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[[File:Aerial image of the Hallig Süderoog at high tide.jpg|upright=1.5|thumb|Aerial image of [[Süderoog]], a privately owned island belonging to the ''[[Halligen]]'' group of islands in |
[[File:Aerial image of the Hallig Süderoog at high tide.jpg|upright=1.5|thumb|Aerial image of [[Süderoog]], a privately owned island belonging to the ''[[Halligen]]'' group of islands in Germany]] |
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An '''island''' or '''isle''' is a piece of sub-continental land completely surrounded by water. Very small islands such as emergent land features on [[atoll]]s can be called [[islet]]s, [[skerry|skerries]], [[cay]]s or keys. An [[river island|island in a river]] or a [[lake island]] may be called an [[ait|eyot or ait]], and a small island off the coast may be called a [[holm (island)|holm]]. Sedimentary islands in the [[Ganges Delta]] are called [[List of islands of Bangladesh|chars]]. A grouping of geographically or geologically related islands, such as the [[Philippines]], is referred to as an [[archipelago]]. |
An '''island''' or '''isle''' is a piece of sub-continental land completely surrounded by water. Very small islands such as emergent land features on [[atoll]]s can be called [[islet]]s, [[skerry|skerries]], [[cay]]s or keys. An [[river island|island in a river]] or a [[lake island]] may be called an [[ait|eyot or ait]], and a small island off the coast may be called a [[holm (island)|holm]]. Sedimentary islands in the [[Ganges Delta]] are called [[List of islands of Bangladesh|chars]]. A grouping of geographically or geologically related islands, such as the [[Philippines]], is referred to as an [[archipelago]]. |
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== Etymology == |
== Etymology == |
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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 language|Dutch]] ''eiland'' ("island"), [[German language|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 [[Etymology|etymologically]] unrelated Old French loanword ''isle'', which itself comes from the Latin word ''insula''.<ref>{{cite dictionary |url=http://dictionary.reference.com/browse/Island |title=Island |access-date=March 5, 2007 |dictionary=[[Dictionary.com]] |url-status=live |archive-url=https://web.archive.org/web/20070307143713/http://dictionary.reference.com/browse/island |archive-date=March 7, 2007 |df=mdy-all }}</ref><ref>{{cite journal|last=Wedgwood|first=Hensleigh|author-link=Hensleigh Wedgwood|title=On False Etymologies|journal=Transactions of the Philological Society|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3924121;view=1up;seq=76|year=1855|issue=6|pages=66|access-date=September 22, 2018|archive-date=November 6, 2018|archive-url=https://web.archive.org/web/20181106160600/https://babel.hathitrust.org/cgi/pt?id=uc1.b3924121;view=1up;seq=76|url-status=live}}</ref> Old English ''ieg'' is actually a [[cognate]] of Swedish ''ö'' and German ''Aue'', and related to Latin ''aqua'' (water).<ref>{{cite book |
The word ''island'' derives from [[Middle English]] ''{{linktext|iland}}'', from [[Old English]] ''igland'' (from ''ig'' or ''ieg'', similarly meaning 'island' when used independently, and [[-land]] carrying its contemporary meaning; cf. [[Dutch language|Dutch]] ''eiland'' ("island"), [[German language|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 [[Etymology|etymologically]] unrelated [[Old French]] loanword ''isle'', which itself comes from the [[Latin]] word ''insula''.<ref>{{cite dictionary |url=http://dictionary.reference.com/browse/Island |title=Island |access-date=March 5, 2007 |dictionary=[[Dictionary.com]] |url-status=live |archive-url=https://web.archive.org/web/20070307143713/http://dictionary.reference.com/browse/island |archive-date=March 7, 2007 |df=mdy-all }}</ref><ref>{{cite journal|last=Wedgwood|first=Hensleigh|author-link=Hensleigh Wedgwood|title=On False Etymologies|journal=Transactions of the Philological Society|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3924121;view=1up;seq=76|year=1855|issue=6|pages=66|access-date=September 22, 2018|archive-date=November 6, 2018|archive-url=https://web.archive.org/web/20181106160600/https://babel.hathitrust.org/cgi/pt?id=uc1.b3924121;view=1up;seq=76|url-status=live}}</ref> [[Old English]] ''ieg'' is actually a [[cognate]] of [[Swedish language|Swedish]] ''ö'' and [[German language|German]] ''Aue'', and related to Latin ''{{linktext|aqua}}'' (water).<ref>{{cite book |
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|title=A Linguistic History of English: From Proto-Indo-European to Proto-Germanic |
|title=A Linguistic History of English: From Proto-Indo-European to Proto-Germanic |
