Bedrock Mortars

3D ModelNoAI

The hills around Mount Diablo were home to many tribes over more than 10,000 years. The bedrock features were used to process acorns that needed to be soaked 7 times to extract the bitter tannic acid. The acorns were then cooked using hot stones, unsually in woven baskets. It appears that incoming acorns were processed in bulk from the top down. The acidic water combined with wear shaped this place to make it more habitable. Typically, seven grinding holes would be used by each family. Some of these large basins suggest group activities and other ways of processing.