OSL dating and sedimentary and morphological analysis of the gold panning mounds along two streams in the Ardennes (Rougerie and Schinderbach, Belgium)

Abstract

In the Belgian Ardennes, ancient alluvial gold mining profoundly reshaped rivers and valley bottoms. The resulting morphologies remain visible today, still influencing the evolution of rivers. Yet, they have received little scientific attention and are increasingly threatened with destruction by agriculture and forestry. This study addresses this gap by evaluating the potential of quartz-based optically stimulated luminescence (OSL) dating for gold-panning mounds and by analysing exploitation methods and related deposits. Two sites were investigated: the Rougerie stream and the Schinderbach-A. The single-aliquot regenerative dose (SAR) protocol was applied under the assumption that quartz grains were sufficiently bleached during washing operations. Radiocarbon dating was also performed on charcoal samples from both sites. Complementary approaches included topographic surveys, coring across valley transects, stratigraphic logging, and the development of a typology of mining-related morphologies based on fieldwork and LiDAR-based mapping The unprecedented application of OSL to gold-mining mounds proved promising: although incomplete resetting limited the accuracy of final ages, equivalent dose distributions revealed a predominance of young values consistent with mining activity. Radiocarbon ages provided firm chronological anchors, dating the Rougerie to the Roman period (230–380 cal. AD) and the Schinderbach-A to the Celtic or Gallo-Roman period (196–41 cal. BC). Geomorphological analyses further led to a revised conceptual model of valley evolution for the Rougerie and a new model for the Schinderbach-A. Tailings deposits were also characterised and presented similarities with those produced during the 19th-century American gold rush. These findings establish the first reliable chronological framework for gold-panning mounds in the Stavelot Massif. They also provide new insights into the history of ancient mining in the Ardennes and demonstrate the potential of OSL for broader applications to gold mining tailings worldwide.