bird boulder chalk chalk cliff coastal coastline crumble crumbling crumbling cliff crumbling coast danger disintegrate disintegrating Disintegration erode eroding erosion fall gull insecure nature rock sea seabird seagull shore shoreline unsafe wave cliff cliffs coast dangerous drop edge England fallen sandstone seagulls sheer summer Sussex white bay face hazard hazardous high landscape south folly foolhardiness foolhardy foolish foolishness risk risky silly stupid stupidity tourism tourist barrier fence hole pit post quarry sand cliff sign warning warning sign work works blue boulders Malta mediterranean Natural landscape St Paul's Bay water