Mesas and gulleys, Petrified Forest National Park, Arizona. Interestingly, the luminance histogram of this image also looks like a mesa.

Shot with the Nikon D70s and the 18-70mm f/3.5-4.5 zoom at 18mm, ISO 200, f/13 shutter 1/320 sec. Exposure, contrast, saturation, levels, highlights, and color adjustments in Aperture.