Résumé : The early developments of Antwerp are still poorly understood, and therefore subject to ongoing research. Archaeological excavations and historical sources report the presence of a 9th century AD settlement, the core of the further development of medieval Antwerp, on the right bank of the river Scheldt. New excavations in this area, the so-called Burchtsite, took place between July 2008 and April 2009. Archaeologists discovered the remains of a 9th to 10th century early town, surrounded by an earthen rampart and palisade. This settlement shows characteristics comparable with contemporary early towns in the North Sea basin, such as Haithabu. Beneath the 9th century structures, a Dark Earth: a thick, dark-coloured, humic, non-peaty and homogeneous layer, has been observed, covering in situ traces of Roman age. Such layers are of particular interest, as they can provide information about the early formation of medieval cities. However, interpretations based on field observations remain difficult. Therefore, soil micromorphology, combined with phytolith and granulometrical analyses, have been realised to study the Dark Earth and the well stratified layers between the Dark Earth and the earthen rampart.The soil micromorphological study of the Dark Earth reveals a series of activities: ground raising, long lasting crop growing, possibly in combination with episodes of pasture. The study of the layers between the Dark Earth and the rampart suggests the presence of a stable. Furthermore, the study revealed that the environment of the site became progressively wetter. This might be related to a significant sea level rise, attested for this period. Whether or not this changing environment explains the end of the agri- cultural activities on the site still needs to be confirmed by future investigations within the city of Antwerp.