The fiordlands south of Merchants Bay contain an extensive, well-preserved moraine record of a late Foxe advance of local valley glaciers. This has allowed accurate reconstruction of former glacier margins and computation of former equilibrium-line altitudes (ELAs) by a variety of methods. Statistical comparison of three methods (maximum lateral-moraine elevation, median elevation, and accumulation area ratio (AAR)) shows that different techniques can give different results for the same glaciers. Lateral moraines gave estimates that were too low, probably due to post-glacial erosion or to non-deposition. Median elevations and the AAR method produced statistically similar results but only for glaciers of simple geometry. The median-elevation method fails to take into account variations in valley morphology and glaciological parameters, and so is not reliable in all situations. The AAR method is supported by empirical evidence and is the best of the three methods for estimating former ELAs.

Analysis of trend surfaces of present and late Foxe ELAs shows changes in elevation and orientation through time due to changing environmental factors. Present ELAs are strongly influenced by local factors, southerly storm tracks, and warm maritime conditions. Paleo-ELAs do not show this influence, suggesting that Davis Strait may have been ice-covered during the late Foxe stade and that storm tracks were from the north.

Data of the heat balance measured during EGIG 1959 and 1967 are applied to calculate the shift in equilibrium line due to climatic changes. The analysis follows Kuhn’s algorithm by determining from the data: (i) response of the net radiation balance due to changes in air temperature, cloudiness, and albedo, (ii) the response of the sensible heat flux due to changes in air temperature, (iii) the altitudinal gradients of air temperature and cumulative accumulation, (iv) the duration of the ablation season, and (v) the significance of superimposed ice. The shift of the equilibrium line due to changes in cloudiness is negligible compared to that which is caused by changes in temperature. The formation of superimposed ice, however, influences the result considerably. The shift of the equilibrium line amounts to +77 m K−1 at constant cloudiness and –4 m per 1/10 cloudiness at constant temperature.

An index of regional snow-pack stability based on occurrences of natural slab avalanches was developed using a statistical distribution and a sequential testing procedure. The study interprets avalanche information on 185 paths in the Colorado Front Range. Results show general agreement with operational hazard estimates; test results have real-time evaluation potential.

The formation of frazil in water of different salinities and initial supercoolings was studied in the laboratory. Experiments were conducted both on genuine and artificial sea-waters. From analysing the experimental results, it was found that the production rate of frazil is highly sensitive to the initial supercooling of the water and will increase over three orders of magnitude as the initial supercooling increases from zero to 2° C. By properly non-dimensionalizing the parameters, it was found that the normalized concentration of frazil in water is principally a function of the normalized time. For the rate of production of frazil, however, it was found that the normalized rate of frazil production, besides being a function of the normalized time, is also affected by the salinity and the initial supercooling of the water. Different frazil crystals formed in water of different salinities and initial supercoolings are thought to be the reason for the different curves of frazil production rate. The normalization of parameters requires the determination of some characteristic parameters which were found to be well-defined functions of initial supercooling and salinity.

Various field experiments have shown that microwave radars can be used to distinguish multi-year from first-year ice, although optimum radar parameters are not yet fully defined.

This paper presents the results from two theoretical models that, using selected physical parameters of sea ice, are able to predict the backscattering from multi-year and first-year ice under cold conditions. The possible ranges of the backscattering coefficient under various conditions (surface roughness, salinity, temperature, density, and air-bubble size) are calculated for multi-year and first-year ice by adjusting the parameters within the reported range of values.

Although the calculations show no specific resonance that would favor any particular frequency or incidence angles, the results confirm the experimental findings that Ku- and X-band frequencies, and incidence angles greater than 30°, are better for distinguishing sea-ice types than lower frequencies.

Measurements made at the terminus of Emerald Glacier in the Rocky Mountains of Canada indicate terminal re-advance in the order of one to two metres per year sustained since 1978 at least. Re-advance is maximum along that part of the terminus which is heavily covered with supraglacial debris, where ice remains in contact with a push-moraine all summer. Re-advance may represent fluctuations of a small, responsive ice mass, or the early effects of recent climatic deterioration.

