The Roman road “Via di Villadose” and its relations with the paleaeohydrography (Rovigo - Italy)

The study area is about 30 km far from the Adriatic coast, between the cities of Rovigo and Adria, and delimited respectively to the north and to the south by the Adige and Po rivers. From the archaeological viewpoint the area is of great interest due to the presence of important Bronze and Iron Age sites and the existence of an exceptionally well-preserved roman centuria, which extends for 250 km2 from the city of Rovigo almost to the Lagoon of Venice and dates back to 1st century BC-1st century AD. Prominent is the case of Villadose which lies on a stretch of low plain consisting of Late Holocene fine sediments from both the Adige and Po system. The main archaeological feature is the Roman road “Via di Villadose”, that is the decumanus maximus of the centuria and runs north of the modern town. This research aims at understanding how the geomorphic and palaeoenvironmental evolution of the area influenced the pattern, typology and distribution of the ancient settlements and infrastructures. Our investigations are focussed on a crevasse splay which is crossed by “Via di Villadose” in the area called Ca’ Motte. The investigation takes advantage of microrelief survey, photo-aerial interpretation, analysis of boreholes obtained with Edelman hand auger down to the depth of 4-6 m and a methodic archaeological top layer survey of all the area, performed by Gruppo Archeologico di Villadose. A digital elevation model of the investigated area has been developed, based on contour lines with spacing of 0.5 m. For the construction of the contour lines, a manual interpolation of spot heights of the “Carta Tecnica Regionale del Veneto” at scale 1:5000 has been adopted. This method allows to discard the points that are related to present-day artificial structures and to reconstruct the natural swale-and-ridge systems. Aerial photographs were used to map natural morphologies such as the crevasse palaeochannels and splay and to help the analysis of their interaction with anthropic structures such as ancient roads, ditches and field patterns. Aerial photos and microrelief indicated also the convenience of drilling a set of boreholes across the crevasse splay placed north of “Via di Villadose” to develop a stratigraphical cross section that shows a complex sedimentary history characterized by different depositional environments before local centuriation took place. Periods of rapid aggradation due to the upbuilding of fluvial ridges and crevasse splays alternated with periods when overbank clays and peats accumulated with low depositional rates. Results will eventually indicate whether distribution of ancient settlement and infrastructures is casual or influenced by particular sedimentological conditions. The radiocarbon dating of the backswamp peats, currently under way, and the relative chronology based on archaeological evidences may help to date and understand the deposition of natural sediments and their interactions with the Roman settlements and structures.