In 1915 the first edition of The Origin of Continents and Oceans, a book outlining the Continental Drift theory of Alfred Lothar Wegener, a German meterologist, was published; expanded editions were published in 1920, 1922, and 1929. About 300 million years ago, claimed Wegener, the continents had formed a single mass, called Pangaea (from the Greek for "all the Earth"). Pangaea had split, and its pieces had been moving away from each other ever since. Wegener was not the first to suggest that the continents had once been connected, but he was the first to present extensive evidence from several fields. He was subsequently proved right, although he was wrong in one respect; the continents don't drift on their own, they move as part of much larger "plates" of the Earth's surface, much of which is ocean floor.