High concentration of relict mining shafts and relict charcoal hearths as a geomorphological legacy of ancient-modern metallurgy in southern Poland

In this study, we used DTMs from airborne LIDAR data to reveal an unexpectedly high concentration of relict mining shafts and relict charcoal hearths, small landforms that record past metallurgy and can potentially provide new data on its history and environmental impact. We determined the number and distribution of relict shafts in the mining area of Tarnowskie Góry and Bytom (Silesian Upland, southern Poland) and relict charcoal hearths in the adjacent Mała Panew River valley (Silesian Lowland, southern Poland). We also aimed to explore details of relief and structure of selected shafts and hearths located in past mining and smelting centres, date their age with the radiocarbon method and compare dating results with existing historical data. On the mining field under study, we have found 13 864 relict mining shafts spread over 10,5 km2, varying in size (2-50 m in diameter) and relief details (with common features such as central depression and surrounding collar-shaped spoil heap). Radiocarbon dates of selected relict shafts indicate mining in the following periods: Roman Period (since the beginning of the Common Era, up to 5th century AD), Early Medieval to Medieval Period (7th-13th century AD) and Modern Period (15th-17th century AD). At the same time, historical documents provide information only about medieval and modern mining (since the 12th century). In the Mała Panew valley, we have found as many as 166 356 relict charcoal hearths, resulting in an extremely high concentration of 184 relict charcoal hearths per 1 km2 on avg. A typical single relict charcoal hearth in the area under study is 14 m in diameter, c 2 m high with a volume of c 205 m3. Around the central mound of each relict charcoal hearth, 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 selected relict charcoal hearths correspond well with historical data on the nearest individual smelting centres (15th-19th century). However, in some cases, radiocarbon dates from relict charcoal hearths can indicate that the smelting plants may have been established earlier (12th-13th century) than historical sources suggest or that charcoal was used for another kind of activity. The considerable number and concentration of relict mining shafts and relict charcoal hearths record large-scale relief changes caused by silver, lead and iron mining in the study area, as well as significant changes in the environment (i.e. forest cover) caused by wood exploitation for charcoal.