Chasing aeroplanes: developing a vehicle-towed caesium magnetometer array to complement aerial photography over three recently surveyed sites in the UK

Aerial photography combined with airborne lidar can often provide information on the location of archaeological sites at a near landscape level of coverage. Ground-based geophysical techniques may then be deployed to complement the aerial survey, particularly where the soils or land use may not be ideal for either producing crop marks or preserving topographic features. This paper describes the development of a vehicle-towed caesium magnetometer array, from an original handpushed system, to allow high-density datasets to be rapidly acquired over large areas required to provide a meaningful comparison at the scale demanded by the aerial survey results. Technical details of the system are presented together with methodological considerations for both data acquisition in the field and appropriate post processing to obtain high-sensitivity field measurements over more weakly magnetized sites. Results are presented from a number of recent collaborative research projects within the English Heritage Remote Sensing Team to illustrate the benefits of a combined aerial and ground-based approach to mapping the historic environment.