Geophysical Investigation Using Ground Penetrating Radar (GPR) to Detect Unmarked Burial Sites
Abstract:Comprehensive Ground Penetrating Radar surveys were conducted at the Old Carlisle Cemetery, east of Little Rock, Arkansas, to investigate the locations of historic burial sites and to identify unmarked graves. The Old Carlisle Cemetery, Arkansas, since 1872 has been in use and a potential expansion will be planed if the geophysics data help to identify unused lands. GPR survey was conducted at the cemetery using GSSI SIR-3000 with 400 MHz antenna and 900 MHz antennas. A total of 234.5 m profiles of GPR data were acquired from three locations within the old and new parts of the cemetery.
At the 1stlocation, GPR data collected along 6 parallel profiles. Data reveals, after the normal comprehensive processing; two unmarked graves at about a depth of 1m and one misplaced headstone or collapsed grave were detected. Other marked graves around 1m depth with headstones were also verified by their typical reflections hyperbola on the GPR profiles.
At the 2ndlocation, the data collection was performed along 4 parallel profiles to locate potential areas that were not used for burial in the past. The GPR data showed that there were no graves in the area below at least two of the profiles. Three marked graves which were verified by their headstones might have metal caskets due to their strong reflection hyperbolas around a depth of about 1.2 m. Three other graves were either collapsed or decomposed due to their very weak reflections within a subsided surface area. Animal burrows and a rusted old key were found and verified by near surface digging.
At the 3rd location, the data was collected along 3 parallel profiles. The GPR was able to detect one unmarked grave and two marked graves, each with two coffins, by showing strong reflection hyperbolas at about 0.75 m depth. A grave with a headstone to the north of the two graves did not show strong reflection hyperbola although the burial date (1987) is younger than the other two. This might reflect different type of burial practice or material than the other two graves. GPR did not detect any additional burial site at the studied locations.