A permanent source of heat:
The bowels of the Earth closely resemble a giant thermal power station, powered by convection currents that heat the surface by taking energy from the rocks buried deeper underground. At the very centre of this giant factory we have the inner core and the molten outer core. Moving outwards, we have the terrestrial mantle, followed by the Earth’s crust. The outer layer of the mantle and the whole of the crust are sometimes collectively referred to as the lithosphere: a puzzle comprised of twelve enormous pieces that move against each other to the rhythm of powerful subterranean currents. These pieces are known as tectonic plates, and the boundaries between them are where the Earth’s inner workings can most clearly be seen; as these are places where one frequently finds earthquakes and volcanoes.
CNRS