abstract appearance background brown colored coloring colors coloured colouring colours contours contrast contrasts cracks fissures flaws grit gritty layered layers levels light lines natural ribbons rock rock-face rockface rocky rough rugged sandstone sandy shade shades of color shades of colour shadows shape shaped shapes stone strata stratum sunlight sunny sunshine surface surfaces texture textured textures veins wallpaper animal Balanus barnacle boulder cluster crowd crustacea Gower group invertebrate marine pool sea sessile wales