Arizona is all about the rocks. We took a detour from I40 through the Petrified Forest National Park, stopping first at a couple of cool rock shops.
The Petrified Forest/Painted Desert has a small but cool visitor center with friendly rangers, Late Triassic dino fossils, and a great walking trail lined with giant petrified logs. Further into the park we stopped and looked at some petroglyphs. People lived in this area for thousands of years and left many archeological traces.