Geology


The San Andreas Fault, local volcanoes, and other remnants of tectonic plate activity

Santa Lucia Range

Santa Lucia Range

Most of the geological features in California’s Central Coast region were formed through the movement and collisions of  tectonic plates.

Around 60-40 million years ago, the oceanic plates adjacent to the continental North American Plate were changing. First, a dense oceanic plate, the Farallon Plate, dove under the lighter weight North American Plate (a process known as subduction). 

The Carrizo Plain

The Carrizo Plain

Then, about 30-35 million years ago, another tectonic plate followed behind the Farallon Plate: the Pacific Plate. Instead of being subducted, however, the Pacific Plate ground against the North American Plate’s edge and created the transform fault known as the San Andreas Fault. The rocks and features to the west of the San Andreas migrate northwest relative to those on the other side of the fault.

You can actually view the San Andreas fault line in specific areas such as San Juan Bautista and the Carrizo Plain.

Pinnacles National Park

Pinnacles National Park

A spectacular remnant of plate tectonic activity can be seen at Pinnacles National Park. Pinnacles National Park. It features two-thirds of a volcano that originally formed in Southern California. When the Pacific tectonic plate ground against the North American plate, the Pinnacles volcano sat astride the resulting San Andreas fault. And earthquake by earthquake, the Pinnacles moved along the San Andreas fault, to its current location 195 miles north of its birthplace.

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Big Sur Jade

"Jade" is the common name for two different rock types, jadeite and nephrite. Big Sur jade is a green nephrite jade, often found near serpentine.

The best time to find Big Sur jade is after a big Winter storm. The best place? Jade Cove, just south of Plaskett Point in Big Sur. To reach the narrow beach at Jade Cove, you will have to walk along a brushy trail and clamber down the cliff holding on to a rope to reach water level. The entire trail loop is about 1.5 miles.

Look for green pebbles in tide pools between boulders. Then try scratching them with a knife. If you can scratch a pebble, it’s serpentine. If not, it’s nephrite--Big Sur jade. We encourage "catch and release" rock hounding; leave the jade for everyone to enjoy. Jade Cove is protected as part of the Monterey Bay Marine Sanctuary.

You can see an enormous piece of Big Sur Jade in the Museum's Native Plant Garden. It was sculpted and polished by artist  Don Wobber, who hoisted the original boulder from the bottom of ocean in Jade Cove (years ago, before the Monterey Bay Marine Sanctuary was established).

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Pinnacles National Park

Pinnacles National Park

Pinnacles National Park

Visit the amazing rock formations at Pinnacles National Park. Wildflowers are in bloom in the Spring and the Caves are most likely fully open around October. Sometimes portions of the caves are closed to protect bats so you should check the cave status before you go. Some places in the caves require crawling and the caves are pitch black in spots so you must bring a flashlight -preferably a headlight to keep your hands free. Also look for tarantulas walking the trails in the Fall looking for a mate. Did we mention that you may see a California condor flying overhead?

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The Monterey Submarine Canyon

Get as close to the vast, submarine Monterey Bay Canyon System as you can without leaving land. Just offshore of Moss Landing is the main head of the Monterey Canyon. It extends 95 mi (153 km) into the Pacific Ocean while reaching depths of 11,800 ft (3,600 m). A subsidiary canyon head that also comes close to shore is the Carmel Canyon, and it can be appreciated from the dry sands of Monastery Beach or Point Lobos State Natural Reserve.  (WARNING: Monastery Beach is beautiful and deadly. Stay FAR away from the water.)

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Carmel Valley Gem and Mineral Society

Adults and children are all welcome to hear from gem and mineral experts and enthusiasts at the Carmel Valley Gem and Mineral Society monthly meetings. These meetings are held at the Museum at 7pm on the second Friday of each month (except June, November, and December.) Interested members are also welcome to attend the club's board meeting, held at the same location one hour before the general meeting.

The Carmel Valley Gem and Mineral Society (CVGMS) is a non-profit, educational organization dedicated to promoting the study of mineralogy and geology; to encourage the collecting of specimens and the practice of the lapidary arts; to promote field excursions to mineral locations and further the education of all.

CVGMS is a group of individuals with a common interest in Gems, Minerals and all forms of related trades and arts. Located on California's Central Coast, CVGMS attracts members from Carmel, Monterey, Pacific Grove, Seaside, Marina, Prunedale, and surrounding areas. We've been helping to raise awareness in our community of the natural geological resources for over 40 years.

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Upcoming Geology-Related Events