The design, construction, and testing of a portable constant strain-rate testing machine for determining the mechanical behavior of avalanche snow is described. The machine is intended for use in determining the stress strain time behavior of low-density natural snows in the field. A technique for making direct measurements of strain in the snow sample is described and stress-strain curves are presented for strain-rates ranging from 0.5 to 5.0 x 10-5 s-1. The densities of the snow samples tested range from 186 to 335 kg m-3 Ultimate-strength data and relaxation curves arc also presented.

Liquid saturation and porosity control most of the important material properties of wet snow, hence accurate measurements of these two parameters is of the utmost importance for both field research and glaciological applications. For example, the movement of liquid water through snow is highly sensitive to the volume of water present and accurate measurements of the water saturation are necessary in order to infer the temporal and spatial variations in the flow field. Nevertheless, most of the instruments in use are not capable of making accurate determinations of saturation.

An error analysis shows that only direct measurements of the liquid volume can provide accurate values of water saturation, hence the melting calorimeter is inherently inaccurate. While centrifuges extract some of the liquid for direct measurement, there is always some residual liquid left depending on the grain size and structural parameters of the ice matrix. Therefore, some uncertainty exists over the interpretation of the data obtained from centrifuges. High-frequency capacitance probes can be used either in situ or on the surface and are very sensitive to the volume of liquid present. Capacitance probes are by far the best of the available devices. Remote-sensing techniques, like the active microwave system, require more development for use in operational forecasting schemes and as research tools.

A radiometer prototype has been constructed using the S band. In this band, a theoretical evaluation of the differences of temperature which are measurable by the radiometric method proves the influence of the parameters liquid-water content of snow and snow thickness.

When there is no victim, the apparent temperature of a snow layer depends on these parameters and presents important variations because of its natural inhomogeneity. In order to detect the local variation of the apparent temperature due to the presence of a victim, we must refer to an average local temperature obtained by a servo-system. Thus, we obtain a certain number of false alarms which can be suppressed only with a manual sounding. The search itself becomes very long and also requires a systematic exploration of the snow surface by parallel traverses spaced every 2 m. This exploration seems impossible on uneven ground such as a real avalanche area.

An instrument which continuously records the run-off from a small, well-defined snow cover is described. The lysimeter is reasonably priced and effective, requiring only modest service attention; details of the records which it takes are given also. The relevance of the instrument to snow hydrology and to the energetics of a snow-cover is discussed.

A glacier-caused slide occurred in July 1975 within the Devastation Glacier basin, British Columbia. An estimated 2.5 × 106 m3 of glacier ice, representing about 9% of the total mass, was incorporated into displaced debris. Four human lives were lost.

The formation of ogives is examined from a structural point of view. It is suggested that the dark bands represent large-crystal, bubble-free ice which was transported from near the glacier base up toward the glacier surface by the processes of folding and/or reverse faulting due to compressive flow at the base of an ice fall, while the white bands represent relatively small-crystal, bubble-rich near-surface ice. The variation in compression to account for periodic folding and/or reverse faulting is explained by seasonal variation in flow velocity through an ice fall.

From a study of 205 slab avalanches it is concluded that failure initiates where the slope is 25° or steeper, that slab failure stress is in the range 102N m-2 to 104N m-2, and that the slab failure plane is most commonly at a temperature of -5°C or warmer. The study also indicates that the shear strength of weak layers varies approximately as the square of the density.

Early work by Farrington at the northern end of the Leinster mountains established a framework for glacial episodes throughout Ireland. The recent excavation of a small pit in commercial gravel workings in southern County Dublin has confirmed the relationship between four of the five events described by Farrington.