Rocktown

Archeological Geophysics in the Upper Sabina Tiberina Region of Italy

Roman villa sites proliferate the Upper Sabina Tiberina region within the Lazio district of Italy (~40 miles north of Rome).  It is believed these sites contain clues regarding the cultural, agricultural, and subequent economic development of this region during the Republican Era (third - first centuries BCE).

Google maps image of suspected Roman villa sites
Google maps image of suspected Roman villa sites

In cooperation with the Rutgers-Newark Department of History and the Rutgers Study Abroad program, an annual archeological field school is offered to undergraduates interested in learning archeological field and laboratory methods as well as geophysical prospecting in archeology.

500 MHz grid survey of the Vacone site in progress
500 MHz grid survey of the Vacone site in progress

The first year of the program focused on excavation of a villa site in Vacone, Italy.  Ground penetrating radar was used to help identify features at the site before excavation began.  An initial survey in October 2011 revealed the potential of GPR to identify walls.  During the primary campaign in July 2012, an extensive grid survey was performed.  These results are being groundtruthed with actual excavation results to help guide future surveys in the region.

At left is a GPR radargram over trench one before excavation commenced, at right is the excavated trench showing the topsoil (dark brown) and a mosaic tile floor. The GPR results show strong reflections from the mosaic. The multiples observed in the radargram are likely repeated reflections from the base of the topsoil and the mosaic flooring.
At left is a GPR radargram over trench one before excavation commenced, at right is the excavated trench showing the topsoil (dark brown) and a mosaic tile floor.  The GPR results show strong reflections from the mosaic.  The multiples observed in the radargram are likely repeated reflections from the base of the topsoil and the mosaic flooring.

Key geophysical challenges observed from year one include (1) the relatively small signal penetration depth, likely resulting from Mie scattering effects in the very near surface, (2) the presence of archeologically significant finds within the first half meter of soil that were unresolved by the 500 MHz antennas employed, and (3) an inability to accurately convert two-way travel time to depth, due to a lack of detailed electromagnetic velocity information about the site.

Child grave unearthed during the summer 2012 campaign. GPR cannot be used to detect this level of detail, but it can be used to guide excavations to produce meaningful results.
Child grave unearthed during the summer 2012 campaign.  GPR cannot be used to detect this level of detail, but it can be used to guide excavations to produce meaningful results.

Perhaps the overarching question, from a geophysical standpoint, is 'how accurately can GPR infer archeological features within the Upper Sabina Tiberina region?'  Preliminary results suggest that GPR can be used to characterize major structures and their boundaries.  This result forms the basis for the July 2013 geophysical campaign - to identify the extent of villa sites within the Upper Sabina Tibernia region.