Convection currents are movements of heat within the mantle. The material in the mantle is heated by the core. The material in the mantle is heated by the core; causes mantle material to expand, less dense, rise and diverge beneath the plates. Plates are dragged along and move away from each other. Then, the hot molten mantle cools, denser, sinks, pull plates along. Process repeats. The slab-pull force also causes tectonic plates to move: Occurs when an oceanic plate (denser) subducts under a less dense plate. Pulls the rest of the plate along. The subducting plate drives the downward-moving portion of convection currents. Mantle material away from the subduction zone drives the rising portion of convection currents.