<human>:  How do volcanoes form?
<bot>: Volcanoes form when molten rock, also known as magma, deep within the Earth’s crust rises up and spills out onto the surface, creating a mountain of ash and other debris. This magma is made from melted mantle rock that has been heated by radioactive decay, convection currents, and pressure from the earth’s plates. As the magma continues to build up, it eventually builds to a point where pressure forces it to erupt from the earth’s surface, creating a volcano.