In which variations in the magnetic properties of the soil are detected and recorded and the data thus obtained is analysed to see if any of said variations could be the product of ancient human activity.

Actvities which would produce a detectable signal include:

• building and using hearths or kilns; using burnt / fired material in construction (brick walls);
• disposing of used or broken burnt / fired material in a sensible manner (chucking it into a ditch or pit);
• similarly disposing of organic waste material and leaving it to decay over a long period of time (while going to live somewhere else less smelly);
• laying an iron pipe.