blue bluebells campion Cornish cornwall England english flowers forest Great Britain green natural nature oak pink spring tree wild woodland avalanche beach beware caution cliffs danger falls grunge grungy red rock sand sign stand warning background broken eroded erosion geology gray grey layers sedimentary texture worn fragments pieces shattered yellow coastline rocky sandy sea shore tide waves Anthyllis vulneraria coast flora kidney vetch May developing fern fresh frond garden growth pinnae plant pteridophyte stems temperate barnacles Cirripedia low tide Mollusca mussels Mytilus rocks seashells sessile shellfish ancient architecture battlements Cotehele fortified historical house manor national trust old stone tower windows