Heard Island & McDonald Islands
Located in the far southern reaches of the Indian Ocean, some 1,500 km north from East Antarctica and 4,100 km southwest from Perth, Western Australia, lie the remote islands that make up the Heard and McDonald Islands group. The group consists of the 368 km² Heard Island and the smaller McDonald Islands, located 43 km to the west of Heard Island. The nearest neighbours to the islands are the Kerguelen Islands located 440 km to the north. The territory covers a total area of 372 km² and are territorially a part of Australia.
The islands are located upon a submarine feature known as the Kerguelen Plateau — the largest volcanic plateau of the Southern Ocean and one of the largest on Earth — which rises some 3,500 m above the surrounding ocean floor. Much of the plateau may have at one time in the remote past been emergent or covered by shallow waters. Today the only emergent land masses are those of the Kerguelen Islands, Heard Island and the McDonald Islands.
Heard Island itself, consists of three distinct units extending for around 43 km west to east: the central mass of the island, the Laurens peninsula in the west and the lowlands terminating in Elephant Spit in the east. The main body of Heard Island is roughly circular, with a diameter of about 25 km. It is dominated by the impressive bulk of the Big Ben massif, that is topped by the volcanically active Mawson Peak which reaches a height of 2,745 m (Australia's highest peak outside of Antarctic claims). The peak itself, lies within a 6 km wide summit caldera. In the northwest the island is connected by a narrow isthmus of less than 100 m in width to the Laurens Peninsula (formed by the Mt. Dixon volcano). The peninsula's hilly and volcanic terrain rises to a height of 715 m at Anzac Peak. In the east of the island are areas of low coastal flats and lagoons from which the Elephant Spit extends for around 10 km as a narrow ridge of sand, rocks and shingle.
Offshore are a number of smaller islets and rocks: Shag Islet, Sail Rock, Morgan Island and Black Rock with a combined area of 1.1 km².
Most of Heard Island is composed of the heavily glaciated slopes of the Big Ben Massif. The snow and ice covers around 70% of the island and reaches thicknesses of over 150 m. In all, there are 12 major glaciers — most descending from the mountain peak — some of which reach the sea. To a lesser extent, the Laurens Peninsula is also glaciated. Those areas that are ice-free are found along the coasts consisting of grassy slopes, low coastal flats, beaches composed of sand or shingle, and areas of dotted with coastal lagoons. The largest of the lagoons are Winston Lagoon and Compton Lagoon, both visible in the large size image.
The islands are a premier example of an original sub-Antarctic island ecosystem — and represent the least disturbed islands of this type remaining. They provide important breeding and feeding grounds for numerous species of marine mammals and seabirds. In all, there are 34 bird species including 7 species of seal and 17 sub-Antarctic plant species. The islands are also contain important populations of invertebrate species. The islands were proclaimed as a World Heritage site in 1997 and, along with their territorial waters, are a Wilderness Reserve managed by the Australian Antarctic Division.
The McDonald Islands (2.5 km²) are located 43 km west from Heard Island; they are small and rocky and consist of McDonald Island, Flat Island and Meyer Rock.
