Detection of Resistive Features using Towed Slingram Electromagnetic Induction Instruments

摘要

Slingram frequency domain electromagnetic (FDEM) instruments allow simultaneous measurement of both magnetic susceptibility and electrical conductivity, which should justify their widespread use in archaeological surveying. However, this is not the case and their application remains quite limited due to: (i) a lack of knowledge about the role of coil orientation and spacing in terms of the detection abilities for archaeological features (especially for resistive bodies); and (ii) a lack of instrumentation specifically designed for shallow targets. We present here a test of a new version of the CS60 instrument (VCP coil configuration and 0.6 m intercoil spacing) for shallow depth resistive feature detection. This experiment was undertaken on the Roman site of Vieil-Evreux where a complete series of control resistivity and radar data was obtained. Detection of buried Roman walls was successful, in accordance with what can be expected from three-dimensional modelling. This confirms that the application of this type of instrument in archaeological surveys merits to be extended significantly.