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|first=Donald A. |
|first=Donald A. |
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There is a widely accepted difference between islands and continents in terms of [[geology]].<ref>{{cite encyclopedia |url=https://www.britannica.com/story/is-australia-an-island |encyclopedia=Encyclopædia Britannica |edition=Online |title=Is Australia an Island? |last=Cunningham |first=John M. |access-date=20 August 2022 |archive-date=January 25, 2019 |archive-url=https://web.archive.org/web/20190125074036/https://www.britannica.com/story/is-australia-an-island |url-status=live }}</ref> Continents are often considered to be the largest [[landmass]] of a particular [[plate tectonics|continental plate]]; this holds true for [[Australia (continent)|Australia]], which sits on its own continental lithosphere and tectonic plate (the [[Australian Plate]]).<ref>{{cite web |title=Continent |url=https://www.nationalgeographic.org/encyclopedia/Continent/ |website=National Geographic |publisher=National Geographic Society |access-date=20 August 2022 |archive-date=July 16, 2019 |archive-url=https://web.archive.org/web/20190716045120/https://www.nationalgeographic.org/encyclopedia/continent/ |url-status=live }}</ref> |
There is a widely accepted difference between islands and continents in terms of [[geology]].<ref>{{cite encyclopedia |url=https://www.britannica.com/story/is-australia-an-island |encyclopedia=Encyclopædia Britannica |edition=Online |title=Is Australia an Island? |last=Cunningham |first=John M. |access-date=20 August 2022 |archive-date=January 25, 2019 |archive-url=https://web.archive.org/web/20190125074036/https://www.britannica.com/story/is-australia-an-island |url-status=live }}</ref> Continents are often considered to be the largest [[landmass]] of a particular [[plate tectonics|continental plate]]; this holds true for [[Australia (continent)|Australia]], which sits on its own continental lithosphere and tectonic plate (the [[Australian Plate]]).<ref>{{cite web |title=Continent |url=https://www.nationalgeographic.org/encyclopedia/Continent/ |website=National Geographic |publisher=National Geographic Society |access-date=20 August 2022 |archive-date=July 16, 2019 |archive-url=https://web.archive.org/web/20190716045120/https://www.nationalgeographic.org/encyclopedia/continent/ |url-status=live }}</ref> |
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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]].<ref>{{Cite web |date=2012-08-27 |title=Island |url=http://www.nationalgeographic.org/encyclopedia/island/ |access-date=2022-05-02 |website=National Geographic Society |archive-date=June 17, 2021 |archive-url=https://web.archive.org/web/20210617165729/https://www.nationalgeographic.org/encyclopedia/island/ |url-status=live }}</ref> |
By contrast, islands are usually seen as being extensions of the [[oceanic crust]] (e.g. [[High island|volcanic islands]]), or as belonging to a [[Plate tectonics|continental plate]] containing a larger landmass (continental islands); the latter is the case of [[Greenland]], which sits on the [[North American Plate]].<ref>{{Cite web |date=2012-08-27 |title=Island |url=http://www.nationalgeographic.org/encyclopedia/island/ |access-date=2022-05-02 |website=National Geographic Society |archive-date=June 17, 2021 |archive-url=https://web.archive.org/web/20210617165729/https://www.nationalgeographic.org/encyclopedia/island/ |url-status=live }}</ref> |
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===Continental islands===<!-- This section is linked from [[Great Barrier Reef]] --> |
===Continental islands===<!-- This section is linked from [[Great Barrier Reef]] --> |
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Continental islands are bodies of land that lie on the [[continental shelf]] of a [[continent]].<ref>{{cite web|title=Island (geography)|url=https://www.britannica.com/EBchecked/topic/295958/island#ref234009|website=Encyclopædia Britannica|access-date=16 September 2014|url-status=live|archive-url=https://web.archive.org/web/20141008102906/https://www.britannica.com/EBchecked/topic/295958/island#ref234009|archive-date=October 8, 2014|df=mdy-all}}</ref> Examples are [[Borneo]], [[Java (island)|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 (island)|Newfoundland]], [[Long Island]], and [[Sable Island]] off [[North America]]; and [[Barbados]], the [[Falkland Islands]], and [[Trinidad]] off [[South America]]. |
