Nature conservation

Biodiversity Reform

Australian Alps - landform


The Australian Alps Bioregion constitutes the highest section of the Great Dividing Range, and contains Australia's highest mountain, Mt Kosciuszko (2,228 m). The landscape is characterised by peaked ranges, and broad, forested valleys, and is the only true alpine environment in NSW.

Geology and geomorphology

The alpine area comprises granites that have formed faulted, stepped ranges at the point where the South Eastern Highlands in NSW turn west into Victoria. More recent volcanic activity produced basalts and, in the Pleistocene, the cold climate superimposed glacial features on the landscape.

The bioregion was the only part of the mainland to have been affected by Pleistocene glaciation and contains a variety of unique glacial and periglacial landforms above 1,100m altitude. Evidence of glaciation has been obtained from pollen preserved in alpine and subalpine lakes and bogs.

The original uplift of the steep seaward scarp of the Great Divide is attributed to the intersection of two coastal uplift zones created by the opening of the Tasman Sea and Southern Ocean during the break up of Gondwana. Elsewhere, more recent volcanic activity in the Tertiary produced the basalts found in the Cabramurra-Kiandra area.

The upper surfaces of the granite blocks have a low relief and form an environment of high plains where cold air drainage has a major impact on vegetation patterns. Stream patterns have also been affected by the geology. Meandering systems on the high plains become deeply incised gorges with waterfalls and cascades as the streams cross the fault block margins. Larger streams follow major fault lines such as the Thredbo-Crackenback valley.


Important features include the following:

  • the bioregion contains Australia's highest mountain (Mt Kosciuszko 2,228m) and is the only part of the mainland to boast a suite of Pleistocene glacial and periglacial landscape features;
  • there are well-documented karst landforms at Yarrangobilly and Cooleman;
  • there are pseudokarst landforms in alpine block streams and boulder piles;
  • the sub-basalt sediments at Kiandra are exposed by mining and contain important leaf fossils preserved in lignite;
  • mining heritage items relating to sluicing and dredging operations are present; and
  • construction works of the Snowy Mountains Hydro-Electric Authority, which began in 1949, are also heritage items in the context of engineering geology.



The soils of this bioregion reflect the extreme climatic gradient across the ranges. The lowlands consist mainly of texture contrast soils, grading to uniform, organic soils and peats at the highest elevations.

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Page last updated: 18 April 2016