In 1912, a German, Alfred Wegener, published his theory that a single continent existed about 300 million years ago. He named this supercontient Pangaea. published this theory of continental drift and claimed that it was supported by several pieces of evidence that these areas were once joined. Wegener's theories were unable to explian how continental movement could have taken place and his ideas gained little ground. From the 1940s onwards, however, evidence began to accumulate to show that Wegener could have been correct.
The mid-Atlantic ridge was discovered and studied. A similar feature was later discovered in the Pacific Ocean.
