posted by Ashton .
The thermal energy of volcanoes and natural hot springs comes from trace amounts of radioactive minerals in common rock in the Earth's interior. Why isn't the same kind of rock at the Earth's surface warm to the touch?
Inside the Earth the heat is trapped; so, over billions of years, it heats up magma and the4 metloaqllic core to the melting point. Near the surface, the heat can escape to the surface and be transferred to the atmosphere or be radiated away.