Even if you’re not looking for them, you might find them: rock carvings portraying abstract shapes or distinct figures. Petroglyphs, or imagery made by scraping away at the surface of rocks or other materials, exist across the U.S. as well as other parts of the world. Those in the U.S. belong to Native Americans and, of those tested by scientists, date back 10,000 to 15,000 years. Some communities still create these images.
Some petroglyphs can be found in parks and reserves meant to protect the imagery, like Petroglyph National Monument in New Mexico or Sanilac Petroglyphs Historic State Park in Michigan. Other petroglyphs can be found in surprisingly-accessible parts of cities. Tempe Butte next to the Sun Devil Football Stadium in Tempe, Arizona, has dozens of petroglyphs, and many lie next to a public walking trail, says Chris Loendorf, a senior project manager for the Gila River Indian Community in Arizona. “If people knew what they were looking for, they couldn't miss them,” he says.
