The Western Valleys Natural Park is located at the nothwest end of the aragonese Pyrenees, bordering to the north with France and to the west with Navarre. Its relief has been moldeled by the accion of glaciers, which sculpted slender peaks while they dug cirques and U-shaped valleys, as well as depressions that brought about todays ibon (mountain lakes). The valleys contain a great wealth in species of fauna, some of which are endemic species of the Pyrenees.