Since the advent of space exploration, we have gained a new perspective on the globe we call the Earth. Photographs from space show a view of Earth floating in the heavens, white clouds swirling above the oceans and continents. Within this sphere is contained a series of concentric layers. At the centre is a solid core surrounded by a dense, bubbling mass of super-heated molten rock. We live on the surface of a fragile, shifting crust in places barely 3 miles thick. The Earth's surface is constantly moving at all times. Some 200 million years ago, there was only one vast continent on the earth, Pangaea. Over millions of years, the land masses have moved and separated and continued to do so. Today, about 135 million years ago, South America began to drift away from Africa. The Earth's crust consists of rigid plates which are continually shifting position. The plates are moved by convection currents in the molten layer beneath the surface. As the plates separate, usually along the thinner oceanic trenches, molten lava rises from beneath the surface and moves into the gap that is created. New Rock helps push the plates apart.