Crevasse pattern and accumulation layering. At low pressures, ice is rigid whereas at high pressures its reaction is more like that of a fluid. The transition between the brittle and plastic zones within the ice, indicate that crevasses are only able to reach a maximum depth of approximately 60 m. Bagley Icefield. Wrangell St.Elias National Park and Preserve (Hand held 6 x 6 cm fuji velvia film, Hasselblad 503CW camera, Carl Zeiss Planar T 80 mm lens), 2011.