Big Sur Geology

The mountains of the rugged Big Sur coastline rise to 5,000 foot summits within two miles of the ocean, the most abrupt elevation change of the entire Pacific shore.

Several hundred million years ago, river-borne sediments from a mountain range in what is now Mexico were deposited along the western coast. These layers of sandstone, siltstone and limestone were compressed and folded by the underriding of tectonic plates at the continent's edge. The sediments metamorphosed with pressure into schist, gneiss, granofels and marbles--now the oldest rocks in the Santa Lucia range.

By sixty five million years ago, this plate -- called the Salinan block -- began to drift northward. In response to the clockwise rotation of the Pacific Ocean's crust, the block was temporarily halted in its smooth progress and became jostled with faulting and uplifting, a process that still continues today. Seismic activity along the many faults is common as the mountains continue to be uplifed. Stream canyons frequently follow fault lines. Lateral faults are in the majority here, hence, most canyons parallel the coast rather than descend directly to it.

The highest peaks visible are granitic rock, which tends to be more resistant to erosion. In places where stream erosion was minor, the taller peaks may also be marble (metamorphosed limestone)--Pico Blanco is one such marble summit. The original sediments of sandstone and siltstone have been tilted up into cliffs in some areas. The sculpted shapes at Point Lobos are rare local examples of conglomerate formations.