A continent is one of several large areas of land on Earth, which are identified by convention rather than any strict criteria. The specific areas of land vary, but seven areas are commonly reckoned as continents - they are, in order of size, Asia, Africa, North America, South America, Antarctica, Europe and Australia.
Plate tectonics is the geological theory and study of the movement, collision and division of continents, earlier known as continental drift.
The term "the Continent" (capitalized), used predominantly in the British Isles, means Continental Europe, that is, mainland Europe.
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[edit] Definitions and application
"Continents are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water."[1] However many of the seven most commonly recognized continents are identified by convention rather than adherence to the ideal criterion that each be a discrete landmass, separated by water from others. Likewise the criterion that each be a continuous landmass is often disregarded by the inclusion of the continental shelf and oceanic islands.
[edit] Extent of continents
The narrowest meaning of continent is that of a continuous[2] area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term continental Europe is used to refer to mainland Europe, excluding islands such as the British Isles, and the term continent of Australia may refer to the mainland of Australia, excluding Tasmania.
From the perspective of geology or physical geography, continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the continental shelf)[3] and the islands on the shelf (continental islands), as they are structurally part of the continent.[4] From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level.[5] In this sense the British Isles are part of Europe, and Australia and the island of New Guinea together form a continent (Australia-New Guinea).
As a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland may be considered part of Europe and Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers take Australia and all the islands of Oceania (or sometimes Australasia) to be equivalent to a continent, allowing the entire land surface of the Earth to be divided into continents or quasi continents.[6]
[edit] Separation of continents
The ideal criterion that each continent be a discrete landmass is commonly disregarded in favor of more arbitrary, historical conventions. Of the seven most commonly recognized continents, only Antarctica and Australia are separated from other continents.
Several continents are defined not as absolutely distinct bodies but as "more or less discrete masses of land."[7] Asia and Africa are joined by the Isthmus of Suez, and North America and South America by the Isthmus of Panama. Both these isthmuses are very narrow in comparison with the bulk of the landmasses they join.
The division of the landmass of Eurasia into the separate continents of Asia and Europe is an anomaly with no basis in physical geography. The separation is maintained for historical and cultural reasons. An alternative view is that Eurasia is a single continent, one of six continents in total. This view is held by some geographers and is preferred in Russia (which spans Asia and Europe) and Eastern Europe.
North America and South America are now treated as separate continents in much of Western Europe, China, and most native English-speaking countries. However in earlier times they were viewed as a single continent known as America or, to avoid ambiguity with the United States of America, as the Americas. They are still viewed as a single continent, one of six in total, in Latin America, Iberia, Italy and some other parts of Europe.
