Antarctica’s largest island hid as mainland until 1940
Alexander Island, west of the Antarctic Peninsula in the Bellingshausen Sea, is the continent’s biggest island—yet explorers thought it was mainland until a 1940 sledge journey proved water in George VI Sound. Ice still hides most of its mountain spine today.
Russian explorer Fabian Gottlieb von Bellingshausen sighted it on 28 January 1821 and named Alexander I Land for the reigning tsar. Separated from Palmer Land by Marguerite Bay and George VI Sound, it stayed “land” on maps until two United States Antarctic Service sledgers—Finn Ronne with partner Carl Eklund—proved the water gap in December 1940.
Britain claimed it in 1908; Chile in 1940 and Argentina in 1942 followed. The Antarctic Treaty recognises none of those claims. British Fossil Bluff sits among north–south ranges whose nunataks pierce the ice, beside rare ice-free ground such as Ablation Point Massif.
One of its oddest features is Hodgson Lake, a former subglacial lake now exposed, roughly 2 by 1.5 kilometres, with a 93-metre column of water sealed beneath about four metres of permanent ice. At the height of the last ice age it lay under at least 470 metres of ice sheet, which began thinning around 13,500 years ago and left the lake capped by lasting ice before 11,000 years ago. Meanwhile the George VI Ice Shelf fills the sound completely, physically binding the island to Palmer Land.
Features poking through the ice carry musical names: Beethoven Peninsula, Brahms Inlet, the Elgar Uplands, the Lully and Finlandia Foothills, and a glacier named in 1987 by Soviet scientists after the composer Anatoly Lyadov. The rocks record subduction of proto-Pacific crust along the peninsula's western margin from the latest Triassic into the Tertiary. LeMay Group accretionary rocks dominate the west, while the Fossil Bluff Formation, dropped down east of a north–south fault, yields ammonites, belemnites and bivalves.
Source: Alexander Island