Deep gravel-pit exposures reveal the distribution and structure of till and underlying sand and gravel in drumlins near Waukesha, Wisconsin. The subglacial sediment is interpreted to have moved laterally into the drumlin sites because the till thickens from the margin to the core of the drumlins, the stone orientation in the till is perpendicular and oblique to ice flow on the drumlin margins, and recumbent isoclinal folds occur in sand on the drumlin margins with axes parallel to the drumlin axes. The resulting accumulations of sediment presented obstacles to ice flow and were streamlined into the minimum-drag drumlin shape by erosion on the margins and by remolding of material in the core of the drumlins. These drumlin nuclei may have formed at spots where there was low effective stress on the bed. The subglacial sediment became mobile as a result of high pore pressure that may have developed as ground water and subglacial melt water were trapped behind a frozen bed at the ice margin. Under certain conditions, however, lateral sediment flow might also have occurred when the sediment was frozen.

Two flood waves from the terminus of Peyto Glacier occurred as a result of very high precipitation in early July 1983 and a landslide which exposed a large section of ice-cored moraine. The flood waves induced erosion, and subsequent melt, of the moraine and deposited an estimated 6000 m3 of gravel in the valley. The majority of the deposition occurred in an area approximately 200 m × 20 m to depths of 3 m at the site of the National Hydrology Research Institute gauging station 1 km from the glacier terminus. The initial flood washed away most of the equipment from the site and the gravel deposition totally destroyed the rest of the installation. These events appear to be unique in the period that hydrological records have been maintained for Peyto Creek.

The paper presents data on the snow cover in the Cairngorm Mountains, Scotland, and compares typical Scottish snow profiles with those measured in alpine, continental, and polar areas. The paper shows that in the Cairngorms snow temperatures are higher and as a result densities and ram penetration resistances are also higher. Typical densities are between 350 and 500 kg m−3 and ram resistances are frequently above 50 or even 100 kg. Typical profiles show large masses of windslab above an equigranular basal layer of old snow, and ice layers are common throughout the profile. Avalanche activity is related to two types of profile both of which share low ram resistance in common. Dry-slab avalanches release when densities are of the order of 250 kg m−3 or less and snow temperatures down to – 10° C in the upper layers. Wet slabs and sluffs fall when the snow is isothermal at the melting point. Densities are usually over 450 kg m−3 and may reach over 600 kgm−3 in slush layers supported by ice lenses.

The ice-flow properties at great depths have a strong impact on the depth–age relationship of the strata in the Greenland ice sheet. Previous attempts to calculate this relationship have used Glen′s flow law with a temperature-dependent flow-law parameter. The data from the bore-hole-tilting at Dye 3, south Greenland, make it possible to calculate the flow-law parameter versus depth. The flow-law parameter shows a big change at the Holocene/Pleistocene transition with a mean flow enhancement factor of 3 for the ice deposited during the last glaciation. This high enhancement factor is believed to be due to high concentrations of dust and other impurities and small ice-crystal size in the Pleistocene ice. The derived flow-law parameter and the up-stream basal topography are used in a two-dimensional, multi-layer, first-order perturbation model to calculate the surface undulations and strain-rates. The results compare favourably with the observations. The results depend strongly on the flow-law parameter profile, which can therefore be estimated in other areas by perturbation-model calculations along flow lines, if the surface and base topographies are known.

A freezing slope, distinct from that of precipitation, is displayed on a δD–δ18O diagram by basal ice in different circumstances. However, if the subglacial reservoir allowed to freeze is mixed in the course of time with an input having a lighter isotopic composition, basal ice cannot be distinguished from glacier ice in terms of slope. Such a situation is encountered at the base of Grubengletscher and is indicated by a computer simulation using the open-system model of Souchez and Jouzel (1984). Suggested implications for the paleoclimatic interpretation of deep ice cores recovered from the bottom part of polar ice sheets are given.

