The convection currents shown in points 1 and 3 transfer heat from the outer core (number 4) to the lithosphere. Here, the lower density hot magma breaks apart the plates at point 2 creating a divergent plate boundary. This new magma mass will drive a lateral movement of the plates. The edges of the plates which have a higher density basalt rock will sink into the mantle and get consumed in trenches/subduction zones
