A set of petroglyphs in western Nevada dated in August 2013 to between 10,500 and 14,800 years old, are the oldest rock art ever found in North America, tracing back to a time in which it is believed the first inhabitants had recently arrived in North America.

The previous oldest rock art in North America was dated at 6,700 years old and can be found at Long Lake in Oregon . The Oregon petroglyphs were carved in rocks across approximately 60 sites, before being covered in ash from the Mount Mazama volcanic eruption.

The ancient petroglyphs in Nevada are carved into limestone boulders located on the west side of the now dried-up Winnemucca Lake. The rock art includes both simple petroglyphs such as straight lines and swirls and more complex petroglyphs that resemble trees, flowers, or the veins of a leaf. There is also a series of abstract designs that look like ovals or diamonds in a chain. The deeply carved lines and grooves in geometric motifs share similarities with the petroglyphs found in Oregon. However, the meaning and symbolism has not yet been deciphered.

A petroglyph found in Nevada appearing to depict the veins in a leaf

Nevada petroglyphs depicting geometric shapes

"We have no idea what they mean," said study researcher Larry Benson of the University of Colorado Boulder. "But I think they are absolutely beautiful symbols. Some look like multiple connected sets of diamonds, and some look like trees, or veins in a leaf. There are few petroglyphs in the American Southwest that are as deeply carved as these, and few that have the same sense of size."

The team of researchers were able to determine the age of the rock art by calculating when the boulders were last above the water line – though Winnemucca Lake is now barren, at other times in the past it was so full of water that the lake would have submerged the rocks where the petroglyphs were found.

A combination of sediment core samples and radiocarbon tests on the carbonate film left from the overflowing lake enabled researchers to conclude that the boulders were exposed first between 14,800 and 13,200 years ago and again between about 11,300 and 10,500 years ago. Regardless of which age range it is, the petroglyphs are at least 4,000 years older that the Oregon rock art, and possibly as much as 8,000 years older.

The findings were detailed in the December 2013 issue of the Journal of Archaeological Science.

By April Holloway