Exploring the potential of multi-receiver EMI survey for geoarchaeological prospection: A 90 ha dataset

The archaeological evaluation of landscapes in the framework of developer-led archaeology is often based on extensive trenching programmes complemented with auger surveys in wetland environments. During the archaeological evaluation of a 90 ha polder site in the north-west of Belgium, a mobile multi-receiver electromagnetic induction (EMI) survey was used as a main prospecting technique. The use of a mobile survey allowed to map the entire study area at a very fine resolution (over 25 measurements per m2). Incorporating a multi-receiver EMI instrument enabled measuring the apparent electrical conductivity (ECa) and the apparent magnetic susceptibility (MSa) of four different soil volumes simultaneously at each location. The detailed maps provided insight into the archaeological and geomorphological features of the site. Among the detected structures were a large medieval farmstead, a palaeoriver system and a number of military remains from World War I (WWI). The vertical discrimination potential added insight into the vertical facies changes, which allowed modeling the palaeolandscape and helped determining the depth of detected medieval features. The different MSa measurements gave additional insight into the WWI structures. In this paper, we give an overview of the possibilities of combining multiple ECa measurements for interpreting vertical soil variability together with an example of the added information from simultaneously gathered MSa data. More generally, the diverse potential of multi-receiver EMI survey for geoarchaeological research is demonstrated.