A multidisciplinary approach in wetland geoarchaeology: Survey of the missing southern canal connection of the Fossa Carolina (SW Germany)

Abstract

In this manuscript we document a multidisciplinary approach in wetland geoarchaeology for detecting artificial structures in a middle European floodplain. By means of a large set of different prospection methods (cadastral analysis, aerial archaeology, LiDAR, SQUID based magnetic prospection, electrical resistivity tomography, seismic refraction tomography, ground penetrating radar) and a subsequent geoarchaeological drilling campaign we provide an overview about the potentials and limits of the applied methods.Our site-specific aims focus on the Fossa Carolina, Charlemagne's shortcut for linking the Rhine-Main and the Altmühl-Danube inland navigation systems during the Early Middle Ages. Our results show that Altmühl meander loops were quasi stable since Carolingian times and that an Altmühl floodplain-crossing trench of at least 650–700 m was required for linking the Altmühl River with the – archaeological known – southernmost position of the existing Carolingian canal. However, our large set of remote sensing and geophysical prospection tools and the corresponding drilling campaign do not show any evidence for the missing Carolingian trench within the Altmühl floodplain. Our results support the idea that the Carolingian canal was never entirely completed although large parts of the canal were almost finished in the northern sections.