ArchaeoPhysica Ltd on the WWW

Severn Beach Bristol, South Gloucestershire

ArchaeoPhysica was asked to undertake a set of trial magnetic surveys over potential Roman features buried in deep alluvium. Surveys by other surveyors in the past had mixed results but the high sensitivity of caesium vapour magnetic survey had not been attempted.

The object was to determine whether typical archaeological features in this environment could be located & also to explore the magnetic context in more detail than before.

The surveys showed that magnetic survey is indeed able to detect features of interest in deep alluvium, even if deeply buried. In addition the technique has identified some negative ditch features that could not be seen in the silt during excavation.

Finally, an investigation into the use of different data sets was made to determine the magnetic dynamics of features in the alluvium. This included examination of the total magnetic field intensity at two heights & also the vertical magnetic gradient. The combination of these allowed more information to be gathered than from any individual data set while the total field intensity close to the ground proved to be the most informative overall.

Client

English Heritage & Wessex Archaeology