1In the years 1884 and 1887, Samuel Jenny (Jenny, 1889) conducted archaeological excavations in Altenstadt, a small village north of the town of Feldkirch in Vorarlberg, western Austria. He discovered the buried remains of several buildings that he interpreted as the Roman road station “Clunia”, which is mentioned on the Roman street map Tabula Peutingeriana on route from curia [Chur] to brigantium [Bregenz] (Fig. 1).
Figure 1. Georeferenced plan of the excavations conducted in the 1880s with the area of the GPR-prospection 1998/99 (black) and 2015 (red).
2In 1998, 114 years later, the city of Feldkirch planned the development of an industrial zone in the area “uf dr Studa”. The exact location of the excavation that took place over a century earlier was forgotten by then. In order to relocate the Roman site, the archaeological prospection service provider Archaeo Prospections® of the Central Institute for Meteorology and Geodynamics (ZAMG) were called in to undertake geophysical archaeological prospection surveys involving magnetometry, earth resistance and GPR measurements in the area (Neubauer & Löcker, 1999; Neubauer et al., 2001). The successful prospection surveys of 1998 and 1999 did not only reveal the remains of the large building complex and of the two adjacent buildings that Jenny had partially excavated, but also uncovered ten additional buildings as well as structures that were interpreted as remains of a Roman road. Since then, several further archaeological excavations took place in the surrounding area of the main building complex with the aim to follow up on the prospection results (Fig. 2).
Figure 2. Depth slice (50-60 cm) of the GPR-prospection 1998/99.
3In 2015, the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology revisited the Roman site “uf dr Studa” with a motorised high-resolution 16-channel 400 MHz MALÅ Imaging Radar Array. The newly acquired and processed GPR data permitted the mapping of the entire archaeological site in so far highest possible imaging resolution. The available datasets lend themselves now to a detailed comparison of the latest prospection results, including their GIS-based interpretation, with the earlier ones and the outcome of the archaeological excavations (Fig. 3).
Figure 3. Depth slice (50-60 cm) of the GPR-prospection 2015.
4In the framework of an ongoing Master thesis, the recently acquired prospection data is interpreted and compared with the interpretations of the radar data derived in 1999. The prospections of 1998/99 still are highly important in finding and identifying the previously known as well as earlier unknown structures, having resulted in one of the largest archaeological GPR surveys at that time providing invaluable information on the Roman site “uf dr Studa”. The high-resolution GPR survey of 2015 provided more detailed information and thus enables a more precise interpretation and identification of the Roman buildings, especially in the area of the main architectural complex, which is densely packed with structures. Due to the high imaging resolution of the data, it is partly possible to identify different building phases.
5Another focus of the presented work is the research history of the Roman site “uf dr Studa” with regard to the historical excavations of 1884 and 1887, providing an “inverse feedback case”, having been excavated prior to the geophysical archaeological prospection surveys. As the excavations of the 1880s were the only excavations conducted in three buildings in the western area of the site, they provide us with important information on what actually was, or what can be expected in the ground. The comparison of the excavation plan with the GPR-data from 2015 also offers insights into how the excavation was undertaken and documented, shedding light on the weaknesses of an excavation conducted in the 19th century, and especially its documentation. Understanding where exactly and to which depth the excavations were conducted also helps to differentiate between excavated/disturbed and unexcavated areas in the GPR data, rendering the data interpretation more reliable. Although the excavations conducted after 1999 mostly did not cover the survey area of 2015, they helped to understand both the subsurface and soil conditions and the archaeology present at the site.