User:Nurg/Australia (continent)

The mainland or continent of Australia is the smallest of the seven commonly-recognized, contiguous continents of the world. It forms the vast majority of the country of Australia, with the island of Tasmania and other, small islands making up the rest of the country. The mainland itself is also called Australia. Administratively, the mainland is divided into five states and two territories, with Tasmania forming the small, sixth state of the country.

Its continental shelf extends under Bass Strait which separates it from Tasmania, and under the Arafura Sea and Torres Strait which separate it from the island of New Guinea. If the edge of the continental shelf is taken to be the boundary of the continent, the Australian mainland forms part of a larger continent known by various names such as Australia-New Guinea, Sahul and Meganesia.

Terminology
The term "continent of Australia" has various meanings because of different meanings of the word "continent" and different applications of the name "Australia". The narrowest meaning of "continent", used by leading English dictionaries and encyclopedias, is that of a continuous area of land or mainland. By this definition, "continent of Australia" refers solely to the mainland of Australia. The Columbia Encyclopedia, for example, is clear in its entry for "Australia" that Tasmania is not part of the continent: "Australia, smallest continent .... With the island state of Tasmania to the south, the continent makes up the Commonwealth of Australia .... There are five continental states in the nation (Queensland, New South Wales, Victoria, South Australia, and Western Australia) ...". This definition is the one primarily used in this article.

The term "continent of Australia" is also used, less rigorously, to refer to the mainland plus the island of Tasmania, since Tasmania makes up only a small percentage of the total land area of the country of Australia. This usage is a synecdoche in which a word for a part (the continent or mainland) is used for the whole (the country). From the point of view of physical geography or geology though, it makes no sense to include Tasmania as part of the continent but to exclude New Guinea, as New Guinea is also on the same continental shelf and is separated from the Australian mainland by a shallower and narrower strait than Tasmania.

In physical geography or geology, "continent" may be extended beyond the confines of continuous land to include the shallow, submerged adjacent area (the continental shelf) and the islands on the shelf (continental islands), as they are structurally part of the continent. From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. In this sense, the Australian mainland, New Guinea, Tasmania, and intervening islands such as the Aru Islands together form a continent. As these lands are on the continental shelf of the contiguous continent of Australia, they are sometimes considered part of the "continent of Australia", similar to the way that the British Isles are regarded as part of Europe and Japan as part of Asia. However, scientific literature usually refers to this extended continent as Australia-New Guinea, Sahul, Meganesia or Greater Australia. For further information see Australia-New Guinea.

The concept of a continent may go beyond the continental shelf to include continental fragments and oceanic islands. In this way New Zealand is sometimes associated with its nearest continent, Australia or Australia-New Guinea. However, this wider region of Australia, New Guinea and New Zealand is usually known as Australasia. Some geographers, wishing to divide the entire land surface of the Earth into continents or quasi continents, take Australia and all the islands of Oceania to be equivalent to a continent. This quasi continent though is usually referred to as "Oceania" or "Australia-Oceania".

Geography
The mainland of Australia is the smallest and lowest-lying of the Earth's continents, having a total land area of about 7,600,000 square kilometres, roughly the same size as the 48 contiguous states of the United States. As it is easily circumnavigated by sea, it is sometimes known as the "island continent". The distinction between an island and a continent is somewhat arbitrary and Australia has not always been recognised as a continent, but it is significantly larger than Greenland, the largest commonly-recognised island — see also List of islands by area.

The continent sits on the Australian Plate which is very much larger as it includes big areas of oceanic crust and other areas of continental crust. The continent was joined with Antarctica as part of the southern supercontinent Gondwana until the plate began to drift north about 96 million years ago (mya). When sea levels were lower during the Pleistocene ice age, including the last glacial maximum about 18,000 years ago, the Australian mainland was joined to Tasmania and New Guinea.

The mainland has been inhabited for more than 42,000 years by Indigenous Australians. It was also visited by fishermen from the north and, starting in the seventeenth century, by European explorers and merchants. It was named New Holland by the Dutch seafarer Abel Tasman in 1644 and was called by this name for over 150 years. Between December 1801 and June 1803, Royal Navy captain Matthew Flinders circumnavigated the continent, having previously circumnavigated Tasmania.