Results of the Ross Ice Shelf Geophysical and Glaciological Survey (RIGGS) provide the most complete data set available for any large portion of the polar ice sheets. In this paper, we use the RIGGS data to calculate some of the ice-shelf characteristics. These include steady-state particle trajectories through the ice shelf and the depth of isochronous surfaces, which are of particular importance in choosing a drilling site where ice from the grounded West Antarctic ice sheet is likely to be near the surface. Our estimates for depth to ice originating from the 500 m elevation contour show good agreement with depths to a glaciochemical transition in four ice cores that is believed to be associated with this elevation. This suggests that, for much of the ice shelf, there have been no dramatic and sustained departures from steady state during the past 1500 to 2500 years. With the RIGGS data and an assumed bottom melting rate distribution we calculate steady-state temperature profiles at each of the measurement stations. Then, adopting an ice flow law deduced from laboratory experiments and ice-shelf measurements, we obtain an effective flow-law parameter for each of these sites. Using these values, the measured strain-rate field is transformed to an equivalent stress field over the ice shelf. The stresses are determined by the ice-shelf freeboard and by the force field exerted on the ice shelf by its sides and by grounded ice rises, and our analysis yields estimates of these “restraining” forces F for the Ross ice Shelf. An apparent increase in F very close to the ice front suggests that the ice shelf possesses a narrow seaward fringe of anomalously stiff ice. We suspect that this represents the effects of increased bottom melting rates (and therefore colder and stiffer ice) very close to the ice front. In order to illustrate the role of the restraining forces in controlling ice-shelf behavior, we calculate the strain-rate field for an unrestricted Ross Ice Shelf—one that is detached from its sides and contains no ice rises. Currently the creep-thinning rates for most of the ice shelf is (0.5–1) m year−1; for an unrestricted ice shelf, they would increase to ( 1–10) m year−1, with values up to 60 m year up stream of the ice rises.

The heat and ice balances of a temperate sub-Antarctic cirque glacier were measured through the 1973–74 melt season at an altitude midway between the climatic firn limit and the snout. The melt calculated from mean daily measurements at a single level of net radiation, wind-speed, temperature, and humidity agreed with that observed at nearby budget stakes. In the central ablation zone, radiation provided (54 ± 6)% and sensible fluxes (46 ± 6)% of the heat income through the summer, which was exceptionally warm and sunny. Latent-heat fluxes made no significant contribution to the heat balance. The calculation by Smith (1960) that the radiative, sensible, and latent heat fluxes contribute about equally to ablation in this zone has not been substantiated by measurement. The measured partition of the glacier’s heat balance suggested that maritime influences on its regime are mitigated by its position in the lee of a major mountain range.

In August 1978 “Hazard Lake” released 19.62 × 106 m3 of water through a subglacial tunnel beneath Steele Glacier, Yukon Territory, Canada. The discharge during the outburst flood was measured by recording lake level changes with time, and a peak discharge of approximately 640 m3 s–1 was estimated from the data. We have attempted to model the 1978 flood from “Hazard Lake” using an adaptation of Nye’s (1976) theoretical model for jökulhlaups from Grimsvötn. Our aim has been to calibrate the Nye model as a first step toward using it as a peak discharge estimator for other glacier–dammed basins. The agreement between our measured and simulated hydrographs is good, and we find that creep closure, though included in our analysis, appears to play an insignificant role in limiting the discharge of “Hazard Lake”. Release of thermal energy from the relatively warm lake water is the dominant factor contributing to tunnel enlargement.

The Manning roughness of outlet channels from glacier–dammed lakes is not known a priori and must either be assumed or estimated after the fact from the flood hydrograph. For “Hazard Lake” our fit implies Manning roughness in the range n′ = 0.105 m–1⁄3 s, consistent with Nye’s estimate of n′ = 0.12 ml⁄3s for the 1972 Grimsvötn flood and our estimate of n′ = 0.12 m 1/3 s for the 1967 Summit Lake flood. If the Manning roughness for flood conduits can be shown to lie within a narrow range, this would constrain one of the least certain variables of the Nye model.

By making several simplifying assumptions, we have succeeded in reducing our adapted version of Nye’s model to a simple mathematical description involving dimensionless numbers characterizing reservoir geometry and the relative magnitudes of creep closure and tunnel enlargement by melting. In this simplified form, the influence of lake temperature, reservoir geometry, and creep closure on the character of flood hydrographs can be conveniently studied.

