Think of Earth as a giant ball. The middle of the ball is called the core, and around the core is the mantle. Both these layers of rock are fiery hot. They’re so hot, the rock is in a liquid state.
The outermost layer of Earth is called the crust. Unlike a ball, however, the crust is not one smooth, continuous surface. Instead, it is made up of a number of huge slabs, called tectonic plates. The plates fit together like a giant jigsaw puzzle, but they are constantly moving—a few inches every year. As the plates move, mountains take form.
