There are different types of stresses that can act on rock and cause it to change shape or volume, including tension, shearing, and compression. Faults occur along plate boundaries when the rock breaks, and can be normal faults when the rock pulls apart, reverse faults when the rock pushes together, or strike-slip faults when the blocks of rock move past each other sideways. The hanging wall is the block of rock above a fault, while the foot wall is below.