelogram patterns occur on Vaughan Lewis Glacier and the Gilkey Glacier System, Juneau Icefield, Alaska. The patterns are within the firn at the firn-ice interface, are formed by differential recrystallization within narrow preferred zones, and are apparently manifestations of stresses transferred upward from the glacier ice. On the glaciers of the Gilkey System the patterns occur where intense lateral shortening is indicated by abrupt convergence of medial moraines and an abundance of extension crevasses. The short axes of the rhombi and the obtuse angle bisectors of the rhomboids are subparallel to the strike of extension crevasses, therefore to the axis of shortening. The long axes of the rhombi and the acute angle bisectors of the rhomboids are parallel to the foliation, and ice-flow direction. The angles of the parallelograms are variable locally, but average 105° and 75°; the variation seems to reflect intensity and duration of stress. Similar parallelograms occur within the troughs of wave bulges below the Vaughan Lewis Icefall. In the wave bulges, the foliation arcs parallel the wave. The long axes of the rhombi and acute angle bisectors of the rhomboids parallel the foliation around the foliation arc. The short axes of the rhombi and the obtuse angle bisectors of the rhomboids parallel the strikes of radial crevasses, are perpendicular to the direction of extension, and form a fan divergent down-stream. The precise mechanisms and conditions of formation of the parallelograms are not yet understood. Preliminary strain-rate measurements suggest, however, that correlations exist between the orientations of the principal strain-rates and the axes of the patterns, and between the magnitude of the strain-rates and the axial lengths of the patterns.

The turbulent flux of sensible heat in the energy balance of a glacier surface is assumed to be proportional to the temperature difference between the glacier surface and the atmosphere at the same level but outside the thermal influence of the glacier. The factor of proportionality between them is first explained in terms of friction velocity, roughness height, and stability function of the logarithmic wind and temperature profile. It is then derived from climatological records and measurements of the energy balance and its altitudinal gradients at Hintereisferner. Examples of the energy-balance components and their change with altitude are given for the entire ablation season as well as for short periods. The heat transfer coefficients derived have a mean value of 1.7±0.2 MJ m−2 d−1 K−1 (40 ± 5 ly d−1 K−1).

Field investigations of supraglacial debris were carried out during the monsoon season in 1974 on G2 glacier near Tukche Peak in Hidden Valley, Mukut Himal, Nepal. The thickness of the debris layer was observed to increase down-glacier. Laboratory analysis, however, showed a decrease in particle size in the same direction. This decrease is explained in terms of mixing of particles contained in glacier ice with the original debris as melting proceeds. A simple relation between debris mass and glacier flow is introduced to explain the observed results.

Vertical shear stress in ice shelves cannot be precisely zero, since the upper and lower surfaces are generally not parallel. By performing stress balance on a vertical column in an ice shelf we calculate what its magnitude must be. This is done for an unconfined glacier tongue and for a confined bay ice shelf; first, using the assumption of constant temperature and density with depth, and secondly, using realistic data and profiles for Erebus Glacier tongue and for the Amery ice shelf. Shear stresses increase almost linearly with depth and are proportional to surface slope. For Erebus Glacier tongue the shear stress is at most 5% of the magnitude of the direct stress deviators and its action through the ice shell should result in differential movement of 1.8 cm a−1 between the top and bottom of the ice shelf. For the Amery ice shelf, the shear stress is at most 0.4% of the magnitude of the direct stress deviators and this should lead to differential movement of 2.5 cm a−1 between the top and bottom of the ice shelf. Shear stresses are therefore generally negligible in comparison with direct stress deviators and can be ignored when considering the overall dynamics of ice shelves. Differential movement is unlikely to be detectable.

In order to assess the effect of non-local stress transferral through the ice cover empirically, a linear viscous model (employing both bulk and shear viscosities) is used to predict drift-rates for one Soviet and two U.S. drifting stations over the time period May 1962 to April 1964. The predictions, based on available atmospheric pressure and ocean-current data, are compared to free-drift results and to observed values. The empirical viscosity values giving the best fit to observations show a pronounced seasonal variation that correlates well with the growth rate of thin ice. Drift predictions, especially long-term net drift results, show drift magnitudes and turning angles to be simulated significantly better by a viscous model than by a free-drift model. The effects of steady currents are shown to be small for velocities averaged over days but significant for averages over years.

Total transmission, absorption, and reflection of solar radiation have been determined for bare blue and white ice between 0.02 and 0.8 m in thickness as well as for blue ice covered with 0.01 to 0.4 m of dry packed snow. The calculations were performed at 45 wavelengths between 400 nm and 2150 nm using a two-stream model to account for the finite thickness of the ice and snow layers. Total radiative energies were found by numerical integration over wavelength. The results were compared with corresponding calculations for optically thick ice of the same types. Albedos increase from about 0.05 for open water to a maximum of 0.9 for thick snow. For 0.8 m blue and white ice, predicted albedos on cloudy days are 0.28 and 0.67 respectively. Under clear skies these albedos decrease by 10 to 30%. Total transmission through thin ice (less than 0.8 m) is from 50% to 300% greater than is predicted by Beer’s law depending on ice type and cloud cover. Radiative energy absorption at the surface is independent of thickness, but significant departures from Beer’s law of as much as 200% are evident in all cases below a depth of 2.5 mm. A parameterization scheme is presented for incorporating these results into heat- and mass- balance studies.

