Archaeogeophysics at Walker Cemetery
October 5, 2002
Fayetteville, Arkansas
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In association with Arkansas Archeology Month, the Washington County Historic Preservation Association and the Arkansas Archeological Survey conducted an archaeogeophysical remote sensing and mapping survey at historic Walker Cemetery to help locate unmarked graves. The work will assist local preservationists in cemetery conservation efforts, and provided a guided demonstration of these technological methods.
The
demonstration was well attended with approximately forty people visiting
the site between 10 AM and noon on Saturday October 5th. Paula Marinoni
gave an introduction that included history about the site and some of
the people buried there. With the help of volunteers from the Arkansas
Archaeological Society and graduate students from the University of
Arkansas, Jami Lockhart of the Arkansas Archeological Survey demonstrated
and described the work being done on the site. Lockhart has been conducting
this type of research on prehistoric and historic sites throughout Arkansas
for the past three years while pursuing a Ph.D. in Environmental Dynamics
at the University of Arkansas, Fayetteville. Survey Archeologist Jerry
Hilliard demonstrated the use of laser-driven land survey equipment as
he and volunteers gathered data for an accurate map of the cemetery.
This initial work at Walker Cemetery involved the use of two different archaeogeophysical technologies. The term archaeogeophysics describes the use of devices that record the contrasting physical properties of subsurface archeological deposits and surrounding natural soils. Using these devices, researchers can produce maps that identify and locate archeological features and soil changes produced by peoples' activities in the past.
One
of the technologies used, Electrical Resistance, is measured by a device
that injects a small electrical current into the ground. Archeological
features and man-made objects under the surface generally have a different
resistance to electricity than the natural or undisturbed soil that surrounds
them. Those differences can be measured and mapped.
Ground penetrating radar (GPR) was also used during the demonstration. GPR devices inject continuous pulses of radar energy into the ground that are then reflected back to the surface by buried objects. The resulting computer images are a series of profiles or sections, which can be further processed as map views of specific depths. Just prior to the demonstration, GPR data were collected within an area of marked graves in order to establish image signatures for known burials in this particular geology and soil type. The initial surveys were very successful and this baseline information will be compared to imagery in other areas of the cemetery in weeks to come in order to help locate unmarked burials.
The data from each of these initial surveys has been downloaded to a computer for use with image processing software. Examples of the image maps are on file at the Arkansas Archeological Survey.