The 32Si concentration in a sample of surface ice from the snout of Changme-Khangpu glacier is 0.36 disintegrations per minute/tonne compared to the fall-out value of 0.7 d.p.m./tonne. If this decrease is assumed to be solely due to decay of 32Si, an age off c. 100 years is estimated for the surface ice of the snout, leading to an average flow velocity of c. 40 m/year for the past century. A vertical profile of 210Pb in a core taken at an altitude of 5040 m shows two horizons where this isotope is enriched, one between 3 and 4 m and another between 11 and 12 m, indicating that the primary concentration of 210Pb can change by physico-chemical processes like adsorption on dust. None the less, a longitudinal profile along the glacier shows a systematic decrease of 210Pb activity with decreasing altitude, the surface ice of the snout giving a value of 0.2 d.p.m./l, corresponding to an age of 100 years which is concordant with the 32Si age. This surface flow-rate of the glacier is much larger than the average contemporary flow-rate (c. 13m/year). The difference can be understood in terms of the past history of advance and recession of the glacier as revealed by the geomorphic evidence.

A comparison of data from aircraft altimetry, Landsat imagery, and radia echo-sounding has shown characteristic surface topographies associated with sheet and stream flow. The transition between the two is abrupt and occurs at a step in the subglacial topography. This marks the onset of basal sliding and high velocities caused by subglacial water; it results in crevassed amphitheatre-like basins round the head of outlet glaciers. It is also the zone of maximum driving stress beyond which values decline rapidly as velocities increase. This abrupt transition appears to be topographically controlled since basal temperatures are at the pressure-melting point well inland of the change in regime. The Marie Byrd Land ice streams exhibit qualitative differences from other ice-sheet outlets, however; the change to lower driving stresses is much more gradual and occurs several hundred kilometres inland. Such ice streams have particularly low surface slopes and appear in form and flow regime to resemble confined ice shelves rather than grounded ice. The repeated association of the transition to rapid sliding with a distinct subglacial feature implies a stabilizing effect on discharge through outlet glaciers. Acceleration of the ice is pinned to a subglacial step and propagation of high velocities inland of this feature seems improbable. Rapid ice flow through subglacial trenches may also ensure a relatively permanent trough through accentuation of the feature by erosion. This is concentrated towards the heads of outlet glaciers up-stream of the region where significant basal decoupling occurs. This may be a mechanism for the overdeepening of fjords at their inland ends and the development of very steep fjord headwalls.

Re-definition of the interior drainage basin Lambert Glacier, using the most recent sources of ice-surface elevations, has shown its area to be 902000 km2, that is, 17% less than previous estimates. Landsat imagery of the steepest sloping part of the basin shows there is bare ice over an area of 56000 km2. Other evidence also indicates exceptionally low mass inputs and the distribution of accumulation rates has been up-dated. The result is a positive mass balance for the interior basin (+2 Gt a–1 ) and error limits which fall below zero. This is 47% less than the most recent calculation and illustrates the difficulty in deriving mass budgets in regions where data are scarce.

Analyses of fluoride, chloride, sodium, sulfate, bromide, nitrate, and iron from a 3 m snow pit on Heard Island, collected at an elevation of 2450, m are used to assess the potential of glaciochemical studies on. Heard Island glaciers. Sources for the chemical species are identified and, in particular, chloride, sodium, and sulfate are found to be useful seasonal indicators. The total record measured is believed to be less than one mass-balance year.

