It's no accident that South America looks as if it once rested beside Africa. The moveable crust of planet Earth. Rachel, some of Earth's continents look a lot like pieces to a jig-saw puzzle. Pull the eastern edge of South America to the western edge of Africa and you've got a near perfect fit. Fossils and rocks along the boundaries of those jig-saw pieces are similar.
Hot magma oozes from the ridge to create new ocean crust.
As new crust is formed, the sea floor spreads. Thus immense geological forces became known, which move the tectonic plates on Earth's surface. Now scientists have actually begun to measure plate movement itself. With thanks to the National Science Foundation, we're Block and Byrd for Earth and Sky.