Land bridge

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A land bridge is a term in biogeography. It is a narrow land connection between otherwise separate areas, sometimes called an isthmus.

Its significance is that animals and plants may cross over it when the sea level is lower. They cannot easily cross when the sea level is higher, and water covers the land bridge. The separation of a once connected population often leads to speciation, the splitting of one species into two.

There are several causes which affect whether a land bridge is above or below the water. Plate tectonics may cause the rise or lowering of land. The causes of general sea level changes are not fully understood, but when sea levels fall, shallow sections of continental shelf may get exposed. Sometimes the sea floor rises due to "post-glacial rebound" after an ice age.

Notable examples[change | change source]