The view from the top of Bishop Peak looking towards Morro Rock.
The Nine Sisters or the Morros are a chain of nine volcanic mountains and hills in western San Luis Obispo County, central California. They run from Morro Bay east through San Luis Obispo.
The peaks were created over 20,000,000 years ago during the Miocene Epoch of the Neogene Period, as volcanic plugs of magma which welled up and solidified inside softer rock which has since eroded away.
Two of the plugs are in Morro Bay State Park. The highest plug is Bishop Peak at 1,559 feet (475 m).
The peaks in order from Morro Bay to San Luis Obispo including their height.
- Morro Rock 576 feet (176 m)
- Black Hill 665 feet (203 m)
- Cerro Cabrillo 911 feet (278 m)
- Hollister Peak 1,404 feet (428 m)
- Cerro Romauldo 1,306 feet (398 m)
- Chumash Peak 1,257 feet (383 m)
- Bishop Peak 1,559 feet (475 m)
- Cerro San Luis 1,292 feet (394 m)
- Islay Hill 775 feet (236 m)
The Nine Sisters, being less accessible to human intrusions, support a wide variety of Coastal sage scrub and California oak woodlands flora, and of birds and other fauna.
Their volcanic origin makes them of significant geological interest. They are popular with photographers and rock climbers.