Today I traveled to a 600 acre “Mima Mound” rock circle area north of Weed, CA., near the Interstate 5 Weed rest areas and took these photos.
Per the internet: Each mound is similar, measuring about 60 feet in diameter and two feet high circled with rocks that appear to be set in a trench around the mounds. The largest rocks are up to boulder size.
Some scientists have proposed that the Mima Mounds are made of deposits from sediment rich floods from a glacially dammed lake. Other scientists added a new twist by suggesting that the mounds are sediment that collected where the water flowed around vegetation. Some have suggested that the mounds were the result of early Native American agricultural activity or the upheaving by frost or gopher activity.
The exact origin of the mounds and stone circles remains a mystery.