Geologic Trips, Angel Island

Perimeter Road


Angel Island is a State Park and is easily accessible by ferry from Tiburon or Fisherman’s Wharf. The ferry dock is at Ayala Cove and from there the  easy 5-mile Perimeter Road provides good access to the island.


Most Franciscan rocks have not been metamorphosed, however, the Franciscan rocks that make up Angel Island are metamorphosed by extreme high pressure in the subduction zone. These rocks  must have been carried to greater depths in the subduction zone than most Franciscan rocks. You can see examples of all of the metamorphic rocks of the Angel Island terrane during a trip to Angel Island: schistose sandstone at Ione Point, blueschists at Camp Reynolds, schists and metamorphosed pillow basalt at Perle’s Beach, and metamorphosed serpentine a short distance north of Perle’s Beach.


Angel Island was an important military base during the Civil War. Stuart Point (lower photo), at the western tip of the Island, provides a commanding view of San Francisco Bay, as shown in this Civil War reenactment. Stewart Point is formed from hard pillow basalt of the Angel Island terrane.


Related Link

Geologic background:  Angel Island (pdf)


Exterior Websites

Angel Island Conservancy: 

          Visitor Information  

California State Parks: 

          Angel Island      Brochure


          Angel Island

The ferry dock at Ayala Cove on Angel Island.

Civil war reenactment at Stewart Point.