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
Ice Age: Continental Drift Ester Dean, performed by Keke Palmer. Both songs play during the credits and are not available on the soundtrack. "Chasing The Sun" can be found on The Wanted's 2012 American debut extended play, "The Wanted EP", while an alternate version of "We are (Family)" sung only by Keke Palmer is available for download. "Ice Age: Continental Drift" had its premiere on June 20, 2012, at the CineEurope film distributors' trade fair in Barcelona. It publicly premiered on June 27, 2012, in Belgium, Egypt, France, Switzerland, and Trinidad, and was released on July 13, 2012, in the USA. The film is