A MULTI-METHOD GEOPHYSICAL APPROACH TO LOCATE UNMARKED GRAVES IN MILTON, PENNSYLVANIA

In fall of 2005 ground penetrating radar (GPR), electromagnetic, and resistivity methods were used at two study sites in Milton, Pennsylvania. The integrated investigation delineated multiple unmarked graves from the late-nineteenth and early-twentieth century. Ultisols were present at both locations, 0.5 to 3 meters thick, overlying the Silurian Bloomsburg formation of the Valley and Ridge Province in Central PA. The first site location is a 13 m by 20 m area located in the southeast corner of Milton Cemetery described as a "potter's field" with a relatively unknown history of burials and maintenance. The second site is a 10 m by 33.5 m area in the southwest corner of Harmony Cemetery and may contain bodies re-interred after flooding of the original cemetery in 1889. At both sites the state of the remains, burial techniques, and identities of the pre-1930's graves are unknown. The multi-method approach utilized a dipole-dipole array with an IRIS switch 48 resistivity meter, GSSI SIR-2000 GPR with a 400 MHz antenna, and both frequency and time-domain electromagnetic systems. Multiple geophysical methods allowed for measurements of several properties that allowed constraints to be placed on interpretations regarding subsurface targets. Multiple anomalies were detected in the subsurface at both locations by each instrument and the anomalies were correlated to confirm and eliminate possible burial locations using surface features including adjacent tombstones and trees. In addition, interpretations were partially constrained by control lines taken of known graves dated 1927 and 1956. The control line of the 1927 grave provided information about the type of response expected from a rough box burial while the 1956 grave provided information about the response expected from a more recent casket burial. More graves were found at the Milton Cemetery than at Harmony Cemetery where it appears few graves are located. The non-invasive multi-method geophysical approach used was successful in the determination of grave locations.