Hundreds of ancient rock rings have been found in northeastern San Diego's Anza-Borrego Desert State Park.
Roughly 500 of these ancient formations are visible in a 10-square mile area of the park. Experts have confirmed that they were made thousands of years ago, but haven't been able to pinpoint their exact age. What they have confirmed is that the formations are not natural.
Associate state archeologist Haley Elsken told FOX5 “There’s no way the rock line circles are naturally occurring.”
The Anza-Borrego is the traditional homeland of the Cahuilla, Kumeyaay and Cupeño, and Elsken attribute the circles to these Native Americans. The formations are primarily in the remote, elevated sections of the park not frequented by hiking or campers. However, Elsken cautions anyone who may encounter one of the ring formations to leave it untouched.
“This is the Kumeyaay land and we’re guests on it,” Elsken said. “Respect that land, especially when we see cultural sites.”
One theory about the purpose of the circles comes from archeologist Malcom J. Rogers, who says similiar formations were documented in California during the early 20th century. Rogers dubbed them "sleeping circles," and theorized that early hunters may have used them to bed down at night.