The document discusses the movement and deformation of Earth's crust. It describes the two types of crust - continental and oceanic - and how they undergo stress that causes rocks to break, tilt, and fold. There are three basic types of deformation: compression squeezes rocks closer together, tension stretches rocks out, and shearing causes rocks to twist or tear apart. Faults form when rocks move along breaks or cracks, and can cause earthquakes. Folding also bends and shapes the crust. These processes of deformation continually change Earth's surface features over long periods of time.