Petroglyphs are found all over the varnished desert rock here at Grimes Point near Fallon, Nevada.  Here on the rock are an abundance of crater depressions known as "pit and groove".  The carvings are from different time periods, the oldest date back to nearly 7,000 years ago when the Lahontan Valley was still home to the large Lake Lahontan during the Ice Age.  More recent ones were created around 1500 AD.