Internal Structure of Sandy Glacier, Southern Victoria Land, Antarctica

Abstract

AbstractThis narrow, 600 m. long cirque glacier is apparently composed throughout of alternating layers of ice and sand that strike parallel to the edge of the glacier and dip into the glacier at an angle of 82°. The thickness of the sand layers averages 10 cm., and that of the ice layers 20 cm. The sand layers are generally composed of thin parallel laminations but micro-cross-bedding is present locally. The layers have been broken into angular blocks 0.5 to 3.0 m. long, separated by ice columns connecting adjacent ice layers. The ice layers show thinner zones of contrasting bubble content which bend into the columns separating the sand blocks.The sand was probably blown into this cirque from the floor of Wright Valley 6 km. south-west and 1,100 m. below. Each pair of sand and ice layers may record accumulation during one year. The steeply dipping yet otherwise undeformed layers clearly prove that rotational movement has taken place. The breaking of the sand layers into blocks is the result of plastic extension within the glacier.