Geography of Australia


, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island state of Tasmania, and thousands of minor islands. It occupies a total area of, making it the sixth-largest country in the world. Located in the Southern Hemisphere between the Indian and Pacific oceans, Australia’s jurisdiction spreads across thousands of kilometres beyond the main landmass, including Norfolk Island, Christmas Island, the Cocos Islands, the Coral Sea Islands, Ashmore and Cartier Islands, the Heard and McDonald Islands in the southern Indian Ocean and thousands of other islands, as well as the Australian Antarctic Territory, a territorial claim covering almost half of the continent.
The country’s geography encompasses a wide range of environments, from arid and semi-arid interior regions to tropical rainforests, temperate woodlands, and alpine areas. Most of the population lives in the temperate coastal zones of the east, southeast, and southwest, while the heartland—known as the Outback—is sparsely populated and characterized by semi-arid and desert landscapes. Australia’s geographic isolation and environmental variety have contributed to its distinctive landforms and exceptionally high levels of endemic biodiversity. Furthermore, its peculiar position in the middle of the Australian plate makes Australian territory one of the least geologically active in the world, with little volcanic and seismic activity.

Physical geography

Overview

Australia is a sovereign state located at in the eponymous continent, within the loosely defined region of Australasia / Oceania in the Southern Hemisphere of the Earth. Officially known as the Commonwealth of Australia, its territory comprises a mainland portion, the island state of Tasmania and another 8,222 islands ranging from minor fringing islets to larger landmasses. This makes Australia the sixth-largest country in the world by land area of jurisdiction, which comprises.
Beyond its continental boundaries, Australia’s sovereign territory extends far into surrounding oceans, with external and remote islands scattered across thousands of kilometres of ocean in an expanse extending from Antarctica almost to the equator. Some of these, such as Macquarie Island and Lord Howe Island are legally parts of states, but many are included in separate territories such as the Cocos Islands, Heard and McDonald Islands, Norfolk Island, Christmas Island, the Coral Sea Islands and Ashmore and Cartier Islands. Excluding Tasmania, Australian islands cover an area of. Although it has no land borders, Australia shares boundaries with Timor Leste, Papua New Guinea, Indonesia, New Caledonia and New Zealand through its extensive maritime jurisdiction.

Extreme points

The points that are farther north, south, east or west than any other location in continental Australia are as follows:
The landmass stretches approximately from its northernmost point to its southernmost point in Tasmania, and nearly from east to west.

Topography

Unlike other major landmasses, where some landscapes date back only tens of thousands of years, when great ice sheets retreated, the age of landforms in Australia is generally measured in many millions of years. This gives Australia a very distinctive physical geography.
Mainland Australia can be broken into four major landform regions: the Coastal Plains, the Eastern Highlands, the Central Lowlands and the Western Plateau.
Along the eastern seaboard of the mainland are the Coastal Plains; a narrow strip of land along the east continental coastline of Australia from Queensland to Victoria. However, other sources refer to the Coastal Plains as the entire coastline of the mainland, outspreading beyond the east coast. This area is flat and has relatively high rainfall, making it suitable for human settlement and thus the most densely populated area in Australia. Towards the east, the flat land rises to the Great Dividing Range which runs parallel to the east coast from the tip of the Cape York Peninsula in Queensland almost south to the Grampians in Victoria. This separates rivers flowing to the west and north from those flowing to the Pacific. This region, known as the Eastern Highlands, are made up of a series of mountains in the south topped by Mount Kosciuszko and volcanic plugs, ash domes and flow remnants further north. Right at the west of the Highland lies the Central Lowlands, stretching from Australia's largest river basin, the Murray-Darling, through the Great Artesian Basin, extending north to the Gulf of Carpentaria. Further west, the Western Plateau show up as a relatively flat area about less than above sea level with numerous low mountainous ranges such as the MacDonnell and Musgrave Ranges as well as some individual structures, of which the best known is Uluru. This area makes up one third of the country.
Tasmania, the island state, has its own topological distinctions. The Tasmanian central east area, known as the Midlands, is fairly flat by comparison and is predominantly used for agriculture. The most mountainous region is the Central Highlands area, which covers most of the central west parts of the state. Tasmanian mountain ranges has a 'rounded smoothness', similar to that of mainland.
The Commonwealth of Australia is located in the lowest continent in the world with an average elevation of only ; around 86.77% of the country's surface does not exceed an altitude of. Mainland Australia's highest point is Mount Kosciuszko, located within the Australian Alps, while the highest point on Australian sovereign territory is Mawson Peak on Heard Island, which is high and forms the summit of an active volcano called Big Ben.

