High concentration of charcoal hearth remains as legacy of historical ferrous metallurgy in southern Poland

In the preliminary research by using DTMs from airborne LIDAR data we found an unexpectedly high concentration of charcoal hearth remains which can potentially provide new data on historical ferrous metallurgy. Our study (based on LIDAR data) was designed to determine the number and distribution of charcoal hearth remains along three water courses used for powering iron smelters in the past the Klodnica River, Czarna River and Mala Panew River (southern Poland). The second aim was to characterise the relief and internal structure of selected charcoal hearth remains, to perform radiocarbon dating of selected charcoal hearth remains located near historic ferrous metallurgy centres and to compare dating results with historical data. We also checked what tree species were used for charcoal production. In the three areas under study a total of 208,085 charcoal hearth remains have been identified. The majority of charcoal hearth remains have been found along the Mala Panew River (74.9%, 184 charcoal hearth remains per 1 km(2) on average). A typical charcoal hearth in the areas under study was 14 m in diameter, c 2 m high with a volume of c 205 m(3). Around the central mound of each charcoal hearth remains, 4 to 9 depressions are present (each 2-3 m in diameter and around 0.5 m deep). Most of the radiocarbon dates obtained for the charcoal hearth remains analysed correspond well with historical data on the development of the nearest individual smelling centres. However, in some cases radiocarbon dates from charcoal hearth remains can serve as indications that the smelling plants may have been established earlier than historical sources suggest or that charcoal was used for another kind of activity. All charcoal samples taken in the areas under study originated from wood of coniferous species, mainly from Scots pine.