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From Wikipedia, the free encyclopedia

An island or isle is a piece of sub-continental 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.

There are two main types of islands in the sea; continental and oceanic. There are also human-made islands.

Etymology

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.[1][2] Old English ieg is actually a cognate of Swedish ö and German Aue, and related to Latin aqua (water).[3]

Relationships with continents

Differentiation from continents

There is no standard of size that distinguishes islands from continents,[4] or from islets.[5]

There is a widely accepted difference between islands and continents in terms of geology.[6] 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).[7]

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.[8]

Continental islands

Continental islands are bodies of land that lie on the continental shelf of a continent.[9] 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.

Micro-continental islands

A special type of continental island is the micro-continental island, which is created when a continent is horizontally displaced or rifted[10][11] Examples are Madagascar and Socotra off Africa, New Caledonia, New Zealand, and some of the Seychelles.[11]

Subcontinental islands

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 km ² (770,000 sq mi).[12]

Bars

Another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. This includes:

Oceanic islands

Tectonic versus volcanic

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.[16] The vast majority are volcanic in origin, such as Saint Helena in the South Atlantic Ocean.[17] 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.

Volcanic islands

Arcs

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.[18][19] The only examples in the Atlantic Ocean are some of the Lesser Antilles and the South Sandwich Islands.

Oceanic Rifts

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.

Hotspots

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.[20] 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.[21] Another hotspot in the Atlantic is the island of Surtsey, which was formed in 1963.[22]

Atolls

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 and the Maldives in the Indian Ocean.[23]

Tropical islands

Approximately 45,000 tropical islands with an area of at least 5 hectares (12 acres) exist.[24] Examples formed from coral reefs include Maldives, Tonga, Samoa, Nauru, and Polynesia.[24] Granite islands include Seychelles[25] 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.[26] 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.

De-islanding

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).[27][28]

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.[28] 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.

Another type of connection is fostered by harbor walls/breakwaters that incorporate offshore islets into their structures, such as those in Sai harbor in northern Honshu, Japan, and the connection to the mainland which transformed Ilhéu do Diego from an islet. De-islanded through its fixed link to the mainland, the former islet's name, Ilhéu do Diego, became functionally redundant (and thereby archaic) and the location took the fort as its namesake. Some former island sites have retained designations as islands after the draining/subsidence of surrounding waters and their fixed linkage to land (England's Isle of Ely and Vancouver's Granville Island being respective cases in point). Their names are thereby archaic in that they reflect the islands' pasts rather than their present structures and/or transport logistics. Other examples include Singapore and its causeway, and the various Dutch delta islands, such as IJsselmonde.

Artificial islands

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).[29][30]

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.[31]

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.[32]

Island superlatives

Largest island in a lake: Manitoulin Island, Ontario, Canada[33]

Largest island in freshwater: Marajó, Pará, Brazil

Lowest island: Franchetti Island, Lake Afrera, Ethiopia

Island shared by largest number of countries: Borneo (Brunei, Indonesia, Malaysia)

Island with the highest point: New Guinea (Puncak Jaya, 4,884 m, 16,024 ft), Indonesia

Northernmost island: Kaffeklubben Island, Greenland

Southernmost island (not fully surrounded by permanent ice): Ross Island, Antarctica

Island with the most populated city: Honshu (Tokyo), Japan

Island with earliest known settlement: Sumatra (Lida Ajer cave), Indonesia

See also

References

1. ^ "Island". Dictionary.com. Archived from the original on March 7, 2007.

2. ^ Wedgwood, Hensleigh (1855). "On False Etymologies". Transactions of the Philological Society (6): 66. Archived from the original on November 6, 2018.

3. ^ Ringe, Donald A. (2006). A Linguistic History of English: From Proto-Indo-European to Proto-Germanic. Oxford University Press. p. 109. ISBN 0-19-928413-X.

4. ^ Brown, Mike (2010). How I Killed Pluto and Why It Had It Coming. New York: Random House Digital. pp. 186-187. ISBN 978-0-385-53108-5. Archived from the original on April 19, 2016.

5. ^ Royle, Stephen A. (2001). A Geography of Islands: Small Island Insularity. Psychology Press. pp. 7-11. ISBN 1-85728-865-3. Archived from the original on September 21, 2015.

6. ^ Scrutton, Roger A. (March 21, 2013), "Microcontinents and their Significance", in Drake, Charles L. (ed.), Geodynamics: Progress and Prospects, Special Publications, Washington, D. C.: American Geophysical Union, pp. 177-189, doi:10.1029/sp005p0177, ISBN 978-1-118-66490-2

7. Broek, J. M.; Gaina, C. (August 2020). "Microcontinents and Continental Fragments Associated With Subduction Systems". Tectonics. 39 (8). Bibcode:2020Tecto..3906063V. doi:10.1029/2020TC006063. ISSN 0278-7407. S2CID 225376789.

