are metamorphic rock in mountains
Metamorphic Rocks of Ring Mountain, Tiburon. At only 602 feet in elevation, Ring Mountain is hardly a mountain. But it is well known to geologist and biologist alike because of its unusual geology and the unique plants that grow in the serpentine soils on the Tiburon peninsula. Serpentine is a metamorphic rock: a rock changed by heat and pressure. The high concentration of magnesium and calcium in the soils is usually toxic to plants, but some rare plants thrive [see: http://www.marin.cc.ca.us/~jim/ring/rplant.html].