OPTIMIZING PROCESSING AND INTERPRETATION OF GROUND PENETRATING RADAR (GPR) RADARGRAMS IN THE COMPLEX GEO-ARCHAEOLOGICAL ENVIRONMENTS PRESENT IN SOUTH MOUNTAIN, PENNSYLVANIA

Ground-penetrating radar (GPR) is used in archaeological studies as a shallow non-invasive technique to study sub-surface characteristics of archaeological sites prior to a dig. Although GPR is widely used in geoarchaeology, few archaeological sites have similar sub-surface characteristics, therefore, analysis of radar grams (RGs) can be hard site to site. This nascent study aims to develop optimized post-processing routines to apply to an interpreted periglacial landslide feature within the Catoctin Metarhyolites of PA. This project continues pilot work by Cornell et al. (2019), who analyzed GPR characteristics of solifluction lobes and Native American metarhyolite quarry pits. The goal of this study is to standardize post-processing parameters paramount to developing superior RGs to refine interpretations of GPR transect data in this geologic setting.

The study area contains 73 quarry pits on or adjacent to the landslide feature. These pits vary in shape and of the 73 quarry pits, 69 are on the landslide feature. Quarries were likely excavated over time by Native Americans who may have used the site as early as the Archaic Period, 11,700-3,200 BP (Raber et al. 1998) or possibly earlier. Given this heterogeneous environment, this study site presents unique challenges for analyzing GPR RGs relative to other sites in the region. Bedrock features such as fracturing/jointing, near-surface groundwater, colluvium, and generations of mining waste add to a complex sub-surface environment that makes GPR interpretation complicated. It is critical that efforts are focused on producing viable RGs, and to target ground-truthing of the RGs to both the surficial and sub-surface environments.

Data processing with RadExplorer and other software allows for a suite of post-processing routines to be joined into workflows for easy RG generation following standardized protocols. This study evaluates multiple routines to assess algorithms used to produce optimal results for the complicated geology of this study site (#36AD0569). The results of this study will directly affect the efficiency of planning future archaeological research at this site, and within other sites that have similar geoenvironmental histories. The goal is to prompt archaeological exploration efforts to answer several important research questions.