View source for Earth:Land bridge

{{Short description|Connection between two land form bodies}}
[[Image:Pm-map.png|thumb|upright=2|The Isthmus of Panama is a land bridge whose appearance 3 million years ago enabled the Great American Biotic Interchange, in which animals and plants from the north colonized the south, and vice versa.<ref name="Webb 2006">{{cite journal  |last=Webb |first=S. David |title=The Great American Biotic Interchange: Patterns and Processes |journal=Annals of the Missouri Botanical Garden |volume=93 |issue=2 |pages=245–257 |date=23 August 2006 |doi=10.3417/0026-6493(2006)93[245:TGABIP]2.0.CO;2 |s2cid=198152030 }}</ref>]]

In [[Earth:Biogeography|biogeography]], a '''land bridge''' is an isthmus or wider land connection between otherwise separate areas, over which animals and [[Biology:Plant|plant]]s are able to cross and [[Biology:Colonisation|colonize]] new lands. A land bridge can be created by [[Earth:Marine regression|marine regression]], in which [[Sea level|sea level]]s fall, exposing shallow, previously submerged sections of [[Earth:Continental shelf|continental shelf]]; or when new land is created by [[Earth:Plate tectonics|plate tectonics]]; or occasionally when the sea floor rises due to [[Earth:Post-glacial rebound|post-glacial rebound]] after an [[Earth:Ice age|ice age]].

== Prominent examples ==

[[Image:Map of Sunda and Sahul.svg|300px|thumb|Map of Sahul and Sunda, land masses that have provided land bridges at various points throughout the Pleistocene]]

=== Former land bridges ===

* The Bassian Plain, which linked {{wipe|Australia}} and Tasmania
* The [[Earth:Beringia|Bering Land Bridge]] (aka Beringia), which intermittently connected [[Earth:Alaska|Alaska]] ([[Place:Northern America|Northern America]]) with Siberia ([[Place:North Asia|North Asia]]) as sea levels rose and fell under the effect of ice ages
* [[Earth:Land bridges of Japan|Land bridges of Japan]], several land bridges which connected Japan to Russia and Korea at various times in history.
* [[Earth:De Geer Land Bridge|De Geer Land Bridge]], a route that connected Fennoscandia to northern [[Place:Greenland|Greenland]]
* [[Earth:Doggerland|Doggerland]], a former landmass in the southern North Sea which connected the island of Great Britain to [[Earth:Continental Europe|continental Europe]] during the last ice age
* The [[Earth:Thule Land Bridge|Thule Land Bridge]], a since disappeared land bridge between the [[Place:British Isles|British Isles]] and [[Place:Greenland|Greenland]]
* Torres Strait land bridge, [[Earth:Sahul Shelf|Sahul]], between modern-day West Papua and Cape York
* [[Earth:Sundaland|Sundaland]], a 1,800,000 km<sup>2</sup> area which connected the islands of Southeast Asia at various points during the [[Earth:Pleistocene|last 2.6 million years]]

=== Current land bridges ===
*Adam's Bridge (also known as Rama Setu), connecting {{wipe|India}} and Sri Lanka
*The Isthmus of Panama, whose appearance three million years ago allowed the Great American Biotic Interchange between [[Earth:North America|North America]] and [[Earth:South America|South America]]<ref name="Webb 2006" />
*The [[Place:Sinai Peninsula|Sinai Peninsula]], linking [[Earth:Africa|Africa]] and [[Earth:Eurasia|Eurasia]]

== Land bridge theory ==

[[File:Land bridges to explain Aus NZ S.Am plant groups.svg|thumb|upright=1.35|The botanist Joseph Dalton Hooker, noting similarities of the floras of Australia, New Zealand, and southern South America in his six-volume ''Flora Antarctica'', published between 1844 and 1859, proposed land bridges between these land masses.<ref name="Winkworth 2010"/>]]

In the 19th century, scientists including [[Biography:Joseph Dalton Hooker|Joseph Dalton Hooker]] noted puzzling geological, botanical, and zoological similarities between widely separated areas. To solve these problems, they proposed land bridges between appropriate land masses.<ref name="Winkworth 2010">{{cite journal |last=Winkworth |first=Richard C. |title=Darwin and dispersal |journal=Biology International |volume=47 |year=2010 |pages=139–144 |url=https://www.researchgate.net/publication/258120865}}</ref><ref name=corliss>{{cite book |last=Corliss |first=William R. | title=Mysteries Beneath the Sea|publisher= Apollo Editions|date= June 1975|isbn=978-0815203735}} Chapter 5: "Up-and-Down Landbridges".</ref> In geology, the concept was first proposed by Jules Marcou in ''Lettres sur les roches du Jura  et leur distribution géographique dans les deux hémisphères'' ("Letters on the rocks of the [[Earth:Jura Mountains|Jura [Mountains]]] and their geographic distribution in the two hemispheres"), 1857–1860.<ref name=corliss/>

The hypothetical land bridges included:<ref name=corliss/>
* ''Archatlantis'' from the West Indies to North Africa 
* ''Archhelenis'' from Brazil to South Africa
* ''Archiboreis'' in the North Atlantic
* ''Archigalenis'' from Central America through Hawaii to Northeast Asia
* ''Archinotis'' from South America to Antarctica
* ''[[Philosophy:Lemuria (continent)|Lemuria]]'' in the Indian Ocean

The theory of [[Earth:Continental drift|continental drift]] provided an alternate explanation that did not require land bridges.<ref name="Holmes 1953">{{cite journal |last=Holmes |first=Arthur |title=Land Bridges or Continental Drift? |journal=Nature |date=18 April 1953 |pages=669-671 |url=https://www.nature.com/articles/171669a0.pdf}}</ref> However the continental drift theory was not widely accepted until the development of [[Earth:Plate tectonics|plate tectonics]] in the early 1960s, which more completely explained the motion of continents over geological time.<ref name="Pichon">{{cite journal |last=Le Pichon |first=Xavier |date=15 June 1968 |title=Sea-floor spreading and continental drift |journal=Journal of Geophysical Research |volume=73 |issue= 12 |pages=3661–97 |doi=10.1029/JB073i012p03661 |bibcode=1968JGR....73.3661L}}</ref><ref name="McK-Park">{{cite journal |last1=Mc Kenzie |first1=D. |last2=Parker |first2=R.L. |year=1967 |title=The North Pacific: an example of tectonics on a sphere |journal=Nature |volume=216 |pages=1276–1280 |doi=10.1038/2161276a0 |issue=5122 |bibcode= 1967Natur.216.1276M|s2cid=4193218}}</ref>

== See also ==

* [[Biology:Habitat fragmentation|Habitat fragmentation]]
* [[Earth:Sea level rise|Sea level rise]]

== References ==
{{Reflist}}

== Further reading ==
{{refbegin}}
* {{Cite Americana|wstitle=Land-Bridges Across the Oceans|author=Ernest Ingersoll|short=x|ref=none}}
{{refend}}

== External links ==

{{DEFAULTSORT:Land Bridge}}
[[Category:Landforms]]
[[Category:Historical geology]]
[[Category:Biogeography]]

{{Sourceattribution|Land bridge}}