The tiny Juan de Fuca plate is largely responsible for the volcanoes that dot the Pacific Northwest of the United States. The plates make up Earth's outer shell, called the lithosphere. (This includes ...

Build mountains. Trigger volcanoes. Create new sea floor. You now have the power to change the landscape with the slightest push of your mouse. Four types of plate tectonic activity are demonstrated ...

New crust is continually being pushed away from divergent boundaries (where sea-floor spreading occurs), increasing Earth's surface. But the Earth isn't getting any bigger. What happens, then, to keep ...

The Earth is made of different layers: the core, mantle and crust. Plate tectonic theory shows that the crust of the Earth is split into plates (pieces of the Earth’s crust). The movement of these ...