Foraminiferal caracterisation of the archeological environment and landscape - example of Quentovic (the Canche river mouth, France)

Abstract

Quentovic is a Merovingian and Carolingian emporium, located in the village of La Calotterie, a dozen kilometers to the east of the river mouth of the Canche (Northern France). If the contours of this emporium on the left bank are known, the exact geographical configuration and extent of this portus need to be specified. Twenty-one sediment samples (three samples for each of the seven analyzed stratigraphical units: four on a section North and three on a South section) were sampled in 2014 during the archaeological excavation of parcel AC277. The objectives of this study are to reconstruct the depositional environments and their temporal evolution during the first phase of occupation, and, possibly, to specify the proximity of the portus. The tools implemented in addition to the archaeological approach are fossilizable micro-organisms, diversified and widespread: foraminifers. They are widely distributed in all marine and continental environments. The taxonomic composition, species diversity and spatial distribution of assemblages are strongly controlled by the environment. By crossing the information contained in the sediments (particle size distribution, meiofauna, archaeological results) and by interpreting the meiofaunistic data using a discriminant analysis (LDA) coupled with a neural network analysis (NNET), the environment reconstituted corresponds to an estuarine landscape at the transition between the marine marsh and the intertidal mudflat conducive to the development of habitat in the Carolingian era.