Continental Drift.

U.S. geologist Frank Bursley Taylor first put forward the theory of continental drift in a lecture in 1908. (People had never seriously questioned the permanence of the earth's continents until Sir Francis Bacon, in 1620, noted that the coastlines of South America and Africa, if pushed together, appeared to fit into each other like the pieces of a puzzle.) In 1912 the German geologist and meteorologist Alfred L. Wegener daringly proposed that about two hundred million years ago all the earth's land was a single gigantic land mass, which he called pangaea (Greek for "all-earth"). His theory set off a scientific debate that continued for many years. Wegener argued that the Earth's crust floated on a basalt layer and that over millions of years the original single supercontinent had broken up into the seven continents. Wegener was able to demonstrate that mountain chains on separate...