Abstract
Geophysical methods have been used with increasing frequency in archaeology since 1946; aerial photography has been used since 1919. The geophysical methods that are most commonly used at present are electrical resistivity, magnetic, and ground penetrating radar. Magnetometry, particularly when used in a gradient mode or with a continuously recording base station, is used at almost all sites where any geophysical methods are used. Electromagnetic soil-conductivity systems are also being increasingly used because of their very high rate of data acquisition. Less commonly used methods include self-potential, microgravity, radiometric, thermal infrared imagery, and sonic or seismic techniques. Recent developments in image processing and graphic representation have contributed substantially to the archaeologist’s ability to do ‘‘rescue archaeology’’, that is, to carry out high-speed, non-destructive reconnaissance surveys for ancient human cultural evidence in advance of modern industrial development.