Remote Sensing (Archaeology)

Remote Sensing is the term used for the technique of gathering images using equipment that is at some degree removed from the subject matter and therefore covers a very wide range of techniques for analysing the environment. The Wroxeter Hinterland Project, commenced in 1994 and managed by the University of Birmingham (http://www.arch-ant.bham.ac.uk/bufau/research/wh/base.html), was an innovative model for the combined use of a number of these techniques and amassed a very significant amount of data about the Romano-British town of Wroxeter and its surrounding landscape without recourse to excavation.

Magnetometry is a technique for measuring and mapping the magnetic properties inherent in soil and will determine whether certain areas of sub-surface material have been subject to disruption or movement. If soil from one area has been moved to another, the variations in the magnetic properties can be plotted using software tools. At Wroxeter, more than 2 million data points were collected during the principle magnetometer survey and using the principle that relatively non-magnetic building stone can be differentiated from the surrounding soil, the ancient Roman street system was largely reconstructed showing evidence of higher and lower status buildings in particular parts of the town, as well as areas which may have been dedicated to agro-industrial activities.

The presence of archaeological features (e.g. a buried wall, a cobbled road surface) will also affect the electrical resistance of soil and a resistivity meter is a device that passes a weak electrical current between metal electrodes which are inserted into the soil every 0.5 or 1m apart. Once again, this data is fed into a graphics programme to plot the results.

Ground Penetrating Radar (GPR) was also used at Wroxeter over an area of 2.25 hectares and involves the use of equipment that can measure the nanosecond delay times of microwaves that ‘bounce’ back off buried archaeological features. In combination with seismic surveys, where the reflection of soundwaves are measured to identify sub-surface features (also applicable to maritime archaeology in the form of sonar), and a range of airborne techniques such as multi-spectral photography and airborne thematic mapping, the amassed data has enabled researchers at Wroxeter to put together compelling evidence to explain the changing fortunes of this historically important provincial Roman city.

Additional more current initiatives relating to remote sensing, such as the use of LIDAR (Light Detection and Ranging; or Laser Imaging Detection and Ranging), are referenced on the Methods Network website in the form of case studies (http://www.methodsnetwork.ac.uk/resources/casestudies.html). Information is also available about the Access Grid Support Network for Visualization and Remote Sensing (http://www.methodsnetwork.ac.uk/activities/act10.html), organised by the Institute for Archaeology and Antiquity at the University of Birmingham, which has been established to provide a virtual forum for the discussion of methodologies and solutions in this burgeoning area of research.

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