ISLANDS

islands

The islands are ground extents  surrounded by water  of any share.

One finds islands not far from the continental coasts, or on the contrary in the beautiful medium of the seas and the oceans. Some  are insulated, others are joined together in  a group of other islands  (it is what one calls  an archipelago).

Certain islands is of volcanic  origin  (they were created by volcanic eruptions), others of coral  origin  (they are formed by coral reefs), as it is the case of  the atolls. Some are due to the erosion of marine rocks. Others, like Madagascar or Corsica, originate in the movements of the continental plates (plate tectonics): in fact pieces of the earth's crust are separate continents. Lastly, certain islands are the result of  a rise in the sea level: only the reliefs emergent and are isolated in the mediums from water.

Isolated from the continents, the islands often shelter many animal and vegetable species "original", that one does not find nowhere elsewhere in the world (one speaks about endemic species). In Madagascar for example, 85 % of the plants and 90 % of the animals are endemic.

TO GO FURTHER 

? seas and oceans

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