Le terme romane di Viterbo

Abstract

Geothermal high temperature springs (52°C to 65 °C) of sulphate-alkaline-earthy waters and the remains of Roman thermal baths of Viterbo are located along the Via Cassia road in the territory immediately west of this city, in a delimited area, the “Piano di Viterbo” or “Piano dei Bagni”, characterized by extensive travertine formations. These baths were used between the Late Republican age and the Late Imperial times; in many cases, they were re-used during the late Medieval and Modern epochs. This peculiar amount of ancient installations is strictly linked to the geological setting of the area: a sector of the large volcanic plateau produced by the emplacement of lavas and pyroclastic deposits from three volcanic districts (Cimino, Vico, and Volsini), active between 1,35 Ma e 90 ka. This area corresponds to a buried structural high, interpreted mainly on geophysical data as a complex horst that was previously involved in thrust folds and later affected by the Plio-Quaternary extensional tectonics. The geothermal springs occur along the main structural discontinuity produced by polyphasic tectonics (extentional and/or transtensional) and by the subsequent volcano-tectonic activity. The results of field work, geomorphological and facies analyses of related continental carbonate deposits, as well as the interpretation of geophysical and drilling data, associated with the historical and archaeological data, were managed in a GIS model to define the complex interactions between all these aspects. The analysis has been integrated with the interpretation of historical and recent aerial photos that show some archaeological traces and remains nowadays not visible. This study allowed the reconstruction of the ancient topography of the area crossed by Via Cassia and the collection of new inter-disciplinary data for the knowledge of the monumental complexes and their features.