A Petroglymph. You can see the different layers of rock if you know what you’re looking at. June 23, 2012 by Matt ThomasA Petroglymph. You can see the different layers of rock if you know what you’re looking at. Hovenweep National Monument About Matt Thomas Matt is an avid writer and explorer, who loves to showcase his home state of Colorado. His favorite place to be is right here in the Centennial State. Previous Post:A Petroglymph. You can see the different layers of rock if you know what you’re looking at.