Continental drift

Continental drift, theory that the continents change position over time, moving very slowly. The theory was first suggested in 1912 by Alfred Wegener, a German meteorologist, who believed that the earth's land masses had once been joined in one supercontinent, Pangaea, which broke apart about 200 million years ago, forming the earth's continents. The theory was controversial for a long time, and it has since been revised by the modern concept of plate tectonics, which also incorporates continental drift.

See also: Geology.