abstract appearance background coloring colors colouring colours contours contrast contrasts cracks fissures flaws gorge layered layers levels light lines natural pool ravine reflections rock rock-face rockface rocks rocky rough rugged shade shadows shape shapes steep stone stones strata stratum sunlight sunny sunshine surfaces texture textured textures walls water block brown colored coloured edged edges edging heavy large red shadow solid split strength surface variations wallpaper conglomerate grit gritty shaped veins mica silicate