A time-dependent numerical model of temperate glacier flow without sliding is developed and applied to the quiescent phase of surge-type Variegated Glacier, Alaska. The model is based on a one-dimensional continuity equation but the transverse channel shape is explicitly included allowing the complex geometries of real glaciers to be modelled. Velocities and volume fluxes are calculated from the glacier geometry. Transverse stress is taken into account by shape factors which are fitted to measurements of geometry and velocity and are chosen to be insensitive to changes in geometry. Longitudinal stress gradients are taken into account by use of a large-scale surface slope. A Crank-Nicholson finite-difference approximation is used and it is unconditionally stable when a small contribution from the local slope is added to the average slope.

Model parameters are fitted to extensive data collected on Variegated Glacier in 1973 and 1974. Predictions of the model over a four year interval agree well with field measurements. Predictions of the current quiescent phase (1965–84) indicate depth increases in the upper glacier of more than 75 m with a twenty-fold increase in the volume flux. During this interval the base shear stress increases 40% in the upper glacier and decreases 20% in the lower glacier. During the mid to late quiescent phase, ice motion becomes more important than mass balance in the redistribution of mass over the central region of the glacier. If normal flow were to persist, the predicted steady-state profile would be an average of 100 m deeper and 41% more voluminous than in 1973.

The predicted base shear-stress gradient is never negative enough to satisfy Robin and Weertman’s (1973) condition for blockage of subglacial water flow. The annual rate of water production by dissipation of mechanical straining at the bed remains two orders of magnitude below that produced by summer surface melt. The predicted fractional increase in base stress during the quiescent phase is a maximum in the region believed to be the trigger zone of the surges.

A study of the geomorphology of the Prince Charles Mountains using colour vertical air photographs shows well–preserved old moraines throughout much of the outcrop area. Along Fisher Glacier, lower Lambert Glacier and the Amery Ice Shelf, within the altitude range 50–2 000 m, the old moraines show that the ice level had risen 150–200 m above the present level at least three times. Old moraines elsewhere show that none of the other glaciers had risen significantly in their upper parts; the rise of their lower parts was caused by the rise of lower Lambert Glacier and the Amery Ice Shelf. The changes in ice level are unlikely to be due to climatic change because this would not repeatedly affect only one glacier draining central Antarctica. It is thought that the changes in ice level are caused by repeated surges of Fisher Glacier.

Recent geophysical and glaciological investigations of the Ross Ice Shelf have revealed many complexities in the ice shelf that can be important factors in iceberg structure. The presence of rift zones, surface and bottom crevasses, corrugations, ridge/troughs, and other features could substantially modify the hydraulics of iceberg towing and lead to disintegration in the course of transport.

The relationships between the elevation above sea-level and total ice thickness for three ice shelves (Ross, Brunt, and McMurdo) are given; from them, expressions for the thickness/freeboard ratios of tabular icebergs calved from these ice shelves are obtained. The relationships obtained from the measured values of surface elevation and ice thickness are in agreement with models derived assuming hydrostatic equilibrium.

Areas of brine infiltration into the Ross Ice Shelf have been mapped. Examples of radar profiles in these zones are shown. Absorption from the brine layers results in a poor or absent bottom echo. It is probable that little saline ice exists at the bottom of the Ross Ice Shelf front due to a rapid bottom melting near the ice front, and that the thickness of the saline ice at the bottom of icebergs calving from the Ross Ice Shelf is no more than a few meters, if there is any at all.

We have observed many rift zones on the ice shelf by airborne radar techniques, and at one site the bottom and surface topographies of (buried) rift zones have been delineated. These rift zones play an obvious role in iceberg formation and may also affect the dynamics of iceberg transport. Bottom crevasses with different shapes, sizes, and spacings are abundant in ice shelves; probably some are filled with saline ice and others with unfrozen sea-water. Existence of these bottom crevasses could lead to a rapid disintegration of icebergs in the course of transport, as well as increasing the frictional drag at the ice-water boundary.

Radar profiles of the ice shelf front at four sites in flow bands of very different characteristics are shown. In some places rifting up-stream from the front shows regular spacings, suggesting a periodic calving. Differential bottom melting near the front causes the icebergs to have an uneven surface and bottom (i.e. dome shaped).

