Morphology and variations of glacial drainage basins in the King George Island ice field, Antarctica

Abstract

A Systeme probatoire pour l'observation de la terre (SPOT) mosaic of King George Island, the largest (1250 km2) of the South Shetland Islands, West Antarctica, shows its major morphological features. Three main ice domes and 70 glacier drainage basins, covering 92.7% of the King George Island area, strongly controlled by the subglacial morphology and drained by relatively fast-moving tidewater outlet glaciers, were delineated. A general retreat of ice fronts through four decades, more intensely on the eastern side of the island (to the Bransfield Strait), resulted in the loss of about 7% of the glacial cover area. Superficial snow facies were derived from SPOT multispectral imagery and, together with field observations, allowed the transient-snowline elevation to be obtained. The latter is estimated to have risen from about 200-250 m in the mid-1950s to 300-350 m by 1988. Spot radio-echo sounding surveys give an overview of the bedrock morphology.