The Use of Geophysics in Cemetery Location

Cemetery location is a complex process that intertwines legal, ethical, and logistical challenges. With increasing urban sprawl and rural development, there is also an increased need to relocate cemeteries. TerraX recognizes the sensitivity required in matters involving cemeteries, and we are dedicated to employing advanced practices to identify and map both marked and unmarked burial sites before our cemetery location team even arrives at the location.

Today, state-of-the-art cemetery location practices focus on minimizing ground disturbance and completely avoiding disruption to graves. Geophysical techniques, especially ground penetrating radar (GPR) and archaeological geophysical surveys, are crucial in cemetery location. These methods provide significant advantages in identifying and mapping burial sites, facilitating more respectful and efficient locations and relocations. The TerraX geophysics department is committed to fully utilizing these techniques to achieve the best outcomes.

Understanding Cemetery Location

As urban development projects and infrastructure expansion continue to expand on lands previously left fallow or forested, the chances of discovering a cemetery grow. Regardless of the reasons, the process must adhere to legal frameworks and community sensitivities. When human remains and historical artifacts are involved, the stakes are even higher. Missteps in this process can lead to legal repercussions, community backlash, and ethical dilemmas.

Traditionally, establishing the boundaries of an unmarked or neglected cemetery has relied heavily on historical records and visual inspections. However, these methods can often be imprecise, leading to the unintentional disturbance of unmarked graves or even the complete loss of historical context. This is where geophysics comes into play.

This is what a GPR read-out looks like!

Ground Penetrating Radar (GPR)

Ground penetrating radar is a non-invasive geophysical method that uses radio waves to create an image of the subsurface. It’s particularly effective in detecting and mapping buried objects, including graves, without disturbing the soil. For these reasons, GPR is widely used in various fields, including archaeology, engineering, and environmental studies. As our goal is to disturb these burials as little as possible, the GPR is an increasingly helpful tool in cemetery location efforts.

How GPR Works

GPR systems consist of a transmitter and a receiver. The transmitter sends high-frequency electromagnetic waves into the ground, which reflect off different subsurface materials. These reflections are captured by the receiver and processed to create images of the underground features. The depth and clarity of these images depend on various factors, including soil composition, moisture content, and the frequency of the radar waves used.

Applications in Cemetery Location

In cemetery location projects, GPR serves several critical functions:

1. Identifying Grave Locations: GPR can detect the presence of graves, even those that are unmarked. This allows for a more comprehensive mapping of the burial site, ensuring that no graves are overlooked during the location process.

2. Assessing Grave Conditions: By analyzing the data collected, GPR can provide insights into the condition of the graves, such as the depth and the extent of decay. This information is crucial for planning the appropriate methods for exhumation and reburial, if relocation is required.

3. Preserving Historical Context: GPR can help identify the layout and orientation of graves, which can be essential for maintaining historical integrity. This information is invaluable for historians and archaeologists who aim to preserve the cultural significance of the site.

4. Reducing Disturbance: Since GPR is a non-invasive method, it minimizes the disturbance of the surrounding environment. This is particularly important in cemeteries where respect for the deceased and their families is paramount.

   
   

Limitations of GPR

While GPR is an invaluable tool, it does have limitations. For example, the effectiveness of GPR can be affected by soil conditions. Highly conductive soils, such as clay, can impede radar signal penetration, making it difficult to obtain clear images. Additionally, the depth of burial can also limit the effectiveness of GPR, particularly for older graves that may be deeper than the radar's range.

Additionally, densely wooded areas, areas with large root systems, broken terrain, and steep slopes can hinder the effectiveness of GPR. The images created by the reflected radar waves rely on steady passing and clean, organized paths over the entire area.

Multimethod Remote Sensing

Here's our resident geophysics expert, Shaun, out on a survey!

A multimethod remote sensing survey encompasses a broader range of techniques beyond GPR. These surveys combine multiple techniques to gain a more comprehensive understanding of a site. In the context of a cemetery location project, a multimethod remote sensing survey can include methods like magnetometry, electrical resistance, metal detection, and even cadaver dog surveys.

Key Techniques in Cemetery Surveys

1. Magnetometry: This technique detects variations in the Earth’s magnetic field caused by buried features and other objects with varying magnetic intensities. For example, metal components in caskets can create detectable anomalies, helping locate graves.

2. Electrical Resistance: This method measures the flow of an electrical current through soil, which can indicate the presence of voids, such as graves, and other objects. Different materials (like human remains, coffins, and soil) have varying degrees of resistance, making this method useful in detecting anomalies associated with burial sites.

3. Metal Detection: Combining multiple techniques like metal detection with those above can aid in determining the nature and extent of some subsurface objects or features (typically termed “anomalies” unless ground-truthed through excavation). These surveys can also be effective in locating hardware associated with graves, especially in areas where machines may struggle to reach due to many obstacles or other survey impediments, such as in densely wooded areas.

4. Cadaver Dogs: Cadaver dogs have been shown to be effective in aiding in the location of human remains and unmarked graves. TerraX is familiar with the process of teaming with cadaver dog teams to perform investigations of suspected cemetery areas. Cadaver dogs may be able to assess locations where other methods may not be able to reach due to impediments, and may detect scents in contexts that are otherwise unconducive to more standard geophysical survey techniques.

   
   

Integrating Techniques for Improved Results

One of the significant advantages of conducting a multimethod remote sensing survey is the ability to integrate multiple techniques. By combining GPR with other methods, surveyors can cross-reference data, leading to more accurate identification of burial locations. This multi-faceted approach can uncover graves that may be missed by using a single technique.

Ethical Considerations

As with GPR, most remote sensing techniques are minimally invasive and are non-destructive to graves. The respect for the deceased and their families must be paramount in every step of the process. Surveys should be conducted transparently, with clear communication to the community about the methods being used and the findings.

Additionally, it’s crucial to involve archaeologists and other experts who understand the cultural significance of the site. This collaboration can ensure that the location and relocation processes are handled with the utmost care and sensitivity.

Challenges and Considerations

While the use of remote sensing methods can significantly enhance cemetery location efforts, several challenges must be addressed:

1. Cost and Accessibility: Implementing remote sensing surveys can be costly. Budget constraints may limit the use of these techniques, particularly in smaller or underfunded projects.

2. Training and Expertise: Proper training and expertise are essential for conducting effective surveys. Misinterpretation of data can lead to errors in locating graves, which can have significant consequences during location or relocation efforts.

3. Community Engagement: Engaging with the community throughout the process is vital. Community members often have a deep connection to burial sites, and their insights can help guide the location and relocation processes respectfully.

   
   

Conclusion

The use of geophysics, and particularly ground penetrating radar, represents a significant advancement in cemetery location practices. Remote sensing technologies not only enhance the accuracy of locating graves but also uphold the ethical and historical significance of the sites involved. By minimizing disturbance and preserving historical context, geophysical methods help ensure that cemetery location and relocation projects are conducted with the respect and care they deserve.

As urban landscapes continue to evolve and sprawl, TerraX is committed to integrating innovative remote sensing techniques into cemetery location and relocation planning — that’s why we’ve built a geophysics team. Under the leadership of Shaun West, our resident remote sensing expert, our team has conducted numerous GPR and other geophysical surveys. By leveraging these methods, we can navigate the challenges of modern development while honoring the past and the memories of those who have come before us.