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.
