"This book brings together fifteen articles from Scientific American that describe the latest scientific revolution - the revolution in ideas about the behavior of the earth's surface. Formerly, most scientists regarded the earth as rigid and the continent as fixed, but now the surface of the earth is seen as slowly deformable and the continents as "rafts" floating on a "sea" of denser rock. The continents have repeatedly collided and joined, repeatedly broken and separated in different patterns, and, very likely, they have grown larger in the process."--Preface.