Continental islands are bodies of land that lie on the [[continental shelf]] of a [[continent]].<ref>{{cite web|title=Island (geography)|url=https://www.britannica.com/EBchecked/topic/295958/island#ref234009|website=Encyclopædia Britannica|access-date=16 September 2014|url-status=live|archive-url=https://web.archive.org/web/20141008102906/https://www.britannica.com/EBchecked/topic/295958/island#ref234009|archive-date=October 8, 2014|df=mdy-all}}</ref> Examples are [[Borneo]], [[Java (island)|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 (island)|Newfoundland]], [[Long Island]], and [[Sable Island]] off [[North America]]; and [[Barbados]], the [[Falkland Islands]], and [[Trinidad]] off [[South America]]. |
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==== Micro-continental islands ==== |
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A special type of continental island is the |
A special type of continental island is the micro-continental island, which is created when a continent is horizontally displaced or [[rift]]ed<ref>{{Citation |last=Scrutton |first=Roger A. |title=Geodynamics: Progress and Prospects |chapter=Microcontinents and their Significance |date=2013-03-21 |chapter-url=http://doi.wiley.com/10.1029/SP005p0177 |series=Special Publications |pages=177–189 |editor-last=Drake |editor-first=Charles L. |place=Washington, D. C. |publisher=American Geophysical Union |doi=10.1029/sp005p0177 |isbn=978-1-118-66490-2 |access-date=2022-08-20}}</ref><ref name=microcont >{{Cite journal |last1=Broek |first1=J. M. |last2=Gaina |first2=C. |date=August 2020 |title=Microcontinents and Continental Fragments Associated With Subduction Systems |journal=Tectonics |language=en |volume=39 |issue=8 |doi=10.1029/2020TC006063 |bibcode=2020Tecto..3906063V |s2cid=225376789 |issn=0278-7407|doi-access=free }}</ref> Examples are [[Madagascar]] and [[Socotra]] off [[Africa]], [[Geography of New Caledonia|New Caledonia]], [[New Zealand]], and some of the [[Seychelles]].<ref name=microcont /> |
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==== Subcontinental islands ==== |
==== Subcontinental islands ==== |
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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 {{convert|2000000|km2|mi2|abbr=on}}.<ref>{{Cite web |title=Technical Program |url=https://www.earmp.ca/technical-program |access-date=2022-10-29 |website=Eastern Athabasca Regional Monitoring Program |language=en-US}}</ref> |
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 {{convert|2000000|km2|mi2|abbr=on}}.<ref>{{Cite web |title=Technical Program |url=https://www.earmp.ca/technical-program |access-date=2022-10-29 |website=Eastern Athabasca Regional Monitoring Program |language=en-US |archive-date=October 29, 2022 |archive-url=https://web.archive.org/web/20221029170950/https://www.earmp.ca/technical-program |url-status=live }}</ref> |
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==== Bars ==== |
==== Bars ==== |
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Another subtype is an island or [[shoal|bar]] formed by deposition of tiny rocks where water current loses some of its carrying capacity. This includes: |
Another subtype is an island or [[shoal|bar]] formed by deposition of tiny rocks where water current loses some of its carrying capacity. This includes: |
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* [[barrier island]]s, which are accumulations of [[sand]] deposited by sea currents on the continental shelves<ref>{{Cite journal |title=Barrier Island Formation |url=https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/78/9/1125/6224/Barrier-Island-Formation |doi=10.1130/0016-7606(1967)78[1125:bif]2.0.co;2 |access-date=2022-08-21 |date=1967-09-01 | |
* [[barrier island]]s, which are accumulations of [[sand]] deposited by sea currents on the [[Continental shelf|continental shelves]]<ref>{{Cite journal |title=Barrier Island Formation |url=https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/78/9/1125/6224/Barrier-Island-Formation |doi=10.1130/0016-7606(1967)78[1125:bif]2.0.co;2 |access-date=2022-08-21 |date=1967-09-01 |first=John H. |last=Hoyt |journal=GSA Bulletin |volume=78 |number=9 |pages=1125–1136 |archive-date=January 19, 2022 |archive-url=https://web.archive.org/web/20220119034448/https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/78/9/1125/6224/Barrier-Island-Formation |url-status=live }}</ref><ref>{{Citation |last=Davis |first=Richard A. |title=Barrier Island Systems — a Geologic Overview |date=1994 |url=http://link.springer.com/10.1007/978-3-642-78360-9_1 |work=Geology of Holocene Barrier Island Systems |pages=1–46 |editor-last=Davis |editor-first=Richard A. |place=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |language=en |doi=10.1007/978-3-642-78360-9_1 |isbn=978-3-642-78362-3 |access-date=2022-08-21 |archive-date=August 21, 2022 |archive-url=https://web.archive.org/web/20220821154154/https://link.springer.com/chapter/10.1007/978-3-642-78360-9_1 |url-status=live }}</ref> |
