Volcanoes are mountains that form when magma and ash escape from an opening in the Earth’s surface. The type of geologic setting in which volcanoes form is determined by the type of plate boundary where the Earth’s crust is being pulled apart.
Volcanoes can form on three different types of plate boundaries: convergent, divergent, and transform. Convergent boundaries occur when two plates collide. The force of the collision pushes the plates together, and the thickened crust forms mountains, such as …