Land bridge

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For other uses, see Land bridge (disambiguation).
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. Land bridges 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[edit]

Land bridge theory[edit]

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.[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

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[edit]

References[edit]

  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[edit]