Fault-block mountains are produced when normal (near vertical) faults fracture a section of continental crust. Vertical motion of the resulting blocks, sometimes accompanied by tilting, can then lead to high escarpments. Tilted blocks are common in the Basin and Range region of the western United States. Level blocks lead to the horst and graben terrain seen in northern Europe. Fault block mountains commonly accompany rifting and are indicators of tensional tectonic forces.
Block Mountains can also be referred to as a horst. It is a steep-sided mountain, formed where a block of the earth's crust has been squeezed upward between two parallel fault lines.