The Franciscan Formation of California - Franciscan rocks in the Bay Area range in age from about 200 million to 80 million years old.

The sandstones are composed of grains which are similar mineralogically to the underlying Franciscan Formation.

The Espada resembles some strata of the underlying Franciscan Formation, even though the two units may have been deposited at great distances from each other, and brought together by tectonic forces along the boundaries of the Pacific and North American Plates.

Immediately south of the wilderness, opposite the Big Pine and Camuesa Faults, is a large region of the Franciscan Formation.

Franciscan Formation (United States)

Examples include the Franciscan Formation along the Coast Ranges of central and northern California and the Bay of Islands ophiolite complex in Newfoundland.

The orebody is a massive sulfide deposit of pyrite, chalcopyrite, and pyrrhotite along a shear zone in the Franciscan Formation.

In the Laytonville quarry, Zussmanite occurs in metamorphosed shales, siliceous ironstones and impure limestones of the Franciscan Formation.

The unit lies unconformably on the Espada Formation, also of Cretaceous age, and in places on the older Franciscan Formation, which is probably of Jurassic age.

Occurrences exist in western North America, including the southwest and the Franciscan Formation of the California Coast Ranges.