DE PIPPO T., DONADIO C. & PENNETTA M.
Morphological evolution of Lèsina Lagoon (Southern Adriatic,Italy)
Pages 29-41
Abstract
Geomorphological features of the lagoonal system of Lèsina (Apulia Province, south-eastern Italy) are highlighted in this research; it has been possible to point out the late Quaternary evolution of this coastal transitional environment through morphological surveys, both of the emerged and underwater landscape of the basin. The lagoonal system is the result of a constant evolution due to mutual equilibrium between eustatism, coastal paleomorphology, sediment supply, tidal effects and modification of the hydrographic network pattern. The Quaternary geologic history and the morphological characteristics of this coastal zone suggest that the lagoon development and evolution are linked to interactions between tectono-sedimentary, climatic and hydrodynamic factors during the late Pleistocene-Holocene. These physical factors acted on a landscape of inherited morphostructures bordered by high morphological relief, generating a different positioned littoral compared to the present-day one. The genesis of Lèsina Lagoon is linked to littoral dynamics that led to progressive development of composite littoral spits inside a shallow-water marine bay. During the post-glacial age, the bay was gradually filled with clasts drifted out from the Fortore River mouth, few kilometres westward of the lagoon. Probably, the lagoonal system has developed after the Holocene climatic optimum, when the neotectonic phases had already faded and the landscape was rough enough but quite comparable to the presentday one. The growth of a steady littoral sandy ridge, first NW-SE then W-E oriented, on which dune ridges developed, led to the genesis of a lagoon behind the dunes. Subsequently, the lagoon shape has undergone a change because of constant sediment filling, reducing the area of an originally trapezoidal basin. The same process caused the decrease of lagoon depth and number of channels. Thin peat levels alternating with marine sandy-silty sediments, suggest that marine and marshy stages alternated during the lagoonal system evolution.