Faulting

A fault is a break or fracture in the rocks along which the rocks are displaced relative to each other. The stresses and strains in the rocks cause this process when the plates move. The surface where the rocks have been displaced is called a fault plane. There are three major types of faults. Rift valleys and block mountains may be formed.

A normal fault, caused by tension, forms when the lithosphere is pulled apart by tensional forces. There is vertical or nearly vertical displacement of the rocks as one block is lowered relative to the adjacent block. It forms a steep scarp.

A reverse fault occurs when the lithosphere is subjected to compression. There is displacement of the rocks as a block rises relative to the adjacent block to form an overhanging escarpment.

A tear fault is caused when adjacent blocks of rocks slide past each other horizontally along the fracture.

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