Human or climate: which geomorphological agent?The example of Holocene tufa systems in Provence (Southeastern France) as a tool for analysis

Calcareous tufas are exceptional sedimentary archives for retracing the evolution of past environments and detect the impact of human activities on geomorphological processes in piedmont areas.

The analysis of the sedimentary dynamics of six natural sequences located in southeastern France, in close proximity to archaeological sites, has has enabled the identification of direct and indirect signs of occupation at the watershed scale. This analysis has also revealed the influence of these activities on surface formations characteristic of calcareous environments, and their development.       
The multi-proxy approach, at the interface between geomorphology, sedimentology, and archaeology, integrates sedimentological and physicochemical analyses with paleoenvironmental, chronological, and archaeological data. This approach aims to discretize the geomorphological agents responsible for the evolution of sedimentation patterns from the Late Glacial to the Medieval periods.

A notable finding is the variation in the nature and geochemical composition of the facies, as well as the frequency and amplitude of the periodicity of the tufa sedimentation cycle. These variations intensify from the Late Neolithic period onwards, a time when human impact on the environment was particularly significant. Prior to the Late Neolithic period, these indicators do not appear systematically in the studied sequences, suggesting a heterogeneous occupation of the territory, as also detected by the paleoenvironmental analyses. The proposed analytical framework is of a dual nature, with the objective of 1) detecting potential occupations at the watershed scale ; and 2) highlighting the influence of these occupations on sedimentary deposition processes and modalities.

In the end, the contribution of this work reaffirms the key role of these sedimentary archives in understanding landscape evolution and their ability to record anthropogenic modulations during their sedimentation. This geomorphological approach, when applied to the Provence tufa systems, offers new perspectives for understanding human-environment interactions during the Holocene. Moreover, it also possesses strong potential for generalization to other geographical and chronological contexts, including more recent periods.