Mountain ranges hold new clues to Pangaea's formation

The upper Paleozoic period, from roughly 400 million to 260 million years ago, saw the surface of the Earth go through a radical transformation. It was during this period that most of the Earth's dry land came together to form the supercontinent Pangaea. The collisions and rifts caused by the tectonic drift left marks still visible today; among these are the Allegheny and Appalachian mountain ranges in eastern North America and the Variscan Mountains in northwestern Africa and Europe. These ranges share the same origin: the collision of Gondwana and Laurasia roughly 300 million years ago.