Petroglyph Canyon, Valley of Fire State Park, Nevada, USA. Southern Nevada has many petroglyph and pictograph sites crated by Paiute, Shoshone, Chemehuevi, and Anasazi. Some of them date back to 3000 years and possibly even further. Petroglyph images are scratched into desert varnish or patina, a dark thin coating on the rocks that usually consists of iron and manganese dioxides. Photograph taken in January 2008.