GEOPHYSICS TO CADAVER DOGS: MULTI-METHOD APPROACH TO SURVEYING HISTORICAL CEMETERIES

As urban sprawl impinges on rural areas, tracts of land slated for development conceal family or small cemeteries. These cemeteries have often fallen victim to agricultural pursuits, the destruction of grave markers, or have been left to overgrowth. At a minimum, the cemeteries might have been marked on a quadrangle map, associated with a church, or given mention in the local book of deeds. Most often however, historic cemeteries are disregarded in the modern consciousness, relegated to the fading memories of an aging generation.

Traditional land survey methods can often locate the grounds where graves exist, or where stones once stood, but cannot necessarily assess how many individual graves are present, or how extensive the cemetery is. In these cases, geoarchaeologists typically employ a range of non-invasive, geophysical surveying techniques such as ground-penetrating radar (GPR), electrical resistance, and magnetic survey.

Another non-invasive survey method that has gained interest over the past decade is the use of cadaver (HRD – Human Remains Detection) dogs in locating burials and mapping cemeteries. The scientific literature involving HRD dogs is relatively limited, as these dogs are most often utilized in highly sensitive criminal investigations and searches for missing persons. What literature is available is often empirically derived, painting a picture of a technique that is not fully understood, particularly in how dogs recognize human decomposition that has occurred over decades or even centuries.

Over the last decade, to better understand why HRD dogs respond or alert to certain graves (but not all graves), we have mapped historic cemeteries using HRD dogs in concert with geophysical methods (i.e., GPR, resistivity, and mag). Geophysical methods tend to be most effective in detecting modern graves where shafts and coffins are still preserved and distinguishable, but less reliable in older, graves where high contrast materials have decomposed. HRD dogs tend to be quite effective in narrowing the initial extent of survey, and in detecting older burials where remains are in advanced states of decomposition due to minimal embalming and coffining. Thus, a multi-method approach that employs both HRD dogs and geophysical methods provides a greater likelihood for success in mapping historic cemeteries.