Locating and characterizing burials using 3D ground-penetrating radar (GPR) and terrestrial laser scanning (TLS) at the historic Mueschke Cemetery, Houston, Texas

Abstract

We use ground-penetrating radar (GPR), terrestrial laser scanning (TLS), cemetery records, and oral histories to locate and characterize unmarked burials at the Mueschke Cemetery in Houston, Texas. We employ TLS surveying for the reconnaissance of the various types of burials in the cemetery. Concrete burials were used after 1940 while wooden burials were common before 1940. Strong correlations of TLS shallow surface mounds and depressions with known burials provide substantial motivation to follow-up with a detailed investigation with GPR. To calibrate the GPR survey, we undertook excavation and lab experiments to measure relative dielectric constant (3−10), moisture content (14%–21%), and electrical conductivity (0.36–0.38S/m) of the location's soil. Grain-size experiments indicated that the soil at the survey location is reasonable for GPR, which was subsequently reinforced by the high quality GPR images with a depth of penetration of about 2.5m and a vertical resolution of 6cm. Numerical modeling provided a signature of a concrete burial with a flat rectangular top while a wooden burial resembles a typical hyperbola shape. 2D GPR template surveys over concrete and wooden burials show strong response and follow the numerical modeling findings. Three methods were used to estimate the soil radar velocity: CMP, two-way travel time (TWTT), and hyperbola fitting. These techniques yielded a soil velocity of about 0.055–0.067m/ns. 3D GPR surveys produced anomalies that were consistent with headstones, cemetery records, and oral histories. Taking GPR depth slices overlain on the TLS elevation profile and cemetery records strongly indicated the location of two suspected unmarked graves including the oldest burial (1875) of James West.