Deep, partly snow-filled gullies cutting the sea cliffs of part of the Vestspitsbergen strandflat are noted. They do not appear to have been cut by streams, and it is suggested that a process of frost action and snowpatch erosion has been largely responsible for their formation.

A short note on glacial recession in part of Vestspitsbergen is added.

The firn field on the volcano Popocatépetl is most extensive, lowest in altitude (4573 m.) and thickest (40 m.) on the northwest side of the cone. An expansion of the firn field on this side in the form of two small glaciers, one with miniature lateral moraines, has appeared since 1945 and still persists. Crevasses in the firn appear, widen, progress downslope and disappear, with new ones replacing them from above. Accumulation of snow from November through January and also from June through September exceeds ablation, and permits development of the firn field with expected seasonal and annual marginal fluctuations. A recession of 100 m. in altitude of the firn field from 1906 to 1920 is indicated by photographic studies and by field evidence.

X-ray diffraction photographs were taken of ice dendrites grown from water and from the vapour. In both cases [1120] was found to be the growth direction.

A method of growing cylindrical single crystals of any desired orientation has been devised. Some of these crystals were extended to several times their original length. Slip took place exclusively on the basal plane. Experiments designed to locate the glide direction gave inconclusive results and suggested that, in general, crystals near the melting point can glide in any direction.

Before deformation, ice crystals gave fairly sharp X-ray diffraction spots on Laue photographs. After deformation the spots are drawn out into streaks which later break up into rows of small spots. This indicates that bending of the crystals is followed by the formation of small crystallites of slightly differing orientations. Analogous effects are observed in metals.

The growth of single crystals of ice for the study of plasticity has to be done with care, since a disturbing lineage structure is easily generated. The orientation of specimens can be found from growth figures (dendrites) and Tyndall’s “flowers”; these give the a-axis, as the branches in both cases point in the [1120] direction. Slip occurs on the basal plane without following a definite glide direction. In pure shear two stages of creep exist, the first for a glide of 10–20 per cent in an undeformed crystal, the second for greater shears having a higher creep velocity. Both stages obey the law , n being 2.3–4 in the first case and 1.3–1.8 in the second. The deformed state above the transition remains stable and no recrystallization takes place in pure shear. Restoration of the undeformed state by recrystallization occurs only in inhomogeneously deformed parts. This observation may have an influence in interpreting measurements of glacier movements and tests on polycrystalline specimens in the laboratory.

Two tunnels were dug through a small cirque glacier to the rock wall behind (a) the névé, and (b) the lower glacier. The upper tunnel revealed shattering of the rock wall due to the freezing of melt water. The bedrock at the end of the lower tunnel was both smoothed and fractured. The problem is to account for the fracturing of the resistant gneiss where the temperature remains at 0° C. throughout the year. The solution offered is that the release of pressure beneath a thick glacier immediately downstream from a roche moutonnée, or from a small steep step, enables the stresses locked within the gneiss to crack the rock. These stresses result from the gradual removal of the overburden, since the gneiss consolidated under the pressure of thousands of metres of rock strata. The glacier can later remove the jointed and broken rock.

Morsárjökull is a small outlet glacier of Vatnajökull, Iceland. Two outlet streams from the ice cap unite at the foot of a precipitous step and carry a well-developed medial moraine; the north-west glacier stream is fed by a steep ice fall, the south-eastern one has been fed only by avalanches since 1938.

The movement of the glacier was measured and showed that the alternate dark and light ogives were one year’s movement apart. Their characteristics are described and tentative suggestions concerning their mode of origin are proposed.

The construction and use of some portable ice-boring equipment are described. The total weight of equipment for boring to a depth of 20 m. is about 36 kg. The weight increases by 1 kg. for each extra metre of depth.

A simple equation is developed for ablation in a snow cover on the basis of the principle of conservation of mass. Sinking of the snow surface as measured with ablation stakes or ablatographs is commonly accepted as a measure of ablation. In so doing, a principal term associated with density changes in the snow with time in the above-mentioned equation is neglected. In a few investigations, ablation was determined from sinking of the snow surface alone, and also by other methods. These investigations demonstrated errors in the calculated ablation values resulting from neglect of density changes in the order of 15–20 per cent for long observation periods, and as great as 65 per cent for short observation periods. The terms are also discussed which must be measured to determine short period values of melting and evaporation of the snow for analyses of the heat exchange at a snow surface.