These are the locations of former piles, so-called pile slabs. Coal was produced from wood in the piles. In order to minimize the distance the wood had to be transported to the pile, the piles were built in the middle of the forest. To do this, the charcoal burner piled up logs and covered them with plaggen and earth. As the charring process took around 14 days, the charcoal burner lived in a hut near the piles in the forest.
The charcoal was mainly needed as a source of energy for the ironworks and hammer mills. It took four and a half wagons of charcoal to produce one wagon of pig iron, which in turn required 36 wagons of wood. This required the felling of around 1.5 hectares of 18-year-old beech forest. Even Brilon's extensive forests could not meet this immense demand for wood in the long term, so that by the end of the 18th century there was a veritable wood shortage.