Osservazioni preliminari sull'evoluzione quaternaria dell'area del Porto Vecchio di Genova

Abstract

The studied area is the stretch of coast where the old port of the town of Genoa was located. This area has suffered for an intense anthropic development from pre-Roman times onwards due to the spread of both the town and the port. The geomorphological study of the area was integrated with data from cores of boreholes drilled in the urban and port areas during last few years prior to the construction of civil buildings and harbour facilities. The data indicate that since the Pliocene, evolution has gone through different phases, governed by sea level fluctuations and tectonic activity. Several terraces are present at approx. 45, 75-80 and 90-100 m a.s.l.: The lowest terraces cut Pliocene sediments and can thus be dated to Quaternary, although more precise age determinations are not possible given the absence of deposits above them. Another group of terraces is at higher elevations - approximately at 175, 275 and 350 m a.s.l. Their height is possibly related to neotectonic uplifting movements of the mountain chain around Genoa. In the sea, a particularly significant level was found at the depth of 23-24 m below sea level, in cores recently drilled for the construction of new harbour infrastructures. This level, which consists of flattened and rounded pebbles in a sandy matrix rich of shell fragments, can be interpreted as a littoral deposit of a sea level highstand during the Versilian transgression.