A series of nine peaks between San Luis Obispo and Morro Bay originated as volcanoes beneath the sea that covered this area some fifteen million years ago. After the sea and volcanic explosions subsided, erosion began dissolving the softer mountain material around the volcanic rock and left nine volcanic peaks standing high above the surrounding landscape. These volcanic plugs include Hollister Peak and the famed Morro Rock.
Black Hill, the last peak in the volcanic series before Morro Rock, has a trail that tours a little of everything – chaparral, eucalyptus, oaks, pines, and coastal shrubs. From the mountain's 640-foot summit, you can view the Morro Bay Estuary, the sand spit, and the hills of nearby Montaña de Oro.