Pompeii geoarchaeological setting – An archive older than 40,000 years of volcanism, soil formation and geoarchaeological landscape

The present work describes the results of full lithostratigraphic, pedological and geoarchaeological studies carried out in the Pompeii archaeological area (southern Italy), combined with logs data, surface and underground survey of lava and tephra outcrops. The ancient Pompeii is probably the most famous and complex site of archaeological investigation in the world. Through many studies have been devoted to various archaeological aspects, detailed reconstructions of the geological setting and history of geoarchaeological landscapes are still lacking. At present, Pompeii landscape consists of low hills recognized as volcanic landforms and attributed to the Somma-Vesuvius volcano activity; they correspond to ancient local vents covered of a multilayered succession of repeated volcanic deposits and paleosoils, mainly related to alternating volcanic activity and quiescence periods with consequent pedogenesis (De Maio and Stefani, 2004; D’Ambrosio et al., 2001; Cinque and Irollo, 2004). This succession comprises at least the last 40,000 years of sedimentation history, reflecting the entire spectrum of eruption types of the Somma-Vesuvius, i.e. from Plinian to sub- Plinian eruptions, relatively small eruptions to effusive volcanic events and, on the other hand, soil formations of different durations, intensities and soil-forming environments. Before the foundation of the city, paleosoils repeatedly reveal clear evidence of anthropogenic activity, represented by agricultural practices. Once the city has taken to develop, anthropogenic landscape changes become particularly pronounced. The various periods of edification of the city walls required different types of land management, related to the variable morphological profiles encountered along of defensive wall circuit (longer than 3 km). Outcrops were deeply modified with quarries, underground excavations, earthworks. Several wells were drilled deeper than 20 meters to reach the water table. Two main geological sections, carried out through the Tempio di Venere and the Regio VIII Insula southern lava cliff, show a core of lavas locally capping buried deposits of the Campanian Ignimbrite. Geological risk assessment in such a complex archaeological site needs specific evaluations/methods and flexibility, according to specific conditions and case studies. Di Maio G. & Stefani G. 2004. Considerazioni sulla linea di costa del 79 d.C. e sul porto dell'antica Pompei. Rivista di studi Pompeiani, L'Erma di Bretschneider, Roma,14, 141-195. D’Ambrosio A., Deino A., Di Maio G., Mastroberto M., Melluso L., Morra V., Rota L., Santangelo N., Sperandeo G., Stefani G. 2001. Assetto geoarcheologico dell’area pompeiana. Nuovi dati per un’ipotesi di ricostruzione paleoambientale”. Pompei e società, Electa, Napoli, 207-208. Cinque A. & Irollo G. 2004. The “Pompei Volcano”: new geomorphological and stratigraphical data. Il Quaternario, Italian Journal of Quaternary Science, 17, 101-116.