Geology

Tafoni Around the Bay

January 1, 2007

The tafoni weathering formation featured at El Corte de Madera Creek Preserve is a particularly accessible example of an uncommon phenomenon, but there are several other places to see tafoni in the Bay Area.

At Castle Rock State Park west of San Jose, similar Vaqueros Sandstone outcrops line the steep canyons that gird the crest of the Santa Cruz Mountains. The tafoni’s precipitous situation along rock faces and its likeness to Swiss cheese—providing ample finger- and toe-holds—makes it a favorite hang-out for rock climbers. Castle Rock State Park is located off Highway 35, 2.5 miles southeast of Highway 9.

Along the coast, two more beaches boast honeycomb tafoni formations, in the Pigeon Point Formations found at Bean Hollow State Beach and Pebble Beach in San Mateo County. The marine sedimentary rock is pocked with tafoni fretwork, but don’t confuse these formations with the rocks of nearby beaches that are scarred instead by rock-boring clams, who work their rough shells into the soft rock. Those scars can be distinguished from tafoni by the clam’s shell remains left behind in their furrows. Pebble Beach is located south of Pescadero State Beach off Highway 1, approximately 14 miles south of Half Moon Bay, while Bean Hollow State Beach is located off Highway 1, three miles south of Pescadero.

To the north of the Golden Gate, in the northernwestern corner of Sonoma County, you can find tafoni along the rugged seacliffs of Salt Point State Park. Here, the elemental forces of wind and waves have played a supporting role in sculpting the exposed rock faces. Salt Point State Park is located on Highway 1 about 18 miles north of Jenner, 90 miles north of San Francisco.

State Park Home Pages

Castle Rock

Pescadero State Beach

Bean Hollow State Beach

Salt Point State Park

If you happen to have a pair of red-blue 3D classes on hand, take a look at this USGS page of 3D photos of Pebble Beach, including tafoni formations.

About the Author

Matthew Bettelheim is a freelance writer and a wildlife biologist with URS Corporation.

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