Loose sand and rock fragments, transported by high winds, impact on the bedrock and slowly remove parts of the surface - the natural effect mimicked by a sand-blaster. If these winds blow in the same direction for long enough, 'wind-lanes', as seen in the picture, can form given the right ground conditions. The linear walls of rock left standing are called yardangs. Where the rock is more resistant, the erosive force of the wind may not be enough to cause this sandblasting. Such variation in erodability might be the reason for the three flat, relatively unsculpted regions (in the foreground...