In pre-industrial times, charcoal was of comparable importance to modern oil in the economy. The investigation of the squad of Prof. Michał Słowiński from the Institute of Geography and Spatial Management of the Polish Academy of Sciences shows the past of Poland from the position of this frequently overlooked natural material.
You needed a grinder.
Wood charcoal was needed for the melting of glass, iron or powder and tar, which allowed for very advanced temperatures. Without it, the medieval and modern economy could not function, and stone coal began to replace it only in the industrial age.
The production of wood charcoal required a memeller – a pile of wood about 10 m in diameter, covered with turf and sand to cut off oxygen and then burned for 10-20 days at about 300°C. It burned up to 200–250 m of wood 1 time, after which the mill was moved to a fresh place, close to the available natural material. The mobility of smolters made them stay unnoticed for a long time. The pollen analysis showed changes in the forest that were not visible on the old maps.
I realized that cartographers only marked forest boundaries. Meanwhile, in its depth the smollers led an intense cut. They did not grub the forest under the cultivated fields, but exploited it point-by-point, burned coal, and went on. The forest utilized to grow back, masking traces of this powerful production – explained Prof. Słowiński in an interview with PAP.
Aeroplane laser scanning
Though the traces of grounders are hard to see with their bare eye, the burning of coal permanently altered the soil, sterilizing it and raising the concentration of dense metals. The key to assessing the scale of production was photos from the aircraft laser scan (LiDAR), which uncover somewhat collapsed, circular places after grinding. Analysis of specified maps allowed the scholarship holder Krzysztof Szewczyk to identify more than 630 1000 of these objects in Poland.
Most of the tenants have been identified in today’s forests, due to the fact that in agricultural and urban areas their traces have obscured human activity. The erstwhile production of charcoal is besides witnessed by the names of the towns prior to the 17th century, specified as Smolary, Budy or Szklary.
Prof. Słowiński emphasizes that the tenants are part of the industrial heritage and announced the provision of an open database of their location.