Transform faults are important structures fundamental to the mechanism of sea floor spreading and plate tectonics, and yet, since they were first defined and explained by J. T. Wilson in 1965, they have been the subject of relatively little study in comparison with the other 2 major plate boundaries: mid-oceanic ridges and subduction zones. To my knowledge there has never been an international symposium concerned exclusively with transform faults, and for this reason the one-day meeting at the Geological Society was organized, with the aim of bringing together in a comprehensive manner the diverse aspects of trans- forms; this thematic set of papers results from the meeting. Transforms are faults along which 2 plates move past each other by simple shear with no creation or destruction of lithosphere. They were first recognized in the NE Pacific (Mendocino, Murray and Pioneer fracture zones, e.g. Vacquier 1965), but recent study has been concentrated on the N Atlantic, e.g. on the Famous (c. 37°N), Kurchatov (40.5°N), and Charlie- Gibbs (52°N) fracture zones (Searle 1979), and the Oceanographer zone (35°N). Attention has often been focussed on 2 aspects: (a) the composition of the igneous rocks, ranging from basalts to gabbros, and serpentinized peridotites and breccias dredged from the fracture mne walls (Bonatti et al. 1974); and (b) the morphology and structure of the zones using bathymetric data (Searle 1979). These data provide unique constraints on the tectonic character and evolution of these oceanic boundaries.

In an important link paper, DeLong et al. (1979) present

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