Man-made landforms and geodiversity within old Genoa city (Italy): an unique and complex geomorphological landscape in Mediterranean area

The city of Genoa is internationally known for its seaport, which is the largest in Italy and the second one in Mediterranean. Genoa, capital of a Maritime Republic from 1099 to 1815 ("The Superb"), shows many elements of aesthetic, historical, cultural, socio-economic and scientific value, with an extraordinary geodiversity linked also to built-stone heritage. The geomorphological layout of the city has contributed to the success of Republic of Genoa over the centuries: today the urban landforms are not immediately recognizable, because they are characterized by several stages of urban growth. In this research, the results of a geomorphological survey of Genoa historical amphitheatre are presented. The area developed in the Middle Ages and it was surrounded by the seventeenth-century walls which protected the old port between the Promontory of the Lighthouse to W and Carignano hill to E. The amphitheatre’s area is 8.5 km2, with seven small and steep catchments characterised by high degree of urbanization. The study was carried out by multi-temporal cartographic and photographic comparison, with on-site observations, and through the interpretation of hundreds of drill surveys carried out for construction work. An original geomorphological map, with specific attention to man-made landforms, was produced. The map highlights three main issues of urban geomorphology, reflecting the major changes of the landscape due to man-made activities: sea embankments, mainly for the construction of port and facilities; river networks modifications and particularly culverts, diversions and canalizations; slope construction excavations and backfills, both on stream networks and roads. The identification and mapping of geomorphological heritage sites could contribute to their popularisation and to the establishment urban geotourism itineraries: guided tours along alleys, main roads, promenades and underground environments could unveil to the public the geological and geomorphological features of historical centres and the evolution of urban areas through the centuries