LAGO SUBTERRÁNEO Y GALERÍAS FÓSILES EN UN RELIEVE RESIDUAL: ARRATETAKO KOBA (SIERRA DE ARALAR).

The finding of a fossil cavity (= hydrologically inactive) with a network of 340 meters of galleries is described. The cave is developed under structural control and has an extensive underground lake, 62 m in length. It draws attention to its unusual location, as it is hung in a high position, on the top of a limestone reef residual bar (of early Cretaceous age), in the region of Txindoki (Aralar mountains). The cavity has various morphological features, speleothems and an interesting representation of troglobiont cave fauna. The probable genesis and evolution experienced by the cavity and surface relief in the region is discussed.