Displacements along strike slip faults in the ocean floor are measured by fitting magnetic anomaly patterns. In the northeastern Pacific Ocean the combined left lateral displacement of 1400 km across the Mendocino and the Pioneer faults can now be followed with a few interruptions from 140 to 165 degrees W, or a distance of 2200 km. The western end of the correlatable pattern has not yet been reached. In latitude the pattern stretches between 28 and 41 degrees N, or a distance of 1450 km. Right lateral displacements of 150 and 680 km separated by a disturbed zone have been measured on the Murray fault between 125 and 152 degrees W. The disturbed zone occurs on the south side of the Murray fault. It is characterized by more rugged topography and is bordered by groups of volcanoes at its eastern and western boundaries. Across the faults the bathymetric contours are displaced in the same direction and roughly by the same amount as the magnetic intensity pattern. Fourteen magnetic profiles across the Mid-Atlantic Ridge between 30 and 6 degrees S show a persistent magnetic anomaly on the crest of the ridge which can be followed from one profile to the next, whereas topographic features lack this continuity. Mapping the position of the crest anomaly suggests that if the ridge was originally continuous, it has now been cut into sections by strike slip faults.