CAUTION: Post Storm Damage to Coastal Trail
The Presidio Coastal Trail segment just north of the Pacific Overlook and adjacent to Lincoln Blvd remains CLOSED indefinitely. We have posted signage to alert bicyclists and hikers and with information for safe trail alternatives. More »
Will Elder, NPS
Basalts are a type of volcanic rock and are the most common crust rock. Volcanic rocks are extruded above land or the seafloor, resulting in very fine-grained textures. Basalts have less silica and more iron than other volcanic rocks and tend to be black in color. The Franciscan Complex contains pieces of oceanic crust that include basalts erupted at mid-ocean ridge and island arc settings in the Pacific.
Many times these Franciscan basalts have been metamorphosed by hydrothermal activity into a greenish rock known as greenstone.
Did You Know?
Crissy Field was the only Army airfield in the western United States continuously active from 1919 to 1936.