Arctic Ice Island and Ice Shelf Studies: Part I

Summarizes some physical characteristics of ice island T-3 and its presumed source, the ice shelf off northern Ellesmere. Investigations since 1952 are described, results tabulated and graphed. The maximum ice thickness of the ice shelf was 60 m and that of T-3, 68 m (averaging 0.905 gm/cm³ in density from the surface to a depth of 16 m). Dust from dirt layers (collecting in small holes) on T-1 and T-3 appears to have originated from a land mass underlain partly by volcanic rock and partly by metamorphic and plutonic types and to have been wind-deposited. Deep cores on T-3 revealed a sequence of dirt layers to 28 m with clear ice below, the composition and grain size the same in all the layers; the heaviest were near the surface (amounting to 114-122 gm/m²) and at depths of 25 and 28 m (80 gm/m²). Four types of ice were observed on Ellesmere ice shelf and on T-3 in 1953 and 1954: iced firn, glacier, lake and sea ice; in 1955 only iced firn and lake ice were identified on the island. Temperatures recorded below the depth of annual change at the ice rise near Ward Hunt Island were -17.7 °C at 12.2 m and -17.3 °C at 18.0 m. Rocks, and plant and animal specimens found on T-3 are examined in relation to the possible origin of the island. Strand cracks at the junction between floating and grounded ice on the Ward Hunt ice shelf are also considered. From SIPRE [Snow, Ice, and Permafrost Research Establishment].