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. Adam's Bridge (also known as Rama Setu), connecting India and Sri Lanka The Bassian Plain, which linked Australia 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 Land bridges of Japan, several land bridges which connected Japan to Russia and Korea at various times in history. De Geer Land Bridge, a route that connected Fennoscandia to northern Greenland Doggerland, a former landmass in the southern North Sea which connected the island of Great Britain to continental Europe during the last ice age The Isthmus of Panama, whose appearance three million years ago allowed the Great American Biotic Interchange between North America 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 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. 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.