Australia

I

Introduction

Australia, island continent located southeast of Asia and forming, with the nearby island of Tasmania, the Commonwealth of Australia, a self-governing member of the Commonwealth of Nations. The continent is bounded on the north by the Timor Sea, the Arafura Sea, and the Torres Strait; on the east by the Coral Sea and the Tasman Sea; on the south by the Bass Strait and the Indian Ocean; and on the west by the Indian Ocean. The commonwealth extends about 4,000 km (about 2,500 mi) from east to west and about 3,700 km (about 2,300 mi) from north to south. The area of the commonwealth is 7,682,300 sq km (2,966,200 sq mi), and the area of the continent alone is 7,614,500 sq km (2,939,974 sq mi), making Australia the smallest continent in the world, but the sixth largest country. The capital of Australia is Canberra, and the largest city is Sydney; both are located in the southeast.

The Commonwealth of Australia is made up of six states—New South Wales, Queensland, South Australia, Tasmania, Victoria, and Western Australia—and two territories—the Australian Capital Territory and the Northern Territory. The external dependencies of Australia are the Territory of Ashmore and Cartier Islands, the Australian Antarctic Territory, Christmas Island, the Territory of Cocos Islands (also called the Keeling Islands), the Coral Sea Islands Territory, the Territory of Heard Island and McDonald Islands, and Norfolk Island.

The first inhabitants of Australia were the Aboriginal people, who migrated to the continent some 50,000 to 60,000 years ago. The continent remained relatively unknown to most of the outside world until the 17th century. The first permanent European settlement was established in 1788 at Port Jackson, in southeastern Australia, as a British penal colony; it grew into the city of Sydney. Australia developed as a group of British colonies during the 19th century, and in 1901 the colonies federated to form a unified independent nation, the Commonwealth of Australia.

II

Land and Resources

Australia lacks mountains of great height; it is one of the world’s flattest landmasses. The average elevation is about 300 m (about 1,000 ft). The interior, referred to as the outback, is predominantly a series of great plains, or low plateaus, which are generally higher in the northeast. Low-lying coastal plains, averaging about 65 km (about 40 mi) in width, fringe the continent. In the east, southeast, and southwest, these plains are the most densely populated areas of Australia.

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In the east the coastal plains are separated from the vast interior plains by the Great Dividing Range, or Eastern Highlands. This mountainous region averages about 1,200 m (about 4,000 ft) in height and stretches along the eastern coast from Cape York in the north to Victoria in the southeast. Much of the region consists of high plateaus broken by gorges and canyons. Subdivisions of the range bear many local names, including, from north to south, the New England Plateau, Blue Mountains, and Australian Alps; in Victoria, where the range extends westward, it is known as the Grampian Mountains, or by its Aboriginal name, Gariwerd. The highest peak in the Australian Alps, and the highest in Australia, is Mount Kosciuszko (2,228 m/7,310 ft), in New South Wales.

A section of the Great Dividing Range is in Tasmania, which is located about 240 km (about 150 mi) from the southeastern tip of the continent and is separated from it by Bass Strait. The waters of the strait are shallow, with an average depth of 70 m (230 ft). The major islands in the strait are the Furneaux Group and Kent Group in the east, and King, Hunter, Three Hummock, and Robbins islands in the west.

The western half of the continent is an enormous plateau, about 300 to 450 m (about 1,000 to 1,500 ft) above sea level. The Great Western Plateau includes the Great Sandy, Great Victoria, and Gibson deserts. Western Australia has, in its northern half, several isolated mountain ranges, including the King Leopold and Hamersley ranges. The interior is relatively flat except for several eroded mountain chains, such as the Stuart Range and the Musgrave Ranges in the northern part of South Australia and the Macdonnell Ranges in the southern part of the Northern Territory.

The central basin, or the Central-Eastern Lowlands, is an area of vast, rolling plains that extends west from the Great Dividing Range to the Great Western Plateau. In this region lies the richest pastoral and agricultural land in Australia. Uluru (Ayers Rock), in the center of Australia in Uluru-Kata Tjuta National Park, is one of the largest monoliths in the world. It is 9 km (6 mi) around its base and rises sharply to some 348 m (1,142 ft) above the surrounding flat, arid land. Other mountain ranges of limited size in the central part of Australia are the Flinders Ranges and Mount Lofty Ranges in South Australia. The area along the south central coast is called the Nullarbor Plain. The Nullarbor is a vast, arid, limestone plateau that is virtually uninhabited. It has an extensive system of caverns, tunnels, and sinkholes that contain valuable geological information about life in ancient Australia. Extinct volcanic craters are located in the southeastern part of South Australia and in Victoria.

