Convection inside the Earth
. Elongated convection cells in the asthenosphere may be aligned in long cylinders that drive the overriding lithosphere plates along like a conveyor belt. A larger-scale circulation transports heat from the volcanic mid-ocean ridge to a deep-ocean subduction trench. Similar large-scale convection currents may lift and lower entire continents. Heat-driven convection in the fluid outer core probably generates and maintains the Earth's magnetic field.
Copyright 2010, Professor Kenneth R. Lang, Tufts University