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* [[fluvial processes|fluvial]] or [[alluvium|alluvial]] islands formed in [[river delta]]s 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 long-lived.<ref>{{Cite thesis |type=MSc |last=Cooperman |first=Michael S. |date=1997-01-01 |title=The process of mid-channel alluvial island formation as inferred from plant distribution patterns on islands of the Swan River northwest Montana |url=https://scholarworks.umt.edu/etd/6939 |publisher=The University of Montana |access-date=August 21, 2022 |archive-date=December 15, 2021 |archive-url=https://web.archive.org/web/20211215134545/https://scholarworks.umt.edu/etd/6939/ |url-status=live }}</ref> |
* [[fluvial processes|fluvial]] or [[alluvium|alluvial]] islands formed in [[river delta]]s 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 long-lived.<ref>{{Cite thesis |type=MSc |last=Cooperman |first=Michael S. |date=1997-01-01 |title=The process of mid-channel alluvial island formation as inferred from plant distribution patterns on islands of the Swan River northwest Montana |url=https://scholarworks.umt.edu/etd/6939 |publisher=The University of Montana |access-date=August 21, 2022 |archive-date=December 15, 2021 |archive-url=https://web.archive.org/web/20211215134545/https://scholarworks.umt.edu/etd/6939/ |url-status=live }}</ref> |
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==== Tectonic versus volcanic ==== |
==== Tectonic versus volcanic ==== |
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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.<ref name="zug">{{cite book |last1=Zug |first1=George R. |title=Reptiles and Amphibians of the Pacific Islands: A Comprehensive Guide |date=2013 |publisher=University of California Press |page= |quote=}}</ref> The vast majority are [[volcano|volcanic]] in origin, such as [[Saint Helena]] in the [[South Atlantic Ocean]].<ref>{{cite book |chapter=The Biota of Long-Distance Dispersal: I. Principles of Dispersal and Evolution |last=Carlquist |first=Sherwin |editor-last1=Lomolino |editor-first1=Mark V. |editor-last2=Sax |editor-first2=Dov F. |editor-last3=Brown |editor-first3=James H. |date=2004 |chapter-url=https://books.google.com/books?id=KbkCgsEPv6YC&dq=Oceanic+island&pg=PA316 |title=Foundations of Biogeography: Classic Papers with Commentaries |archive-url=https://web.archive.org/web/20160418233729/https://books.google.com/books?id=KbkCgsEPv6YC&pg=PA316&dq=Oceanic+island&hl=en&sa=X&ei=NlR_UaycEMqhigLGhYHoAw&ved=0CEEQ6AEwAw |archive-date=18 April 2016 |publisher=University of Chicago Press |page=316 |isbn=0-226-49236-2}}</ref> The few oceanic islands that are not volcanic are [[tectonics|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. |
Oceanic islands are typically considered to be islands that do not sit on [[Continental shelf|continental shelves]]. Other definitions limit the term to only refer to islands with no past geological connections to a [[Continent|continental landmass]].<ref name="zug">{{cite book |last1=Zug |first1=George R. |title=Reptiles and Amphibians of the Pacific Islands: A Comprehensive Guide |date=2013 |publisher=University of California Press |page= |quote=}}</ref> The vast majority are [[volcano|volcanic]] in origin, such as [[Saint Helena]] in the [[South Atlantic Ocean]].<ref>{{cite book |chapter=The Biota of Long-Distance Dispersal: I. Principles of Dispersal and Evolution |last=Carlquist |first=Sherwin |editor-last1=Lomolino |editor-first1=Mark V. |editor-last2=Sax |editor-first2=Dov F. |editor-last3=Brown |editor-first3=James H. |date=2004 |chapter-url=https://books.google.com/books?id=KbkCgsEPv6YC&dq=Oceanic+island&pg=PA316 |title=Foundations of Biogeography: Classic Papers with Commentaries |archive-url=https://web.archive.org/web/20160418233729/https://books.google.com/books?id=KbkCgsEPv6YC&pg=PA316&dq=Oceanic+island&hl=en&sa=X&ei=NlR_UaycEMqhigLGhYHoAw&ved=0CEEQ6AEwAw |archive-date=18 April 2016 |publisher=University of Chicago Press |page=316 |isbn=0-226-49236-2}}</ref> The few oceanic islands that are not volcanic are [[tectonics|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 [[Atlantic Ocean|North Atlantic Ocean]] and [[Macquarie Island]] in the [[Pacific Ocean|South Pacific Ocean.]] |
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==== Volcanic islands ==== |
==== Volcanic islands ==== |
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===== Arcs ===== |
===== Arcs ===== |
