Badlands of South Dakota
South of Wall, which has (or had) that drugstore with roadsign adverts stretching across the US. These Badlands are a sea of grey from the lookouts. But there is some color as seen from this vista down inside the National Park.
Badlands may form when a harder, layered and perhaps poorly consolidated rock formation with soft rock below meets erosion coming sideways at it.
here's a link to a gallery of badland labyrinths from around the world: