The movement of which layer of Earth drives the motion of the plates on Earth's crust?

Mantle Layer. The movement of the tectonic plates caused by convection currents in molten rock in Earth's mantle below the crust drives the motion of the plates on Earth’s crust. The mantle is a layer between the crust and the outer core. Earth's mantle is a silicate rocky shell with an average thickness of 2,886 kilometres It makes up about 84% of Earth's volume