Australian Landform Divisions
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Wind and water have over millions of years, worn down the surface of the Australian Landmass. It is the lowest and flattest of the world's continental landmasses, with a highest peak of 2228 m at Mt Kosciuszko, this is very low compared to other continents. Erosion and weathering are said to have a profound effect on this, as a result of the age of the Australian Continent and its exposure to the elements. Only 2% of the continental landmass is above a kilometre high. Australia is divided into 3 distinct landform divisions however, some recognise a fourth, the Coastal Plain, as one as well.[citation needed]
- the Eastern Highlands (or the Great Dividing Range)
- the Central Lowlands
- the Western Plateau
- the Coastal Plain
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[edit] The Eastern Highlands
The Eastern Highlands cover just 10% of the continent and run in a strip up to 200km wide along the east coast, from the Cape York Peninsula to Tasmania. In many places the highlands are quite rugged and deep valleys and gorges are a common feature. This is due to the result of erosion from rivers and streams cutting into the softer rock.
The majority of the Highlands are composed of faulted or folded igneous rock uplayed over sandstone rock. This provides evidence to the theory of volcanic activity occurring in the Great Dividing Range. Volcanic cones have also been eroded, leaving towers of hard rock that plugged the vents into the earth's surface.
While not very high by international standards, the ranges and tablelands that make up the eastern highlands are rugged enough to influence the region's climate, soils, vegetation, settlement patterns and landuses. The name Great Dividing Range is derived from the role the highlands play in dividing the Queensland, New South Wales and Victorian Rivers into eastward or westward flowing rivers.
[edit] The Central Lowlands
The Central Lowlands are a low-lying , largely featureless plain, the majority of which are less than 200m above sea-level. This geographical area occupies approximately 25% of the Australian continent and contains much of the Arid/Semi-Arid Zone of Australia. The lowlands are primarily composed of sediment deposited on the floor of an ancient inland sea, whose occurance resulted as an effect of isolation of Australia from Gondwanaland, the large supercontinent that Australia was once a part of. Landform features include salt-pans and sand ridges.
The Central Lowlands are home to these physical landforms
- The Simpson Desert, reaching an elevation of 40m and occupying an area of approximately 170 000 square kilometres.
- Australia's largest lake, Lake Eyre, which covers an area of about 9500 square kilometres. It drains the Lake Eyre Basin. At 15m below sea-level it is Australia's lowest point. It has only been filled with water 3 times during the past century and is usually a salt-pan.
- Australia's largest River Catchment, the Murray-Darling Basin.
[edit] Coastal Plains
This is a narrow strip that extends along the Eastern edge of the continent. The coastal plains, consisting of Australias largest cities Brisbane, Sydney, Melbourne and Adelaide are densely populated. Over 80% of Australia's Population can be found in the strip from Brisbane to Adelaide alone.
[edit] Western Plateau
The Western Plateau covers the western two thirds of the continent. It is made up of a huge, stable block of ancient igneous and metamorphic rock which is up to 3.6 billion years old. This block has been levelled, due to millions of years of erosion and weathering. It is generally flat and low, under 500m above sea level.
[edit] Sources
- Internet
- Australian Government, Geosciences Australia[1]
- Books
- Kleeman, Lane, Hamper, Rhodes, Elliot; "Australian Explorations", Investigating Australia's Physical Environments.
