THE SEARCH FOR GRAVES

Over the decades, grave markers in old cemeteries have been lost. Geophysical exploration can sometimes locate the unmarked burials. The two techniques which may be best for this search are a ground-penetrating radar survey and a soil conductivity survey. A ground-penetrating radar survey, with its capability for estimating the depth and shape of buried objects, is particularly suitable. With an electromagnetic induction survey, the disturbed soil in the grave shaft can sometimes be detected as a change in electrical conductivity. Both of these surveys also can locate large metal objects. These surveys have limitations. At some sites, the radar cannot profile deeply enough; at others, the soil strata are so complex that graves cannot be distinguished. A conductivity survey can be degraded by metallic trash and other small objects in the topsoil; it can give the best results where the earth is distinctly stratified. Results from nine surveys are illustrated here. The sites are all in the U.S.A. and the graves are not older than the 17th century. Magnetic and resistivity surveys may be suitable for some sites, but they have not been very successful for the sites discussed here. The success of these surveys has ranged widely, from excellent to poor. While little archaeological excavation has followed these surveys, geophysical tests at marked graves show the capability of the instruments.