Radiocarbon dating service
The rocks are located on the coast of Sonoma County about 75 km north of San Francisco, within Sonoma Coast State Beach, a unit of the California State Park System.
To date, I have located six sites consisting of one or more rubbing rocks, all within an area about 4 km in diameter.
Jasper Rock: A, midsection of an obsidian serrated projectile point; B, obsidian corner-notched serrated projectile point; C, chert burin-like end scraper with blade scars on dorsal surface; D, chert backed bladelet; E, quartz blade-like flake (? ); G, chert backed bladelet; H, obsidian backed bladelet; I, chert backed bladelet.
CA-SON-1719: J, chert blade-like flake; K, chert blade-like flake; O, chert side scraper; P, obsidian burin spall (? SCSB-03-2: L, quartz thumbnail scraper; M, chalcedony side scraper (has polish on edge at bottom of image). CA-NAP-58: Q, obsidian microblade; R, obsidian microblade; S, obsidian microblade, 35 mm long.
The other two loci are smaller blueschist boulders (4 and 5 m tall).
(1) These are features that I believe were used for grooming by now-extinct Ice Age megafauna such as .
The spring and fall 2003, and spring 2004 archaeological field classes from Santa Rosa Junior College, under the direction of Thomas Origer, and a summer 2003 volunteer crew under my direction, have to date excavated approximately 30 cubic m of the site.
In spring 2003, six 1x1 m units were excavated near the jasper outcrop.
Additionally, an auger test within the deep unit had been excavated to a depth of 403 cm.
As we excavated down, we discovered that the rock outcrop is polished to a depth of 2 m below the current ground surface.