BACK TO THE BASICS: EVALUATING THE APPLICABILITY OF GROUND-PENETRATING RADAR FOR DETECTING PREHISTORIC ANIMAL REMAINS

Bone-beds can provide a wealth of information at archeological sites, including age of the site, site formation processes, seasonality of the kill, size and gender of the herd, paleoenvironmental conditions at the time of the kill, and cultural affiliation of the hunters. As with most prehistoric archaeologic sites, bone-beds are usually stumbled upon by accident, and the primary method of determining the extent and condition of the bone beds has been excavations. This paper addresses the applicability of non-invasive geophysical methods for detecting the vertical and horizontal extent of buried prehistoric animal remains.

There have been previous attempts, mostly in forensic studies and studies that involve mapping graveyards, to locate buried bone using geophysics, especially magnetic, ER, and electro-magnetic methods. Although geophysical tools have successfully identified buried remains of homicide victims and the location of graves, these finds resulted from the identification of anomalies related to the disturbed soil in graves and not to an anomalous signal from the bone itself. It is important to determine the signal from bone and how its electrical properties change due to the effects of weathering, because prehistoric animal remains typically were not buried immediately upon death, but instead were gradually mantled by sediment. Furthermore, if a bone signature can be identified using geophysics, then prehistoric cultural features such as burials could be identified and avoided.

My research explores the use of ground-penetrating radar (GPR) to detect buried bones. First, over 90 thin section samples were cut using four different modern faunal skeleton remains: bison, cow, deer, and elk. One sample of mammoth core was also analyzed. The electrical characteristics of these samples, including relative permittivity and loss tangent values, were identified using an impedance analyzer in the frequency ranges of 10 MHz to 1 GHz. Statistical analysis of the results will be presented, as well as an overall model showing the relationship between weathering of the bone samples (measured using overall porosity) and the relative permittivity. Information gathered from these experiments will be used to create simulated GPR models that will be compared to GPR data collected over controlled sandbox experiments.