The area east of Rancho Santa Fe, California, is characterized by the presence of a series of slightly metamorphosed andesitic volcanic and volcaniclastic rocks which are interbedded with sedimentary rocks of Late Jurassic age. These volcanic units are the result of explosive andesitic vulcanism in the area. Erosional remnants of the volcanic centers are preserved in the stratal record and indicate a local source for some of the volcanic rocks. The Southern California Batholith intrudes the Santiago Peak Volcanics and is the source of the metamorphism of the area. Metamorphism and intrusion were followed by deposition of a Cretaceous conglomerate on the erosion surface of the basement complex. Subsequent submergence produced the rocks of the La Jolla Formation. Post Eocene uplift of the area has produced the present topography.
