Geophysical Identification of Unmarked Historic Graves

Down-hole magnetic susceptibility techniques were explored as a means of improving near-surface geophysical surveys in historic grave detection. These techniques were used to document distinctive magnetic characteristics of grave shafts at three historic cemeteries first surveyed using various near-surface geophysical methods. Tests revealed a low magnetic susceptibility signature that soil magnetic studies indicated was largely related to differential soil compaction associated with the excavation and refilling of grave shafts. Most apparent at depths beyond those reached by soil penetrometers, this magnetic signature offers a way to assess anomalies identified by near-surface techniques that potentially represent graves. At one cemetery, magnetic studies of the interments themselves suggested spatially patterned, magnetically enhanced zones that might also aid in burial identification in certain contexts. While down-hole techniques will not be foolproof, they do provide another geophysical tool that can be used to improve grave detection. (C) 2010 Wiley Periodicals, Inc.