An island or isle is any piece of sub-continental land that is
surrounded by water. Very small islands such as emergent land
features on atolls can be called islets, skerries, cays or keys. An
island in a river or a lake island may be called an eyot or ait, and a
small island off the coast may be called a holm. A grouping of
geographically or geologically related islands is called an
archipelago, such as the Philippines, for example.
An island may be described as such, despite the presence of an
artificial land bridge; examples are
Singapore and its causeway, and
the various Dutch delta islands, such as IJsselmonde. Some places may
even retain "island" in their names for historical reasons after being
connected to a larger landmass by a land bridge or landfill, such as
Coney Island and Coronado Island, though these are, strictly speaking,
tied islands. Conversely, when a piece of land is separated from the
mainland by a man-made canal, for example the
Peloponnese by the
Corinth Canal or Marble Hill in northern
Manhattan during the time
between the building of the
United States Ship Canal
United States Ship Canal and the
filling-in of the
Harlem River which surrounded the area, it is
generally not considered an island.
There are two main types of islands in the sea: continental and
oceanic. There are also artificial islands.
2 Difference between islands and continents
3 Types of islands
3.1 Continental islands
3.2 Oceanic islands
3.3 Tropical islands
4 Artificial islands
6 See also
8 External links
The word island derives from
Middle English iland, from Old English
igland (from ig or ieg, similarly meaning 'island' when used
-land carrying its contemporary meaning; cf. Dutch
eiland ("island"), German Eiland ("small island")). However, the
spelling of the word was modified in the 15th century because of a
false etymology caused by an incorrect association with the
etymologically unrelated Old French loanword isle, which itself comes
from the Latin word insula.
Old English ieg is actually a cognate
of Swedish ö and German Aue, and related to Latin aqua (water).
Difference between islands and continents
Greenland is the world's largest island, with an area of over 2.1
million km2, while Australia, the world's smallest continent, has an
area of 7.6 million km2, but there is no standard of size which
distinguishes islands from continents, or from islets. There is
a difference between islands and continents in terms of geology.
Continents sit on continental lithosphere which is part of tectonic
plates floating high on Earth's mantle.
Oceanic crust is also part of
tectonic plates, but it is denser than continental lithosphere, so it
floats low on the mantle. Islands are either extensions of the oceanic
crust (e.g. volcanic islands) or geologically they are part of some
continent sitting on continental lithosphere (e.g. Greenland). This
holds true for Australia, which sits on its own continental
lithosphere and tectonic plate.
Types of islands
Continental islands are bodies of land that lie on the continental
shelf of a continent. Examples are Borneo, Java, Sumatra, Sakhalin,
Hainan off Asia; New Guinea, Tasmania, and Kangaroo Island
off Australia; Great Britain, Ireland, and
Sicily off Europe;
Greenland, Newfoundland, Long Island, and
Sable Island off North
America; and Barbados, the Falkland Islands, and
Trinidad off South
A special type of continental island is the microcontinental island,
which is created when a continent is rifted. Examples are Madagascar
Socotra off Africa, the Kerguelen Islands, New Caledonia, New
Zealand, and some of the Seychelles.
Another subtype is an island or bar formed by deposition of tiny rocks
where water current loses some of its carrying capacity. This
barrier islands, which are accumulations of sand deposited by sea
currents on the continental shelves
fluvial or alluvial islands formed in river deltas or midstream within
large rivers. While some are transitory and may disappear if the
volume or speed of the current changes, others are stable and
Islets are very small islands.
Main article: High island
Oceanic islands are islands that do not sit on continental shelves.
The vast majority are volcanic in origin, such as
Saint Helena in the
South Atlantic Ocean. The few oceanic islands that are not volcanic
are tectonic in origin and arise where plate movements have lifted up
the ocean floor above the surface. Examples are Saint Peter and Paul
Rocks in the Atlantic Ocean and
Macquarie Island in the Pacific.
One type of volcanic oceanic island is found in a volcanic island arc.
These islands arise from volcanoes where the subduction of one plate
under another is occurring. Examples are the Aleutian Islands, the
Mariana Islands, and most of
Tonga in the Pacific Ocean. The only
examples in the Atlantic Ocean are some of the
Lesser Antilles and the
South Sandwich Islands.