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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]].<ref>{{Cite journal |last=Marsh |first=B. D. |date=1979-11-01 |title=Island Arc Development: Some Observations, Experiments, and Speculations |url=https://www.journals.uchicago.edu/doi/10.1086/628460 |journal=The Journal of Geology |volume=87 |issue=6 |pages=687–713 |doi=10.1086/628460 |bibcode=1979JG.....87..687M |s2cid=129932810 |issn=0022-1376 |access-date=August 21, 2022 |archive-date=March 9, 2022 |archive-url=https://web.archive.org/web/20220309064935/https://www.journals.uchicago.edu/doi/10.1086/628460 |url-status=live }}</ref><ref>{{Cite journal |last=Katili |first=John A. |date=1975-04-01 |title=Volcanism and plate tectonics in the Indonesian island arcs |url=https://dx.doi.org/10.1016/0040-1951%2875%2990088-8 |journal=Tectonophysics |language=en |volume=26 |issue=3 |pages=165–188 |doi=10.1016/0040-1951(75)90088-8 |bibcode=1975Tectp..26..165K |issn=0040-1951}}</ref> The only examples in the Atlantic Ocean are some of the [[Lesser Antilles]] and the [[South Sandwich Islands]]. |
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]].<ref>{{Cite journal |last=Marsh |first=B. D. |date=1979-11-01 |title=Island Arc Development: Some Observations, Experiments, and Speculations |url=https://www.journals.uchicago.edu/doi/10.1086/628460 |journal=The Journal of Geology |volume=87 |issue=6 |pages=687–713 |doi=10.1086/628460 |bibcode=1979JG.....87..687M |s2cid=129932810 |issn=0022-1376 |access-date=August 21, 2022 |archive-date=March 9, 2022 |archive-url=https://web.archive.org/web/20220309064935/https://www.journals.uchicago.edu/doi/10.1086/628460 |url-status=live }}</ref><ref>{{Cite journal |last=Katili |first=John A. |date=1975-04-01 |title=Volcanism and plate tectonics in the Indonesian island arcs |url=https://dx.doi.org/10.1016/0040-1951%2875%2990088-8 |journal=Tectonophysics |language=en |volume=26 |issue=3 |pages=165–188 |doi=10.1016/0040-1951(75)90088-8 |bibcode=1975Tectp..26..165K |issn=0040-1951 |access-date=August 23, 2022 |archive-date=March 3, 2023 |archive-url=https://web.archive.org/web/20230303042647/https://www.sciencedirect.com/science/article/abs/pii/0040195175900888?via%3Dihub |url-status=live }}</ref> The only examples in the [[Atlantic Ocean]] are some of the [[Lesser Antilles]] and the [[South Sandwich Islands]]. |
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===== Oceanic Rifts ===== |
===== Oceanic Rifts ===== |
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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. |
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 Ocean|Atlantic]]. |
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===== Hotspots ===== |
===== Hotspots ===== |
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{{Main|Hotspot (geology)}} |
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A third type of volcanic oceanic island is formed over volcanic [[Hotspot (geology)|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 [[isostasy|isostatic adjustment]] and eroded, becoming a [[seamount]].<ref>{{Cite journal |last1=Huppert |first1=Kimberly L. |last2=Perron |first2=J. Taylor |last3=Royden |first3=Leigh H. |date=2020-01-03 |title=Hotspot swells and the lifespan of volcanic ocean islands |journal=Science Advances |language=en |volume=6 |issue=1 |pages=eaaw6906 |doi=10.1126/sciadv.aaw6906 |issn=2375-2548 |pmc=6938699 |pmid=31911939|bibcode=2020SciA....6.6906H }}</ref> 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 Atoll|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.<ref>{{Cite journal |last1=Schlömer |first1=Antje |last2=Geissler |first2=Wolfram H. |last3=Jokat |first3=Wilfried |last4=Jegen |first4=Marion |date=2017-03-15 |title=Hunting for the Tristan mantle plume – An upper mantle tomography around the volcanic island of Tristan da Cunha |url=https://www.sciencedirect.com/science/article/pii/S0012821X16307415 |journal=Earth and Planetary Science Letters |language=en |volume=462 |pages=122–131 |doi=10.1016/j.epsl.2016.12.028 |bibcode=2017E&PSL.462..122S |issn=0012-821X}}</ref> Another hotspot in the Atlantic is the island of [[Surtsey]], which was formed in 1963.<ref>{{Citation |last=Claudino-Sales |first=Vanda |title=Surtsey, Iceland |date=2019 |url=http://link.springer.com/10.1007/978-94-024-1528-5_35 |work=Coastal World Heritage Sites |series=Coastal Research Library |volume=28 |pages=237–242 |place=Dordrecht |publisher=Springer Netherlands |doi=10.1007/978-94-024-1528-5_35 |isbn=978-94-024-1526-1 |s2cid=240206292 |access-date=2022-08-21 |archive-date=August 21, 2022 |archive-url=https://web.archive.org/web/20220821154209/https://link.springer.com/chapter/10.1007/978-94-024-1528-5_35 |url-status=live }}</ref> |
