Morfologia e genesi delle Isole Chéradi e del Mar Grande (Taranto, Puglia, Italia)

Morphology and genesys of Isole Chéradi and Mar Grande (Taranto, Apulia, Italy)

Abstract

The Isole Chéradi – San Pietro and San Paolo islands – placed about 5 miles to the SE of Taranto, border towards the Gulf of Taranto two wide sounds of sea, roughly circular in shape; the Mar Grande and the Punta Rondinella bay. These bays show the bottom sculptured on Plio-Pleistocene clays, marked by deep apenninic (NW-SE) and antiapenninic (NE-SW) oriented submerged river valleys. The particular shape of shoreline seems to be the effect of the geological structure of this area and wave diffraction. The coast is generally represented by an even sloping surface. It is characterized by slow evolution along die coastal tracts facing the open sea where well-cemented Tyrrhenian calcarenites crop out. These last ones gently slope seaward, sheltering the underlying weak clayey units from wave erosion. Along the two bays, the coast is represented by cliffs, with the foot cut in the Plio-Pleistocene days, in fast retreat because of effective wave undercutting. Wave diffraction induced by the narrow openings of bays, which developed along the submerged valleys, and the natural evolution of cliffs which tend to stretch parallel to wave crests are responsible for the characteristic shape of the sea bays.