Lyla Lindsey
Australia's landscape is incredibly diverse, ranging from snow-capped mountains to large deserts, tropical rainforests, grasslands, and heathlands. The geography of Australia encompasses a wide variety of biogeographic regions, and its landscape is the product of millions of years of climatic and geological processes. Australia's mainland has a total coastline length of 35,821 km, and the country has the largest area of ocean jurisdiction of any country on Earth. The landscape of Australia has been shaped by tectonic movements, changes in sea level, erosion by wind and water, and volcanic activity. Today, Australia's landscape is facing new challenges due to climate change, with rising ocean temperatures, changing rainfall patterns, and the introduction of feral pests threatening its unique wildlife and natural environments.
| Characteristics | Values |
|---|---|
| Tectonic movements | Australia continues to move north by about 7 centimetres each year |
| Sea level changes | The Eastern Highlands were uplifted to form the Great Divide, separating rivers flowing inland from those flowing to the Pacific Ocean |
| Erosion | The Great Escarpment was formed by the erosion of the newly formed continental edge on the eastern side |
| Volcanic activity | Australia's youngest mainland volcano, Mt Gambier, last erupted about 6,000 years ago |
| Climate | The largest part of Australia is arid or semi-arid, with only the southeast and southwest corners having a temperate climate |
| Droughts | Droughts have become more prominent and severe due to accelerated climate change |
| Forest cover | In 2020, forest cover was around 17% of the total land area, up from 13.88% in 1990 |
| Coastline | The Australian mainland has a coastline of 35,821 km (22,258 mi), with 758 estuaries |
| Coral reefs | The Great Barrier Reef, the world's largest coral reef complex, is off the northeastern coast of Australia |
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What You'll Learn
Tectonic movements and sea level changes
Australia's landscape is largely shaped by tectonic movements and long-term changes in sea levels. The continent has a long geological history, dating back to the formation of the supercontinent Rodinia over 1 billion years ago. During the Proterozoic era, the supercontinent began to break up, and the landmass that would become Australia consolidated. This landmass was composed of Archaean rocks, which are among the oldest known rocks on Earth, dating back more than 2.5 billion years.
The tectonic processes that shaped Australia are complex and multifaceted. The continent was influenced by the convergence of the Pacific Plate, which included alternating back-arc spreading and subduction. This activity accreted the eastern third of Australia during the Phanerozoic era. Australia's isolation as a continent began around 55 to 10 million years ago, and it continues to move northward by about seven centimetres each year.
Sea levels have played a significant role in shaping Australia's landscape. During the Mesozoic era, sea levels rose, and much of the continent was submerged. This rise in sea levels was influenced by tectonic activity, particularly volcanic activity in eastern Australia. The Tasman Sea to the southeast and the Coral Sea to the north were formed during this period.
In the last 5 million years, sand deserts and large inland salt lakes formed in Australia. The Pleistocene epoch, which began around 2.5 million years ago, saw repeated phases of glaciation with lower sea levels that linked Australia to New Guinea. During interglacial periods, sea levels rose, isolating the mainland from New Guinea and Tasmania.
The Great Divide, a significant feature of Australia's landscape, was formed due to the uplift of the Eastern Highlands. This divide separates the rivers flowing towards inland Australia from those flowing to the Pacific Ocean. The Nullarbor Plain, on the other hand, is an example of an uplifted sea floor, showcasing the diverse geological processes that have shaped the country's landscape.
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Erosion by wind and water
Australia's landscape is the product of millions of years of climatic and geological processes. The shape of the country is largely due to tectonic movements and long-term changes in sea level, but its topography is the result of prolonged erosion by wind and water.
The unique geography of Australia is susceptible to erosion by wind and water. The country experiences a range of climatic conditions, from tropical rainforests and grasslands in the north to arid and semi-arid regions, with frequent droughts. These factors contribute to the erosion of the landscape over time.
Wind erosion is a significant issue in Australia, particularly in areas with poor ground cover, such as during dry seasons. In the south-west of Western Australia, climate change has led to lower rainfall, higher temperatures, and delayed starts to the growing season, increasing the risk of wind erosion. This erosion results in the deposition of sand on fence lines and in waterways and dams, requiring time and resources for removal. To manage wind erosion, various technologies and management systems can be employed, such as planting shallow-rooted annual grasses to cover bare soils.
Water erosion has also played a crucial role in shaping Australia's landscape. About 50% of Australia's rivers drain inland and often end in ephemeral salt lakes. The Finke River in central Australia is one of the oldest rivers in the world, and the salt lakes in the Yilgarn region are remnants of an ancient drainage pattern. The Great Escarpment, formed by the erosion of the newly-formed continental edge, can be traced from Cape York Peninsula to southeastern Victoria.
The combination of wind and water erosion, along with other geological processes, has contributed to the diverse geography of Australia, including its mountains, basins, and coastal landscapes.
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Climate change and drought
Australia has always had a variable climate, but climate change is making the situation worse. The country is becoming hotter and more prone to extreme heat, bushfires, droughts, floods, and longer fire seasons. Since the beginning of the 20th century, Australia has experienced an increase of over 1.5 °C in average annual temperatures, with warming occurring at twice the rate over the past 50 years compared with the previous 50.
The impact of climate change is evident in the increasing number of heatwaves and droughts in Australia. The number of days that break heat records has doubled in the past 50 years, and heatwaves are of particular concern as they are occurring more frequently and with greater intensity. In recent decades, more people have died in Australia from heatwaves than all other natural disasters combined.
