Land bridge - in the biogeography of the isthmus or other connection, allowing plants and animals to colonize the new land. Land bridges are usually formed as a result of sea level regression when the continental shelf becomes land. Land bridges are also formed when the glacier retreats, in this case the load on the tectonic plate decreases and it experiences a rise. Example: Öland , Sweden .
The recent marine regression took place 20,000 years ago (during the Upper Paleolithic ), then the sea level was 120 lower than today. 10,000 years ago, sea level rose only 20 meters below today's. Sea level rise can occur both from global warming, from melting glacier, and from tectonic movements.
Perhaps the most famous example of a land bridge is Beringia , connecting modern Alaska and eastern Siberia at least six times during the Pleistocene ice ages, allowing people to migrate from Eurasia to America.
Another example is Doggerland , the former land in the south of the North Sea that connected the island of Great Britain with mainland Europe during the last ice age.
Land Bridge Theory
Prior to the theory of plate tectonics, it was believed that land bridges could explain the emergence of such species on individual continents. Many land bridges were painted on maps, the most famous of them Lemuria . But when the bottom of the Atlantic Ocean was mapped using a sonar from 1924 to 1927, there was no doubt about their absence. Although this was an influential argument in favor of the theory of drift of the continents of Alfred Wegener , it would still take 50 years for it to become dominant.