Ruqayyah Snyder
Australia's landscape has been shaped over millions of years, resulting in a geographically diverse country. The Finke River in central Australia is one of the oldest rivers in the world, and the continent began its journey as an isolated landmass around 55 to 10 million years ago. Australia's topography has been influenced by its proximity to the South Pole during the Permian Period, the formation of sedimentary basins, and the separation of the continent from Antarctica. The country's landscape varies from snow-capped mountains to large deserts, tropical rainforests, and grasslands, with the Eastern Highlands or Great Dividing Range separating the eastern coastal plain from the rest of the continent.
| Characteristics | Values |
|---|---|
| Central lowlands | The Great Artesian Basin, Murray-Darling basin, and Lake Eyre Basin |
| Terrain | Mostly low plateau with deserts, rangelands, and a fertile plain in the southeast |
| Geography | Snow-capped mountains, large deserts, tropical and temperate forests, grasslands, heathlands, and woodlands |
| Climate | Tropical/subtropical with cold waters off the western coast |
| Waterways | Headwaters of some waterways are located in tropical regions where summer rains create a high rate of discharge |
| Tectonic activity | No active volcanism; minor earthquakes are frequent, and major earthquakes (magnitude 6+) occur on average every five years |
| Geological history | Began its journey as an isolated continent between 55 and 10 million years ago; the current topography is the result of millions of years of erosion and redistribution of sediments |
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What You'll Learn
Australia's topography began in the Permian Period
Australia's topography is the result of a long landscape history, which, fundamentally, started in the Permian Period, between 290 and 245 million years ago. During this time, Australia was very near the South Pole, and much of the continent was covered by large ice caps.
After the ice melted, parts of the continent subsided and formed sedimentary basins such as the Eromanga Basin in South Australia. The Permian Period was a time of immense global change and unique paleogeographic configurations. Land masses were assembled into one great continent of Pangea, which extended from pole to pole, and the mega-ocean Panthalassa dominated the Earth's surface. Climatic and oceanic conditions were favourable for the formation of vast quantities of energy resources and mineral deposits, such as petroleum, coal, phosphorite, and evaporites.
During the Late Permian, central northern Pangea experienced voluminous volcanic eruptions that produced the Siberian traps. The Permian ended with the greatest mass extinction of biota recorded in Earth's history. After the Permian Period, in the early Cretaceous Period, Australia was so flat and low that a rise in sea levels divided it into three landmasses as a shallow sea spread over the land. The Eastern Highlands were also uplifted around this time, forming the Great Divide, which separates rivers flowing towards inland Australia from those flowing to the Pacific Ocean.
The topography of central Australia today is mostly flat, but there are numerous ranges such as the MacDonnell and Musgrave Ranges, as well as some individual structures, of which the best known is Uluru. Faulting and folding in the areas took place long ago, and the current topography is the result of millions of years of erosion and redistribution of sediments removed from high areas and filled-in depressions in this largely internal drainage system.
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The continent separated from Gondwana
The continent of Australia separated from Gondwana in stages, beginning in the Early Jurassic Period around 180 million years ago. During this initial break-up, the western half of Gondwana (Africa and South America) separated from the eastern half (Madagascar, India, Australia, and Antarctica).
The separation of Australia from East Antarctica began around 132 million years ago, with seafloor spreading occurring approximately 96 million years ago. This separation led to the development of a shallow seaway over the South Tasman Rise during the Early Cenozoic. As the oceanic crust continued to divide the continents during the Eocene, around 35.5 million years ago, global ocean temperatures dropped significantly.
The final stages of the Gondwana break-up saw the fragmentation of the Antarctic land bridge, resulting in the separation of Antarctica from South America and Australia. This occurred during the Cretaceous-Paleogene extinction event, coinciding with the eruption of the Deccan basalts.
