Las Médulas is a scenic environment located near the eponymous village in the county of El Bierzo, province of Leon, autonomous community of Castilla y León. In the year 1997 Las Médulas was declared a UNESCO World Heritage Site. It is considered the largest open-pit gold mine in the entire Roman Empire.
In the 1st century A.D. the Roman Imperial authorities began to exploit the gold deposits of this region in north-west Spain, using a technique based on hydraulic power. After two centuries of working the deposits, the Romans withdrew, leaving a devastated landscape. Since there was no subsequent industrial activity, the dramatic traces of this remarkable ancient technology are visible everywhere as sheer faces in the mountainsides and the vast areas of tailings, now used for agriculture.
The engineering work carried out for the extraction of the mineral involved the alteration of the environment but resulted in a landscape of reddish sand, now partially covered with chestnut and oak vegetation. It is considered a “cultural landscape” and has the name of “Cultural Park”.
This environment was declared an Asset of Cultural Interest in 1996, in response to its archaeological interest. In 1997, it was declared a World Heritage Site by Unesco and Natural Monument in 2002. In its vicinity there is a quarry that despite being declared illegal in 2008 continues to operate.
The Romans began to work in the area at the time of the Emperor Octavius Augustus, who personally directed most of the actions that took place between 26 and 19 BC. C. definitively conquered the towns of the north of the Iberian Peninsula.
The current place name should not be confused with Mount Medulio, where the holocaust of Galicians, Cantabrians and Asturians took place, who preferred to die rather than surrender. However, the location of Mount Medulio is still under discussion.
Pliny the Elder, who in his youth was administrator of the mines, reports that 20,000 pounds of gold were extracted per year, which taking into account the 250 years of exploitation, would give 5,000,000 pounds of gold. According to the data of the professor and archaeologist Antonio García Bellido, the removed lands reach 500 million cubic meters, which calculating an average yield of 3 grams per ton of land would result in 1,635,000 kg. However, other studies reduce these figures considerably, considering that during the 200 years in which the mines were explored, an average annual production of less than 25 kg was obtained, and therefore the final figure was less than 5,000 kg.
Regarding the number of workers, Plinio speaks of 60,000 workers who have been released. Modern studies, based on the removed earth, speak of 10,000 or 20,000 men, with suppliers, guardians, etc. Pliny comments in his writings the hardness of the work: “it is less foolhardy to look for pearls and purple at the bottom of the sea than to get gold from these lands.”
In the environment that we know today as Las Médulas, there were a series of favorable circumstances for the extraction of gold: they were alluvial lands with gold dust; there was abundant water and enough slope to use it as a hydraulic force; and there were gentle slopes towards the Sil for the drains.
The system used was called Ruin montium . 8 The water from the mountain streams was channeled and embalmed at the top of the farm; the mountain was pierced with a careful network of very steep galleries, releasing the water through them. The force of the water undid the mountain and dragged the auriferous lands to the laundries. The hydraulic system of the Médulas is the most spectacular of the known, for the amount of water used and the length and the large number of ramifications of its channels. At the moment all this layout is known, visitable in part with the company of a guide.
One of the many captures was made from the northeast slope of Mount Teleno. At an altitude of 2000 meters snow accumulated, later converted into water reaching the Cabo River, which in turn fed the seven canals that, bordering the mountain, reached the exploitation ponds. These channels whose total length is estimated at about 300 kilometers, have a slope of between 0.6 and 1%. The width is 1.28 meters, except in the curves, of 1.60, and its depth is 90 centimeters. The construction of these channels, which in some sections run under the rock in the form of a tunnel, was by far the most difficult and expensive work of exploitation.
Subsequently, the water of the channels reached some deposits built by the leveling and excavation of the land. The extracted earth was piled around, forming slopes. These deposits had gates to distribute the water.
Abandoned in the third century, the native vegetation once again begantaking over the place: oaks, brooms, Carquoise, holm oaks and holm oaks. At the same time the cultivation of chestnut trees expanded, of which today numerous specimens can be seen in the park, some of them cataloged as centenary trees. All this resulted in the emergence of a spectacular environment characterized by the capricious shapes of the terrain, formed by reddish sand perfectly integrated with the vegetation.
Currently, the fauna of the area include wild boar, roe deer, wildcat etc. In terms of birdlife, there are more than one hundred species located mostly on the Cabrera river. In the vicinity of Lake Carucedo, which tradition says was formed by the stagnation of the water used for exploitation, grow a variety of orchid whose flower simulates a bumble bee to attract insects and facilitate pollination. In the riverside forests insectivorous birds are numerous.