Approximately 667 potential unmarked burials were located at a large cemetery by Seramur & Associates over the last few years. It is one of the largest continuous projects that we have ever taken on.

The figure above is a map showing compiled data collected using ground-penetrating radar (GPR). The GPR sends electromagnetic pulses into the ground and is able to detect changes in dielectric properties in the subsurface. Changes in material such as disturbed soil in a grave shaft, vaults, and intact coffins can be detected this way.

Our GPR data is interpreted from profiles (vertical slices in the ground that follow the path where we push the GPR) and depth slices (where values are averaged horizontally, providing us with a plane view of the subsurface's electromagnetic properties).

The image above is an example of a GPR profile. Yellow arrows indicate each burial. Hyperbolas like the ones in this GPR profile are created when the GPR's waves are strongly reflected off of a surface.

Most burials in the United States are oriented east-west. However, there are a few graves in the cemetery that face different cultural sites instead (top right image). Younger or vaulted burials show strong reflections and can be spotted by a sharp change that is visible in the image above. Older graves were typically a wooden casket or shroud burial.

Over time, only the low-density backfill is left as the organics decay. This too is visible using GPR (see the images below).