This movement is called continental drift or plate tectonics. The lithosphere determines what we see on the surface of the planet. Thick lithosphere means boring. Size of lithosphere determined by the internal temperature of the planet. Heat transported outward by conduction and convection.
Conduction is the main process for transporting heat through the lithosphere.
Heat transfer when two solids are in contact with each other. The hot material expands, gets less dense, and rises. It cools when it gets away from the heat source, gets denser, and falls again. The planets' interiors are cooling. The initial heat of formation is gone.