Grinding Rock at Indian Grinding Rock State Park

Indian Grinding Rock State Park is located 12 miles east of Jackson off of highway 88 on Pinegrove Canyon Road.   This area was originally part of the Miwok territory.  The area had three different types of oak trees which produced acorns which was the primary food of their diet.  The park has a limestone outcropping which has been used for many years to grind the acorns.  There are 1,125 mortar holes in the park.  The acorns need to be leached because of the tannins in the acorn meat.  The Miwoks would shell, and then grind the acorn using a pestle in the mortar holes.  This is basically a rock that is rounded for grinding.  They would then leach the acorns by putting them in a sand basin and then pouring cold water on them.  The water would leach through the sand taking the tannins with it.  This was repeated until the water ran clear.  Also at the State park is a museum with cradle boards and weapons.  The park also included a round house and a Miwok village.  This included a granary and shelters.  The shelters were made from tree bark.