CNN - Researchers have made an amazing discovery - one that dates back thousands of years.
High-tech analysis shows engravings found on several boulders in western Nevada date back at least 10,000 years - but some researchers say they could be up to 14,800 years old.
Researchers used several methods to determine the age of the etchings, including testing mineral layers on the rocks. The findings mean these are the oldest known rock carvings in North America.
The boulders are located near Winnemucca Lake - 35 miles northeast of Reno. Researchers say the carvings consist of "large, deeply-carved grooves and dots forming complex designs."
Researchers have known about these engravings for decades, but weren't show how old they really were.