Luis José García-Pulido

This paper is devoted to the study of the different towers of the Nasrid kingdom of Granada (1232 to 1492) and their linked landscapes, as well as the evolution, preservation, resilience or transformation of their environment until present days. These late Islamic territories in medieval Iberia occupied the mountainous areas of the southeastern area of today’s Spain. There, a natural border was established between the Nasrid kingdom and the expansion of Castile during more than two centuries and a half. To control this frontier and establish visual communication between it and the Nasrid power centres lead by the Alhambra citadel, an extensive network of watchtowers and defensive towers linked to farmsteads was constructed. These towers are located in unique sites; being erected as reference landmarks of the territories on which they stand. These fortifications, with very diverse typology and morphology, are a faithful testimony to the different territorial structure that has taken place throughout history.

The Royal Water Channels are inherent part of the Cultural Landscape of the Alhambra. They flow along the river Darro valley and the Peri-urban Park "Dehesa del Generalife", and form part of much appreciated itineraries by daily visitors. The values that they encompass are very diverse; from those of a historical and heritage nature to those of an environmental landscape, ethnographic and symbolic nature.

The water running along these medieval channels stimulates the growth of a gallery forest. The filtration and the spillage keep the hillsides covered with vegetation, increasing the biodiversity and recharging the water table levels that created the existence of some springs. The last one of these Royal Water Channels stopped fulfilling its function some decades ago. From the mid-1990s the Alhambra and Generalife Trust has carried out several projects focused on the protection and valuation of this important legacy. Recently the restoration of a first section was undertaken, documenting scientifically the elements linked to these arteries of the Alhambra and safeguarding its heritage values.

The aim of the research program MineMet 2012-2015 financially supported by ANR (French National Agency for Research) is to study and characterise the economic implications of new mining districts on secondary deposits during the Antiquity. Our study is focused on two regions with Au placer deposits, one in Gaul to the Lemovices (Limousin and North Perigord) and another one in Hispania, to the Cerretanes in Cerdagne, and on tin placer deposit in Gaul to the Eduens in Morvan (Burgundy). We present here our results on gold from Cerdagne and tin from Morvan.

The project propose to identify and characterise new mining districts which are detectable in the landscape as topographical anomalies of the slopes and show similarities with certified Antique mining sites known from other locations. To accomplish the project’s purposes a new field research approach was initiated with the mapping of the supposed new mining districts and the detailed mapping of several excavated structures showing similarities with channels and water tanks, remnants of an ancient hydraulic network as well as exploitation sites. Their study involving archaeological diggings also allow identifying the dynamic of exploitation and uncovering hidden structures (channels, basins) and artifacts which together prove the presence of mining driven structures and offer clues for chronology. Metal provenance studies (geology, geochemistry/isotopes) are going on in parallel for the alluvial gold from Cerdagne and the colluvial cassiterite from Morvan. EIectrum/gold grains and cassiterite grains sampled in the vicinity of the studied mining structures will be compared with pre-Roman and Roman gold and bronze artifacts discovered in the same two regions.

The first research in Cerdagne started in 2008 in the valley of Segre between French and Catalan Cerdagne in a broad partnership between historians, archaeologists and geologists from Toulouse and Barcelona (Olesti et al., forthcoming). About 30 sites presenting deep erosional profiles and being strictly contoured on the slopes have been mapped. These negative anomalies in the landscape are very similar to the trench mining sites as are known in NW Spain or NW Romania for the alluvial gold mining during Antiquity.

These deep incisions were considered until now as traces of natural erosion along the slopes. However, several panning campaigns in Cerdagne on the Catalan side around the village of All, and on the French side NE of Sail/agouse confirmed the constant presence of electrum/gold grains in the alluvial deposits. In the frame of the MineMet program the collected electrum grains are currently prepared for geochemical and isotope analyses for traceability purposes.

Between 2010 and 2011 several diggings made in Las Guilleteres (All, Catalonia, Spain) revealed a sort of basin or water tank made of two superposed dams of stones situated on the slope upstream of deep trenches cut in alluvial deposits. The presence of common ceramic fragments found in the filling of the basin indicates an Antique occupation of the structure. It is possible to consider this structure as a water reserve for alluvial Au exploitation downstream but for the moment we did not identified any trace of channel connecting the basin with the exploitation sites. New diggings are necessary in Cerdagne to ultimately prove the surface exploitation of the alluvial gold.

South and east of Autun (Burgundy, France) BRGM discovered a significant tin anomaly (cassiterite) within secondary deposits (alluvial and arenitic deposits) developed on granite rocks. Furthermore, the forestry slopes from these areas are crosscut by a dense network of up to 4 m deep trenches which downstream pass into large cirques. These lowlands in the landscape were interpreted as surface mines in secondary deposits. These surface works were created by hydraulic mining of secondary cassiterite deposits. Upstream of cirques and trenches it is easily to follow a hydraulic network made of channels and several basins. The source of water is situated in the upper part of the hills, the so-called Montjeau domain, south ofAutun, where several lakes still exists.

Archaeological diggings were done in 2005 close to a trench exploitation for tin in the so-called La Montagne (Autun) site. A hidden channel was revealed firstly by geophysical prospection and it was afterwards confirmed during the diggings by the presence of iron hydroxides concentrated along the lowermost part of the channel. The diggings allowed us to discover two hidden channels going towards the exploitation site validating thus the hypothesis of placer mining. The ceramics discovered on the bottom of the channels date its abandon during 1st c. AD.

The trenches and cirques are located downstream of the hydraulic system (channels and basins) to which they are connected and altogether are found in a forested area and thus invisible for classical aerial investigations. The difficulty of the field covered by forests imposed the use of LIDAR technique which was finally made in the frame of MineMet ANR program. The LIDAR output obtained end 2013—early 2014 allow us to make a detailed mapping of the mining structures, i.e. channels, basins, exploitation sites until now completely hidden by the forests in the aerial views. The first results are outstanding and the field may be "read" perfectly as an unforested one.

The mining complex for tin located south of Autun comprises surface mining works covering about 300 hectares and partly active during Roman times (Cauuet and Tamas, 2009). Close to the water sources the LIDAR investigations revealed a big enclosed site situated in the vicinity of a bronze deposit from Bronze Age. Furthermore, just above the channels and exploitation sites the LIDAR results indicate two Prehistory enclosures (Bronze Age or more probably Iron Age). These dwellings associated to mining structures showing multiple crosscutting relationships which are currently identified indicate a long period of exploitation during several ancient ages. Presently, the inventory and the mapping of the mining vestiges is advancing on the basis of numerical data model generated by the acquisition of LIDAR mapping on 60 k centred on Autun.

This work is a first approach to the study of an interesting religious complex, probably occupied from the High Middle Ages, located in the municipality of Guadix (Granada, Spain). In this enclosure made up of a group of caves with a church, a hermitage tomb and other annexed structures such as adjacent water cisterns, threshing floors, other caves in the surroundings, etc., was the burial place of St Torcuato, the apostolic saint who, according to tradition, preached in this region of the Iberian Peninsula during the beginnings of Christianity. The survey done in order to map the church and caves has been decisive for its interpretation like a cave-monastery.