USING GROUND-PENETRATING RADAR TO LOCATE NINETEENTH CENTURY GRAVES

Ground-penetrating radar (GPR) is a valuable tool in accurately locating unmarked prehistoric and historic graves. During the winter of 1819-1820, over forty soldiers sickened by scurvy arrived at Fort Osage, a fort and factory trading post located by the Missouri River in Jackson County, Missouri. Despite attempts to save them, all the soldiers died. The soldiers stationed at Fort Osage dug a trench grave for the dead, creating a large unmarked mass grave. This survey used ground-penetrating radar to locate the mass grave, plus other unmarked graves in the historic Fort Osage cemetery. As older historic cemeteries contain graves where the coffin has either long since disintegrated or was not used at all, the reflections indicating these graves should appear significantly smaller and more angular than reflections off a modern casket. This ground-penetrating radar survey focused on a 4200 square foot section of the cemetery, using a Mala RAMAC ground-penetrating radar system and 400 MHz antennas. Runs were taken on north-south then east-west transects. The profiles were filtered using automatic gain control and time varying gain. Several reflections stood out after processing, including a reflection seen in all the runs and interpreted as the previous ground surface. Other reflections include a modern casket burial, several burials from unmarked graves and a long, shallow disturbance interpreted as the mass grave.