Alexander Island - Geography

Geography

The surface of Alexander Island is predominantly ice covered. There exist some exposed nunataks and a few ice free areas, i.e. Ablation Point Massif, of significant size. The nunataks are the peaks of north-south trending mountain ranges and hills. They include the Colbert, Havre, Lassus, Rouen, Sofia University, and Walton mountains; Staccato Peaks; Lully Foothills; Elgar Uplands; and Douglas Range. These mountains, peaks, hills, and uplands are surrounded by a permanent ice sheet, which consists of glaciers that flow off of Alexander Island. These glaciers flow west into the Bach and Wilkins Ice Shelves and Bellingshausen Sea, and east into the George VI Ice Shelf. The George VI Ice Shelf is fed by both by outlet glaciers from the ice cap on Palmer Land and Alexander Island.

Another notable feature of Alexander Island is Hodgson Lake. It is a former subglacial lake that has emerged from under an ice sheet that covered it. It is 2 km (1.2 mi) long by 1.5 km (0.93 mi), and has a 93.4 m (306 ft) deep water column that lies sealed beneath a 3.6 to 4.0 m (12 to 13 ft) thick perennial lake ice. The northern side of this lake is bounded by the Saturn Glacier, which flows east into George VI Sound, while the southern side of Hodgson Lake is bounded by the northern face of Citadel Bastion. During the Last Glacial Maximum, Hodgson Lake was covered by the ice sheet at least 470 m (1,542 ft) thick. This ice sheet started thinning about 13,500 years ago. It retreated and left Hodgson Lake covered by perennial ice sometime before 11,000 years ago. This lake has been covered by perennial ice since that time.