abstract nature background rock rockface shapes stone strata texture green isolated lines marbled pattern sedimentary wavy coastal coastline Cornish cornwall England english eroded erosion Great Britain layers natural nature rocks rocky sea shore tide water worn Arizona canyon colorado colours gorge grand canyon landscape national park river rock geology usa algae blue brown exposed Lofoten Islands low norway norwegian ocean plants rockpools seaweed weed appearance background colored coloring colors coloured colouring contours contrast contrasts cracks fissures flaws levels light ribbons rock-face rough rugged shade shades of color shades of colour stratum surface surfaces textured textures veins wallpaper