The sensor detects and records weak changes in magnetic susceptibility, identifying archaeological features beneath the surface.
The Geoscan Research FM256 Fluxgate Gradiometer is normally used in logging mode collecting data on zig-zag traverses, enabling the operator to cover large areas in a short timeframe. Data is processed through TerraSurveyor software, enabling a variety of graphics to be viewed for understanding the below-ground archaeology. This instrumentation has been used on several sites successfully in Dorset.
Global Navigation Satellite System (GNSS)
GNSS equipment receives data from satellites and allows ground positions and heights above datum to be computed producing accurate contour surveys.
The TopSURV 8 comprises a Base and Rover configuration, the latter can be mounted on a three-wheeled buggy for rapid automatic topographical data gathering or manually operated over a grid system if the terrain is not suitable for the buggy. The data collected is processed through Surfer software that allows a variety of data representations to depict the terrain, often identifying features that remain invisible to the naked eye.
Resistivity Meter (RM)
An elecrical current is passed between probes in the soil and the resistance is measured and recorded. Walls with high resistance and ditches with low resistance can be identified.
The Geoscan RM85 is the latest equipment of its type, benefiting from a fast download of data using USB ports. Fast and accurate data collection enables quick surveys across large areas to be undertaken and has been used successfully on a number of sites in Dorset. The data is processed through TerraSurveyor software to produce graphics in a variety of modes to elicit maximum information as possible about the site.
The DCRG now has access to the following equipment enabling the group to undertake a full archaeological investigation, providing topographical and below-ground prospection. We are very pleased to assist voluntary and charitable organisations with their geophysical surveys.
The level and staff is a simple and inexpensive way of measuring the differences in heights to produce a topographical representation of an archaeological site. Recording of the data has to be referenced to the system of OS Bench Marks usually found on buildings and annotated on the OS maps.
Level and staff
Radar waves are transmitted into the soil and the time it takes for these pulses take to return is measured and digitized into a refection trace.
Ground penetrating radar has been used by the DCRG and hires the equipment when required. A series of three dimensional representations can be built up indicating archaeological features normally buried too deep for other geophysical techniques.
Ground Penetrating Radar (GPR)