Undisturbed iron industry sites in the Sonian Forest, Belgium

Abstract

In the Sonian Forest of Middle Belgium, undisturbed remnants of ancient metallurgic activity, dating from the Early Middle Ages, are found. They occur in an area with iron-rich geological formations at shallow depth below a loess cover. Iron-industry traces include scoria mounds, which always occur in pairs. Associated with each pair is a single large zone with a reddish-pink colour of the upper part of the soil. These zones were formed by heating of the soil from the surface, most likely during roasting of the iron sandstone ore as pretreatment. The surface horizon was later homogenised by biological activity, down to the top of the Bt horizon or the compacted part of the E horizon. Charcoal mounds, whose distribution is not clearly related to that of other archaeological structures, date at least partly from more recent periods. Another associated feature is an area with a surface cover of yellowish sands, representing a site where the sandstone was unloaded or cleaned before further treatment. The preservation of these various features related to ancient metallurgic activity is due to the unique land-use history of the Sonian Forest, where a centuries-long continuous prohibition of agricultural practices has prevented the destruction of shallow surface structures.