Magnetometry, sometimes called gradiometry, is the method of choice for fast evaluative surveys over large areas. It works by measuring the tiny fluctuations in the earth’s natural magnetic field caused by buried archaeological features or other objects. It is especially effective at identifiying brick structures, features with a high metal content, or structures that have experienced extreme heat, such as kiln or other industrial remains. Magnetometry will also detect most large buried excavated features, such as ditches and pits, especially if they contain organic remains. As the method is highly responsive to metallic objects it is considered unsuitable for brownfield survey in urban areas.
Gradiometer survey at Carnforth, Lancashire, England
When we recommend magnetometry:
For quick surveys or when needing quick results
For large areas
In rural or greenfield areas
For prospection when the existence of archaeology is unknown