The separation of Australia from Gondwana played a significant role in shaping the continent's landscape and climate. Australia's present topography is a result of its long landscape history, which began in the Permian Period when the continent was near the South Pole and covered by large ice caps. After the ice melted, parts of the continent subsided, forming sedimentary basins such as the Eromanga Basin in South Australia.
The Australian continent encompasses diverse biogeographic regions, ranging from snow-capped mountains to large deserts, tropical and temperate forests, grasslands, heathlands, and woodlands. The Western Plateau, which includes the Nullarbor Plain, has existed as a landmass for over 500 million years. The Eastern Highlands, or the Great Dividing Range, separate the narrow eastern coastal plain from the rest of the continent.
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Australia's landscape is shaped by erosion
Australia's landscape is diverse, ranging from snow-capped mountains to large deserts, tropical and temperate forests, grasslands, heathlands, and woodlands. While the shape of Australia is largely due to tectonic movements and long-term changes in sea levels, its topography is primarily shaped by prolonged erosion by wind and water.
The Finke River in central Australia is one of the world's oldest rivers, and the salt lakes in Western Australia's Yilgarn region are remnants of a drainage pattern that predates Australia's separation from Antarctica. Australia's current topography is the result of a long landscape history that began in the Permian Period when the continent was glaciated by large ice caps. After the ice melted, parts of the continent subsided and formed sedimentary basins such as the Eromanga Basin in South Australia.
During the Paleogene and Neogene Periods, Australia's landscape was varied, with sedimentary basins and the uplifted Eastern Highlands forming the Great Divide. Erosion of the eastern continental edge formed the Great Escarpment, which stretches from Cape York Peninsula to southeastern Victoria. Volcanic activity during this period also covered eastern Australia with lava plains, with Mt Gambier in South Australia being the country's youngest mainland volcano.
The landforms of today are the result of prolonged and continuous processes of movement and erosion over millions of years, giving rise to a variety of landscapes across Australia. The MacDonnell and Musgrave Ranges, as well as iconic structures like Uluru, are the result of faulting and folding that occurred long ago, followed by the erosion and redistribution of sediments in internal drainage systems.
Additionally, coastal erosion has played a significant role in shaping Australia's landscape. The Twelve Apostles along the Great Ocean Road, for example, are the result of millennia of landscape change and coastal erosion. Human activities, such as the construction of coastal structures and the removal of sediments, can also contribute to erosion in certain areas. Climate change, both natural and human-induced, can influence the likelihood and rate of coastal erosion.
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The Finke River is one of the world's oldest
The Finke River in central Australia is widely considered one of the oldest rivers in the world. The river is usually a string of waterholes, but during rare flood events, it can become a raging torrent. The Finke River is thought to be between 350 and 400 million years old, with its source in the MacDonnell Ranges in the Northern Territory of Australia.
The river's age has been deduced by observing and analysing various factors in the geology of the area. One key piece of evidence is the presence of deeply incised meanders, which only form on flat plains. As the Finke River flows through the James Range, a mountain-building event, it must have formed before the ranges were pushed up. This formation of meanders is also seen in other large mountain-sourced river systems in central Australia, such as the Todd and Hale Rivers, indicating that they are of similar antiquity.
The Finke River was named by John McDouall Stuart in 1860 after William Finke, an Adelaide man who promoted his expedition. The Aboriginal name for the river is Larapinta, or "Lara Beinta" in the Western Arrernte language, which was incorrectly translated by Ernest Giles in 1872. Giles deduced from conversations with Southern Arrernte people that the name derived from the gigantic mythological snake or Rainbow Serpent, believed to have created the river.
The age of the Finke River is not without controversy, as it is challenging to determine the oldest river with absolute confidence. While the Finke River is largely accepted as the oldest, other rivers, such as the New River in North America and the Meuse in Europe, are also estimated to be ancient, ranging from 10 to 360 million years old.
