Magnetometry Survey

Magnetometry survey is a non-invasive geophysical technique that maps buried archaeological features by detecting the tiny variations they produce in the Earth's magnetic field. Many human activities alter the magnetic properties of the ground: burning enhances the magnetism of soil in hearths and kilns, while pits and ditches filled with topsoil are more magnetic than the surrounding subsoil, and stone walls may be less magnetic. A magnetometer carried across a gridded survey area records these faint anomalies, which are processed into a plan-view image revealing the shape and arrangement of subsurface features without digging. First applied archaeologically by Martin Aitken and John Belshé in 1958 and developed into modern fluxgate and caesium gradiometry, magnetometry is among the fastest and most informative prospection methods, as detailed in Aspinall, Gaffney, and Schmidt's standard reference and in general texts such as Renfrew and Bahn.