Ibon

The entrance measures about four by six metres and has an access between blocks leading to a vestibule chamber about 10 m in diameter, formed by a strong channel filled with rounded pebbles, with erosion forms on the walls and vaults. Continuity develops on a steep gradient to give entry to narrow planes between vertical curtains and a passage on the right; this passage may be about 10 m higher than the entrance, this level coinciding with forms outside that may have coincided with a first water outlet. It continues in a spacious gallery with a clean floor and various potholes in continuous planes and in the manner of steps, increasing the gradient until reaching a spacious chamber with vertical walls. On its right side and above flowstone there is a 10 m access where another large chamber forms; this space climbs its floor over scree on its opposite wall and from the vault. The limestones develop in a stretch of about a few hundred metres in thickness.

The large chamber located above the flowstone has stalagmite formations.

From its mouth a strong flow usually emerges in winter-spring, which in summer becomes a spring at river level. In vertical fall the water drops from a cylindrical hole about 25 m higher. This water flow forms part of the supply to the village of Isaba, giving in summer a constant flow to the intake on the left bank of the Belagua river. The water supply of Izaba is partly from this point, appearing that at a level lower than the river there is a strong flow, its origin not being known and appearing that its previous outlet was at a higher level.

From the entrance, the access between blocks leads to the vestibule chamber; continuity on a steep gradient gives entry to narrow planes between vertical curtains and to a passage on the right. It continues in a spacious gallery with a clean floor and various potholes in continuous planes and in the manner of steps, increasing the gradient up to a spacious chamber with vertical walls. On its right side and above flowstone, a 10 m access leads to another large chamber.

It was monitored in the first phase of the hydrogeological plan for 3 years.