Lasers Help Located Roman Goldmine in Spain

Thanks to a laser system called LiDAR, scientists were able to locate an ancient Roman goldmine in Spain, according to a new study, shedding light on mining in the region during one of the greatest empires in human history.

Las Médulas in León, created 2,000 years ago, is considered to be the largest opencast goldmine of the Roman Empire. Despite its enormity, it wasn't found until recently, hidden under the vegetation and crops of Spain's Eria Valley many miles further southeast. The NASA-developed Light Detection and Ranging (LiDAR) laser system, attached to an airplane overhead, is what allowed researchers to rekindle its existence.

"Unlike traditional aerial photography, this airborne laser detection system allows the visualization of archaeological remains under vegetation cover or intensely ploughed areas," geologist and study co-author Javier Fernández Lozano said in a statement.

Along with the gold mining network, Fernández Lozano and his colleagues also discovered complex hydraulic works, such as river diversions, to direct water to the mines of the precious metal. The Romans used these hydraulic systems in the 1st century BC to extract gold, and were more complex and invasive than researchers realized.

"We have established that the labor that went into extracting the resource until its exhaustion was so intensive that after removing the gold from surface sediments, operations continued until reaching the rocks with the auriferous quartz veins underneath," explained Fernández Lozano.

The University of Salamanca team suspects that the water transport and storage systems were modeled after those already existing in North Africa, where the Egyptians had been using them for centuries.

Though possibly a copycat, the discovery of this ancient goldmine provides insight into the life of the Romans.

"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.

The findings were published in the Journal of Archaeological Science.