The landscape of central Australia, where the Finke River flows, has a long and diverse history. Australia began its journey as an isolated continent between 55 and 10 million years ago and continues to move north by about seven centimetres each year. The topography of the region is the result of various processes, including glaciation, erosion, and the filling of depressions in the internal drainage system. The central region of Australia is mostly flat, with numerous ranges and structures, the most famous being Uluru.
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Australia's terrain is mostly low plateau with deserts
Australia's terrain is diverse, ranging from snow-capped mountains to large deserts, tropical and temperate forests, grasslands, heathlands, and woodlands. The geography of the continent includes six distinct landform divisions. The terrain is mostly low plateau with deserts, rangelands, and a fertile plain in the southeast.
The Eastern Highlands, or Great Dividing Range, lie near the eastern coast of Australia, separating the relatively narrow eastern coastal plain from the rest of the continent. These Eastern Australian temperate forests have the greatest relief, the most rainfall, the most abundant and varied flora and fauna, and the densest human settlement. The Eastern Highlands were uplifted during the Paleogene and Neogene Periods, forming the Great Divide, which separates rivers flowing towards inland Australia from those flowing to the Pacific Ocean.
Between the Eastern Highlands and the Western Plateau lies the Central Lowlands, which include the Great Artesian Basin, Australia's largest river systems, the Murray-Darling basin, and the Lake Eyre Basin. The Great Artesian Basin is the world's largest and deepest freshwater basin and is an important source of water for the country.
The Western Plateau, which includes the Nullarbor Plain, is generally flat but is broken by various mountain ranges such as the Hamersley, MacDonnell, and Musgrave Ranges. The Western Plateau region has existed as a landmass for over 500 million years and is made up of individual plateaus, including the Kimberley, Hamersley, and Yilgarn. The Nullarbor Plain, on the other hand, is an uplifted sea floor, a limestone plain of Miocene age.
Much of Australia's interior is arid, with low annual rainfall and high temperatures, resulting in dry rivers and empty lakes. The outback covers 70% of the continent, and about 40% of Australia is covered by dunes. The deserts in the interior and south lack significant summer rains, and the western desert can be explained by the little evaporation of the cold sea current of the West Australian Current, preventing rainfall in the interior. The Great Australian Desert covers about 18% of the Australian mainland, but about 35% of the continent receives so little rain that it is practically desert.
The Australian landscape has been shaped by a long history of geological processes, including faulting and folding, glaciation, and erosion. The Finke River in central Australia is one of the oldest rivers in the world, and the salt lakes of the Yilgarn region in Western Australia are remnants of a drainage pattern that existed before continental drift separated Australia from Antarctica. Australia's present topography is the result of its geological history, which began in the Permian Period when the continent was near the South Pole and covered by large ice caps.
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Frequently asked questions
The Central Australian landscape was formed over millions of years. The Finke River in central Australia is one of the oldest rivers in the world. Australia's topography is the result of a long landscape history, which started in the Permian Period when Australia was near the South Pole and much of the continent was glaciated by large ice caps.
Central Australia is mostly flat, but there are ranges such as the MacDonnell and Musgrave Ranges, and individual structures like Uluru. The Finke River is one of the oldest rivers in the world, and the Great Artesian Basin is an important source of water.
The Eastern Highlands, or Great Dividing Range, lie near the eastern coast of Australia, separating the eastern coastal plain from the rest of the continent. Between the Eastern Highlands and the Western Plateau lies the Central Lowlands, which are made up of the Great Artesian Basin and Australia's largest river systems, the Murray-Darling basin and the Lake Eyre Basin.
Australia's landscape has changed over millions of years due to movement and erosion. During the Paleogene and Neogene Periods, volcanoes erupted in eastern Australia, and lava plains covered large areas. Australia's youngest mainland volcano, Mt Gambier, last erupted about 6,000 years ago. The last glacial period was at its most intense about 20,000 years ago, and by 11,700 years ago, rising sea levels separated mainland Australia from Tasmania and New Guinea.
