( ) or isle
( ) is any
piece of land that is surrounded by water. Very small islands such
as emergent land features on atolls
. A key
or cay is another
name for a small island or islet.
An island in a river or
lake may be called an eyot
, .There are two main
types of islands: continental islands
. There are also artificial islands
. A grouping of
geographically and/or geologically related islands is called an
The word island
comes from Old
(from 'ig', similarly meaning 'island'
when used independently, and -land carrying its contemporary
meaning). However, the spelling of the word was modified in the
15th century by association with the etymologically
unrelated Old French loanword
, which itself comes from the latin word
There is no standard of size which distinguishes islands from
When defining islands as pieces of land that are surrounded by
water, narrow bodies of water like rivers
are often, but not always, left out of
consideration . For instance, in France the Canal du Midi connects the Garonne river to the
Sea, thereby completing a continuous water connection
from the Atlantic
Ocean to the Mediterranean Sea. So technically, the
land mass that includes the Iberian Peninsula and the part of France that is south of the Garonne
River and the Canal du Midi is surrounded by water.
completely natural example, the Orinoco
River splits into two branches near Tamatama, in Amazonas state,
Venezuela. The southern branch flows south and joins the Rio Negro,
and then the Amazon. Thus, all of the Guianas (Guyana, Suriname,
and French Guiana) and substantial parts of Brazil and Venezuela
are surrounded by (river or ocean) water. These instances are not
generally considered islands. However, small pieces of land
bordered by rivers are considered islands.
helps explain why Africa-Eurasia can be seen as one continuous
landmass (and thus technically the biggest island): generally the
Canal is not seen as something that divides the land mass
The mainland of Australia is often considered the
largest island because it is covered on all sides by water while
not being connected to another body of land.
other hand, an island may still be described as such despite the
presence of a land bridge, e.g., Singapore and its causeway or the various Dutch delta
Islands, such as IJsselmonde. Some places may even retain "island" in their
names after being connected to a larger landmass by a wide land
bridge, such as Coney
The retaining of the island description may
therefore be to some degree simply due to historical reasons -
though the land bridges are often of a different geological nature
(for example sand instead of stone), and thus the islands remain
islands in a more scientific sense as well.
Types of Island
Continental islands are bodies of land that lie on the continental shelf
of a continent.
include Greenland and Sable
Island off North America;
Barbados and Trinidad off South America;
Britain, Ireland and Sicily off Europe; Sumatra, Borneo and Java off Asia; and New Guinea, Tasmania and Kangaroo Island off Australia.
A special type of continental island is the
, which results when a
continent is rifted
. Examples are Madagascar and Socotra off Africa; New
Zealand; the Kerguelen Islands; and some of the Seychelles.
Another subtype is an island or bar
deposition of tiny rocks where a water current loses some of its
carrying capacity. An example is barrier
, which are accumulations of sand
deposited by sea currents on the continental shelf. Another example
is islands in river deltas
or in large
rivers. While some are transitory and may disappear if the volume
or speed of the current changes, others are stable and long-lived.
are very small islands.
Oceanic islands are ones that do not sit on continental shelves.
The vast majority are volcanic
The few oceanic islands that are not volcanic are tectonic in
origin and arise where plate movements have lifted up the deep
ocean floor to above the surface. Examples of this include 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
. These islands arise from volcanoes where the
of one plate under another is
occurring. Examples include the Mariana
Islands, the Aleutian Islands and most of Tonga in the
Some of the Lesser Antilles
and the South Sandwich Islands
are the only
Atlantic Ocean examples.
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 Atlantic.
A third type of volcanic oceanic island is formed over volcanic
. 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
. 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
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.
Cunha is an example of a hotspot volcano in the Atlantic
Ocean. Another hot spot in the Atlantic is the
island of Surtsey, which was formed in 1963.
An atoll is an island formed from a coral
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 include the Maldives in the Indian Ocean and Line
Islands in the Pacific.
There are approximately 45,000 tropical
islands on Earth. Among coral tropic
islands for example are Maldives, Tonga, Nauru and Polynesia.
Granite islands include Seychelles and Tioman.
socio-economic diversity of these regions ranges from the Stone Age societies in the interior of Madagascar, Borneo or Papua New
Guinea to the high-tech lifestyles of the city-islands of
Singapore and Hong
Kong. The international tourism is a significant
factor in the local economy of Seychelles, Sri Lanka, Mauritius, Réunion, Hawaii or Maldives.