Question: How are volcanoes made ?

David Pyle answered on 23 Mar 2011:

Volcanoes form when molten rock reaches the Earth’s surface, and erupts. Most molten rock forms between about 60 km and 100 km deep, and it rises because it is lower density than the rocks around it. When it erupts, the molten rock freezes, and becomes a solid. It’s this solid rock that then helps to build up a volcano around the vent. Most volcanoes seem to be active on and off for several hundred thousand years – with many eruptions, of different sizes, and plenty of time for erosion in between. This is why volcanoes can end up being quite complicated!