Journal of History and Culture Journal of History and Culture

j o u r n a l o f h i s t o r y a n d c u l t u r e
Several trenches were dug around the cemetery site in order to determine the stratigraphy. A layer of reddish-
brown sand was found to overlie a hard gray clay. The sand ranges from 3 to 6 feet in depth across the area, with
the depth generally changing gradually. We interpret the surface to consist of Pleistocene Willis sand overlying
Tertiary Fleming clay.
Geophysical Survey
The use of ground-penetrating radar in archeology is well-established 36 . GPR is a non-destructive method
for studying the subsurface that can provide information on buried features without digging or trenching. GPR works
by sending a tiny pulse of energy into a material and recording the strength and the time required for the return of
any reflected signal. Excavation of cemeteries to answer archeological questions can be considered desecration 37 .
GPR provides a non-intrusive method for examination.
Ground-penetrating radar is useful for locating graves by detecting anomalies in the soil where graves
were dug or for the detecting of buried coffins or vaults. If a vault or coffin does not exist, GPR can be used to
study disturbed soil or other remains of the burial. Remains of burials are easier to locate in sandy soils that do not
contain tree roots or stones. GPR is operated above the ground surface, and produces a cross-sectional image of
the ground.
GPR can produce ambiguous results and is often used in conjunction with other methods, such as magnetic
surveys 38 . Soil conditions and choice of antenna frequency are often responsible for this ambiguity. High clay
content and water content can suppress the return radar signal 39 . Unknown depth and dimensions of targets can
make antenna choice difficult. However, given the right soil conditions and antennae, GPR can provide an accurate
and detailed picture of the subsurface.
In July 2007, a group from Rice University’s Department of Earth Science conducted a preliminary GPR
survey of Wyatt Chapel Cemetery. A GSSI cart-mounted 500 MHz system antenna was used for this survey. The
dielectric constant was determined to be 17 based upon depth to a known target. Records were 80 ns in length,
which corresponds to a depth of about 105 inches (8.75 feet).
With support from Prairie View A&M’s School of Architecture, the group was able to acquire and interpret
59 GPR profiles and 100 global positioning system (GPS) positions in a period of two weeks (Figure 3). Numerous
geophysical anomalies were identified and two of them were excavated with the help of an archeology team from
Texas A&M University. One excavation resulted in the discovery of a metal plank thought to be a burial cover, and
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