Route 1 - San Luis Obispo North Coast Byway
The Morros, CA

Bishop Peak is the highest of nine volcanic cores called the Morros (the noses) or the Nine Sisters, which run from San Luis Obispo to Morro Bay in central California. A tenth Morro, Davidson Seamount, sits submerged offshore. All of them are volcanic plugs dating from the early Miocene era, 20-25 million years ago. All formed as an abrupt change in the local tectonic regime opened this subduction wedge to rhyodacitic volcanism. The sticky, high-silica lavas of the Morros, which once were the deep cores of volcanoes, contrast vividly with the surrounding serpentinite and melange of the Franciscan formation.