Geoparque Unesco

5 A geological race (Broto)

A geological race (Broto)

Localización: Camino acceso a la Cascada de Sorrosal.

Coordinates. 735842 4721168 30 N

Textos Esperanza Fernández (Geopage)

The Sorrosal waterfall is a work of art created by the action of two great sculptors: the ice of a glacier and the water from a mountain stream. Both carved a special material: rock with a layered and geometrical appearance, forged on ancient sea floors and subsequently folded during the formation of the Pyrenees.

Cascada de Sorrosal, en la que se aprecia la diferencia de altitud. Fotografía: Montse Montmany.

To understand the origins of the cascade, it is sufficient to observe the geography of where we are standing: we are about 900m high, at the confluence of two valleys, the Broto and the Sorrosal, a hanging valley about 125 m above us. What caused the difference in altitude between the two valleys?

During the Ice Age, this area was occupied by a huge tongue of ice, over 30 km long and about 370 m thick. As it advanced, the glacier wrenched materials from the valley floor and sides, consisting of boulders and sand which it dragged along, chiselling away and carving out the open depression we now call the Broto valley.

Realizado por Albert Martínez.

At the same time, the Sorrosal River, fed by a small glacier at its head, carved out the valley which today is occupied by villages such as Linas de Broto or Viú. The erosive action of a river is much weaker than that of a glacier, so the Sorrosal could not carve out as deep a valley as the Broto glacier. In essence, both competed in a geological race to see "who could erode the fastest".

Realizado por Albert Martínez.

Geology at work

Although the ice appears to have won, the competition is not yet over. Today, several geological processes continue to erode these rocks. The water and sediments that hurtle over the waterfall are still carving out this natural amphitheatre, creating rock falls, forming depressions at the base and causing the waterfall to retreat. These are the processes that have shaped the landscape and continue to do so here and now, right before our eyes.

Al caer al fondo de la cascada, el agua circula primero en forma de remolino. Especialmente cuando transporta rocas, arenas, maderas u otros objetos, este movimiento erosiona las rocas de la base. En consecuencia se forma una especie de cueva con un techo inestable que tiende a caer. Este mecanismo, repetido de forma continuada en el tiempo, origina el retroceso de la cascada hacia el valle de Sorrosal y su alejamiento de la confluencia con el río Ara. Figura: Oscar Rubio.

What do you feel?

The Sorrosal waterfall is a place to enjoy the simple yet enriching experiences provided by nature. Here, we can feel the rock vibrating beneath our feet. When the melt water storms past, our breast beats to the rhythm of its thunder. Sometimes, the hypnotic geometry of the rocks is softened by the water spray, which bedews our face. In the summer months, the natural pool at its base invites us to play in the water. And the natural beauty of the amphitheatre arouses, especially in lovers of rock climbing, an inevitable desire to scramble up to where the water swirls above before it leaps over the void.

La forma de acercarse a estos lugares de gran poder telúrico depende de cada persona, pero nadie queda indiferente ante un escenario como la cascada de Sorrosal. Fotografía: Ander Gómez.

Recomentations in your visit to Sobrarbe-Pirineos Geopark

  • Safe visits, unforgettable experiences. There are companies who collaborate with the Geopark where you can hire specialized guides to make your tour a unique and safe experience.
  • Respect the geological outcrops. Do not break off samples of rock, mineral or fossils.

Avda. Ordesa 79. 22340 Boltaña. Huesca. 974 518 025.