Electrical resistivity soundings on the ice shelf can be applied to estimate the temperature-depth function, and from that the basal mass-balance rate. With some modifications, the technique may also be applied to estimating the basal mass balance rates of tabular icebergs.

A non-linear parabolic equation describing the evolution of an isothermal linearly viscous ice sheet is numerically solved in non-dimensional coordinates obtained by normalization over the horizontal size of a glacier. The horizontal size of the ice sheet is defined from the solution of an ordinary differential equation, the integral mass balance. For simple climate models, approximate relations describing the evolution of glaciers are proposed. These relations and palaeogeographical data are used to estimate changes in the mass balance on the surface of the Scandinavian and Laurentide ice sheets during retreat of the last glaciation.

A simple model suggests that the ablation under a debris layer could be estimated from meteorological variables if the surface temperature data of the layer are available. This method was tested by analyzing the data obtained from experiments with artificial debris layers. Fairly good agreement was obtained between the estimated and the experimental data.

The differential equation determining the elevations of a perfectly plastic three-dimensional steady-state ice sheet is set up. Analytical solutions of the equation are obtained in two simple case, (1) an ice sheet on a horizontal base with an arbitrary edge curve, and (2) an ice sheet on a plane sloping base with a rectilinear ice margin. The solutions are discussed, particularly with reference to the development of ice divides and ice streams.

For arbitrary base and ice-margin geometries, solutions are obtained by means of the method of characteristics, which reduces the problem to solving simultaneously three ordinary first-order differential equations. The integration, which is performed by numerical methods, is generally commenced at the ice margin, where the necessary boundary conditions are known.

The method has been applied to model the elevation contours and the flow pattern of the central Greenland ice sheet, using the bottom topography revealed by radio echo soundings and the present ice margin geometry. The result is in surprisingly good agreement with our knowledge of the ice-sheet topography and flow pattern, all significant ice divides and ice streams being reproduced. This suggests, that the method can be applied to model the shape and flow pattern of ice sheets under glacial conditions, using information about former ice-margin positions.

A model for the isotopic composition in δD and δ 18O of ice formed by refreezing at the glacier sole is developed. This model predicts relatively well the distribution of points representing samples from basal layers of an Arctic and an Alpine glacier on a δD–δ 18O diagram. The frozen fraction which is the part of the liquid that refreezes can be determined for each basal ice layer. This may have implications on the study of the ice–water system at the ice–rock interface.

The tensile force required to break bonds between ice grains after short contact times (1–500 s) is measured as a function of temperature and contact pressure. The results indicate a sharp increase of the tensile load capacity of bonds alter short contact times near the melting point and a maximum rate of increase of the load capacity at −5 °C. The initial state or sintering is modelled, assuming viscous surface flow and plastic deformation as the main mechanisms.

A mathematical model is presented for the stability of sheet flow of water beneath a temperate glacier. Enhanced viscous heat dissipation in thick parts of the sheet tends to make sheet flow unstable, the instability increasing as sheet thickness and pressure gradient increase. However, incipient channels may be destroyed as the glacier slides over protuberances on its bed. Quasi-stable sheet flow may be possible for sheets up to several millimeters in thickness, especially beneath glaciers that have relatively gentle surface slopes and slide at moderate to high speeds. Such water sheets may somewhat reduce the effective roughness of glacier beds, but probably not enough to allow surge initiation. Furthermore, the presence of numerous water-filled cavities at the glacier bed will tend to reduce the sheet thickness and lessen the degree of “lubrication” of the glacier bed by the water sheet.

As part of the Glaciology of the Antarctic Peninsula (GAP) programme, the snow cover at 25 stations was sampled to 10 m depth for oxygen–isotope and total β-radioactivity analysis. The mean annual oxygen–isotope ratio correlates satisfactorily with 10 m temperature despite the complex topography of the area and suggests on average that climatic trends in the region are fairly systematic. The relationship with temperature is similar to that derived from a simple model in which an air mass initially of maritime subtropical characteristics is progressively cooled as it moves towards the region. The detailed isotope profiles show that for future deep drilling the most easily interpretable climatic information will be found in the more continental areas—on the cast coast and on the plateau in the south of the region. The degree of continentality of particular sites is reflected in the amplitude of the annual wave in the upper portion of the isotope ratio profile as well as in the accumulation rate.

