Las Médulas

Galería de Orellán


Useful Information

photography
Las Médulas, Spain. Public Domain.
Location: Ponferrada, comarca of El Bierzo, province of León. From León city AP-76 west to Astorga, A-6 to Ponferrada, N536 (42.460669, -6.759338)
Open: no restrictions.
Visitor Center:
APR to SEP daily 11-14, 16-20.
OCT to MAR daily 11-14, 16-18.
Guided tour Las Valiñas: APR to SEP daily 11:30, 12, 17, 17:30.
OCT to MAR daily 11:30, 12, 16, 16:15.
Galerías de Orellán:
JUN to SEP daily 10-22.
OCT to MAY Wed-Mon 11-14, 16-18.
Aula Arqueológica:
APR to SEP daily 10-13:30, 16-20.
OCT to MAR Sat 10-13:30, 15:30-18, Sun 10-14.
[2020]
Fee: free.
Visitor Center:
free.
Guided tour Las Valiñas: Adults EUR 2, Children (0-18) free.
Groups (15+): Adults EUR 1.50.
Galerías de Orellán:
Adults EUR 1.50, Children (6-18) EUR 0.90, Children (0-5) free, Locals free.
Groups (22+): Adults EUR 0.90.
Aula Arqueológica:
Adults EUR 1.20, Children (8-18) EUR 0.60, Children (0-7) free, Students EUR 0.60, Seniors EUR 0.60.
Groups: Adults EUR 0.60.
[2020]
Classification: MineGold Mine
Light: n/a
Dimension:  
Guided tours: self guided.
Guided tour Las Valiñas: L=3km, D=90min.
Photography:  
Accessibility:  
Bibliography: Jesus Aller, Fernando Bastida, Mayte Bulnes, Francisco José Fernández, Josep Poblet (2013): The Roman gold mine of Las Médulas Field Trip in Honour of the Work of Prof. Richard J. Lisle, Oviedo (Spain)
W. Gibbons (2018): Holiday Geology Guide to Las Médulas pdf
Jesus Aller et al. (2014): The Roman Gold Mine of Las Médulas researchgate
Nemesio Heredia et al. (2015): Depositional style and tectonostratigraphic evolution of El Bierzo Tertiary sub-basin (Pyrenean Orogen, NW Spain) online
José Redondo-Vega et al. (2015): La Balouta exhumed karst: a Roman gold-mine-derived landscape within Las Médulas UNESCO World Heritage Site (Spain) researchgate
Address: Galerías de Orellán, 24444 Orellán, León, Tel: +34-987-545180.
Centro de recepción de visitantes de Las Médulas, 24442 Carucedo, Las Médulas, León, Tel: +34-619-258355.
Aula Arqueológica, Las Médulas, 24442 Carucedo, Tel: +34-987-422848, Fax: +34-987-401954.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.

History

77 mining described by Pliny the Elder in Natural History (33.21).
1997 inscribed on the UNESCO World Heritage List.
2014 Roman mining mapped with LIDAR.

Geology

The oldest rocks containing gold are Cambrian and Ordovician metasediments. They form a hard basement, ehich is exposed in the mountains surrounding El Bierzo. During the variscan orogeny (300Ma) some of the gold became concentrated into quartz veins, a result of volcanic activity and the resulting hydrothermal convection. The gold formed tiny crystals in pyrite, which is an iron sulphide mineral. Post-variscan the surface was covered by lateritic soils produced by weathering under a tropical climate. The weathering of auriferous pyritic quartz veins, the oxidation of the pyrite by meteoric waters circulating through the soils mobilized the fine gold which was carried away in the fluids and precipitated elsewhere as nuggets. This process of weathering and redistribution of ore metals by shallow, circulating waters is named supergene enrichment.

Parts of western Iberia have an extraordinarily long history of 200 million years of supergene weathering. The result were thick auriferous soils. 30 million years ago the Alpine compression of Iberia at the convergent rim between European and African plate, caused uplift of new mountains and thrust faults. Rivers cut deep valleys into the uplifting ground, eroding the gold-bearing soils and forming great alluvial fans, depositing layers of conglomerate and sandstone. The El Bierzo area is such an alluvial fan bearing gold and iron oxide from the pyrite which gives the red colours.


Description

photography
Las Médulas, Spain. Public Domain.

Las Médulas is an antique gold mine, actually it was the most important gold mine and the largest open-pit gold mine in the entire Roman Empire. The landscape is quite spectacular, a series of reddish, brown and yellow peaks similar to the badlands of the western U.S.A.. It is a result of the mining technique the Romans used, which is called ruina montium (wrecking of mountains). The miners excavated narrow cavities down into the mountain. Then they were filled with water, which caused a pressure large enough to fragment thick rock walls. The principle is also known as Pascal's barrel, because it was allegedly performed by Blaise Pascal in 1646. However, the method was described by Pliny the Elder in Natural History (33.21) in 77. Pliny served as procurator in Spain.

In the 1st century the Roman Imperial authorities began to exploit the gold deposits. The required water was transported to the mine on seven huge aqueducts which were built to redirect the water from the nearby river into the mines. After two centuries they withdrew, leaving a devastated landscape. The Romans moved more than 94 million cubic meters of earth to extracted something between 5 and 800 tons (depending on the source) of gold from these mountains. There was no subsequent industrial activity. The vast areas of tailings are today used for agriculture, but the eroded moutains are almost unchanged. The place was inscribed on the UNESCO World Heritage List because the area is an outstanding and well preserved example of innovative Roman technology.

The mine tunnels were mostly destroyed by the process, but some tunnels nevertheless remain. The central sight of the site is the Galería de Orellán, which is reached from the village Orellán. The Roman mine tunnel has electric light and ends in the middle of the cliff face. An balcony offers one of the best views on the mine site. The other way to visit the site is the Senda de las Valiñas trail which starts at Las Médulas. The trail leads to the cavern La Cuevona and La Encantada, both remains of the mining activities. You can either walk on your own, or book a guided walk at the Centro de recepción de visitantes de Las Médulas. The walk is 3km long and takes about two hours. The Mirador de Reirigos and the Cuevas de Reirigo are located at the southern side of the open cast and are best reached from the Galería de Orellán. And finally there is the Aula Arqueológica (Archaeological Information Centre) which has an archaeological exhibition. They also offer guided tours after appointment.