Most of the geologists are of the opinion that block mountains are formed due to faulting.
Block mountains are formed in a number of ways:
(a) Block mountains are formed due to upward movement of middle block between two normal faults . The up-thrown block is also called as horst. The submittal area of such block mountain is of flat surface but the side slopes are very steep.
(b)Block mountains may be formed when the side blocks of two faults move downward whereas the middle block remains stable at its place. It is apparent that the middle block projects above the surrounding surface because of downward movement of side blocks. Such block mountains are generally formed in high plateaux or broad domes.
(c)Block mountains may be formed when the middle block between two normal faults moves downward. Thus, the side blocks become horsts and block mountains. Such mountains are associated with the formation of rift valleys.