The Gulf of California is an integral part of the North American Cordilleran segment located between lat 18° and 35° N.--the trans-Mexico volcanic belt of central Mexico and the Transverse Ranges of Southern California, respectively. Distributions of gross rock types and of major structures within these limits exhibit a characteristically Cordilleran north-northwest structural grain. That structural grain appears to have persisted since the Paleozoic Era, although the evidence is obscured by the effects of intense late Mesozoic orogenic disturbances. The Transverse Ranges structural trend, which terminates the Cordilleran segment that includes the Gulf, also appears to have had an ancient geologic history.

The demonstrable history of the Gulf of California begins with the Miocene, although redeposited older marine fossils and Eocene outcrops at the head of the trough in which the Gulf is situated suggest a possible earlier origin as one of the possible explanations for their anomalous occurrences.

Geological information available at present does not permit a definitive choice between several hypotheses for the origin of the Gulf, although recent geophysical work has ruled out the earlier widely accepted graben theory.