This natural bridge belongs to the most spectacular geological outcrops of the thrust. The Niderenbach brook, on its way to the Legler hut (1820m), gouged its underground course in the younger, lower-lying, schistose, soft flysch rock. The much older Verrucano (top) has now been much eroded and only remains visible to the left and right of the "Chärpfbrücke". At low water, you can walk along the 50m-long, 3m-high underground watercourse (at your own risk!).