Round house at Indian Grinding Rock State Historic Park

Chaw'se Indian Grinding Rock State Historic Park is a historical state park located in the Sierra Nevada foothills of California, eight miles east of Jackson. The park is named after a great outcropping of marbleized limestone with some 1,185 mortar holes — the largest collection of bedrock mortars in North America.

The park is nestled in a little valley 2,400 feet above sea level with open meadows and large specimens of Valley oak (Quercus lobata) that once provided the Miwok peoples of this area with an ample supply of acorns.

Chaw’se is the Miwok word for grinding rock. Upon this rock, they ground the acorns and other seeds into meal, slowly forming the cup shaped depressions in the stone that can still be seen today. Along with the mortar holes, the main grinding rock within the park also features a number of decorative carvings (petroglyphs): circles, spoked wheels, animal and human tracks, wavy lines, etc. Some of these carvings are thought to as much as two or even three thousand years old and are now becoming difficult to see. This association of rock art and bedrock mortar pits is unique in California. Except for one other small site, Chaw'se has the only known occurrence of mortars intentionally decorated with petroglyphs.