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 red reddish-brown shaped surface crack fiber grain knots redwood ripples saw marks slab wood yellow