GEOARCHAEOLOGICAL INVESTIGATIONS AT A HOLOCAUST SITE (PONAR), LITHUANIA: SUBSURFACE IMAGING IN SEARCH FOR A PROCESSING TRENCH AND BURIAL PIT

During 1941 – 1944, over 100,000 people were brought to the outskirts of Vilnius to be killed and later burned within the Paneriai Forest. The site is one of many WWII killing sites in Lithuania. Based on discussions with museum personnel and earlier electrical resistivity tomography (ERT) profiles, ground penetrating radar (GPR) was utilized to image select sites to aid in locating buried archaeological features including a human processing trench, and a previously unlocated human burial pit. Using GPR, which is a non-invasive and non-destructive subsurface imaging geophysical method, our team collected datasets without disturbing the present day sensitive landscape. A Sensors and Software pulseEkko1000 GPR system was used to collect transects as well as grid datasets. After testing several antennae frequencies, we used an antennae frequency of 225 MHz, an antennae separation of 0.5 m and a step size or 0.05 m. In locating a section of the processing trench we laid out and collected a 13 m x 3-6m grid which consisted of 52 transects spaced 0.25 m apart. Both two dimensional and three dimensional datasets show evidence of a buried “trough” which is interpreted as the trench. At the second site, GPR transects were located and collected based on earlier Luftwaffe photos and geophysical datasets that indicate the possible location of a burial pit that presently has little to no surface expression. Two-dimensional results and associated interpretations from the GPR lines highlight several patterns: i) horizontal to sub-horizontal semi-continuous to continuous reflections are interpreted as the natural stratigraphy of the regional landscape, ii) “natural stratigraphic” reflections are erosionally truncated by dipping reflections and are interpreted as the edge of the proposed pit, and iii) within the proposed pit, multiple chaotic reflection patterns are apparent including hyperbolic ones. These reflections are interpreted as the pit contents (burned victims). This tragic Holocaust site - Ponar – provided a collaborative project where scientific methods can corroborate survivor narratives.