An island or isle is a piece of subcontinental land completely 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. Sedimentary islands in the Ganges Delta are called chars. A grouping of geographically or geologically related islands, such as the Philippines, is referred to as an archipelago.
The word island derives from Middle English iland, from Old English igland (from ig or ieg, similarly meaning 'island' when used independently, and -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).
There is a widely accepted difference between islands and continents in terms of geology. Continents are often considered to be the largest landmass of a particular continental plate; this holds true for Australia, which sits on its own continental lithosphere and tectonic plate (the Australian Plate).
By contrast, islands are usually seen as being extensions of the oceanic crust (e.g. volcanic islands), or as belonging to a continental plate containing a larger landmass (continental islands); the latter is the case of Greenland, which sits on the North American Plate.
Continental islands are bodies of land that lie on the continental shelf of a continent. Examples are Borneo, Java, Sumatra, Sakhalin, Taiwan and 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 America.
A special type of continental island is the microcontinental island, which is created when a continent is horizontally displaced or rifted Examples are Madagascar and Socotra off Africa, New Caledonia, New Zealand, and some of the Seychelles.
A lake such as Wollaston Lake drains in two different directions, thus creating an island. If this island has a seashore as well as being encircled by two river systems, it becomes what might be called a subcontinental island. The one formed by Wollaston Lake is very large, about 2,000,000 km2 (770,000 sq mi).
Oceanic islands are typically considered to be islands that do not sit on continental shelves. Other definitions limit the term to only refer to islands with no past geological connections to a continental landmass. 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 the Saint Peter and Saint Paul Archipelago in the North Atlantic Ocean and Macquarie Island in the South Pacific Ocean.
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 islands are in the Atlantic Ocean.
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 Islands, from 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 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 Ocean and Maldives in the Indian Ocean.
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. Granite islands include Seychelles and Tioman.
The socio-economic diversity of tropical islands ranges from the Stone Age societies in the interior of North Sentinel, 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, Puerto Rico and the Maldives.
The process of de-islandisation is often concerning bridging, but there are other forms of linkages such as causeways: fixed transport links across narrow necks of water, some of which are only operative at low tides (e.g. that connecting Cornwall's St Michael's Mount to the peninsular mainland) while others (such as the Canso Causeway connecting Cape Breton to the Nova Scotia mainland), are usable all-year-round (aside from interruptions during storm surge periods).
Some places may 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, more or less the entirety of Fennoscandia by the White Sea Canal, or Marble Hill in northern Manhattan during the time between the building of the United States Ship Canal and the filling-in of the Harlem River which surrounded the area, it is generally not considered an island.
Almost all of 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 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, such as 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.
Plan activities for your Mackinac Island getaway. You can hike the trails, paddle a kayak or ride a bike all the way around the island. Take a ferry under the mighty Mackinac Bridge, enjoy world-famous fudge or relax in a horse-drawn carriage. Opportunity awaits!
St Marys is the gateway to Cumberland Island, Georgia's largest and southernmost barrier island. Here pristine maritime forests, undeveloped beaches and wide marshes whisper the stories of both man and nature. Natives, missionaries, enslaved African Americans and Wealthy Industrialists all walked here. Cumberland Island is also home to over 9,800 acres of Congressionally designated Wilderness.
Angel Island State Park, the largest natural island in the San Francisco Bay, offers some of the best views of the surrounding Bay Area. With great hiking trails and many other recreational opportunities readily available, Angel Island is truly a hidden gem in the midst of the urban Bay Area.
Desert IslandsSo-called "desert islands" rarely have a hot, arid desert climate. Desert islands have nothing to do with desertsthey're just deserted. They have no human inhabitants.
Ellis IslandThe tiny islet in New York Bay was expanded by artificial means in the 19th century. Wells were dug and landfill was hauled in to create a new island. This land was excavated from New York's new subway tunnels.
Moa, PleaseIsolated islands can be home to unusualand vulnerablespecies. When Polynesians called Maori first came to the islands that are now New Zealand, they were met by unusual species: huge birds called moas. Moas weighed up to 230 kilograms (500 pounds) and could reach 4 meters (13 feet) in length. Scientists think moas did not walk upright, so we dont know how tall they stood. There were no small mammals to hunt the moas; their only predator was the huge Haasts eagle.People arrived in New Zealand about 1300. These Maori settlers cleared forests and hunted the large, slow-moving moa. By 1400, moas and Haasts eagles were extinct. 041b061a72