Riggs Canyon Rock Camp
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Riggs Canyon Rock Camp


Riggs Canyon Rock Camp
113 bedrock mortars in a beautiful picnic site.
Elevation 1306 ft.

The Riggs Canyon Rock is a wonder. It is covered with more than 40 mortars, many of them ground into the base of geoconcretions. (In a geoconcretion a harder rock embedded in a softer rock is extruded over time due to various forces. When the harder rock pops out, it leave a cavity in the softer rock.) Did these mortars have special uses? Did the geoconcretions act like hopper baskets? Adjacent to the “Rock” (actually an extension of it) are two flat surfaces containing 46 deep, uniform, bullet-shaped mortars. The Rock was clearly a major processing site for something. Most mortar surfaces here are worn and chipped, a possible indicator of age.

Walk northeast from the Rock toward the cliffs. Stop in the clearing that forms a natural amphitheater. Doesn’t this space seem to recommend itself for ceremonial dances? Imagine chants echoing off the rocks of the amphitheater and feeding back to the chanters. At night, the effect would have been otherworldly and mesmerizing.

Hike up to the ridge above the amphitheater and dig the views. See if you can find the possible tsektsels (prayer seats) there.

This site sits on the principal entry trail into Volvon Territory from the San Ramon Valley.

There are 26 deep bullet-shaped mortars on the buff colored rock face.


This slab lies below the buff colored rock face depicted above. The uniform size and shape of these mortars together with their close spacing suggests that the Riggs Canyon Rock was a site for the mass production of some foodstuff.