The offset of oceanic ridges by faults do not follow the classical pattern of an offset fence or geological marker was well recognized by John Tuzo Wilson in Reid’s rebound theory of faulting. According to the theory, these transform faults produce slip in the opposite direction. The distance between the ridges does not increase because of this slip it separates. As the ridges are spreading centres, this distance remains constant. However, this theory was confirmed when the transform faults were shown pointing in the opposite direction in comparison to the classical interpretation.
Generally, faults are caused by compression, extension, or lateral stress in the rock layers, the effect of which is to relieve strain. The Transform Faults transport the strain between ridges or subduction zones and specifically relieves strain.
The length of the Transform Faults is determined on the type of faults or tectonic structures that connects with it. Hence, types of Transform Faults are as follows:
- Growing Length Faults: The Transform Fault itself grows in length in situations where a transform fault links together a spreading centre and the upper block of a subduction zone or when two upper blocks of those zones are linked.
- Constant Length Faults: The Transform Fault remains constant in many other cases due to different reasons. It is caused by the continuous growth by both the ridges outward in case of ridge-to-ridge transforms, avoiding any change in length. However, when a ridge is linked to a subducting plate, the opposite occurs.
- Decreasing Length Faults: Transform Faults may also shrink in length. This happens in rare cases when two descending subduction plates are linked. The Transform Fault decreases in length as the plates are subducted until it disappears completely, leaving the zones in opposite directions.
One of the most famous Transform Boundary is the San Andreas Fault. It is a continental fault extending through California in the United States. Its motion is right-lateral strike-slip and it forms the tectonic boundary between the Pacific Plate and the North American Plate.