When German meteorologist Alfred Wegener first proposed his groundbreaking theory of continental drift, in 1912, his geologist peers rejected his theory. Wegener's theory of continental drift proposed that the enormous landmasses slowly moved on the earth's surface over millions of years. His idea explained countless observations made about the earth, from how the continents formed, to what causes earthquakes, to how the earth's surface continues to change. It wasn't until decades after his death that the continental drift theory proved fruitful to other scientists in the 20th century.