Continental drift is created at spreading centers, and this, along with subduction, drives the system of plates in a chaotic manner, resulting in continuous orogeny and areas of isostatic imbalance. The theory of plate tectonics explains all this, including the movement of the continents, better than Wegener's theory. Hans Stille and Leopold Kober opposed the idea of continental drift and worked on a "fixist" geosyncline model with Earth contraction playing a key role in the formation of orogens. Other geologists who opposed continental drift were Bailey Willis, Charles Schuchert, Rollin Chamberlin and Walther Bucher. In 1939 an international geological conference was held
Continental drift was missing. A second problem was that Wegener's estimate of the velocity of continental motion, 250 cm/year, was implausibly high. (The currently accepted rate for the separation of the Americas from Europe and Africa is about 2.5 cm/year). It also did not help that Wegener was not a geologist. Other geologists also believed that the evidence that Wegener had provided was not sufficient. It is now accepted that the plates carrying the continents do move across the Earth's surface, although not as fast as Wegener believed; ironically one of the chief outstanding questions is the one Wegener failed to resolve: