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
Association for the Study of Classical African Civilizations derives its membership from African Americans across class and occupational locations. The organization has since expanded into an international organization, with membership regions representing the continental United States, as well as the Caribbean, Africa, and Europe. ASCAC has four commissions which advance this agenda: education, research, spiritual development, and creative production. Along with creating study groups throughout the world, ASCAC holds an annual conference, operates a youth enrichment program, and is editing a comprehensive history of Africa. The Association for the Study of Classical African Civilizations was initially conceptualized and developed during the First Annual Ancient Egyptian Studies Conference in