Bishop Peak, a 1,546-foot volcanic plug in San Luis Obispo, is the tallest of the Morros, or Nine Sisters, stretching toward Morro Bay. Formed about 20 to 25 million years ago when magma cooled into dacite beneath softer rock, it was exposed as erosion wore the surrounding material away. Its thin, rocky soils support oak woodland, sage scrub, and chaparral, along with birds of prey, small birds, deer, foxes, coyotes, bobcats, and mountain lions. Since at least 1890, stone from the peak has been quarried for local curbs and buildings. Much of the mountain is now protected in the 350-acre Bishop Peak Natural Reserve.