zondag 22 februari 2015

Spain, Las Médulas

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.


Las Médulas gold-mining area is an outstanding example of innovative Roman technology, in which all the elements of the ancient landscape, both industrial and domestic, have survived to an exceptional degree. It provides exceptional evidence of a tradition of working and the technological and scientific exploitation of nature in a vanished civilization, which resulted in significant use of applied hydraulics. What is visible today is a unique cultural landscape, shaped by drastic human intervention and natural processes, with in addition the introduction of non-native flora, which has survived since the Roman period without change.
The placer (alluvial) gold deposits of the Las Médulas region were being exploited on a small scale in the late Iron Age. Evidence for this is largely circumstantial, based on excavations of the defended sites (castros ) of the region and the related cemeteries, with their wealth of golden objects.
The north-western part of the Iberian Peninsula was the last to be conquered by the Romans, after the campaign of Augustus in 29-19 BC. Some Roman urban centres were founded and a characteristic Roman road system built, but the indigenous population, although considerably reduced, continued to live on its tribal territories, around its typical defended hill forts for a considerable time. However, from the second half of the 1st century AD a new settlements on the Roman model were set up, with the objective of exploiting the rich mineral resources (notably gold, but also iron) of the region. At the same time, new techniques of extracting the gold were put into practice, on an infinitely larger scale than in the pre-Roman period. Under the Roman system, all mineral resources in imperial provinces were vested directly in the emperor. The mining areas formed part of the province of Hispania Citerior, which included the north-western military regions of Asturia and Callaeciae, and were declared to be imperial estates. Contrary to general belief and unlike the situation in other imperial gold-mining areas (such as Wales), the workers in the mines were free men, not slaves. Their settlements can be found all over the region, alongside yet clearly distinguishable from those which housed the imperial officials and their staffs. Engineering activities, such as the major hydraulic works of building dams and cutting channels and road construction, were the responsibility of the Roman army. The military presence was also maintained to keep the peace and to ensure the safety of imperial officials and their deliveries of gold to provincial capitals and over the sea to Rome. Sweeping changes took place in the Roman monetary system in the 2nd century AD: Caracalla restored the aureus to its former place, and as a result the Spanish mines reactivated their production.
The Archaeological Zone of Las Médulas (ZAM) comprises the mines themselves and also large areas where the tailings resulting from the process were deposited. Within the area there are dams used to collect the vast amounts of water needed for the mining process and the intricate canals by means of which the water was conveyed to the mines. Human settlement is represented by villages, of both the indigenous inhabitants and the imperial administrative and support personnel (including army units). The area contains the route of one major Roman road and a large number of minor routes, used within the mining operations: water from springs, rain, and melting snow was collected in large reservoirs, which led by a system of well built gravity canals to the mines themselves, over long distances. Galleries were cut into the sterile strata many metres deep that overlay the layers of auriferous conglomerate. When the sluices of the dams were opened, enormous quantities of water flowed into the galleries, which were closed at their ends. The pressure thus built up caused the rock to explode and to be washed away by the water flow, forming enormous areas of tailings, several kilometres in length. The process is vividly apparent on the working face at the main Las Médulas site. The operating face of this spectacular form of mining slowly moved across the landscape. The system of water canals and conduits has been traced over large areas of the site, and measures at least 100 km.
The placer (alluvial) gold deposits of the Las Médulas region were being exploited on a small scale in the late Iron Age. Evidence for this is largely circumstantial, based on excavations of the defended sites (castros) of the region and the related cemeteries, with their wealth of golden objects.
The north-western part of the Iberian Peninsula was the last to be conquered by the Romans, after the campaign of Augustus in 29-19 BC. The region remained under direct military control for at least a century after the conquest. The degree of Romanization was less than in other parts of the Iberian Peninsula. Some Roman urban centres were founded and a characteristic Roman road system built, but the indigenous population, though considerably reduced, continued to live on its tribal territories, around its typical defended hill-forts for a considerable period.
However, from the second half of the 1st century AD a new form of occupation becomes apparent New settlements on the Roman model were set up, with the objective of exploiting the rich mineral resources (notably gold, but also iron) of the region. At the same time, new techniques of extracting the gold were put into practice, on an infinitely larger scale than in the pre-Roman period.
Under the Imperial Roman system, all mineral resources in Imperial provinces (as distinct from the older and more traditional Senatorial provinces) were vested directly in the Emperor, as part of his patrimonium, and was administered as part of the Imperial fiscus. The mining areas formed part of the province of Hispania Citerior, which included the north-western military regions of Asturia and Callaecia, and were declared to be Imperial estates. At first they were administered by the provincial governor, but following the reforms of Vespasian in the 70s of the 1st century AD, they were managed by an Imperial procurator Asturiae et Calhciae. Under him were the procuratores metallorum, responsible for individual operations or for groups of mines.
Contrary to general belief, and unlike the situation in other Imperial gold-mining areas (such as Wales), the workers in the mines were free men, not slaves. They continued the mining tradition established in the pre-Roman period in the region. Their settlements can be found all over the region, alongside yet clearly distinguishable from those which housed the Imperial officials and their staffs.
Engineering activities, such as the major hydraulic works of building dams and cutting channels and road construction, were the responsibility of the Roman army. This division of responsibilities and tasks can be seen in other Imperial estates, such as the Weald of south-eastern England, which was a major producer of iron.
The military presence was also maintained in the mountainous and turbulent mining regions to keep the peace and to ensure the safety of Imperial officials and their deliveries of gold to provincial capitals and over the sea to Rome. The Legio VII Gemina (from whence the modem city derives its name) was permanently stationed at León, and auxiliary units garrisoned forts of varying sizes in and around the mining areas.
Sweeping changes took place in the Roman monetary system in the later 2nd century AD, when the gold aureus was devalued, with catastrophic results, not least for the Spanish mines. Caracalla (188-217) restored the aureus to its former place, and as a result the Spanish mines, which had been in crisis, reactivated their production. This may well also explain why Asturia and Callaecia were raised to the status of an independent province, Hispania Nova Citerior Antoniniana. However, both the new province and the resuscitation of the mines seem to have been short-lived, and the lack of later material in the archaeological record shows that gold production effectively came to an end in the opening decades of the 3rd century.

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