The Gulf of California is one of a group of structures which have resulted from the coincident westward dilation of North America and the dextral motion between the Pacific and North American plates. During the early history of the Gulf, this dilation occurred above a subduction zone.

We have subdivided this large province into 22 structural domains, each with a contrasting geologic history and have divided these histories into four intervals. The earliest of these is prior to 23 Ma, when the first nonmarine strata ponded in the initial depression. The period from 23-13 Ma was the premarine interval of arc volcanism; 13-5 Ma was the Protogulf era; and 5 Ma to the Present was the era of the modern Gulf.

The earlier intervals, characterized by large elevational changes and dilation unrelated to rhombochasmic opening, contrast with the recent interval characterized by passive strike-slip translation south of the Transverse Ranges.