A patchwork of plates Most responsible for surface geology are tectonic plates. Plate movements carried the continents to their present-day positions. They split what is now New Mexico, dragging up hot mantle material in a volcanic eruption 500 times larger than that of Mount St. Helens. Plate collisions built mountain ranges such as the Himalayas. Today, as plates slip past each other, we get earthquakes.
Tectonic plates cover the Earth like a giant patchwork.
Much of the plates' geological work occurs when they sink into the mantle, as they do today around the rim of the Pacific Ocean. He considers this progress their most exciting achievement. Plates behave as brittle solids at the planet surface but become soft and plastic as they dive into the pressure cooker of the mantle. With some plate physics in hand, Princeton University's Hans-Peter Bunge, Baumgardner and collaborators are busy reconstructing a history of mantle and tectonic plate motions. It goes back 120 million years in geological time.