8. ^ Hoyt, John H. (September 1, 1967). "Barrier Island Formation". GSA Bulletin. 78 (9): 1125-1136. doi:10.1130/0016-7606(1967)78[1125:bif]2.0.co;2. Archived from the original on January 19, 2022.

9. ^ Davis, Richard A. (1994), Davis, Richard A. (ed.), "Barrier Island Systems - a Geologic Overview", Geology of Holocene Barrier Island Systems, Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 1-46, doi:10.1007/978-3-642-78360-9_1, ISBN 978-3-642-78362-3, archived from the original on August 21, 2022

10. ^ Zug, George R. (2013). Reptiles and Amphibians of the Pacific Islands: A Comprehensive Guide. University of California Press.

11. ^ Carlquist, Sherwin (2004). "The Biota of Long-Distance Dispersal: I. Principles of Dispersal and Evolution". In Lomolino, Mark V.; Sax, Dov F.; Brown, James H. (eds.). Foundations of Biogeography: Classic Papers with Commentaries. University of Chicago Press. p. 316. ISBN 0-226-49236-2. Archived from the original on April 18, 2016.

12. ^ Claudino-Sales, Vanda (2019), "Surtsey, Iceland", Coastal World Heritage Sites, Coastal Research Library, Dordrecht: Springer Netherlands, vol. 28, pp. 237-242, doi:10.1007/978-94-024-1528-5_35, ISBN 978-94-024-1526-1, S2CID 240206292, archived from the original on August 21, 2022

13. Austrian Academy of Sciences (2002). "The Tropical Islands of the Indian and Pacific Oceans". Geographie. Austriaca. doi:10.1553/3-7001-2738-3.

14. ^ Upton, B. G. J. (1982), Nairn, Alan E. M.; Stehli, Francis G. (eds.), "Oceanic Islands", The Ocean Basins and Margins, Boston, MA: Springer US, pp. 585-648, doi:10.1007/978-1-4615-8038-6_13, ISBN 978-1-4615-8040-9, archived from the original on August 21, 2022

15. ^ Arnberger, Hertha, Erik (2011). The Tropical Islands of the Indian and Pacific Oceans. Vienna: Austrian Academy of Sciences Press. ISBN 978-3-7001-2738-3.

16. ^ Baldacchino, Godfrey (2007). Bridging islands : the impact of fixed links. Charlottetown, Prince Edward Island: Acorn Press. ISBN 978-1-894838-24-5. OCLC 70884504.

17. Hayward, Philip (April 28, 2016). "Introduction: Towards an Expanded Concept of Island Studies" (PDF). Shima: The International Journal of Research into Island Cultures. 10 (1). doi:10.21463/shima.10.1.03. Archived (PDF) from the original on February 4, 2022.

18. ^ Mirasola, Christopher (July 15, 2015). "What Makes an Island? Land Reclamation and the South China Sea Arbitration". Asia Maritime Transparency Initiative. Archived from the original on May 27, 2016.

19. ^ "Fraser Island". Government of Australia. May 18, 2008. Archived from the original on May 18, 2008.

20. ^ "Population growth 'good for Papua'". The Jakarta Post. August 24, 2010. Archived from the original on August 24, 2010.

21. ^ "Volcanology Highlights". Global Volcanism Program. June 3, 2012. Archived from the original on June 3, 2012.

External links

# data[].attributes.attachment_link.description
Toggle the table of contents From Wikipedia, the free encyclopedia An island or isle is a piece of sub-continental land completely surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys.

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The vast bodies of water surrounding the continents are critical to life on Earth. But overfishing and global warming threaten to leave oceans barren.

The ocean is a continuous body of salt water that covers more than 70 percent of the Earth's surface. Ocean currents govern the world's weather and churn a kaleidoscope of life. Humans depend on these teeming waters for comfort and survival, but global warming and overfishing threaten Earth's largest habitat.

Geographers divide the ocean into five major basins: the Pacific, Atlantic, Indian, Arctic, and Southern. Smaller ocean regions such as the Mediterranean Sea, Gulf of Mexico, and the Bay of Bengal are called seas, gulfs, and bays. Inland bodies of saltwater such as the Caspian Sea and the Great Salt Lake are distinct from the world's oceans.

