Electromagnetic Surveying

A geophysical surveying method used to locate archaeological features and differences in sediment or soil textures. A pulsed induction meter or soil conductivity meter generate electromagnetic waves at the surface of the earth, penetrating it and inducing currents in conducting ore bodies, thereby generating new waves that are detected by instruments at the surface or by a receiving coil lowered into a borehole. This technique only works at a very shallow level, and no electromagnetic instrument is as accurate as the resistivity meter or a proton magnetometer.

A geophysical surveying method. Instruments designed for this technique have two coils. One, through which an alternating electric current passes, produces a magnetic field. This field induces electrical currents in buried objects, which are detected in the second coil of the apparatus. It is possible to detect buried features of archaeological sites by this method, due to differences in electrical and magnetic properties between the fill of the features and the subsoil. Electromagnetic systems are, however, more widely used in metal detectors.