What explains the movement of the earth's crust?

Answer 1

The earth's crust moves because the earth has tectonic plates that move because the magma under the earth's surface is constantly boiling. Since the water moves, it causes the earth's crust to move.

Answer 2

Beneath the tectonic plates is a thick layer of molten rock called magma. There is a lot of heat generated by radioactive decay deep in the Earth's core and this rises through the outermost magma layer causing it to flow. Since the tectonic plates are effectively floating on this magma layer they are affected by the flow and hence move.

Answer 3

The crust is broken up into plates and these plates move on top of the mantle.