abstract appearance background brown colored coloring colors coloured colouring colours conglomerate contours contrast contrasts cracks fissures flaws grit gritty layered layers levels light lines mica natural rock rock-face rockface rocky rough rugged shade shadows shape shapes silicate stone strata stratum sunlight sunny sunshine surfaces texture textured textures veins wallpaper shaped surface blocks cracked solid split strength angles garden-wall shades-of-color shades-of-colour wall