The heat from the mantle makes the rocks at the bottom of lithosphere slightly soft. This causes the plates to move. The movement of these plates is known as plate tectonics.
Plates at our plantes surface move because of the intense heat in the earth core that causes molten rock in the mantle layers to move. It moves in a pattern called a convection cell that forms when warm material rises, cools and eventually sink down. As the cooled materials sink down, it is warmed and rises again.
