Normal fault

A dip-slip fault in which the hanging wall moves downward relative to the footwall. It commonly forms when the crust is stretched.

Hanging wall: The block of rock above an inclined fault plane. Its downward motion relative to the footwall defines a normal fault.
Fault (geology): A fracture or zone of fractures in rock along which measurable displacement has occurred. A normal fault is a specific fault type, distinguished by its displacement.
Reverse fault: A dip-slip fault where the hanging wall moves upward relative to the footwall. It has the opposite vertical displacement sense under crustal shortening.
Rift valley: A long, low-lying region formed as crustal blocks subside between extensional faults. Paired normal faults can bound a subsiding rift valley.
East African Rift: A zone of continental extension and rifting running through eastern Africa. Its fault systems illustrate active normal faulting during continental breakup.
Footwall: The block of rock beneath an inclined fault plane. It provides the reference block for describing normal-fault displacement.
Strike and dip: Measurements describing a planar feature’s horizontal orientation and inclination. They specify the orientation of a normal fault’s plane.
Thrust fault: A low-angle reverse fault along which the hanging wall moves upward over the footwall. It is a low-angle member of the reverse-fault family, unlike typical extensional normal faults.
Graben: A down-dropped crustal block bounded by faults on both sides. Normal faults commonly form the graben’s bounding structures.
Mid-Atlantic Ridge: A divergent plate boundary where new oceanic crust forms between separating plates. Normal faults accommodate extension along portions of the ridge.

Linked from 22 pages