The oceans are home to millions of Earth's plants and animals-from

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Find out about the world's ocean habitats and more

# data[].attributes.attachment_link.description
The vast bodies of water surrounding the continents are critical to life on Earth. But overfishing and global warming threaten to leave oceans barren. The ocean is a continuous body of salt water that covers more than 70 percent of the Earth's surface. Ocean currents govern the world's weather and churn a kaleidoscope of life.

# data[].attributes.attachment_link.readable_text
The giant garter snake ( Thamnophis gigas), eastern indigo snake ( Drymarchon couperi), blunt-nosed leopard lizard ( Gambelia sila) and dunes sagebrush lizard ( Sceloporus arenicolus) are all key species for Defenders of Wildlife.

Due to habitat loss and fragmentation, these species are facing a hard life in the wild. Land use change - from natural wetland, scrub or desert habitat to extractive industries or agriculture - has destroyed habitat across the country. Unfortunately, humans are encroaching the specific and connected tracts of habitat that these species need in order to survive.

Defending habitat is extraordinarily important for all of these species and we are working across the country to protect both federal and private lands that are home to these snakes and lizards. In California, we are a member of the Central Valley Joint Venture, working to protect and enhance wetland habitat for giant garter snakes and other wildlife.

Our Smart from the Start program encourages responsible renewable energy siting that will protect habitat for wildlife like the blunt-nosed leopard lizard. Defenders works to protect habitat in Florida through our place on the Florida Gopher Tortoise Technical Advisory Group; gopher tortoise burrows provide shelter for 360 other species of wildlife, like eastern indigo snakes.

Using satellite data and cloud computing, we determined that sand mines on the Texas landscape are severely damaging the dune sagebrush lizard's habitat and pushing the lizard towards extinction. We are working with companies that are voluntarily modifying their development plans, but we are also pushing for the dunes sagebrush lizard to be listed under the Endangered Species Act and we sued the Fish and Wildlife Service over its decision not to list the species.

Habitat loss and fragmentation, flood control activities, changes in agricultural and land management practices, predation from introduced species, road mortalities, water pollution and pesticide use are the main causes of the decline of these species.

The dunes sagebrush lizard is not listed.

The giant garter snake and eastern indigo snake are listed as threatened.

The blunt-nosed leopard lizard is listed as endangered.

The eastern indigo snake is a species of least concern.

The giant garter snake and dunes sagebrush lizard are listed as vulnerable.

The blunt-nosed leopard lizard is listed as endangered.

Protect wildlife habitat near your home or business. Snakes and lizards like these need the strong protections afforded to them by the Endangered Species Act and Clean Water Act so speak up in support of bedrock environmental laws.

Giant garter snakes can grow up to 64 inches and eastern indigo snakes, the longest native snakes in North America, can grow up to 102 inches. In contrast, blunt-nosed leopard lizards only grow to be 3.4 to 4.7 inches and dunes sagebrush lizards are small

Snakes and lizards can live for dozens of years depending on the species, but human activity severely limits their lifespans.

The eastern indigo snake survives in peninsular Florida and southeast Georgia, persists in the Florida panhandle, but in low numbers, and has been extirpated from Alabama and Mississippi.The blunt-nosed leopard lizard is found only in the San Joaquin Valley and adjacent foothills, as well as the Carrizo Plain and Cuyama Valley.
Snakes are found throughout the world except Antarctica, Iceland, Ireland, Greenland and New Zealand and lizards are found everywhere except Antarctica and some islands. Biodiversity of both snakes and lizards is concentrated in the tropics, but they are found in many habitats including in the water, forests, deserts and prairies.

Population numbers are unknown, but due to shrinking habitat, populations of many species are declining.

Often observed flicking their tongues, snakes use their forked tongue to smell the air. Snakes and lizards are ectotherms, meaning they must regulate their body temperature externally by sunning themselves or retreating to cool, shaded areas. They are often uniquely camouflaged to their habitat to hide in plain sight. Snakes and lizards are more active in warmer months and many hibernate in winter. Eastern indigo snakes retreat into gopher tortoise burrows and other cavities.

Mating for these species generally occurs during the colder months or at the end of dormancy, with eggs being laid in the late spring or early summer. Giant garter snakes are one of the few species that give birth to live young (ranging from 10-46 young).

Snakes and lizards consume a variety of items including insects and other invertebrates, rodents, birds, frogs, eggs and other reptiles.

# data[].attributes.attachment_link.description
The giant garter snake (Thamnophis gigas), eastern indigo snake (Drymarchon couperi), blunt-nosed leopard lizard (Gambelia sila) and dunes sagebrush lizard (Sceloporus arenicolus) are all key species for Defenders of Wildlife. Due to habitat loss and fragmentation, these species are facing a hard life in the wild.