There are many reasons why burial sites may require investigation. These may include new developments in urban areas, extensions and remedial work to churches, or academic research.
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The most suitable geophysical technique is Ground Penetrating Radar (GPR). This is a high-resolution technique which offers depth information, measuring to the top of the burial, and allows the data to be analysed in plan or section view.
GPR can be conducted over a variety of surfaces, meaning that the same equipment can be used on a grassed graveyard or on a church floor. Individual burials, as well as vaults can be located with GPR. Unless the cremation pots were buried in large pits these remain as very difficult targets; often only the boundary ditch of a cemetery may be located.
Above : Section view of GPR, showing 6 coffin burials below 1m depth.
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Traverses are collected at close centres, generally 0.5m, travelling North to South to ensure that as many passes as possible are achieved over the East-West orientated burial. The GPR data can also been displayed in plan view as a Timeslice, showing anomalies at various depths.
Above : Timeslice plan view of GPR data in a Cathedral Cloisters showing numerous East-West orientated burials at c.1.5m depth.
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The data is analysed and possible graves are interpreted and displayed in an AutoCAD drawing.
Above : GPR data interpretation in AutoCAD, showing location of possible graves (green and red hatch).
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Photogrammetry
Often burials are in a hole which has been quickly dug and backfilled with the same material. Additionally, they may not be in a coffin. This means it can be extremely difficult to identify the grave from the surrounding material, so we have to look for changes in moisture content, organic carbon and texture/density which are affected by the presence of a burial. In these cases, photogrammetry may be a useful technique.
RGB Photogrammetry (the bands of light which are visible to the naked eye) can detect slight changes in the ground surface and potentially show minor depressions or mounds in 3D data, accurate to 1cm. Additionally, Multispectral Photogrammetry (the bands of light which are not visible to the naked eye) can detect changes in vegetation health not visible in RGB, due to differing levels of chlorophyll, which can be caused by buried materials, including graves.
Photogrammetry can also be used in areas which have been stripped of the topsoil. In these instances, RGB Photogrammetry can detect slight changes in soil colour indicating features hard to see from ground level. Whereas, Multispectral Photogrammetry can detect the reflectance in soils which can represent organic Carbon, moisture and texture/density.
Above : Multispectral image outputs of graves (on a stripped site).
Geophysical Engineering Surveys
Air Raid Shelters
Cellars & Basements
Post Tension Cables
Underground Storage Tanks
Air Voids
Chimney Flues
Rebar
Water Engineering
Badger Setts
Earthing Installations
Sinkholes
Burials
Geological Application
Soil Thermal Resistivity Testing
Buried Foundations
Landfills
Structural Investigations
Buried Manholes
Mineshafts