Peculiarities of radio echo-sounding of mountain glaciers and ice fields between nunataks from terrestrial vehicles and from helicopters are considered in this paper. The possibility of using comparatively high frequencies (of up to 865 MHz) for sounding such glaciers is demonstrated on the basis of experimental data. Results of airborne radio echo-sounding of Svalbard glaciers of various types, dimensions, and regime obtained with the help of the 620 MHz airborne equipment of high resolution are shown. Returns from the glacier bed have been obtained on the majority of glaciers under investigation. The firn regions of ice fields with temperate regimes flowing between nunataks are, mostly, an exception. Depression in the glacier bed with the ice thickness up to 540 m, as well as internal reflecting boundaries have been detected in some glaciers. Ice volumes of glaciers have been determined from the airborne radio echo-sounding data with the use of a parabolic approximation to the cross-section glacier profiles. Good correlational dependence between ice volume and surface area of glaciers has been established and is used to estimate the ice and water resources in Svalbard glaciers.

7.8% of 1 105 clasts with a B-axis diameter of >32 mm in lodgement tills from Skálafellsjökull, south-east Iceland, had a stoss-and-lee form. Clasts deeply embedded in the tills were more likely to have such a form than those resting lightly on the surface. Deeply embedded basalt and andesite clasts were also more rounded than lightly embedded clasts of similar lithology, and more striated and more likely to have a stoss-and-lee form than deeply embedded gabbro and granophyre clasts. Lightly embedded basalt and andesite clasts were more striated than lightly embedded gabbro and granophyre clasts. Within each lithological class, larger clasts were more likely to have a stoss-and-lee form. It is suggested that deeply embedded boulders acquire their rounded stoss-and-lee form by abrasion and fracture by over-riding debris-laden ice. This occurs after they have become firmly lodged by ploughing into the subglacial till bed, and before they become buried by lodgement of debris around them. The degree of modification depends in part upon clast size and lithology. The long-axis orientation of deeply embedded boulders is a good indicator of former ice-flow directions.

In Snowdonia, norh-west Wales, the construction of a hydro-electric scheme involved the exposure of a lake bed. Despite the fact that it is over 13 000 years since the bed was glaciated, erosional features on the slate and grit bedrock have been preserved from weathering below the lake waters. Examples of abrasion, bedrock fracture, plucking, and melt-water erosion are described. The formation of transverse friction cracks is briefly discussed and it is suggested that not all crescentic gouges are associated with rolling blocks as recently proposed. The relationship of small-scale erosional forms to the direction of ice movement is briefly reviewed.

Collected data on the mean annual surface values for δ18O over Antarctica have been tabulated and also presented in map form. An additional map shows contours of constant δ18O values.

During the 1978 and 1979 field seasons, ice thicknesses on the Quelccaya ice cap were determined using a Worden geodetic gravity meter along a west–east traverse and using a mono–pulse ice radar sounder along a north–south traverse. The maximum ice thickness measured was 180 ± 10 m. Based upon the known thickness of the ice cap and the net accumulation, depth–age calculations indicate that an ice core record covering at least the past 600 years and perhaps 1 300 years could be obtained from this tropical ice cap.

A topographic map of the Qori Kalis glacier (the largest outlet glacier from the Quelccaya ice cap) has been compiled at a scale of 1:6 000 from 1963 aerial photography. Terrestrial photography of the glacier was obtained in 1978 and coordinates of the edge of the glacier were determined photogrammetrically. Comparison of these two shows that over this 15 year period the glacier has thinned with the terminus retreating more than 100 m. The retreat measured for the Qori Kalis glacier is consistent with the behavior of other tropical glaciers.

Comparison of recent maps of the distribution of drumlins in Great Britain reveals considerable discrepancies. Morphometric analysis and speculation regarding drumlin genesis require accurate maps.

Displacement of an array of eight stakes was measured at approximately 12 h intervals on South Cascade Glacier, Washington, for a period of 638 h during July and August 1979. The array was located on the glacier center-line and had overall dimensions comparable to the 200 m ice thickness in this part of the glacier. Variations in velocity for individual stakes was typically 100% for periods of 12 h but decreased for longer time intervals in accordance with reports in the literature. The constraint of requiring compatible motion for the entire array reduces the averaged short-term fluctuations to the same order as the variations between stakes for a given 12 h period. This implies that non-uniformity in individual stake motion does not represent true velocity variation of the studied portion of the glacier.