Volcanic eruptions are among the most stunning phenomena in the natural world. Volcanoes erupt because of the way heat moves beneath Earth’s surface. Heat is conveyed from the planet’s interior to its surface largely by convection—the transfer of heat by movement of a heated fluid. In this case, the fluid is magma—molten or partially molten rock—which is formed by the partial melting of Earth's mantle and crust. The magma rises, and, in the last step in this heat-releasing process, erupts at the surface through volcanoes.
