Nampaweap Petroglyph Site has the largest collection of petroglyphs on the Arizona strip. The petroglyphs are located on a long basalt flow that may be as recent as 1050 bce. Nampaweap is a very remote location located in the Grand Canyon-Parashant National Monument. There is no water, fuel or services of any kind in the monument. A high clearance 4 wheel drive vehicle is recommended and travel in the winter is inadvisable.
For more information visit the National Park Service here.
For anyone who wants to find out more about this site and the rock art of Northern Arizona we recommend the book Rock Art of the Grand Canyon Region by Don D. Christenson, Jerry Dickey and Steven M, Frees
You can purchase it here from Sunbelt Publications.