A third type of volcanic oceanic island is formed over volcanic [[Hotspot (geology)|hotspots]]. A [[Hotspot (geology)|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 [[isostasy|isostatic adjustment]] and eroded, becoming a [[seamount]].<ref>{{Cite journal |last1=Huppert |first1=Kimberly L. |last2=Perron |first2=J. Taylor |last3=Royden |first3=Leigh H. |date=2020-01-03 |title=Hotspot swells and the lifespan of volcanic ocean islands |journal=Science Advances |language=en |volume=6 |issue=1 |pages=eaaw6906 |doi=10.1126/sciadv.aaw6906 |issn=2375-2548 |pmc=6938699 |pmid=31911939|bibcode=2020SciA....6.6906H }}</ref> 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 Atoll|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 (geology)|hotspot volcano]] in the [[Atlantic Ocean]].<ref>{{Cite journal |last1=Schlömer |first1=Antje |last2=Geissler |first2=Wolfram H. |last3=Jokat |first3=Wilfried |last4=Jegen |first4=Marion |date=2017-03-15 |title=Hunting for the Tristan mantle plume – An upper mantle tomography around the volcanic island of Tristan da Cunha |url=https://www.sciencedirect.com/science/article/pii/S0012821X16307415 |journal=Earth and Planetary Science Letters |language=en |volume=462 |pages=122–131 |doi=10.1016/j.epsl.2016.12.028 |bibcode=2017E&PSL.462..122S |issn=0012-821X}}</ref> Another [[Hotspot (geology)|hotspot]] in the [[Atlantic Ocean|Atlantic]] is the island of [[Surtsey]], which was formed in 1963.<ref>{{Citation |last=Claudino-Sales |first=Vanda |title=Surtsey, Iceland |date=2019 |url=http://link.springer.com/10.1007/978-94-024-1528-5_35 |work=Coastal World Heritage Sites |series=Coastal Research Library |volume=28 |pages=237–242 |place=Dordrecht |publisher=Springer Netherlands |doi=10.1007/978-94-024-1528-5_35 |isbn=978-94-024-1526-1 |s2cid=240206292 |access-date=2022-08-21 |archive-date=August 21, 2022 |archive-url=https://web.archive.org/web/20220821154209/https://link.springer.com/chapter/10.1007/978-94-024-1528-5_35 |url-status=live }}</ref> |
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===== Atolls ===== |
===== Atolls ===== |
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{{Main|Atoll}} |
{{Main|Atoll}} |
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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]].<ref>{{cite book |last1=Woodroffe |first1=Colin |last2=Biribo |first2=Naomi |date=2011-01-01 |chapter=Atolls |editor-last=Hopley |editor-first=D. |title=Encyclopedia of Modern Coral Reefs: structure, form and process |publisher=Springer |url=https://ro.uow.edu.au/scipapers/1060 |location=The Netherlands |pages=51–71 |access-date=August 21, 2022 |archive-date=October 25, 2020 |archive-url=https://web.archive.org/web/20201025061721/https://ro.uow.edu.au/scipapers/1060/ |url-status=live }}</ref> |
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. [[Atoll|Atolls]] are typically ring-shaped with a central [[lagoon]]. Examples are the [[Line Islands]] in the [[Pacific Ocean|Pacific]] and the [[Maldives]] in the [[Indian Ocean]].<ref>{{cite book |last1=Woodroffe |first1=Colin |last2=Biribo |first2=Naomi |date=2011-01-01 |chapter=Atolls |editor-last=Hopley |editor-first=D. |title=Encyclopedia of Modern Coral Reefs: structure, form and process |publisher=Springer |url=https://ro.uow.edu.au/scipapers/1060 |location=The Netherlands |pages=51–71 |access-date=August 21, 2022 |archive-date=October 25, 2020 |archive-url=https://web.archive.org/web/20201025061721/https://ro.uow.edu.au/scipapers/1060/ |url-status=live }}</ref> |
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[[File:On the structure and distribution of coral reefs BHL40453231.jpg|thumb|upright=3|center|Map from [[Charles Darwin]]’s 1842 ''[[The Structure and Distribution of Coral Reefs]]'' showing the world’s major groups of atolls and coral reefs]] |
[[File:On the structure and distribution of coral reefs BHL40453231.jpg|thumb|upright=3|center|Map from [[Charles Darwin]]’s 1842 ''[[The Structure and Distribution of Coral Reefs]]'' showing the world’s major groups of atolls and coral reefs]] |
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== Tropical islands == |
== Tropical islands == |
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{{Main|Low island}} |
{{Main|Low island}} |
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{{See also|Coral island}} |
{{See also|Coral island}} |
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{{See|Coral reef#Formation}} |
{{See|Coral reef#Formation}} |
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Approximately 45,000 [[Tropics|tropical]] islands with an |
Approximately 45,000 [[Tropics|tropical]] islands with an area of at least {{convert|5|ha}} exist.<ref name="TI">{{cite book |
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|doi=10.1553/3-7001-2738-3 |
|doi=10.1553/3-7001-2738-3 |
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|chapter=The Tropical Islands of the Indian and Pacific Oceans |
|chapter=The Tropical Islands of the Indian and Pacific Oceans |
