Contribution de la prospection géophysique à large maille et de la géostatistique à l'étude des tracés autoroutiers. [Application aux ferriers de la Buissière sur l'A77]

摘要

For the first time in France (1995), an electromagnetic survey using a large mesh was undertaken for a detection of archaeological structures over a distance of more than one kilometre (Motorway A77). The original aspect of this project is two fold : a survey of more than one kilometre long, and second, the area which is located only in a forest, a place which is often neglected by archaeologists and surveyors, including geophysicists...The geophysical diagnostic was positive and was at the origin of the change of the main line of the motorway. The structures which were sought after, are heaps of slags. Magnetic susceptibility was systematically measured over a surface of 300 by 1000 m. This measurement enable the distinction between the main areas of metallurgical activity and places where slags were scattered. Problems related with spatial sampling (definition of sample interval in both direction) are also considered using the theory of geostatistics (variograms and kriging). Cross-validations have shown that the original sampling interval was relevant. Finally, this type of study can be applied to other types of archaeological structures when magnetic susceptibility is enhanced not solely as a result of the action of fire or metallurgical works.