Bilan des recherches et nouveaux éclairages sur les terres noires : des processus complexes de stratification aux modalités d’occupation des espaces urbains

Dark earth is a thick layer of urban soil with a homogeneous appearance. It is an important source of information about urban forms in the Early Middle Ages in Europe. For a long time it was ignored, or sometimes incorrectly interpreted as evidence of towns that had been abandoned or been used for agriculture, but the excavation and precise analysis of these deposits reveal the complexity of how space was occupied between the 4th and 11th centuries. A number of experiments, some dating back to the 1970s, provide the methodological foundation for the development and systematisation of inter-disciplinary study protocols of recent operations.By precise observation of the lateral and vertical variations of deposits, the stratigraphic excavation of dark earth can be used to determine when these soils were deposited and the nature of the activities that produced them. The fields of study involved include ceramology, geoarcheology, archeozoology, and archeobotanics. Recently, the aggregation of these data and analysis of the three-dimensional organisation of the deposits, combined with semi-quantitative methods (counting macro-and micro-constituents), have provided greater insight into how these deposits were formed and the organisation of space. Overall, the results show that dark earth provides evidence of phenomena of accretion and bioturbation, and of local organic waste. These patterns are related to very varied activities, outside (horticulture, penning, midden, etc.) or inside (housing, craft production, etc.), revealing the variability over time of dark earth phenomena, as well as the regular, and sometimes long-term, occupation of the space. These results highlight the importance of developing new methodological tools to identify in greater detail when and how deposits were formed (study of archaeological materials, laboratory datings, etc.), and also to determine with greater precision the activities and methods of waste management (organic or metallic pollution)