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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, California|Coronado Island]], though these are, strictly speaking, [[tied island]]s.<ref name=istudies /> 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, Manhattan|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. |
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, California|Coronado Island]], though these are, strictly speaking, [[tied island]]s.<ref name=istudies /> 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, Manhattan|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. |
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Another type of connection is fostered by |
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 [[Johor–Singapore Causeway|causeway]], and the various [[Netherlands|Dutch]] delta islands, such as [[IJsselmonde (island)|IJsselmonde]]. |
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== Artificial islands == |
== Artificial islands == |
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{{Main|Artificial island}} |
{{Main|Artificial island}} |
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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]]).<ref>{{Cite web|url=http://www.popsci.com/technology/article/2012-07/building-artificial-islands-rise-sea|title=Building Artificial Islands That Rise With the Sea |work=Popular Science |last=Gammon |first=Katherine |date=August 6, 2012 |access-date=2016-06-28|url-status=live|archive-url=https://web.archive.org/web/20160605152821/http://www.popsci.com/technology/article/2012-07/building-artificial-islands-rise-sea |archive-date=June 5, 2016|df=mdy-all}}</ref><ref>{{Cite web|url=http://amti.csis.org/what-makes-an-island-land-reclamation-and-the-south-china-sea-arbitration/|title=What Makes an Island? Land Reclamation and the South China Sea Arbitration |publisher=Asia Maritime Transparency Initiative |last=Mirasola |first=Christopher |date=2015-07-15|language=en-US|access-date=2016-06-28|url-status=live|archive-url=https://web.archive.org/web/20160527053430/http://amti.csis.org/what-makes-an-island-land-reclamation-and-the-south-china-sea-arbitration/|archive-date=May 27, 2016|df=mdy-all}}</ref> |
Almost all of [[Earth]]'s islands are natural and have been formed by tectonic forces or [[Types of volcanic eruptions|volcanic eruptions.]] However, artificial (man-made) islands also exist, such as the island in [[Osaka Bay]] off the [[Japanese archipelago|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]]).<ref>{{Cite web|url=http://www.popsci.com/technology/article/2012-07/building-artificial-islands-rise-sea|title=Building Artificial Islands That Rise With the Sea |work=Popular Science |last=Gammon |first=Katherine |date=August 6, 2012 |access-date=2016-06-28|url-status=live|archive-url=https://web.archive.org/web/20160605152821/http://www.popsci.com/technology/article/2012-07/building-artificial-islands-rise-sea |archive-date=June 5, 2016|df=mdy-all}}</ref><ref>{{Cite web|url=http://amti.csis.org/what-makes-an-island-land-reclamation-and-the-south-china-sea-arbitration/|title=What Makes an Island? Land Reclamation and the South China Sea Arbitration |publisher=Asia Maritime Transparency Initiative |last=Mirasola |first=Christopher |date=2015-07-15|language=en-US|access-date=2016-06-28|url-status=live|archive-url=https://web.archive.org/web/20160527053430/http://amti.csis.org/what-makes-an-island-land-reclamation-and-the-south-china-sea-arbitration/|archive-date=May 27, 2016|df=mdy-all}}</ref> |
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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]].<ref>{{Cite web|url=http://top-mark.biz/en/vasilevskiy_ostrov_namyv/|title=Conception of development of the artificial lands of Vasilievsky island |website=top-mark.biz|access-date=2016-06-28|url-status=dead|archive-url=https://web.archive.org/web/20160925003154/http://top-mark.biz/en/vasilevskiy_ostrov_namyv/|archive-date=September 25, 2016|df=mdy-all}}</ref> |
Sometimes natural islands are artificially enlarged, such as [[Vasilyevsky Island]] in the [[Russian language|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]].<ref>{{Cite web|url=http://top-mark.biz/en/vasilevskiy_ostrov_namyv/|title=Conception of development of the artificial lands of Vasilievsky island |website=top-mark.biz|access-date=2016-06-28|url-status=dead|archive-url=https://web.archive.org/web/20160925003154/http://top-mark.biz/en/vasilevskiy_ostrov_namyv/|archive-date=September 25, 2016|df=mdy-all}}</ref> |
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[[File:Kansai International Airport Aerial photograph.2007.jpg|thumb|[[Kansai International Airport]], on an artificial island]] |
