A study of magnetic fields, particularly the magnetic field of the earth.

This is a method of Geophysical Survey which allows archaeological detection of buried features without excavation. Readings are taken at regular points across a dig site. Disturbed earth and physical features such as walls give differing levels of magnetism. The survey allows a picture of features that would impossible to see above ground to be built up on a computer. The survey is then used to pinpoint areas of interest which can then been excavated more fully.