Convection currents in the earth’s mantle are responsible for the movement of tectonic plates. as shown in the diagram, heat from the earth’s core is the driving force that moves magma in a circular motion called "cells.” how is this circular motion achieved? heat ‘"pushes" the magma up, and when it hits the lithosphere it is pushed back down towards the core. heated magma is magnetic and is drawn to the lithosphere where it loses its magnetic force and drops back down due to gravity. heated magma rises from the core, but rocks in the asthenosphere block the magma on each side, causing it to move in small circles. hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.