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A fault block mountain range is formed by tension as rocks are pulled away from each other. A fault block is a section of rock bounded on at least two sides by faults.
Faults commonly break the crust into large, fault bounded blocks. If normal faults down drop one fault block relative to other blocks on either side, the resulting feature is called a Graben.
A block that is uplifted relative to blocks in either side is called a horst.
