San Quentin

Geologic Trips, Ring Mountain

Taylor Road


This photograph looks north from Taylor Road on Ring Mountain toward San Quentin. The boulders in the foreground are exotic blocks in the Tiburon melange. The soft clay of the Tiburon melange has been washed away leaving the exotic blocks on the surface scattered like plums in a plum pudding. The clay that forms the matrix of the melange consists of rocks that were ground into a fine powder by the thrusting action within the Franciscan subduction zone. The flat top of Ring Mountain is formed from two thick sub-horizontal layers of light yellow-brown serpentine. These layers represent coherent pieces of the lower part of the ocean crust of the Farallon plate that were incorporated into the Tiburon mélange.

Related Link

Geologic background:  Ring Mountain (pdf)


Exterior Websites

Bay Area Hiker: Ring Mountain Open Space Preserve

Marin Country Parks: Ring Mountain