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澳大利亚英文介绍
Australia: An introduction
In land area, Australia is the sixth largest nation after Russia, Canada, China, the United States of America and Brazil. It has, however, a relatively small population.
Australia is the only nation to govern an entire continent and its outlying islands. The mainland is the largest island and the smallest, flattest continent on Earth. It lies between 10° and 39° South latitude.
The highest point on the mainland, Mount Kosciuszko, is only 2228 metres. Apart from Antarctica, Australia is the driest continent.
Australia is the driest inhabited continent on earth. Its interior has one of the lowest rainfalls in the world and about three-quarters of the land is arid or semi-arid. Its fertile areas are well-watered, however, and these are used very effectively to help feed the world. Sheep and cattle graze in dry country, but care must be taken with the soil. Some grazing land became desert when the long cycles that influence rainfall in Australia turned to drought.
The Australian federation consists of six States and two Territories. Most inland borders follow lines of longitude and latitude. The largest State, Western Australia, is about the same size as Western Europe.
Natural environment
Australia has a remarkable diversity of life forms seen nowhere else in the world. Australian plants and animals evolved in isolation from other parts of the world. When the super-continent of Gondwanaland split up about 160 million years ago, Australia joined Antarctica and drifted towards the South Pole, where glaciers formed a barrier between it and other land masses.
Over the past 45 million years, Australia has moved away from Antarctica towards the equator and become warmer and more arid. About 35 million years ago, eucalypts began to displace the dense forests of the cool, damp Tertiary era.
Today Australian eucalypts account for more than half of all eucalypts found throughout the world.
The marsupials native to Australia have a different chromosome structure than mammals in other parts of the world. Typically, they suckle their young in a pouch.
Like the eucalypts, marsupials occupied a wide range of ecological niches in Australia. The first kangaroo marsupials seem to have appeared about 15 million years ago. They vary enormously in size and adaptation. A species of tropical kangaroo lives in trees, but most kangaroos are tough, efficient users of dry bush.
As the world climate warmed and glaciers melted, oceans gradually rose to their current level and the land bridges to New Guinea and Tasmania were cut. Corals colonised a flooded coastal plain, forming the Great Barrier Reef of Queensland.
Ancient plants still grow in the wild. Large ’Antarctic’ tree ferns are common in damp, shaded gullies on the south sides of ridges. Cycad palms form an understorey to tall, silvery spotted gums (eucalypts) along the south-east coast. Rare relics from earlier geological eras are found in small, special habitats, such as desert canyons.
Pressure on native habitats from agriculture and introduced pests like the fox and rabbit have resulted in extinctions of some native species in the past 200 years. Australia now has a strong scientific and legal framework to deal with these issues. Australians care about their unique environment.
History
More than 60 000 years before the arrival of European settlers, Aboriginal and Torres Strait Isl
