A MAGNETOMETER SURVEY OF AN OLD PSYCHIATRIC HOSPITAL CEMETERY, TOLEDO, OHIO

Patients whose bodies were not claimed by relatives after passing away at a former psychiatric hospital in Toledo, Ohio were, until well into the twentieth century, usually buried in poorly documented graves in two fields on the hospital grounds. Although some graves were marked by numbered concrete nubbins smaller than a brick, many markers were lost to vandals or simply sank out of sight. A committee of volunteers is working to locate lost graves and grave markers, reclaiming these long-forgotten cemeteries. We used a G-858 cesium vapor magnetometer (gradiometer configuration) to map about 5000 square meters at one cemetery to aid volunteers in their search for lost graves and markers. Measurements were made along profiles 1 – 2 meters apart at a rate of about 7 to 8 measurements per meter along profile. 136 small (2 meter) dipole anomalies in the 1500 square meter northwest sector of the site suggest that burials are concentrated in the western sector of this survey parcel, that there are few burials in the eastern sector of this parcel, and that some stones found in the eastern sector have probably been moved. The southern part of the site is characterized by broad, high-amplitude anomalies that might show locations of farming buildings and a road that occupied this site before it was used as a cemetery. These strong anomalies obscure the low-amplitude patterns we interpret as burials. Because magnetometer surveys cover the site more rapidly than ground-penetration radar (GPR), our plan is using the magnetometer survey to identify locations where selected GPR profiles can verify the presence or absence of burials, and, then use GPR to cover ground where broad, high-amplitude patterns dominate the magnetic anomaly map. We have not begun investigating the second (6000 square meter) cemetery, awaiting approval and permission from the current owners.