The melting of ice and the subsequent production of regelation ice from the melt water in a large-scale closed system beneath sub-polar and polar glaciers produces progressive fractionation between the melt water and the regelation ice derived from it. A theory is developed which predicts the change of isotopic composition in regelation ice in a subglacial zone of freezing and in the water from which it is derived. The theory is tested against data from the Byrd Station bore hole in West Antarctica, and applied to explain features of the isotopic composition in several other glaciers where thick sequences of regelation ice have formed.

The principal conclusions are:

1. Basal isotopic profiles can be used to reconstruct important features of a glacier’s hydrological system.

2. Isotopic profiles in basal regelation ice do not simply reflect isotopic characteristics of ancient atmospheres but also, by using the theory, some of the isotopic characteristics of the normal glacier ice which was destroyed by melting and subsequently produced regelation ice can be reconstructed. Basal regelation ice at Byrd Station reflects an original ice source isotopically colder than the overlying normal ice, and may have formed during the penultimate glacial period, equivalent to stage 6 of the oceanic record.

3. The subglacially derived debris typically found in basal regelation ice gives a complex strain response to a changing pattern of stresses produced by flow over an irregular subjacent bed. Thus, complex tectonic structures in this ice produce highly variable isotopic profiles. However, its gross isotopic characteristics can still be used to reconstruct some of its history. A sharp change in isotopic values tends to occur at the upper limit of basal regelation ice, the nature of which depends on the style and thickness of tectonic disturbance.

4. Isotopic profiles in basal ice can be used to distinguish normal glacier ice from regelation ice, and give strong support to the view that regelation is the major process by which debris is incorporated into the base of a glacier.

Along the 1040 km extending from Cape Prud’homme (lat. 66°41’S., long. 139°55’ E.), near Dumont d’Urville station, to Dome C (lat. 74°39’S., long. 124°10’E.), the variations in annual accumulation can be analysed by a division of the entire data set into three sub-sets depending on the types of measurements and the character of the spatial distribution. Along the first 33 km, from the coast to stake E40, annual measurements show considerable inter-annual variability, 52% of which can be explained by the spatio-temporal homogeneity of the balance distribution. However, we obtain a better result (64%) for the fluctuation homogeneity standardized using the standard deviation. This means that there is a strong space-time dis-tribution structure, characterized by an equal variation of the balance around the mean value specific to each location. This is so in spite of the existence of considerable surface roughness (sastrugi), the influence of which should be reduced by averaging values around each stake. From stake E40 to stake R60, a distance of 170 km, the almost periodic oscillations in the accumulation with a wavelength close to 40 km can be explained by the formation of a gravity-inertia wave, disturbing the geostrophic equilibrium, occurring at the break in slope 200 km from the coast. The very low values of accumulation for stakes D55 and D58S show that the oscillations were almost stationary during the study period (about 25 years). Finally, along the 840 km from stake R60 to Dome C we can observe a decrease in accumulation resulting from the decrease in mean temperature.

In the Northern Hemisphere, ice layers which have high microparticle concentrations (in particular late Wisconsin) are “softer” than modern or Holocene ice. Such ice deforms more readily in bore-hole tilt and closure measurements. This enhancement in flow, which is shown not to be related to c-axis concentration, has a maximum of three for late Wisconsin ice. The closure and tilt of a bore hole in the Agassiz Ice Cap, Ellesmere Island, drilled in 1977, has been followed every year since its drilling and the flow enhancement observed has been compared to the following quantities measured in the cores: concentration, δ(18O), crystal size, c-axis, Ca, Na, conductivity, and density. Flow enhancement of the ice age and bottom ice was found to be unrelated to c-axis concentration and density. Enhancement of flow is best related to microparticle (or Ca) concentration which in turn seems to be inversely related to crystal size. The latter relationship also seems to hold for the Devon Island Ice Cap and Greenland. In future, modellers of northern ice ages should use model ice that is three times softer than modern or Holocene ice.

Energy fluxes and resultant short-term ablation rates were measured at a ground-ice slump on south-west Banks Island. Net radiation, as a proportion of the ablation flux, is greatest on days with high incident solar radiation, whereas on overcast days, sensible- and latent-heat inputs may supply more than half the necessary energy. A multiple regression equation using net radiation and a turbulent-energy term as independent variables explains 79% of the variation in the measured ablation fluxes. Overall, at least 60% of the energy used for ablation at the slump is derived from net radiation.

Interlocking rectangular ice patterns, with dimensions of several metres, on the surface of a perennial frozen lake in East Antarctica can be related to a strong crystallographic orientation in the underlying ice. Most of the surface patterns are characterized by parallel centimetre-scale ridges and furrows that correspond to an aggregate of tabular-shaped grains. Grain elongation is parallel to the basal plane. The c-axis distribution within each ice pattern lies in a horizontal plane. It defines a discrete maximum perpendicular to the surface ridges and to the long axis of the rectangular pattern. Areas exhibiting no patterning are composed of variably orientated ice grains. The strong c-axis horizontal orientation and the distinctive morphology of these ice patterns are interpreted as having developed by a geometric enhancement over a long period of time.

A 1985 survey at Rakhiot Glacier, Nanga Parbat, Punjab Himalaya, indicates that the glacier terminus is advanced about 200 m from its 1954 position. Between 1930 and 1954, the dates of previous surveys, the glacier terminus had thinned and back-wasted 450 m. The recession prior to the 1960s, followed by advance into the 1970s and perhaps 1980s, parallels patterns of glacier fluctuation found in the adjacent western and central Karakorum.

Finite-element method is used to determine the temperature distribution within the Erebus Glacier tongue based on information from short-term observations (Holdsworth, 1982). It is shown that, provided the up-stream temperature profile along the depth is known, steady-state assumptions are reliable for computing the temperature field within most of the ice mass at any given time for a glacier tongue. Numerical results from analyses of the Erebus Glacier tongue also indicate that the main transport of heat is through advection as expected and, hence, a realistic estimate of the velocity field becomes important.

A simple field test of snow-slope stability is proposed, which allows decisions about a number of factors recently described by Conway and Abrahamson (1984). These include spatial variation of snow strength along a slope, and progression of failure from a localized initial failure. Strength within the snow slab is considered as well as that at its base. A snow saw is required for the test and, because a number of tests can be made in a few minutes, much information on the state of the slope can be obtained in a practical time.

a method of making field measurements of the liquid water fraction of snow has been developed in which a snow sample is dissolved in methanol to produce a temperature depression. The depression is linearly related to the liquid water content of the snow sample. a single operator can perform four to five measurements per hour with a maximum absolute error of 1.0%.

A procedure is described for testing cored ice specimens under uniaxial tension. The procedure incorporates an end-capping system described by Cole and others (1985), two carpeted Synthane end caps, and extensometers mounted directly on the ice. Use of the procedure has resulted in a successful test rate of 75%