Global Processes

The theory of continental drift - that the continents move relative to one another - was proposed by Alfred Wegener in 1910. It was not until 1945 that Arthur Holmes suggested a mechansim for the process - convection in the mantle. Complete evidence to convince most scientists that plate teconics - the movement of large segments of the outermost shell of the earth as a mosaic of large rigid plates - was a reality was not assembled until the 1960's.

Plate tectonics is the unifying theory that explains almost all the processes at work on the planet. It explains earthquakes, volcanoes, mountain-belts, ocean basins, and the topography of the sea floor in a single coherent idea. It forms the basis of the modern understanding of geological history and the evolution of our planet.