German scientist, Alfred Weneger, first made the point that the land mass, in which he named Pangea, seperated into several continents because of continental drift, and also a weakness in the earth's crust. The materials that the earth's crust is made up of a lesser dense material that caused each peice to break away centimeter by centimeter over a billion year time period. Also, these currents called convection currents heated the crust causing it to become softer and more frail. These currents were occuring in the earth's mantle and help drive the movement of each plate. . The evidance to support this is that the same types of plant and animal fossils have been found on the 7 continents. Also today earth's crust moves 2 cm every year.