Roughly halfway along the road that runs through the Petrified Forest National Park, you'll find a small detour to the west, where you can enjoy views of this valley, where the first of this type of fossils were found. At first glance you can see hundreds of fossilized trunks.
Over 600 petroglyphs are concentrated in this part of the Petrified Forest Park. They aren't easy to see with the naked eye, so you can use the telescope that you'll find here. For a closer look, I recommend the Puerco Pueblo area.