abstract appearance background blocks colored coloring colors coloured colouring colours conglomerate contours contrast contrasts cracked cracks fissures flaws layered layers levels light lines natural rock rock-face rockface rocky rough rugged shade shadows shape shapes silicate solid split stone strata stratum strength sunlight surface surfaces texture textured textures veins wallpaper backgrounds bare close-up dark dry edge edges grain gray grey grooves hard-wood lumber patterned patterns perspectives ridges shades-of-colour shaped surfaced timber tree tree-trunk trunk twisted uneven variations varieties wood wood-grain wrinkled wrinkles wrinkly