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Geology of Caves


Cuevas del Aguila are located on a hill of dolomite rocks formed on a carbonate marine platform of the Cambrian Period, more than 500 million years ago.

These types of rocks are susceptible to dissolution under certain environmental conditions, which combined with water can produce cavities over a slow geological process.

The Caves’ Formation

The circulation of groundwater from the rivers Avellaneda and Arenas formed several cavities around the water table in the subsoil. The enlargement of these cavities produced a number of collapses in the bedrock, which created the great main galleries that form Cuevas del Aguila. The last significant collapses occurred more than 75 thousand years ago.

Discover the History


The Caves boast a variety of colors and textures unlike other caves of the Iberian Peninsula, that tend to be more monotonous. This is due to their complex evolution, as consequence from the recurring phases of creation and destruction of the formations, which brings a great diversity of an underground landscape. The complex nature of the caves show a slow but incessant evolution in a continuous process of transformation.

The Formations

Cuevas del Aguila have a rich variety of speleothems: stalagmites, stalactites, pillars, flowstones, anthodites, helictites, straws and even moonmilk. Such diversity comes from the variations in the microclimate of the cave, and the context in which formations appear

Visit the caves

Current and past climate

The Caves have a stable atmosphere with a temperature that varies from 15 to 17ºC and a relative humidity of 100%. In the last 30 years, the temperature has changed by 2ºC as a result of the changes in the environment. Its stalagmites have revealed that the cause of the maximum extent of the glaciers in Gredos, which occurred 26 thousand years ago, were produced by a high rainfall in the region over a very cold period. Due to their special characteristics, scientists have been using Cuevas del Aguila for more than five years as a natural laboratory to study current and past climate changes.

David Domínguez Villar.
Researcher at the National Research Centre on Human Evolution
Carretera Cuevas del Aguila, S/N,
05400 Arenas de San Pedro
Ávila, España
+34 920 37 71 07