Bodega Head lies just on the west side of the
San Andreas Fault, which runs between the base of the promontory and the mainland. During the
1906 San Francisco earthquake, the promontory shifted approximately , displacing the harbor to the north relative to the mainland.
Geologically, the rocks of Bodega Head differ greatly from those on the mainland just to the east. Whereas the rocks of Bodega Head are exposed continental
granite, the mainland rocks are of oceanic origin from the
Franciscan Complex. Bodega Head is the northern tip of a vast geologic province known as the
Salinian Block whose core is of the same origins as the core of the
Sierra Nevada Mountains. The block was torn off the continent as the San Andreas Fault came into existence about 20 million years ago, and was transported northward hundreds of miles. Other nearby examples of the Salinian Block are the
Point Reyes Peninsula and the
Farallon Islands. A controversial attempt by
Pacific Gas & Electric Company to construct
a nuclear power plant on the peninsula was thwarted in 1964 due to environmental concerns and the susceptibility of the site to earthquakes. ==See also==