Cambridge Austerdalsbreen 1955
The original aim of the expedition was to dig a tunnel through the glacier to the back wall of the icefall, thus revealing the erosion processes taking place. Despite initially digging at a slightly upwards angle and installing a drainaige system, water began to accumulate in the tunnel. This eventually forced the expedition to abandon their digging and they elected instead to survey the tunnel. By observing the velocity of pegs in the tunnel wall and the rate of contraction of the cross-section, Glen was able to determine that rotation was occurring and that the rate of contraction was far in excess of what would be hypothesised based simply on the hydrostatic overburden pressure.