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.
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 of San Luis Obispo County". Sierra Club San Luis Obispo. Retrieved 2009-06-25.
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