thumb|upright=1.7|The [[Isthmus of Panama is a land bridge whose appearance 3 million years ago closed the Central American Seaway and enabled the Great American Biotic Interchange, in which animals and plants from the north colonized the south, and vice versa.]]
In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonize new lands. A land bridge can be created by marine regression, in which sea levels fall, exposing shallow, previously submerged sections of continental shelf; or when new land is created by plate tectonics; or occasionally when the sea floor rises due to post-glacial rebound after an ice age.
Prominent examples
300px|thumb|Map of [[Sahul Shelf|Sahul and Sunda, land masses that have provided land bridges at various points throughout the Pleistocene]]
Former land bridges
- The Bassian Plain, which linked Mainland Australia to Tasmania
- The Antarctic Land Bridge, which connected Antarctica, Australia, and South America during the Late Cretaceous and Early Paleogene
- The Bering Land Bridge (aka Beringia), which intermittently connected Alaska (Northern America) with Siberia (North Asia) as sea levels rose and fell under the effect of ice ages
- GAARlandia, a hypothesized land bridge which potentially connected the Greater Antilles with South America during the late Eocene or early Oligocene
- Land bridges of Japan, several land bridges which connected Japan to Russia and Korea at various times in history
- De Geer Land Bridge, a route that connected Fennoscandia to northern Greenland
- Doggerland, a former landmass in the southern North Sea which connected the island of Great Britain to continental Europe during the last ice age
- The Thule Land Bridge, a now-vanished land bridge between the British Isles and Greenland
- Torres Strait land bridge, Sahul, between modern-day West Papua and Cape York
- Sundaland, a 1,800,000 km<sup>2</sup> area which connected the islands of Southeast Asia at various points during the last 2.6 million years
Current land bridges
- Adam's Bridge (also known as Rama Setu), a very shallow series of shoals connecting India and Sri Lanka
- The Isthmus of Panama, whose appearance three million years ago allowed the Great American Biotic Interchange between North America and South America 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 [[Jura Mountains|Jura [Mountains] ]] and their geographic distribution in the two hemispheres"), 1857–1860. However the continental drift theory was not widely accepted until the development of plate tectonics in the early 1960s, which more completely explained the motion of continents over geological time.
See also
- Habitat fragmentation
- Sea level rise