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Land bridge

Connection between two landform bodies

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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.

01Prominent examples

Former land bridges

Current land bridges

Map of Sahul and Sunda, land masses that have provided land bridges at various points throughout the Pleistocene
Map of Sahul and Sunda, land masses that have provided land bridges at various points throughout the Pleistocene
Notable past (purple) and current (orange) land bridges on a bathymetric equirectangular projection centred on 45° E
Notable past (purple) and current (orange) land bridges on a bathymetric equirectangular projection centred on 45° E

02Land bridge theory

In the late 19th and early 20th centuries, vanished land bridges were an explanation for observed affinities of plants and animals in distant locations. Such scientists as Joseph Dalton Hooker noted puzzling geological, botanical, and zoological similarities between widely separated areas, and proposed land bridges between appropriate land masses that allowed species to spread between land masses. 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] and their geographic distribution in the two hemispheres"), 1857-1860.

Hypothesized 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.

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 that land bridges had once existed between these land masses.
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 that land bridges had once existed between these land masses.
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Sources and credits

This article is adapted from the Wikipedia article Land bridge, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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