Continental drift plate tectonics theory. In particular, the English geologist Arthur Holmes proposed in 1920 that plate junctions might lie beneath the sea, and in 1928 that convection currents within the mantle might be the driving force. Holmes' views were particularly influential: in his bestselling textbook, "Principles of Physical Geology," he included a chapter on continental drift, proposing that Earth's mantle contained convection cells which dissipated radioactive heat and moved the crust at the surface. Holmes' proposal resolved the phase disequilibrium objection (the underlying fluid was kept from solidifying by radioactive heating from the core). However, scientific communication in the '30 and
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