Deep-ice temperature measurements have been made in two surge-type glaciers in the Yukon Territory, Canada. Cold ice warming towards the bed was found in Trapridge Glacier and a model of basal ice temperatures predicts large regions of basal temperate ice. Thermal regulation of the surge behavior of this small glacier is inferred; theoretical considerations show that this hypothesis can reasonably be extended to large surging glaciers as well. Temperatures below 0°C were also recorded on Steele Glacier. An anomalously warm layer was detected at a depth of approximately 50 m. This is attributed to the severe crevassing associated with a glacier surge. Numerical modelling of the effects of water-filled crevasses in a cold glacier, refreezing and injecting latent heat into the ice, predicts temperature profiles very similar to that observed. The model further predicts long term maintenance of the resulting trapped water pockets and, in small surging glaciers, a thermal memory of the initial crevassing throughout the entire quiescent phase.

Seismic investigations were carried out at the confluence of the North and Central Arms of the Kaskawulsh Glacier, St. Elias Mts. Low velocities near the glacier surface are apparently due to melting, fracturing, and high porosity. It is concluded that velocity anisotropy is mainly caused by the foliation structure of alternating layers of clear and bubbly ice; it also occurs where surface ice has a strong fracture pattern. Greatest depth of ice in the Central Arm, 3,000 m wide, and in the combined glacier, 5,000 m wide, is about 1,000 m. The North Arm is less deep; both arms are roughly parabolic in cross section. The base of the ice is lower than the glacier terminus, but no bedrock depression was found at the confluence. It is concluded that only under especially favorable circumstances can seismic measurements be used practically to study crystallographic fabrics in glacier ice.

Reports a 1964-65 summer investigation of the north and central arms of this glacier with reference to surface ice deformation at a glacier confluence and its relation to optic-axis fabrics of the ice. The fabrics are concluded to be a result of synkinematic recrystallization, although the nature of the control of this recrystallization is not known.

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for a copy of this paper please contact the Yukon Geological Survey; geology@gov.yk.ca.

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