There are very few methods available for detecting graves. The only reasonable accurate method available is Ground Penetrating Radar (GPR). The cart contains a radar unit in a bucket that must always be in close contact with the ground and a visual display unit for viewing and recording the observations. Information is stored for later use.
Detecting and locating graves – using Ground Penetrating Radar
These graves were 75 years in existence before scanning was done.
Radar signals bounce off objects below the surface and are see on the monitor.
Scanning of the ground revealed the following caskets below the surface.
The radar unit was pushed over the surface perpendicular to the graves. The rounded top of each curve is the centre point of the casket.
Graves (6) approximately 1.5m below the surface and about 1.5m apart from each other.
Ground conditions and locating success
Underground soil conditions are most important in detecting a grave. Radar signals enter the ground an bounce of objects below the surface and are captured and seen on the display unit. In theory a 3D model can be done whereby a grid is set up on the surface. To do that the cart is pushed over the surface in 0.5 or 1.0m spacings in the X and Y directions to create the model. This is then captured and analysed. If the area to be scanned is 20m (X) x 20m(Y) and 0.5m spacing is required it will then involve about 1600m of scanning. In practice this is very seldom achievable as the surface needs to be clear of any obstacle. In practice the scanner is pushed over the surface until objects are located.
Ideal ground conditions are deep dry sand on level, even ground. Success deteriorates with increasing levels of soil moisture, salinity and clay content. In very wet conditions GPR will be of no use as radar penetration will be limited. However, even in some adverse conditions GPR can be of use.
Ground conditions such as soil type, soil moisture, salinity, etc. also play a role in detecting success. Access to all parts of the property.