The deformation and state of stress at the confluence of two glacier streams are analysed using the techniques of slip-line theory. The valley walls are taken to be vertical parallel planes and the deformation is supposed independent of depth. The mechanical behavior of ice is modeled by the ideal rigid/perfectly plastic material.

Detailed solutions are presented for the deformation at the confluence of one or more tributaries with a main stream and of two main streams. Attention is concentrated on predicting the number, position and magnitude of the bands of intense shear which emanate from some of the junction corners. The predictions of this idealized theory are compared with field data from a confluence on the Kaskawulsh Glacier, Yukon Territory, Canada.

All the measurements involved concern the glacier tongue between its end and 2 600 m a.s.l. The total loss of volume of the Unteraargletscher since its last maximum advance (1871) is estimated to be 2.4 km3, which corresponds to a mean surface lowering of 0.67 m/year (referred to a total glacierized area of c. 40 km2 on average). The considerable slowing down of the glacier flow velocity over the 125 years is primarily attributable to the marked decrease in the sliding component, whereas the shear component has only changed slightly. This behaviour is connected with the fact that the decrease in ice thickness has been accompanied by an increase in surface slope, so that the two effects on the shear component partially compensate each other. The seasonal variations in surface velocity were measured simultaneously at two profiles by Agassiz and his team in 1845/46. These variations are due to the variable amount of melt water and the resulting variations in hydrostatic pressure in the contact zone between ice and bedrock, in which the plastic contraction of the water channels plays a decisive role. This leads to the problem of water circulation in the interior of a glacier and its importance in the sliding process. Finally a simple method for the approximate calculation of the longitudinal profile of the surface of a glacier tongue in a steady state and with constant ablation is indicated.

Very considerable amounts of englacial debris derived from the glacier bed are contained in the polar glaciers of Svalbard. It is suggested that this debris is largely incorporated by basal freezing on the down-glacier flanks of bedrock obstructions, although other freezing mechanisms and thrusting may be important. The basal freezing hypothesis predicts that vertical and lateral variations in englacial debris content should reflect the variation in subglacial rocks over which the glacier passes; this prediction is tested against an actual englacial debris sequence. The mode of transport of debris, including its stone orientation fabrics, is described, and also the way in which it reacts in zones of intense compression.

A generalization is suggested: that polar glaciers tend to contain much larger amounts of basally derived debris than temperate glaciers. This supports the view that the englacial incorporation of debris is controlled by the temperature regime of the glacier, and could be of considerable importance in the interpretation of the regimes of ancient glaciers from their deposits.

Two types of basal till are described. First, melt-out tills released by the melting of masses of buried, debris-rich stagnant ice. Top melting of these ice masses is of greatest importance at the present day, and this produces tills which retain some of their englacial fabrics although some are changed by the melting process. Bottom melting of these masses could also produce such tills but these are likely to be much less important. Secondly, tills are also formed subglacially when basal debris-rich glacier ice becomes stationary beneath the over-riding active glacier. When these subglacial masses melt, water is expelled from the resultant till which also shows tectonic shear fractures induced by the over-riding ice. The mode of deposition of these latter tills could also be responsible for the production of certain rock-cored drumlins. Subglacial tills in Svalbard are relatively rare and, except under special conditions, are likely to react to ice loading by water expulsion, compaction and shear fracture rather than by fluid flow.

If a basal freezing hypothesis is accepted for the origin of most englacial debris, the lateral and vertical variations in erratic content can be predicted for many melt-out tills.

The results of 10 years' (1958–68) record of accumulation and ablation from the Ward Hunt ice rise and of 3 years' (1965–68) record from the Ward Hunt Ice Shelf are presented. The net mass balances on the ice rise for the 3 years 1962–65 are positive, while the net mass balances measured in the other years on both ice rise and ice shelf are all negative.

Winter observations in the northern Rocky Mountains of Montana show two periods during which one may expect a collapsing snowpack and accompanying avalanches: (1) shaded and sheltered areas: December-February; (2) sunny and exposed areas: March-May. These periods appear to be linked in part to the cyclic rise and fall of strength in the basal snow layer. It is suggested that sheltered slopes are often about a half-cycle ahead of sunny slopes because sheltered slopes tend to retain the early snows which later become the critically weak basal layer on these slopes.

At places with an annual mean temperature lower than −20°C on the Greenland and Antarctic ice sheets, the temperature at a depth of 10 m is close to the annual mean at the surface and at the level of the meteorological shelter. With temperatures higher than about −35°C the size and sign of the différences vary. With lower temperatures the 10 m temperature becomes increasingly lower than the air temperature, at the coldest Antarctic station, “Plateau”, by nearly 4 deg.

The Workman-Reynolds effect was investigated during the phase change of dilute (about 2 × 10-4 N) KCl solutions into single crystals of ice. The ice crystals were oriented with the c-axes either parallel or perpendicular to the growth direction. The solute distribution in the liquid phase. near the interface (within 10 mm), was obtained with a wire-type conductivity cell. For a crystal growth rate 8.8 μm/s the freezing potentials were + 10.0 V and + 6.0 V and the specific charge séparations were 1.3 ± 0 1 × 10-6 C/g of ice and 1 4 ± 0.1 × 10-6 C/g of ice for growth parallel and perpendicular. Respectively, to the c-axes of the ice crystals . The equilibrium solute distribution coefficient was found to be 4 × 10-3 for KCl solutions for both crystal orientations. An “apparent” (because of convection in the liquid phase) distribution coefficient ranged from 0.031- 0.074. The “apparent” diffusion coefficients ranged from 1.3–4.9 × 10-3 mm2/s and varied linearly with growth rate. The ionic distribution coefficients. K+ and K-, were approximately K+ - K- = - 2 × 10-5 and K+ + K - = 8 × 10-3 for the KCl solutions.

The results of two surveys of the frontal margin of a valley glacier in West Greenland are reported. If they indicate a constant or decreasing mass loss rate, the glacier shows similar behaviour to that of the nearby ice lobes on the ice sheet.