Radar technology gets IU Bloomington's pioneer cemeteries to give up their secrets
Tombstones and old documents tell a great deal about who's buried in Indiana's pioneer cemeteries and where. But they don't tell the entire story.
To fill in the blanks, Nelson Shaffer of the Indiana Geological Survey has been using ground-penetrating radar devices, which can "see" underground and identify where graves are located -- without digging up soil or otherwise altering the burial sites.
"We in no way disturb anything," Shaffer said. "It's just like mowing the grass."
Ground-penetrating radar devices find unmarked graves
In fact mowing the grass is very much what the process resembles. On a recent afternoon, Shaffer and Jason Mysinger, a graduate student in geological sciences, were investigating Dunn Cemetery, one of two pioneer cemeteries on the Indiana University Bloomington campus. Pushing ground-penetrating radar (GPR) devices mounted on wheeled carts, they walked slowly in straight lines between the headstones.
The result: A series of detailed 2-D and 3-D images that can indicate the presence and location of caskets or loose soil where a grave was dug maybe 150 years ago.
It takes a practiced eye to read the images and interpret the irregularities. "We do see tree roots and sometimes animal burrows, and we have to factor those out," Mysinger said.
It's a new specialty for Shaffer, who has spent 30 years investigating what's underground in Indiana, but with a focus on coal, limestone and other valuable resources, not graves. He is head of the Coal and Industrial Minerals Section of the Indiana Geological Survey, an applied research institute at IU that provides objective and unbiased information about the mineral, energy and water resources of the state of Indiana.
GPR equipment sends high-frequency radar pulses into the ground. Some of the waves are reflected back to the surface, where they are detected by antenna on the devices. The time difference between the transmission and reception of the waves shows the depth of the reflection.
The reflected waves can indicate the presence of rock or solid objects, rock fractures, differing soil conditions, changes in moisture and electrical properties or soil, and void spaces -- displayed as lateral changes in depth maps produced by the radar signals.
The Indiana Geological Survey has two GPR devices. One emits 250-megahertz waves and provides a more detailed picture of what's underground. The other uses 100-megahertz waves and can penetrate further, as deep as 150 feet in ideal circumstances; it's equipped with an onboard geographical information system to map the readings.
The technology has valuable applications for geologists, Shaffer said. They can use it to detect underground changes in rock and mineral formations without having to drill. In quarry operations, GPR can be used to locate caves, which can have a significant impact on resource quality, affect drainage and pose serious safety risks for blasting.
The devices can detect hidden features in sand and gravel beds and in underground coal and rock mines, potentially improving efficiency and safety of resource recovery operations.
GPR also comes in handy for archeologists, who use it to home in on buried tools and ancient bones, both human and animal. In the world of construction, it's useful for locating buried pipes and utility lines and for checking on the placement of steel reinforcement in concrete buildings.
The impetus for Shaffer's use of GPR came from the fact that coal companies are prohibited by law from disturbing human burial sites, regardless of whether the sites are marked. The Indiana Geological Survey has received funding from the Division of Reclamation in the Indiana Department of Natural Resources to evaluate the use of GPR to locate pioneer cemeteries and archeological sites.
While headstones should provide some indication of where bodies were buried, Shaffer said, they're not definitive, especially in small cemeteries dating back to Indiana's settlement in the 1800s.
Preserving Dunn family legacy
Over the course of 150-200 years, stones may have been moved or misplaced by caretakers, damaged by vandals or shifted and even covered by settling of the ground. "Some graves were unmarked," Shaffer said. "Some may have been marked with wood, and it didn't last."
GPR can locate irregularities that suggest where the soil was disturbed for a burial, even if a 19th-century wooden casket has long deteriorated or if the person was buried without a casket. In pioneer cemeteries, the technique often turns up evidence of more graves than there are grave markers.
Shaffer and Mysinger recently conducted a study of GPR depth penetration at the Fee Lane/Rogers Cemetery, a small plot enclosed by a stone wall and located in front of IU Bloomington's Foster residence center on North Fee Lane. There, members the Baugh, Knight and Rogers families, buried in the mid-1800s, rest just yards away from the clamor of students heading to and from class.
Their investigation of Dunn Cemetery, located on the east end of the Indiana Memorial Union, adjacent to Beck Chapel, is oriented to the future as well as the past.
The Dunn family's deed for the plot of land stipulates that it will always remain a cemetery -- and that burial there must be limited to the descendants of Eleanor Dunn, Nancy Alexander and Jane Irwin, three sisters who aided American soldiers in the Revolutionary War and later settled in frontier Indiana.
Some descendants of the sisters are still living, and occasionally there's a request for interment in Dunn Cemetery. With nearly 60 people already buried in the small plot, the goal is to prevent future burials from impinging on old and possibly unmarked gravesites.