ARCHAEOLOGY

Magnetometers, electrical resistance meters, ground-penetrating radar (GPR) and electromagnetic (EM) conductivity meters are most commonly applied to archaeology . These methods can resolve many types of archaeological features, are capable of high sample density surveys of very large areas, and of operating under a wide range of conditions. Geophysical methods used in archaeology are largely adapted from those used in mineral exploration, engineering, and geology. Archaeological mapping presents unique challenges, however, which have spurred a separate development of methods and equipment. In general, geological applications are concerned with detecting relatively large structures, often as deeply as possible. In contrast, most archaeological sites are relatively near the surface, often within the top meter of earth. Instruments are often configured to limit the depth of response to better resolve the near-surface phenomena that are likely to be of interest. Another challenge is to detect subtle and often very small features – which may be as ephemeral as organic staining from decayed wooden posts – and distinguish them from rocks, roots, and other natural “clutter.” To accomplish this , it usually requires at least one and sometimes dozens of readings per square meter.