A ride through deep time
The Fuente Dé cable car travels 1,450 meters in length, ascending a 753-meter vertical rock face in under four minutes. The ride takes passengers through a dramatic geological inversion. The massive gray cliffs of the Picos de Europa are composed of Carboniferous limestone, a rock layer formed on a shallow marine platform roughly 325 million years ago. Below these ancient rocks, visible near the base of the mountain, are younger layers of reddish sandstone and mudstone from the Permian and Triassic periods, approximately 250 million years old.
This inverted stratigraphy, where older rocks sit on top of younger ones, is caused by a massive thrust fault. A thrust fault is a type of reverse fault with a low angle, where compressional forces push one block of crust up and over another. The sheer limestone wall ascended by the cable car is the exposed face of this immense geological structure. The fault line represents a clean break where an entire sequence of older Carboniferous rock was shoved horizontally for kilometers, ultimately resting on top of much younger Mesozoic sediments.
The Alpine collision
The forces required to create this structure originated with the Alpine orogeny, a mountain-building event that began around 50 million years ago. This process was driven by the collision of the African and Eurasian tectonic plates. The Iberian Peninsula, caught in the collision, was compressed, causing the reactivation of older faults from a previous mountain-building event, the Variscan orogeny. This intense pressure folded and fractured the existing Paleozoic and Mesozoic rock layers.
The thick, competent Carboniferous limestone acted as a single, massive unit. Instead of folding, it broke and was thrust southward over the weaker, younger clastic rocks. The result is the dramatic terrain seen today. The upper station of the cable car sits at an elevation of 1,850 meters on this displaced block of ancient limestone. From this vantage point, the surrounding high peaks are all part of this allochthonous, or non-native, rock sheet. The valley below, where the cable car begins its journey, represents the autochthonous, or native, younger rock layers that were overridden. The entire structure is a case of large-scale tectonic shortening, made unusually accessible by modern engineering.