John Dent of SAHAAS using the Ground Penetrating Radar during the 2015 survey season.
Geophysical surveying embraces a number of non-invasive techniques for discovering and mapping underground features, such as buried walls, ditches and artefacts.
The Community Archaeology Geophysics Group, which includes members from SAHAAS, has carried out an extensive survey of Verulamium, and has also participated in other projects. The equipment used includes a Foerster magnetometry cart, Ground Penetrating Radar and an Earth Resistance meter.
The resistivity instrument that we use has been developed by members of the Archaeology Group over the past four years for SAHAAS ... How does it work? Pretty simple concept: measure the local electrical resistance of the soil and look for high and low values. If there's a buried wall you would expect high readings because of the stone; if there's a filled-in ditch, you might expect the reading to be low if the ditch was filled with material that was wetter than the surrounding soil. [Extract from article by Bill Martin in Newsletter 162, August 2006]
You can find out more about how the equipment is used and what results have been achieved at the Group's blog. If you would like to join in, please email Ellen Shlasko on firstname.lastname@example.org. No experience is needed as training is provided on the job.
To find out more about how Society members have participated in geophysical surveying, follow the links below to the Herts Geophysics Project.