A crack at the edge of the Sunset District
September 7th, 2007The image below is a view south from the Marin Headlands towards San Francisco’s western shore. The building perched on the edge of the Golden Gate, near the photo’s center, is the Cliff House, and behind it, to its right in the photo, Ocean Beach stretches south. At the southern end of Ocean Beach lies Fort Funston, and just to the right of Fort Funston’s orange cliff, a mile or two further south, one can see what geologists term a ‘horse’.
This particular horse is a product of movement on the San Andreas fault: one side of the fault has been thrust north, into the ocean. Daly City sits perched unsteadily atop the northern lip of the San Andreas’ rift. I live at the foot of this ridge in the Sunset District of San Francisco, below Daly City and just above the Cliff House in the photo.
The prominent ridge behind the San Andreas’ valley is Montara mountain, part of the Salinian block. The Salinian block is a fragment containing Sierra Nevadan granite that has moved several hundred miles north along the San Andreas.
