A geo-archaeological approach to reconstruct Arno plain landscapes (NW Tuscany, Italy) from fluvial to coastal contexts since Etruscan times

The study of recent past landscapes, understood as the result of the interaction between natural environment and human society, needs an interdisciplinary approach able to reconstruct the evolution of both paleo-environments and landforms at a chronological resolution comparable to that marking the succession of historical periods. In the Arno Plain (NW Tuscany, Italy), a fully integrated geo-archaeological approach allowed the reconstruction of paleo-environments, paleo-topography and urban growth patterns of the Pisa city area during the Etruscan and Roman period (first half of the 5th century BC-2nd century AD; Bini et al., 2015), whereas a detailed reconstruction of extra-urban landscapes from fluvial to coastal areas is still lacking. In order to fill this gap of knowledge, we applied the geo-archaeological approach on two different extra-urban areas subject to long-lasting human frequentation since Etruscan times and located at distal and proximal locations, respectively. The first site, located ca. 18.5 km south of the Pisa city and 5 km inland respect to the modern coastline, is supposed to host the ancient harbour of Pisa (Portus Pisanus; Pasquinucci, 2013; Morhange et al., 2015; Rossi et al., 2015). Stratigraphic cross-sections, supported by cores facies analysis and radiocarbon dating, document the establishment of a wide lagoonal basin since the marine transgression peak (ca. 8000 cal yr BP). This basin persisted for several millennia providing a naturally protected landing-place for boats (Portus Pisanus basin?). The integration of stratigraphic and historical data suggests a progressive closing of the lagoon since Roman times, inducing the westward transferring of the middle Ages harbour in the area now occupied by Leghorn port. The other site is located ca. 15 km far from the modern coastline between Pisa and Cascina urban areas, within a fully alluvial context still showing evident traces of Roman Centuriation that was an orthogonal system of axis created to measure, divide and reclaim the territory but also to manage the water resources. However, the paleo-hydrographic network of this portion of the Pisa plain is still unknown. Preliminary core facies analyses, integrated with geomorphological and toponomastic studies, allowed the identification of a paleo-Arno river branch located in a southern position respect the modern course and the identification of a marked change in alluvial plain drainage conditions (from poorly drained to well drained), attributable to Roman reclamation landworks. In both sites the employed geo-archaeological approach, including sedimentological, paleontological, geomorphological, radiocarbon, toponomastic and historical data, enabled a reliable, although preliminary, reconstruction of past landscapes, furnishing new insights into the transformation processes that affected the Pisa plain during the last ca.3000 years.