Experimental procedure and measured estimates of the tensile strength of snow are given by a new method utilizing large sample sizes of naturally deposited snow. Data are presented as a function of average sample density, temperature, loading rate, and snow type. The results show less scatter in the data than previous in-situ estimates and lower mean strength values as a function of density. The relevance of the data to tensile fracture as observed in slab avalanche release is discussed.

Pleistocene ice-sheet temperatures are reconstructed for a west-to-east transect across northern Scotland at the ice maximum using the temperature-profile model of Budd and others (1971[a]). Basal freezing is predicted for the central area of the ice sheet, and zones of basal melting on each side to the west and east. Variations in estimates of annual accumulation rate and ice thickness do not greatly alter this general pattern. However, small errors in estimating mean annual temperature at the ice edge and ice-surface temperature lapse-rate may significantly change the pattern of predicted basal temperature regimes, and basal freezing may have extended over the whole of the area considered. Zones of areal scouring occur in both the west and east of the transect but are absent from the central mountain area. Under some of the temperature conditions modelled there is a partial spatial coincidence of the areal scouring in the west with predicted areas of basal melting, but almost none in the east. Possibly this is explained because glacial erosion relates to time periods other than the ice maximum.

The direction of inland ice movement can, in some cases, be reconstructed by a study of the forms at the base of till strata. These forms are “ribs”, which are formed either as slickensides or as a type of negative “flute”; “edges” and “wedges”, which are caused by shearing movements at the base of the ice; or “undulations”, probably created by restricting movements at the base of the ice. These forms appear to be elongated in the direction of ice movement. As these features can easily be measured, they can be used to check, supplement, or replace the results of till-fabric measurements.

Late Wisconsin-age drumlins west of Milwaukee are clustered atop uplands bounded by discrete scarps. Gravel operations within the uplands have exposed drumlin cores of undeformed till and outwash beds which are truncated at the sides of the drumlin. In a few areas, clastic dikes, faults, overturned bedding and shear folds disturb the original layering. The drumlin shapes are blanketed with a basal till 1–3 m thick (“retreat” till) which truncates all internal structures. This till covering cannot be distinguished from the youngest truncated till (“advance” till).

Truncation of all of these structures shows that these drumlins are erosional forms carved from pre-existing drift. Apparently, during erosion under compressive flow, some beds became unstable and initiated large-scale movements of material into the drumlin from beneath the drumlin form. Failure and mobilization of the finer-grained beds may have been due to increased pore pressures, differing stages of dilatancy, or differing bulk densities. A growth relationship for drumlins may exist that is based upon the rates of material moving into the drumlin from below and rates of erosion of the drumlin form.

Most drumlins are composed of till that appears similar in all characteristics to non-drumlin till. Evidence, however, in the form of till layer sequences and from palaeomagnetic Koenigsberger ratios indicate that drumlin till may have a slightly higher pore-water content at the time of lodgement than nondrumlin till. In order that deposited till remains at the ice-glacier-bed interface to initiate drumlin formation, it must undergo rapid geotechnical changes whereby its pore-water content is dissipated thereby increasing the shear strength of the till. Two mechanisms of pore-water removal are possible. Firstly, pore water may be removed from localized patches within a mobile layer of till at the ice-glacier-bed interface, thus creating nuclei of higher-strength till around which deforming till may adhere. Secondly, removal of water initially from the thin water film at the base of a glacier may result in increased pressure melting of the ice leading to till melt-out and subsequent loss of pore water from the deposited till. The loss of water at the glacier bed may be either via permeable subglacial deposits or bedrock, or within subglacial depressions.

Experience with the calibration and field use of mercury-in-glass calorimeter thermometers provides an indication of the accuracy attainable and the necessary corrections to obtain that accuracy. Secular changes as large as 57 mK have been observed during the first three years of thermometer use. Light physical tapping is found to reduce the thermometer readings by 3–6 mK. Corrections for variations in the external and internal bulb pressure and care to avoid parallax are necessary to obtain the best accuracy in field measurements. The best accuracy obtainable with these thermometers for temperature measurements near 0°C is approximately ±4 mK for laboratory measurements and ±5 mK for field measurements.

A temperature controller is described which uses a thermistor sensor and electrical heating to maintain the temperature of a small bath of fluid to within a few millidegrees.

This paper considers the contribution made to overall glacier flow by deformation of an unlithified bed. The flow pattern in deforming till beneath a glacier is determined for the case of a uniform ice slab resting on a uniform thick till bed. The results obtained show that, once the till is saturated, very little surplus water is needed to produce high velocities in the till near the ice−till interface, the interface velocity varying as the 5/2 power of the surplus water concentration. This sensitivity to water content suggests that this may be a mechanism inducing glacier surging.

Sorted circles and nets formed on the surface of the principal medial moraine on Storbreen, Jotunheimcn, Norway, are described. These consist of “islands” of coarse sand, granules, and small pebbles, surrounded by pebbles and cobbles and underlain by small domes of glacier ice. It is suggested that patterned ground formation on the moraine results from differential ablation in areas of thin (<200 mm) debris cover near the glacier snout, where melting is relatively rapid. It is unlikely that supraglacial patterned ground could survive deposition.

Strain gages set in the snow on an avalanche track recorded accelerating strain for four hours preceeding a naturally released avalanche. On a second occasion when the strain-rate was similar, the strain decelerated and no avalanche occured.