Geomorphological underwater surveys of geoarchaeological sites in Campania, southern Italy.

Submarine surveys carried out in Campania, particularly since the 90s along the coastaland of Sinuessa, allowed to draw up geomorphological maps with archaeological findings. Along the sea bottom, about 650 m off and -7 m depth, a Campanian Ignimbrite bedrock was detected: dated 39 kyr BP, its position is incompatible with the current sea level. Towards the northern edge of the shoal, a depressed area 3 m deep, with 24 cubic elements 3x3 m wide and in concrete (opus cementicium) was surveyed. At the top of the blocks were observed semicircular holes, used for lifting, transporting and juxtapostion operations: these artifacts (pilae) are typical of Roman maritime structures, as described by Vitruvius in De Architectura (80-15 BC). Pilae were widespread along the Phlegrean Fields coast for jetties and docks, as in Baiae and Portus Julius settlements. Beachrocks and accessory morphologies at the same depth as the leveled bedrock, suggest that the tuff bank was emerging and attended by man in Roman times, even for activities related to port facilities. The shoal is markedly dissected by submerged palaeo-channels, more or less deep, in alignment of current watercourses on the mainland. These palaeo-channels were modeled in subaerial environment during the Würm glaciation, following the tuff deposition: at that time the Mediterranean sea level lowered down to -120 m. The northernmost channel, sinuous and next to the pilae, is 3-4 m deep and from 60 to 350 m wide: this probably allowed transit and maneuvering of Roman ships.