The coastline of Australia measures some 25,760 km (16,007 mi). It is generally regular, with few bays or capes. The largest inlets are the Gulf of Carpentaria in the north and the Great Australian Bight in the south. The several fine harbors include those of Sydney, Hobart, Port Lincoln, and Albany.

The Great Barrier Reef is the largest known coral formation in the world. It extends some 2,010 km (some 1,250 mi) along the eastern coast of Queensland from Cape York in the north to Bundaberg in the south. The chain of reefs forms a natural breakwater along the coast for vessels of modest size but is sometimes hazardous for larger ships.

A

Geology

Australia was once part of the enormous landmass Gondwanaland, which earlier formed part of the supercontinent Pangaea. Much of its geological history is remarkably ancient; the oldest known rock formations date from 3 billion to 4.3 billion years ago.

The great plateau of western Australia is underlain by a vast, stable shield of Precambrian metamorphic and igneous rocks, ranging in age from 570 million to 3 billion years old. These form the core of the ancestral continent, which, with Antarctica, had split off from Gondwanaland during the Jurassic Period, less than 200 million years ago, and had begun drifting eastward (see Plate Tectonics). Australia began to assume its modern configuration by the Eocene Epoch, some 50 million years ago, when Antarctica broke away and drifted southward.

The thick sedimentary rocks of the Great Dividing Range were deposited in a long, broad north-south depression, or geosyncline, during an interval that spanned most of the Paleozoic Era (570 million to 225 million years ago). Compressive forces buckled these rocks at least twice during the era, forming mountain ranges and chains of volcanoes. However, the volcanoes have long since become extinct, and as a result the mountain ranges are extremely eroded.

B

Rivers

The Great Dividing Range separates rivers that flow east to the coast from those that flow westerly across the plains through the interior. The most important of the rivers that flow toward the eastern coast are the Burdekin, Fitzroy, Hunter, and Nepean-Hawkesbury. The Fitzroy River forms a large drainage basin in Queensland. The Murray-Darling-Murrumbidgee network, which flows inland from the Great Dividing Range, drains an area of more than 1 million sq km (400,000 sq mi) in Queensland, New South Wales, Victoria, and South Australia. The Murray River and its main tributary, the Darling, total about 5,300 km (about 3,300 mi) in length. The Murray River itself forms most of the border between New South Wales and Victoria. Considerable lengths of the Murray, Darling, and Murrumbidgee rivers are navigable during the wet seasons.

The central plains region, also known as the Channel Country, is interlaced by a network of rivers. During the rainy season these rivers flood the low-lying countryside, but in dry months they become merely a series of water holes. The Victoria, Daly, and Roper rivers drain a section of the Northern Territory. In Queensland the main rivers flowing north to the Gulf of Carpentaria are the Mitchell, Flinders, Gilbert, and Leichhardt. Western Australia has few major rivers. The most important are the Fitzroy (different from the Fitzroy in Queensland), Ashburton, Gascoyne, Murchison, and Swan rivers.

Because of Australia’s scarce water resources, dams have been constructed on some rivers to supply cities with water and to support irrigation farming. The Snowy Mountains Scheme (1949-1972) and the Ord River Scheme (1960-1972) are the two largest water-conservation projects. The Snowy Mountains Scheme, in the southeastern highlands in New South Wales, is an enormous, multipurpose engineering project that was financed by the federal and state governments to supply water for irrigation, domestic and livestock use, and for the generation of hydroelectricity. The Ord River Scheme is an irrigation project in the remote Kimberley region of Western Australia. During its construction the scheme attracted criticism from economists, ecologists, environmentalists, and agricultural scientists. Today the long-term environmental and economic viability of the scheme remains in question, while only a small fraction of the arable land that could receive irrigation water is being cultivated due to destructive crop pests and poor soil quality.

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