Land bridge is essentially a historical term: it refers to dry land exposed during periods of low sea level (see regression), connecting what are now separate continents or islands. The best-known is the Bering land bridge, which connected Asia and North America during the last ice age, enabling humans to migrate to the Americas by walking. Another land bridge connected Great Britain to Europe at around the same time. A historic land bridge surviving to the present day is the Sinai, connecting Africa with Asia; across this land bridge hominids and humans have migrated out of Africa.
Occurance
Land bridges generally occur on continental shelves: the Bering Strait, where the Bering Land Bridge was during the last glaciation, is part of the edge of the North American plate. For causes of sea level changes, see Sea level change.
A land bridge that rose from the sea floor because of upthrust at the edge of a continental plate is Central America. Where the Cocos Plate, an oceanic tectonic plate off the west coast of Central America is being subducted in a convergent boundary under the North American Plate to the north and the South American Plate to the south, first an island arc, and then continuous dry land have been created.
Examples
Other meanings
- Nowadays, the term land bridge is sometimes used for wide bridges built over highways for wildlife and park users to cross. A natural crossing of a waterway is known as a natural arch or natural bridge.
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