In the Ardenne massif (south Belgium) many traces of metallurgical activity are present. An intensive development of iron industry took place from the Middle Ages until the middle of the 19th century. Many small upland rivers powered water wheel of forges and blast furnaces [1]. Among these rivers, the geomorphic evolution of the upstream part of the Aisne River was studied. By means of microslag evaluation [2], topographic surveys and sedimentological analyses, the floodplain history may be reconstructed, fine floodplain sedimentation and channel changes are identified. Analyses of slag concentrations allowed us to reconstruct the evolution of the floodplain topography over the last centuries. In the upstream part of the Aisne catchment, the floodplain aggradation is less than 17 cm since the 15th century, which corresponds to an aggradation rate lower than 3 cm/century. Such rate is very low compared to other rivers [2] and to the lowest part of the Aisne catchment [3]. Moreover, our results show that the thickness of fine alluvia on the low terrace is approximately 50 cm and the incision of the riverbed is of the same order (between 46 and 77 cm). It therefore appears that the floodplain level has reached an equilibrium before the establishment of the ironworks in the valley (in the 15th century) and the sedimentation does not appear to have continued since then.