Electrical Imaging in Archaeology

Abstract A field data acquisition system has been developed to enable an electrical image of the subsurface to be produced rapidly and effectively under computer control. The unprocessed measured apparent resistivity data give a very approximate but nevertheless useful picture of the subsurface and an example section across the ramparts of Salmonsbury Fort (Gloucestershire, England) illustrates this. A section measured across the mediaeval site at Rocester (Derbyshire, England) demonstrates how the data may also be modelled using modern finite element computer software. However, the sharpest images are produced by a newly developed and completely automatic computer inversion process. The technique is illustrated with an image of true resistivity measured across a burnt mound in Birmingham.