Interpretations of the Walls Boundary fault usually take into account only a small part of the previously published evidence, and some even present unsupported speculative interpretations. In particular, geological accounts rarely mention the geophysical evidence available, and geophysical papers take little account of the geology of the area. This paper reviews all published evidence. Geological and marine geophysical evidence show that the fault passes from close to Fair Isle, through Shetland and continues to the northeast; that a 65 km dextral offset occurred in Jurassic times on a gouge-filled fracture; and that prior to this a net sinistral displacement of the order of 100 km had occurred, including a mylonite-producing offset of unknown sense and distance in Carboniferous times.
- Received October 21, 1991.
- Accepted April 3, 1992.
- © Geological Society of London 1992