-Crust: The outer layer of the Earth.
-Plate: A section of the Earth's crust.
-Plate Margin: the boundary where two plates meet.
-Mantle: The dense, mostly solid layer between the outer core and the crust.
-Convection Currents: The circular currents of heat in the mantle.
AQA-The Structure of the Earth;
The CRUST-the outer layer of the Earth-is relatively thin. The crust is split into plates of varying size and at plate margins, it is liable to move. This is because the slabs of crust float on the semi-molten upper mantle. CONVECTION CURRENTS within the mantle determine the direction of plate movement. Therefore, in some cases the plates are moving together and sometimes they are moving apart. There are two types of crust: OCEANIC AND CONTINENTAL.