Island Continental Islands River Islands Volcanic Islands

An island is any piece of land smaller than a continent and larger than a rock, that is completely surrounded by water. Very small islands are called islets. Although seldom adhered to, it is also proper to call an emergent land feature on an atoll an islet, since an atoll is a type of island. A key or cay is also another name for a relatively small island.

There are three main types of islands: continental islands, river islands, and volcanic islands. There are also some artificial islands.

1 Continental islands

Continental islands are bodies of land that are connected by the continental shelf to a continent. That is, these islands are part of an adjacent continent and are located on the continental shelf of that continent. Examples include Greenland and Sable Island off North America, Barbados and Trinidad off South America, Sicily off Europe, SumatraSumatra or Sumatera is the sixth largest island of the world (approximately 470,000 km²) and is part of Indonesia. Geography The longest axis of the island runs approximately northwest southeast, crossing the equator near the center. The interior of the i and JavaJava ( Indonesian: Jawa , area 132,000 square km, has 114 million inhabitants and is the most densely populated island in Indonesia, with 864 people per km². If it were a country it would be the second most densely populated country of the world, except f off AsiaThe continent of Asia is defined by subtracting Europe and Africa from the great land mass of Africa-Eurasia. The boundaries are vague, especially between Asia and Europe: Asia and Africa meet somewhere near the Suez Canal. The boundary between Asia and E, PapuaNew Guinea located just north of Australia, is the world's second largest island having become separated from the Australian mainland when the area now known as the Torres Strait flooded around 5000 BC. The name Papua also refers to the island in whole or and TasmaniaTasmania State flag ( In detail) Coat of Arms ( Full size) Capital Hobart Governor William Cox (Acting Governor) Premier Paul Lennon Area — Land — Marine — Total 68 401 km² 22 357 km² 90 758 km² Population(Sep 2003) Density 478 400 6. 92/km² Time zone UTC off AustraliaAustralia is the sixth-largest country in the world (geographically), the only one to occupy an entire continent, and the largest in the region of Australasia. Australia includes the island of Tasmania, which is an Australian State. Its neighbouring count.

A special type of continental island is the microcontinental island, which results when a continent is riftIn geology, a rift is a place where the Earth's lithosphere is expanding. Typical features are a central linear downdropped fault segment, called a graben, with parallel normal faulting on either side. The central portion of the rift area commonly contained. The best example is MadagascarSee also Madagascar (movie) Madagascar is an island nation in the Indian Ocean, off the eastern coast of Africa. Madagascar is the 4th largest island in the world. It is the home of five percent of the world's plant and animal species, 80 per cent of them off Africa. The Kerguelen Islands and some of the Seychelles are also examples.

Another subtype is the barrier island: accumulations of sand on the continental shelf.

2 River islands

River islands occur in river deltas and in large rivers. They are caused by deposition of sediment at points in the flow where the current loses some of its carrying capacity. In essence, they are river bars, isolated in the stream. While some are ephemeral, and may disappear if the river's water volume or speed changes, others are stable and long-lived.

3 Volcanic islands

Volcanic islands are built by volcanoes. Mid-ocean examples are not geologically part of any continent. One type of volcanic island is found in a volcanic island arc. These islands arise from volcanoes where the subduction of one plate under another is occurring. Examples include the Marianas Islands, the Aleutian Islands, and most of Tonga in the Pacific Ocean. Some of the Lesser Antilles and the South Sandwich Islands are the only Atlantic Ocean examples.

Another type of volcanic island occurs where an oceanic rift reaches the surface. There are two examples: Iceland, which is the world's largest volcanic island, and Jan Mayen—both are in the Atlantic.

The last type of volcanic island are those formed over volcanic hot spots. A hot spot is more or less stationary relative to the moving tectonic plate above it, so a chain of islands results as the plate drifts. Over long periods of time, this type of island is eventually eroded down and "drowned" by isostatic adjustment, becoming a seamount. Plate movement across a hot-spot produces a line of islands oriented in the direction of the plate movement. An example is the Hawaiian Islands, from Hawaii to Kure, which then extends beneath the sea surface in a more northerly direction as the Emperor Seamounts. Another chain with similar orientation is the Tuamotu Archipelago; its older, northerly trend is the Line Islands. The southernmost chain is the Austral Islands , with its northerly trending part the atolls in the nation of Tuvalu. Tristan da Cunha is an example of a hotspot volcano in the Atlantic Ocean.

4 See also

Islands Landforms

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