biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

, 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 A marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land. Evidence of marine ...

, in which sea levels fall, exposing shallow, previously submerged sections of

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

; 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

Adam's Bridge Adam's Bridge, '; ta, ஆதாம் பாலம் ' also known as Rama's Bridge or ''Rama Setu'', '; ta, ராமர் பாலம் '; sa, रामसेतु ' is a chain of natural limestone shoals, between Pamban Island, a ...

(also known as Rama Setu), connecting India and

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

* The

Bassian Plain Bassian may refer to: * Saint Bassian (c. 320 – c. 409), Italian saint * Bassian thrush, a bird of Australia and Tasmania * Bassian ecoregion, a List of marine ecoregions, marine ecoregion * Bassian Patrikeyev, Russian ecclesiastic and political ...

, which linked

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and Tasmania * 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 * East Asia’s former unnamed landmass, During the last Ice Age, which ended approximately 15,000 years ago, Japanese Archipelago was connected to the main continent through several land bridges, notably one linking the Ryukyu Islands to Taiwan and Kyushu, one linking Kyushu to the Korean peninsula, and another one connecting Hokkaido to Sakhalin and the Siberian mainland. Sea of Japan once considered a great

salt lake A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...

. * De Geer Land Bridge, a route that connected

Fennoscandia __NOTOC__ Fennoscandia (Finnish language, Finnish, Swedish language, Swedish and no, Fennoskandia, nocat=1; russian: Фенноскандия, Fennoskandiya) or the Fennoscandian Peninsula is the geographical peninsula in Europe, which includes ...

to northern Greenland * Doggerland, a former landmass in the southern North Sea which connected the island of Great Britain to

continental Europe Continental Europe or mainland Europe is the contiguous continent of Europe, excluding its surrounding islands. It can also be referred to ambiguously as the European continent, – which can conversely mean the whole of Europe – and, by ...

during the last ice age * The

Isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country ...

, whose appearance three million years ago allowed the Great American Biotic Interchange between

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and South America * The Thule Land Bridge, a since disappeared land bridge between the British Isles and Greenland * The Sinai Peninsula, linking Africa and Eurasia * Torres Strait land bridge, Sahul, between modern-day West Papua and Cape York

Land bridge theory

In the 19th century, scientists including 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. Chapter 5: "Up-and-Down Landbridges". 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 ountains and their geographic distribution in the two hemispheres"), 1857–1860. The hypothetical land bridges included: * ''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 * '' Lemuria'' in the Indian Ocean The theory of continental drift provided an alternate explanation that did not require land bridges. 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.

References

External links

{{DEFAULTSORT:Land Bridge Landforms Historical geology Biogeography Bridges

Prominent examples

Land bridge theory

See also

References

Further reading

External links