[[File:Kansai International Airport Aerial photograph.2007.jpg|thumb|[[Kansai International Airport]], on an artificial island]] |
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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.<ref>{{cite book|title=United Nations Convention on the Law of the Sea, Article 13 |url=http://www.un.org/Depts/los/convention_agreements/texts/unclos/closindx.htm |access-date=25 August 2017|url-status=live|archive-url=https://web.archive.org/web/20170902091223/http://www.un.org/Depts/los/convention_agreements/texts/unclos/closindx.htm|archive-date=September 2, 2017|df=mdy-all}}</ref> |
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.<ref>{{cite book|title=United Nations Convention on the Law of the Sea, Article 13 |url=http://www.un.org/Depts/los/convention_agreements/texts/unclos/closindx.htm |access-date=25 August 2017|url-status=live|archive-url=https://web.archive.org/web/20170902091223/http://www.un.org/Depts/los/convention_agreements/texts/unclos/closindx.htm|archive-date=September 2, 2017|df=mdy-all}}</ref> |
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== Island superlatives == |
== Island superlatives == |
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* Largest island: [[Greenland]]<ref name=watlas >{{Cite web |date=2021-05-18 |title=Largest And Highest Islands Of The World |url=https://www.worldatlas.com/geography/largest-and-highest-islands-of-the-world.html |access-date=2022-08-20 |website=WorldAtlas |language=en-US |archive-date=June 11, 2022 |archive-url=https://web.archive.org/web/20220611040215/https://www.worldatlas.com/geography/largest-and-highest-islands-of-the-world.html |url-status=live }}</ref> |
* Largest island: [[Greenland]]<ref name=watlas >{{Cite web |date=2021-05-18 |title=Largest And Highest Islands Of The World |url=https://www.worldatlas.com/geography/largest-and-highest-islands-of-the-world.html |access-date=2022-08-20 |website=WorldAtlas |language=en-US |archive-date=June 11, 2022 |archive-url=https://web.archive.org/web/20220611040215/https://www.worldatlas.com/geography/largest-and-highest-islands-of-the-world.html |url-status=live }}</ref> |
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* Largest island in a lake: [[Manitoulin Island]], Ontario, Canada<ref name=watlas /> |
* Largest island in a lake: [[Manitoulin Island]], [[Ontario|Ontario, Canada]]<ref name=watlas /> |
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** Largest lake island within a lake island: [[Treasure Island (Ontario)|Treasure Island]], in [[Lake Mindemoya]] on Manitoulin Island<ref>{{Cite web |first=Natalie |last=Wolchover |date=2012-01-24 |title=World's Largest Island-in-a-lake-on-an-island-in-a-lake-on-an-island Seen on Google Earth |url=https://www.livescience.com/33679-world-largest-island-lake-island-lake-island-google-earth.html |access-date=2022-08-20 |website=livescience.com |archive-date=April 7, 2022 |archive-url=https://web.archive.org/web/20220407203407/https://www.livescience.com/33679-world-largest-island-lake-island-lake-island-google-earth.html |url-status=live }}</ref> |
** Largest lake island within a lake island: [[Treasure Island (Ontario)|Treasure Island]], in [[Lake Mindemoya]] on [[Manitoulin Island]]<ref>{{Cite web |first=Natalie |last=Wolchover |date=2012-01-24 |title=World's Largest Island-in-a-lake-on-an-island-in-a-lake-on-an-island Seen on Google Earth |url=https://www.livescience.com/33679-world-largest-island-lake-island-lake-island-google-earth.html |access-date=2022-08-20 |website=livescience.com |archive-date=April 7, 2022 |archive-url=https://web.archive.org/web/20220407203407/https://www.livescience.com/33679-world-largest-island-lake-island-lake-island-google-earth.html |url-status=live }}</ref> |
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* Largest island in a river: [[Bananal Island]], Tocantins, Brazil<ref>{{Cite encyclopedia |title=Bananal Island |encyclopedia=Encyclopædia Britannica |edition=Online |url=https://www.britannica.com/place/Bananal-Island |access-date=2022-08-20 |archive-date=September 3, 2017 |archive-url=https://web.archive.org/web/20170903083437/https://www.britannica.com/place/Bananal-Island |url-status=live }}</ref> |
* Largest island in a river: [[Bananal Island]], Tocantins, Brazil<ref>{{Cite encyclopedia |title=Bananal Island |encyclopedia=Encyclopædia Britannica |edition=Online |url=https://www.britannica.com/place/Bananal-Island |access-date=2022-08-20 |archive-date=September 3, 2017 |archive-url=https://web.archive.org/web/20170903083437/https://www.britannica.com/place/Bananal-Island |url-status=live }}</ref> |
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* Largest island in freshwater: [[Marajó]], Pará, Brazil |
* Largest island in freshwater: [[Marajó]], Pará, Brazil |