The three types of stress that act on Earth's rocks are compression, tension, and shear. Earth has three layers, they are the crust, mantle and core. The crust is further divided into different parts called continental plates. When these plates are pulled or pushed or move, a stress occurs. These stresses are: compression, tension, shear and confining stress. A shear stress happens when the stress force forces the crust in altered directions resulting to the breaking of crust making the plates smaller. This usually happens in plate boundaries.