transform fault A type of strike-slip fault in an ocean, occurring at the boundaries of lithospheric plates, in which the direction of movement of the crustal blocks is reversed (or ‘transformed’) in comparison with a strike-slip fault on land. For example, at mid-ocean ridges the offset between adjacent ridge sections is a transform fault; where the displacement is dextral (right lateral) the motion, due to spreading, is left lateral, and vice versa. Generally, transform faults occur at right angles to the ridge itself and indicate the direction of spreading. The active transform fault extends into an inactive fracture zone.

transform fault Special class of strike-slip fault characteristic of mid-ocean ridges. Because of the transform faults, which are at right-angles to the ridge itself, the Mid-Atlantic Ridge does not run in a straight line but in offset steps.