In 1912, Alfred Wegener proposed the theory of continental drift, stating that all the continents were once joined together and slowly moved apart. However, his theory was not widely accepted in his time. In 1962, the discovery of sea floor spreading (sea floor being forced apart by the formation of new crust) eventually led to a more modern and widely accepted theory of plate tectonics. Why did the theory of plate tectonics improve upon Wegener’s theory of continental drift?