The Munree Cemetery Project: An Update on Our Progress

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You may remember our previous post about the Munree Cemetery. We used Human Remain Detection Dogs (or cadaver dogs) and Ground Penetrating Radar (GPR) to help us located unmarked burials in this cemetery located in East Tallahassee. We wanted to compare the results of the dogs with that of the GPR. Well, or preliminary results are in and we wanted to share them with you. You may remember that this is a joint project with FPAN and the Southeast Archaeological Center (SEAC), which is part of the National Park Service. Well, a big thanks to SEAC for allowing us to use their GPR equipment for this project!

So, here is the skinny on how GPR works! These types of surveys have grown in popularity over the past 30 years. Despite the relatively commonplace use of GPR, imaging of buried features can be somewhat difficult. To detect archaeological features (or anomalies, as we call them) they must contrast electromagnetically with the surrounding soil matrix. Unfortunately, these types of instruments respond to archaeological anomalies and natural disturbances (tree roots, rocks, etc…). Therefore, the interpretation of GPR results depends greatly on the recognition of patterns in the data that correspond to the expected form of an archaeological feature (in this case, a pattern of burials like you would expect to find in a cemetery). GPR units operate by transmitting distinct pulses of radio energy from a surface antenna. This energy is reflected off of buried objects, features or soil structures. A second receiving antenna detects reflected pulses of energy. Using this data, GPR systems are capable of producing reliable images of subsurface anomalies. The survey at Munree Cemetery used a Geophysical Survey Systems SIR-3000 data acquisition system with a 400 MHz antenna, capable of resolving features measuring approximately 50 cm in diameter to a maximum depth of 3 meters. However, in practice, the depth of penetration is sually more limited because of varying electrical properties of the soil. The maximum depth of radar penetration during this survey was about 240 cm.


The GPR image from one of our grids, indicating anomalies identified by the GPR and possible burials as indicated by the canines.

As you may remember, the dogs were allowed to do a loose grid search of their assigned areas. If the dogs exhibited a final response the area was marked with a survey flag. Using dogs to identify human remains old enough to be considered archaeological in nature is a relatively new practice and dog handlers and trainers are still fine tuning their training techniques. As part of this survey, we are providing our data to the handlers so that they can use it in their training. Soil, humidity and air temperature can affect how the dogs perform. Large trees, such as live oak, can actually “drop” scent from their leaves. This is caused by the scent of the human remains running up the trunk from the soil and into the leaves. In the morning these large trees “drop” the scent, which can sometimes cause the dog to exhibit their final response at the drip line of the tree. Rodent holes can also vent scent, sometimes a distance from the actual burial. Dogs are best at indicating if a burial is present, but it can be a challenge for them to identify a single burials exact location.

It is important to note that thus far our findings are preliminary and additional work is necessary to determine the efficacy of using cadaver dogs to identify historic burials. At this stage, it is difficult to ascertain with any degree of certainty if burials are present in the areas that we tested. The discovery of several unique anomalies with geometry similar to burials suggests that unmarked graves are possible and perhaps likely in these areas. In total, the dogs identified sixteen targets that may represent unmarked graves. Four of those targets were within the GPR grids; and of those four, three were found to be associated with burial like anomalies. The dogs also actively targeted areas with known burials as evidenced by headstones and slumping. The dogs missed one possible burial in Area A and a possible cluster of burials in Area B. Future work at Munree Cemetery may include expanding the GPR survey area and ground truthing the anomalies corresponding to the targets identified by the canines. Still, the available data suggests that as a tool to expediently investigate an area for unmarked graves, GPR and cadaver dogs provide an effective means to guide research with comparable results.