Airborne archaeology uncovers 2,000-year-old gold mines in Spain

Archaeologists, using plane-mounted lasers, have found a 2,000-year-old network of gold mines in north-western Spain. 

Located in the Eria Valley in the spectacular Las Médulas region of León, the mining network is considered to be the largest opencast gold mine of its type dating from the Roman Empire. The network of mines had remained hidden and overgrown over the centuries.

Photo : J. Fernández Lozano et al.

Researchers from the University of Salamanca discovered the gold mining network using a remote sensing technology known as LiDAR while making an aerial survey of the area. Science Daily reports that LiDAR operates by illuminating targets using a laser beam to measure distance.

The LiDAR technology was originally developed by NASA back in the late 1960s, when it was used to track the retreat of the ice in the Arctic and the composition of the oceans.  The technology today is used with either planes or drones.

Javier Fernández Lozano, a geologist with the University of Salamanca, is co-author of a paper about the discovery which has been published in the Journal of Archaeological Science.

Fernández Lozano said of the technology, "Unlike traditional aerial photography, this airborne laser detection system allows the visualization of archaeological remains under vegetation cover or intensely plowed areas."

This is apparently the first time the LiDAR "geo-archaeology" method has been used in Spain.

Researchers wrote in the paper, "Our intention is to continue working with this technique to learn more about mineral mining in the Roman Empire and clear up any mysteries such as why Rome abandoned such a precious resource as gold from one day to the next."

Nature World News reported the researchers also found evidence that the Romans had diverted rivers in order to supply water to the mines back in the first century BC. This appeared to follow similar practices by the Egyptians in North Africa.

"The volume of earth exploited is much greater than previously thought and the works performed are impressive, having achieved actual river captures, which makes this valley extremely important in the context of Roman mining in the north-east of the Iberian Peninsula," Fernández Lozano concluded. 

Spanish sources:
Sinc
Diario de Leon

Photo of Roman gold coin: CC by-SA Kaly99