This May 2012 photo provided by the U.S. Geological Survey shows ancient carvings on limestone boulders in northern Nevada's high desert near Pyramid Lake. The carvings have been confirmed to be the oldest recorded petroglyphs in North America - at least 10,500 years old. The findings were published August 2013 in the Journal of Archaeological Science. This site was once the shoreline of the now dried up Winnemucca Lake. (AP Photo/USGS, Larry Benson)