Finding Lost Graves: Ground Penetrating Radar Analysis of Dunn County Potter’s Field, Wisconsin, USA

Abstract

Dunn County Potter’s Field contains over 100 unmarked graves of persons from the County Poor House and the County Asylum (both now demolished) in Menomonie, Wisconsin. Community interest in locating the graves prompted non-invasive scans of Potter’s Field using ground penetrating radar (GPR). GPR transmits electromagnetic (EM) pulses into the ground, which reflect off subsurface changes before being received and recorded digitally. A 16x50m grid was collected along the site’s western boundary with a Sensors and Software pulseEKKO Pro GPR unit with 500MHz antennae. GPR traces were triggered every 0.02m via odometer wheel, and lines were collected with a spacing of 0.25m. Alternating strong and weak reflections are repeated in a sub-parallel, semicontinuous pattern throughout the grid. The strong reflections are often underlain by steep-angled hyperbolics. The reflections were identified 0.6–1.5m below the surface, each measuring 1.0m by 2.25m, and spaced 1.0m apart. Reflections were interpreted as two probable rows of individual graves. In Fall 2024, 42 crosses were placed at each probable grave, however further scanning is recommended to locate remaining lost graves. The GPR work at Dunn County Potter’s Field is a model for other cemeteries; providing means of locating and restoring honor upon unmarked graves worldwide.