The theory of plate tectonics, formulated in the 1960s, is the key to a conceptual understanding of the origin and evolution of the major features of the continents and ocean basins. It is now regarded as a great unifying principle and of importance to all the geosciences. This up-to-date book explains the role of plate tectonics in the origin and evolution of the ocean floor, islands, archipelagos and continents using annotated color illustrations.