An Integrated System of Guns
San Francisco's harbor defenses relied on a complex system of guns, underwater mines, and antisubmarine nets. Central to the system were guns of many sizes, each with its own purpose. These guns were classified by the diameter of the projectiles they fired.
Did You Know?
Megafossils (fossils that can be observed with the unaided eye) are rare in Franciscan Complex rocks, but the rocks of “The Rock,” Alcatraz, have yielded significant examples.