The potential of low-destructive characterization of archaeological sites with stony and eroded soils through geostatistics at the Celtic oppidum of Bibracte (France)

Urbanization during Europe's Late Iron Age brought about a rise of enclosed settlements, or ‘oppida’. These centers of human activity left indelible marks on the environment, influencing its geochemistry. The key goal of the research is to identify zones of anthropogenic activities within eroded and stony soils of the Bibracte oppidum’s ‘empty spaces’. We demonstrate an innovative multivariate and geostatistical approach to integrate relevant geochemical and, when available, geophysical records, thereby facilitating a comprehensive understanding of activity areas within oppida in conditions of soil truncation, erosiona and uneven distribution of cores. Our results indicate varied and potentially intensive past human activities in the southern area of La Terrasse, La Chaume, Le Porrey and Le Verger. This is evidenced by elevated values of magnetic susceptibility and chemical elements such as phosphorus and calcium, which reflect here a diverse historical utilization of these spaces. Our robust multivariate statistical analysis effectively deals with the challenges posed by irregular spatial distribution and missing data, enabling the successful correlation of geochemical and geophysical data and providing compelling evidence of spatially differentiated human activities throughout the oppidum. This extends our understanding of Iron Age urbanization and the nuanced utilization of space within these early urban centers.