Glacier Fluctuations in George VI Sound Area, West Antarctica (Abstract only)

Abstract

George VI Sound lies between Alexander Island and the Antarctic Peninsula and is over 20 km wide and 500 km long. At present an ice shelf fills the sound and is nourished largely by ice from the Antarctic Peninsula which flows across the sound to ground against the coast of Alexander Island. Ice-free areas, comprising small nunataks and larger massifs, fringe both sides of the sound and contain evidence of the former glacial history of the area. This paper describes the field evidence in detail and uses geomorphological and sedimentary analyses to put forward a relative glacial chronology, constrained by two absolute dates.The chronology distinguishes: (1) a maximum state during which all ice-free areas were submerged by ice flowing into George VI Sound from both the Antarctic Peninsula and Alexander Island and thence along the sound as an ice stream. This occurred in the late Wisconsin and followed an interstadial or interglacial when George VI Sound was free of an ice shelf.(2) a valley-based stadial during overall deglaciation represented by pronounced marginal moraines on Alexander Island.(3) deglaciation to a stage where there was less landbased ice on Alexander Island than today. At this stage isostatic recovery was incomplete, relative sealevel was higher, and George VI Ice Shelf penetrated further into embayments on Alexander Island than at present.(4) probable disappearance of George VI Ice Shelf by 6.5 14C ka BP.(5) neoglacial readvance of local glaciers on Alexander Island to form three closely spaced terminal moraines and the growth of a new George VI Ice Shelf which was again more extensive than at present.(6) subsequent oscillations of both smaller Alexander Island glaciers and George VI Ice Shelf probably during the Little Ice Age. These fluctuations are similar to those in other sub-Antarctic Islands in the Scotia Sea and also in southern Chile.