Another type of volcanic oceanic island occurs where an oceanic rift
reaches the surface. There are two examples: Iceland, which is the
world's second largest volcanic island, and Jan Mayen. Both are in the
A third type of volcanic oceanic island is formed over volcanic
hotspots. A hotspot 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
"drowned" by isostatic adjustment and eroded, 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
Hawaii to Kure, which continue 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
Tristan da Cunha is an example of a hotspot volcano
in the Atlantic Ocean. Another hotspot in the Atlantic is the island
of Surtsey, which was formed in 1963.
An atoll is an island formed from a coral reef that has grown on an
eroded and submerged volcanic island. The reef rises to the surface of
the water and forms a new island. Atolls are typically ring-shaped
with a central lagoon. Examples are the
Line Islands in the Pacific
Maldives in the Indian Ocean.
See also: Formation of coral reefs
Approximately 45,000 tropical islands with an area of at least 5
hectares (12 acres) exist. Examples formed from coral reefs include
Maldives, Tonga, Samoa, Nauru, and Polynesia.
Seychelles and Tioman and volcanic islands such as Saint
The socio-economic diversity of tropical islands ranges from the Stone
Age societies in the interior of Madagascar, Borneo, and Papua New
Guinea to the high-tech lifestyles of the city-islands of Singapore
and Hong Kong.
International tourism is a significant factor in the economy of many
tropical islands including Seychelles, Sri Lanka, Mauritius, Réunion,
Hawaii, and the Maldives.
Main article: Artificial island
Almost all of the Earth's islands are natural and have been formed by
tectonic forces or volcanic eruptions. However, artificial (man-made)
islands also exist, such as the island in
Osaka Bay off the Japanese
island of Honshu, on which
Kansai International Airport
Kansai International Airport is located.
Artificial islands can be built using natural materials (e.g., earth,
rock, or sand) or artificial ones (e.g., concrete slabs or recycled
waste). Sometimes natural islands are artificially enlarged,
Vasilyevsky Island in the Russian city of St. Petersburg,
which had its western shore extended westward by some 0.5 km in
the construction of the Passenger Port of St. Petersburg.
Artificial islands are sometimes built on pre-existing "low-tide
elevation," a naturally formed area of land which is surrounded by and
above water at low tide but submerged at high tide. Legally these are
not islands and have no territorial sea of their own.
Largest island: Greenland
Largest island in a lake: Manitoulin Island
Largest island in a river: Bananal Island
Largest island in fresh water: Marajó
Largest uninhabited island: Devon Island
Most populous island: Java, Indonesia
Lowest island: Franchetti island in Lake Afrera, Ethiopia
Island shared by largest number of countries:
Island with the highest point:
New Guinea (Puncak Jaya, 4884 m),
Northernmost island: Kaffeklubben Island
Southernmost island (not fully surrounded by permanent ice): Ross
Island with the most populated city:
Honshu (Tokyo), Japan
Most remote island (from nearest land): Bouvet Island
Island with earliest known settlement:
Sumatra (Lida Ajer cave),
List of ancient islands
List of archipelagos
List of artificial islands
List of divided islands
List of fictional islands
List of island countries
List of islands by area
List of islands by body of water
List of islands by continent
List of islands by country
List of islands by highest point
List of islands by name
List of islands by population
List of islands by population
List of islands by population density
List of islands named after people
Island Developing States
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^ "Webster's Dictionary-Island". Archived from the original on October
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^ Lomolino, Mark V. (editor); (et al.) (2004) Foundations of
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^ Arnberger, Hertha, Erik (2011). The Tropical Islands of the Indian
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^ "Building Artificial Islands That Rise With the Sea". Archived from
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^ "What Makes an Island? Land Reclamation and the South China Sea
Asia Maritime Transparency Initiative". July 15, 2015.
Archived from the original on May 27, 2016. Retrieved June 28,
^ "Conception of development of the artificial lands of Vasilievsky
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United Nations Convention on the Law of the Sea, Article 13.
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