Regions

The Australian continental landmass consists of six distinct landform divisions.
These are:
  • The Eastern Highlands—including the Great Dividing Range, the fertile Brigalow Belt strip of grassland behind the east coast, and the Eastern Uplands
  • The Eastern alluvial Plains and Lowlands—the Murray Darling basin covers the southern part; also includes parts of the Lake Eyre basin and extends to the Gulf of Carpentaria
  • The South Australian Highlands—including the Flinders Range, Eyre Peninsula, and Yorke Peninsula
  • The Western Plateau—including the Nullarbor Plain
  • The Central Deserts
  • Northern Plateau and Basins—including the Top End

    Geology

Australia is located on the lowest, flattest, and oldest continental landmass on Earth. Most of the country's topography is a result of prolonged erosion by wind and water, and its shape is the product of tectonic Earth movements and long-term changes in sea level. These geological forces such as the tectonic uplift of mountain ranges and clashes between tectonic plates occurred mainly in its early prehistory, when it was still a part of Gondwana. The breakup of Gondwana began around 165 million years ago, though the separation of the Australian plate was a slow process. In fact, Australian plate, along with Antarctica, was one of the last major continental plates of Gondwana to separate, doing so about 45 million years ago. During the Pleistocene, Australia was part of Sahul, a paleocontinent that included the landmasses of Australia and New Guinea, as well as the land bridges that once connected them.
Australia’s onshore geology is divided into five principal provinces: Archaean to Paleoproterozoic cratons, Palaeo to Mesoproterozoic orogenic belts, Meso to Neoproterozoic sedimentary basins, Paleozoic rocks of the Tasman Foldbelt, and Mesozoic rocks of the Great Artesian Basin. The country contains some of the oldest geological features in the world, with the oldest known rocks dating from more than 3000 million years ago and rare zircon crystals dating back 4400 million years. Other regions, however, are geologically much younger, shaped by volcanic activity that continued until only a few thousand years ago. Geomorphologist Charles Rowland Twidale has estimated that between 10% and 20% of Australia’s present-day landscapes developed during the Mesozoic Era, when the continent was part of Gondwana.
Most of Australia lies near the centre of the continent’s namesake tectonic plate, making it one of the most geologically stable landmasses on Earth. Although the country contains the Newer Volcanics Province—a volcanic field in the southeast that has been dormant for about 5,000 years—significant volcanic activity is rare. The only currently active volcanoes under Australian jurisdiction are found about southwest of Perth, on Heard Island and the nearby McDonald Islands. Earthquakes occur regularly, though most are minor and cause no damage; major events exceeding magnitude 6 typically happen about once every five years.

Hydrology

As being situated in the driest inhabited continent, Australia has few large, fast-flowing rivers or permanent lakes. Many rivers experience highly irregular flow patterns, with prolonged periods of low discharge followed by occasional years of flooding. About half of Australia’s rivers drain inland, often terminating in ephemeral salt lakes. As an example, the Lake Eyre, the largest one in Australia with an area of up when it is full, usually contains little or no water as its catchment is entirely within the arid zones. The country’s natural freshwater lakes occur mainly along the coast as lakes or lagoons, while inland water bodies are typically wetlands or saline lakes located in the arid interior. Glacial lakes and volcanic crater lakes are found primarily in Tasmania In a worldwide comparison of height, Australia’s waterfalls are modest in size, with the highest ranked only 135th by total drop according to the World Waterfall Database. The nation also contains about 758 estuaries, most of which are located in tropical and subtropical regions.
Australia's rainfall regime is highly variable, with low mean annual rainfall over most of the continent and heavy seasonal falls in the tropics, concentric around the continent's extensive arid core. The effects of this varied rainfall pattern and Australia's drainage system can result in parts of the continent being in drought, but inundated by water from rainfall thousands of kilometres away. Rainfall generally increases towards the coast as proximity to both moisture sources and reliable rain-producing weather systems improves. Elevation also has an important influence on rainfall, with the mountain areas of northeastern Queensland, southeastern Australia and western Tasmania receiving higher rainfall totals. On average, only 9% of Australia's rainfall is converted to surface runoff, and about 2% percolates through the ground to recharge groundwater.
File:Drainage_Divisions_of_Australia.svg|thumb|right|Map of major drainage basins as defined by the Bureau of Meteorology
Continental Australia is divided into drainage divisions, which are subdivided into water regions and then into river basins. The drainage divisions depict where water flows across the continent and identify the major hydrological basins. Due to Australia’s high variation in rainfall and streamflow, large reservoirs have been built to ensure reliable supply; in fact, the national per-person surface-water storage capacity in 2018 was about 3.25 ML, relatively high compared to other countries. Groundwater also plays a significant role as a supply for drinking water, industry, farming and other primary industries in the many regions where it is the only reliable water source. The Great Artesian Basin is one of the largest underground freshwater resources in the world and Australia’s largest groundwater basin. It spans almost which is over one-fifth of the Australian continent.