Land bridge

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The Isthmus of Panama is a land bridge whose appearance 3 million years ago allowed the Great American Interchange.

A land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonise 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

Land bridge theory

In the 19th century a number of scientists noted puzzling geological and zoological similarities between widely separated areas. To solve these problems, "…whenever geologists and paleontologists were at a loss to explain the obvious transoceanic similarities of life that they deduced from the fossil records, they sharpened their pencils and sketched land bridges between appropriate continents."[1] 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.[2]

These hypothetical land bridges included:[3]

  • 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
  • Marsupials between South America and Australia.

All of these became obsolete with the gradual acceptance of continental drift and the development of plate tectonics by the mid-20th century.

See also


  1. William R. Corliss, Mysteries Beneath the Sea, Apollo Editions, June 1975, Chapter 5: "Up-and-Down Landbridges" ISBN 978-0815203735
  2. William R. Corliss, op. cit., "The basic idea is usually attributed to Jules Marcou…"
  3. All examples taken from Corliss, op. cit.

External links

  • Wikisource-logo.svg Ernest Ingersoll (1920). [ "Land-Bridges Across the Oceans" ] Check |ws link in chapter= value (help). Encyclopedia Americana.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>