A magnetic anomaly survey in the four deep-water basins in the central and southern Gulf of California shows no obvious pattern of magnetic lineations of the type that would be produced by sea-floor spreading. It is possible that rapid sedimentation from the adjacent land masses attenuated the anomalies by impeding the acquisition of thermal remanent magnetization.
Hypothetical fracture zones were generated about various published locations for the rotational pole of the Pacific and North American plates. These model fracture zones were constructed at the locations of mapped fracture zones in the gulf and show that 52°N., 76°W. suggested by C. G. Chase is an acceptable pole position for Pacific-North American plate boundary motions in the Gulf of California.