Drift-ice abrasion marks are common along present-day rocky shorelines in cold regions. They include polished surfaces, scratches, striations, small grooves, and minor friction cracks. Most are found on relatively soft rocks like shale, sandstone, limestone, dolomite, and basalt, and occasionally on harder rocks like granite and gneiss. They were made by rock fragments frozen at the base of ice cover or by ice floes pushed onshore by wind or dragged along the bottom by waves, tides, and currents. They are found both in the modern and Pleistocene marine, lacustrine, and fluvial environments. Along the Hudson Bay eastern shoreline, these abrasion marks are superimposed on glacially polished and striated surfaces. Along the St. Lawrence Estuary, they are more common on boulders in the tidal zone. Characteristics of drift-ice abrasion marks are described and their significance is pointed out.

Thermal convection in the Antarctic and Greenland ice sheets has been dismissed on the grounds that radio-echo stratigraphy is undisturbed for long distances. However, the undisturbed stratigraphy lies, for the most part, above the density inversion in polar ice sheets and therefore does not disprove convection. An echo-free zone is widespread below the density inversion, yet nobody has cited this as a strong indication that convection is indeed present at depth. A generalized Rayleigh criterion for thermal convection in elastic-viscoplastic polycrystalline solids heated from below is developed and applied to ice-sheet convection. An infinite Rayleigh number at the onset of primary creep decreases with time and becomes constant when secondary creep dominates, suggesting that any thermal buoyancy stress can initiate convection but convection cannot be sustained below a buoyancy stress of about 3 kPa. An analysis of the temperature profile down the Byrd Station core hole suggests that about 1000 m of ice below the density inversion will sustain convection. Creep along the Byrd Station strain network, radar sounding in East Antarctica, and seismic sounding in West Antarctica are examined for evidence of convective creep superimposed on advective creep. It is concluded that the evidence for convection is there, if we look for it with the intention of finding it.

Spatial and temporal observations of electrical conductivity during the summers of 1978 and 1981 on the pro-glacial stream sytem of glacier de Tsidjiore Nouve, Valais, Switzerland, are described. Three space–time scales of electrical conductivity variations are considered: single-site, hourly monitoring for a two-month period; multiple-site sampling over 12 h periods using a 1 h sampling interval, and multiple-site sampling over monthly periods using a 24 h and 48 h sampling interval. Detailed analysis of the information from the three scales shows that the sampling strategies employed can reliably be used to investigate space–time patterns in the data. The results demonstrate that there are diurnal cycles in both electrical conductivity and discharge which are slightly different in form and which are out of phase with one another at the same site. Simultaneous multiple-site sampling of electrical conductivity shows that the tributary streams draining the glacier snout exhibit complementary shifts in electrical conductivity between ablation seasons, between days, and within days. The significance of these complementary shifts in tributary electrical conductivity are discussed in the light of possible source areas, storage, and routing fluctuations of melt water draining from the glacier.

In connection with a glacier-hydrological project at a sub-polar glacier in West Greenland, short-term glacier velocity variations were measured. Both the horizontal and the vertical velocity components showed distinct diurnal variations. Close examination indicates that these variations are caused by the change in atmospheric refraction during the day, with the vertical component as the most important.

An algorithm is developed for adjusting glacier surface-velocity vectors, given on the nodes of a square grid, so that they obey a central-difference approximation of the continuity equation. Also required on the grid nodes are the glacier thickness, the ratio of the surface-velocity to the average velocity in the column, and the difference between the mass balance and the thickness change. All these other variables are assumed to be known exactly, and only the surface-velocity field is adjusted. The result is optimum in the sense that the magnitude of the adjustment is minimized. Either the relative or the absolute adjustment can be minimized, depending on how weights are specified. No restriction is placed on the shape of the solution region, and no boundary condition is required. The algorithm is not iterative. The algorithm first forms a parallel flow field that satisfies the continuity equation, and then uses a stream function to add a divergenceless field to it. The stream function that leads to the minimum velocity adjustment is obtained as four independent, interlacing solutions covering the solution region. For each of the four, a well-conditioned, sparse-matrix system of simultaneous linear equations is solved. A compact, sub-optimum, well-behaved iterative procedure is also developed for transforming part of the velocity adjustment into an adjustment of the thickness field.