All of Earth's spheres interact to shape its surface. Resting above the mantle--and including the mantle's uppermost layer--is the lithosphere.This irregular rocky sphere forms the surface of Earth, which is thinner beneath the oceans and thicker beneath the continents. This book explains how the lithosphere interacts with Earth's other spheres to create the surface on which humans and animals live.It describes the forces that shape the surface--making mountains and valleys, plains and plateaus, gorges and canyons.And it explains the slow, though occasionally dramatic actions that keep Earth in a state of constant change.