Magnetometer Survey

Magnetometry measures local variations in the earth’s magnetic field. The magnetic properties of the soil can be changed by activity such as burning, and cut features are sometimes filled by the magnetised soil. This provides the differentiation to the background soil that we can measure. A magnetometry survey will therefore typically detect ditches, large pits, kilns, hearths, ovens, ceramic dumps and occasionally walls.

There are a number of magnetometer techniques available. Archaeology South-East uses a dual Fluxgate Gradiometer, which is the fastest detailed method of archaeological prospection. Three hectares a day can be covered with relative ease.

It should be noted, however, that:
• Modern disturbance will prohibit survey as the interference will be too great to detect archaeology.
• Interpretation of results can be problematic, especially when determining if anomaly is geological or archaeological.
• The technique is very dependent on local soil type and geology for success.

ASE can advise as to whether or not a geophysical survey will be appropriate.

Recent ASE projects using the dual Fluxgate Gradiometer:

• Peacehaven, Sussex
• Kingshill, Cirencester.

Contact: Darryl Palmer