Preventive archaeological excavations in the context of large-scale engineering works are often an opportunity to implement new working practices. Since 2008, the Europe-Seine-Nord Canal Project undertaken by the INRAP entailed the development of a number of scientific procedures, and notably the use of a geophysical approach to certain archaeological problems. The main specificity of this project, covering 2500 hectares, is to have included the geophysics at the excavation stage, and not merely at the evaluation stage as was previously the case on other projects. The scientific results were specially important as the geophysics was used on a rational basis and only when the archaeological problems had been clearly posed. Thus over the period 2009 to 2013, 31 surveys were successfully carried out. Three main approaches can be distinguished. The first one concerns the prospection of those parts of the site beyond the line of the projected route, in order to delimit the extension of the archaeological remains. The supplementary information contributed by geophysical cartography together with the excavation data provides a pertinent overall view of the site, and a clear characterization of its structures. The second approach aims mainly to situate the archaeological site in its geomorphological context. This approach requires a survey covering much wider areas. It has been notably used in the Oise valley in order to determine the morpho-sedimentary systems linked with the pre- and proto-historic settlements. Finally, the third and last approach is meant to be more original in that it aims to bring fresh thinking after the stripping and observation of the surface levels. Thus, certain man-made phenomena, often difficult, if not impossible, to recognize with the naked eye, may be distinguished. For each of these approaches, we shall discuss the benefits and the conditions of implementation in the Seine-Nord-Europe Canal Project. This summary shows how many different applications geophysics can offer when the archaeological questions have been clearly defined and when the archaeological and pedological context is already known. In this way, geophysics takes its rightful place in the range of tools at the archaeologist’s disposal.

Traduction : Margaret & Jean-louis CADOUX