Non-invasive investigations at Wroxeter at the end of the twentieth century

over a number of field sessions, the Roman city of Wroxeter was surveyed using fluxgate gradiometers. In the paper the authors describe the\r\n strategy for assessing a large site, approximately 0.7 km2 in size, as well as presenting the graphical results. Prior to the survey it was believed\r\n that Wroxeter was a garden city with areas of open space inside the defensive ramparts. The results of the magnetic survey, however,\r\n suggested that almost the whole of the area contains significant archaeological anomalies. The interpretation of the data has provided a wealth\r\n of detail concerning the layout and zonation of the city. Although many of the most prestigious buildings were already known, it is the\r\n evidence for the lower status occupants of the city that is of particular note. For the first time geophysical survey has defined the settlement\r\n areas as well as suggesting industrial zones where the lower status population of Roman Wroxeter are believed to have worked.

concerns a new version of the RATEAU (Résistivimétre AutoTracté à  Enregistrement AUtomatique) system in the pole-pole configuration was field tested in August 1995 on the site in co-operation with the Birmingham University Field Archaeology Unit. The device consists of a small three-wheeled carriage containing a resistivity meter, a PC and batteries. The front wheel measures the position along the profile. The two others, connected to the resistivity meter, are metallic and fitted with spikes ensuring a good electrical contact with the ground (potential, P, and current, C). Two remote electrodes are connected to the resistivity meter through a long electric cable. The carriage is light enough to be\r\n pulled by hand. A large resistivity survey of about 3.5 ha was completed, in average conditions, in a few days. After appropriate data processing, the map shows, with great detail, many interesting features, such as buildings, roads and modern disturbances. A total of 5 h was required to survey an area of 1 ha, consisting of 101 profiles of 100 m. At the time of the survey, this prototype ranged among the lightest and the fastest available for accurate archaeological surveys with small grid spacing.

provides details of the application of this technique to a large-area archaeological site. The GPS potentially removes any dependence on an existing map and allows positional fixes anywhere on the face of the globe. Carrier phase differential GPS allows real-time three-dimensional survey data to be collected in relative space to subcentimetre accuracy. Kinematic GPS survey facilitates the collection of data points at submetre intervals at the same speed as the operator walks or drives across a land surface. This technique is potentially of great significance to the recording of surface archaeological features in a three-dimensional form as a DEM (digital elevation model) or DTM (digital terrain model). Accurate three-dimensional digital data is expensive to collect in terms of man-hours spent using more traditional survey methods. Such data is a vital part of any GIS (geographical information system) based site or landscape analysis. Real-time kinematic (RTK) GPS can replicate the archaeological surface to a level of accuracy that creates a virtual three-dimensional cast of the topography.