Droughts are also becoming more frequent and severe. The Federation Drought, the World War II Drought, and the Millennium Drought are some examples of extreme droughts that have occurred in Australia since the late 1800s. Climate models predict that without intervention, droughts will become even more common and severe in the future. Southern Australia, in particular, is expected to experience a 50% reduction in precipitation by 2090 if global greenhouse gas emissions are not curbed.
The impact of these changes on rural communities and industries such as agriculture has been significant. Livestock farmers have had to shoot their animals when feed and water ran out, and many workers have left the industry due to the challenging conditions. The suicide rate among farmers spiked during the drought years, as entire livelihoods were lost.
Indigenous communities, particularly those in the North, are also disproportionately affected by climate change. They face issues such as thermal stress and reduced access to water resources and ecological landscapes. Traditional landscape management practices, such as burning and clearing savanna areas susceptible to fires, have been banned in some cases, despite their effectiveness in reducing greenhouse gas emissions.
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Volcanic activity
Australia's landscape has been significantly influenced by volcanic activity over millions of years. The country's east coast, in particular, is characterised by numerous volcanoes that have erupted and shaped the surrounding terrain. The most recent volcanic eruption on the Australian mainland occurred at Mount Gambier in South Australia, approximately 6,000 years ago. Mount Gambier is part of the Newer Volcanics Province in Victoria, which includes four shield volcanoes: Red Rock, Mount Napier, Mount Schank, and Mount Gambier. These volcanoes produced explosive eruptions with lava flows, shaping the landscape of the region.
The eastern coast of Australia has witnessed volcanic activity over millions of years, with hundreds of eruptions occurring between North Queensland and Tasmania. This volcanic belt challenges the typical understanding of tectonic activity, as the region's tectonic regime does not justify the occurrence of volcanoes. The volcanic activity in this region is primarily driven by molten rock finding its way to the surface through the Australian crust. The subduction of the Pacific Plate beneath the Australian Plate results in the accumulation of molten rock at significant depths, which then rises through the thinner east Australian coast.
The volcanoes along Australia's east coast differ from iconic volcanoes like Mount Fuji or Krakatoa. Instead of massive explosions, these volcanoes often produce smaller eruptions that resemble bubbles emerging in pancake mix. As a result, many of these volcanic remnants resemble regular hills or notable structures like Cradle Mountain in Tasmania and the Organ Pipes in Victoria. The Undara Lava Tubes in Queensland and Sawn Rocks in New South Wales are also examples of volcanic features that have shaped the Australian landscape.
The volcanic history of Australia extends beyond the mainland. On the remote Australian Territory of Heard Island and McDonald Islands in the Southern Ocean, volcanic activity occurred on Mawson's Peak in the mid-1980s, and the nearby McDonald Islands experienced activity in the 1990s. These volcanic events demonstrate the ongoing influence of volcanic activity on the Australian landscape, even in recent decades.
While Australia's volcanic activity has contributed to its geological diversity, it is important to note that the continent's landscape is also shaped by other factors. Tectonic movements, changes in sea level, and prolonged erosion by wind and water have all played significant roles in forming the unique features of Australia's terrain.
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Aboriginal land management
Australia's landscape is the result of millions of years of climatic and geological processes. The shape of the continent is largely due to tectonic movements and long-term changes in sea level, while its topography is a result of prolonged erosion by wind and water. The geography of Australia encompasses a wide variety of biogeographic regions, ranging from snow-capped mountains to large deserts, tropical and temperate forests, grasslands, heathlands, and woodlands.
One example of Aboriginal land management is the use of fire to regenerate flora and create a mosaic of trees and grasslands. By selecting which areas to burn and when, Indigenous communities were able to encourage the growth of native grasses and create expansive grasslands that attracted kangaroos for hunting. This practice also helped to prevent intense bushfires by reducing the amount of combustible Eucalyptus forests.
Today, there is a growing adoption of traditional Aboriginal burning practices to repair the damage done by European farming methods. By understanding local conditions, including climate, plants, and animals, land managers can use fire as a tool to encourage native grass regeneration, reduce scrub and fuel for bushfires, and promote biodiversity.
Aboriginal and Torres Strait Islander peoples have millennia of knowledge about how to conserve Country, and this wisdom is being increasingly centred and applied in contemporary Australia through initiatives such as Indigenous Protected Areas (IPAs). As of 2023, there are 81 dedicated IPAs, covering over 87 million hectares, which are safeguarded by Traditional Owners through voluntary agreements with the Commonwealth Government.
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Frequently asked questions
Tectonic Earth movements, long-term sea level changes, erosion by wind and water, and volcanic activity have all contributed to the formation of Australia's landscape over millions of years.
Australia is known for its unique wildlife and is home to the world's oldest continuous human culture, with Aboriginal people inhabiting the land for at least 65,000 years. However, the introduction of non-native species, such as feral cats, foxes, and camels, has negatively impacted native animal populations. Climate change, agricultural practices, and drought have also altered the landscape and continue to pose challenges for conservation and the environment.
Australia can be divided into four major landform regions: the Coastal Plains, the Eastern Highlands, the Central Lowlands, and the Western Plateau. The Eastern Highlands, including the Great Divide and the Great Escarpment, separate rivers flowing inland from those flowing to the Pacific Ocean. The Western Plateau has existed as a landmass for over 500 million years and comprises individual plateaus such as the Kimberley, Hamersley, and Yilgarn. The Central Lowlands include flat areas and ranges such as the MacDonnell and Musgrave. The Coastal Plains vary in geography, including tropical rainforests, grasslands, and deserts.
