Land bridge

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.

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.

[2][3] 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.

[4] 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 Isthmus of Panama is a land bridge whose appearance 3 million years ago enabled the Great American Biotic Interchange , in which animals and plants from the north colonized the south, and vice versa. [ 1 ]
Map of Sahul and Sunda, land masses that have provided land bridges at various points throughout the Pleistocene
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. [ 2 ]