Sea of Cortez

The Gulf of California came into being as tectonic forces rifted the Baja California Peninsula off of the North American Plate. As part of this process, the East Pacific Rise propagated up the middle of the Gulf along the seabottom. The Gulf would extend as far as Indio, California except for the tremendous delta created by the Colorado River. This delta blocks the sea from flooding the Mexicali and Imperial Valleys. Volcanism dominates the East Pacific Rise. The island of Isla Tortuga is one example of this ongoing volcanic activity.