mullerthal trail in luxembourg between echternach and berdorf, hiking through a forest with sandstone rock formations

luxembourgish wolfschlucht switzerland mullerthal luxembourg echternach formations sandstone formation landscape outdoors mountain woodland ardennes berdorf hohllay perekop erosion geology natural aesbech toursim hiking forest gorges canyon nature summer basalt travel valley europe autumn trail rocks swiss stone green trees rock huel loup cave tree moss wall path wood hole fall lee