More than four metres of core, covering almost 5000 years of deposition, were collected in a high ash minerogenic peat deposit located in the High Aldudes valley (Basque country), an area well known for its mineral abundance, exploited from Roman Times at least. Although minerogenic peatlands are not generally considered as the best archives to reconstruct past atmospheric metal deposition history, lead isotopic geochemistry demonstrates the integrity of the Pb record at least within the three upper meters; that is to say over the last four millennia. Zn, Cd and Cu may have been widely redistributed either by biological cycling, advective groundwater movements, or diffusional processes. Anthropogenic lead input phases are clearly pinpointed by positive shifts in Pb/Sc ratios with concomitant sharp drops in (206)Pb/(207)Pb ratios. They are often accompanied by significant declines in tree taxa, interpreted as increasing demand for wood to supply energy for local mining and/or metallurgical operations. Periods of mining and/or smelting activity are identified during Antiquity and Modern Times, and are also confirmed by textual and field evidence. Inputs from the Rio Tinto (Southern Spain), often invoked as a major lead contributor to the European atmosphere during Roman Times, were not detected here. This remote source was probably masked by local inputs. Other mining and/or smelting phases, only suspected by archaeologists, are here identified as early as the Bronze Age. Although the durations of these phases are possibly overestimated because of detrital inputs consequent to the release of lead from polluted soils over a long period of time after major pollutant inputs, the periods at which pollution peaks occur are in good agreement with archaeological knowledge and palaeo-botanical data. The combination of geochemical and palaeo-botanical techniques with field archaeology, therefore provides a powerful tool in studying the interaction of early human societies with their environment, as regards early mining and smelting.
Interdisciplinary research was carried out in mid-level mountain areas in France with the aim of documenting historical mining and smelting activities by means of pollen and geochemical analyses. These investigations were made on cores collected in French peatlands in the Morvan (northern Massif Central), at Mont Lozère (southern Massif Central) and in the Basque Country (Pyrénées). Different periods of mining were recognised from Prehistory to modern times through the presence of anthropogenic lead in peat. Some of these were already known from archaeological dates or historical archives, especially for mediaeval and modern periods. However prehistoric ancient mining activities, as early as the Middle Bronze Age (ca. 1700 b.c.), were also discovered. They had all led to modifications in plant cover, probably related in part to forest clearance necessary to supply energy for mining and smelting.
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