Paleoindians are often thought of as pioneering explorers or expert mammoth hunters. But new dating of geometric rock carvings in Nevada’s Winnemucca Lake basin now suggests they were also accomplished artists.

A team led by University of Colorado paleoclimatologist Larry Benson was able to date the carbonate crust that covers the petroglyphs. Benson concluded that the artwork must have been created more than 10,000 years ago, before the carvings were submerged beneath the lake’s higher waters and covered in carbonate. “We knew they were old,” he says. “We just didn’t know they were that old.” According to Benson, it’s possible that paleoartists made the carvings as early as 15,000 years ago.

Just what those artists meant to depict is unclear. Some of the petroglyphs may represent clouds and lightning, others are diamond- shaped, and there are some patterns that might represent trees. Whatever the inspiration for the carvings, the Pyramid Lake Paiute Tribe, which owns the Winnemucca Lake basin, considers them sacred to this day.