When Alfred Wegener first proposed his theory of continental drift, most Earth scientists did not immediately accept it. Many expressed skepticism because the theory did not explain what force was strong enough to move continents. Later, scientists investigating continental drift found evidence that explained how continents are able to move. Plate tectonics, which grew from the theory of continental drift, now explains how continents move over time. How was the initial skepticism of earth scientists useful to the scientific process?