Flexi Says: Tectonic plate motion is driven by mantle convection. Two main forces push and pull on the plates. Buoyant force pushes hot magma from deep in the mantle up toward the surface where it erupts at a mid-ocean ridge. The continual eruption and cooling of magma pushes older material away from a mid-ocean ridge crest. This is called ridge push. The other end of the tectonic plate is cool and dense. Gravitational force pulls this end downward back into the mantle at a subduction zone. This is called slab pull.
