<P> A special class of strike - slip fault is the transform fault, when it forms a plate boundary . This class is related to an offset in a spreading center, such as a mid-ocean ridge, or, less common, within continental lithosphere, such as the Dead Sea Transform in the Middle East or the Alpine Fault in New Zealand . Transform faults are also referred to as "conservative" plate boundaries, inasmuch as lithosphere is neither created nor destroyed . </P> <P> Dip - slip faults can be either "normal" ("extensional") or "reverse". </P> <P> In a normal fault, the hanging wall moves downward, relative to the footwall . A downthrown block between two normal faults dipping towards each other is a graben . An upthrown block between two normal faults dipping away from each other is a horst . Low - angle normal faults with regional tectonic significance may be designated detachment faults . </P> <P> A reverse fault is the opposite of a normal fault--the hanging wall moves up relative to the footwall . Reverse faults indicate compressive shortening of the crust . The dip of a reverse fault is relatively steep, greater than 45 ° . </P>

Dip slip faults in which the hanging wall moves down relative to the footwall are called