coastal sand dunes covered with lush green marram grass overlooking a vast tidal flat under a misty sky in authie bay near berck,

sand dunes marram grass coastal authie bay berck france nature landscape tidal beach wetland overcast misty wilderness fortmahon somme hautsdefrance marquenterre picardy northern europe sea mud slikke schorre salt marsh ecosystem environment flora biodiversity green brown horizon remote untouched estuary grassy meadow cloudy sky habitat ecology conservation serenity natural panoramic french