Speleogenesi e geomorfologia del sistema carsico delle Grotte della Poesia nell ambito dell 'evoluzione quaternaria della costa Adriatica Salentina

The Grotte della Poesia karst system, located along the Adriatic coast of Apulia (southern Italy), is a remarkable site as regards coastal karst geomorphology and archaeology. One of the cave of the system hosts in fact thousands of ancient inscriptions on its walls. Two large sinkholes (named, respectively, Grotta della Poesia Grande and Grotta della Poesia Piccola) open on the tabular coast plain near the calcarenite cliff. The karst system is furtherly made of intervening galleries, minor cavities and a gallery which connects Grotta della Poesia Piccola to the sea. This article deals with description of the geomorphological and hydrogeological setting of a stretch of Adriatic coast extending from the town of Rocavecchia to Torre dell'Orso, and of the inland area, including the palustrian environment of the Tamari. In situ surveys and interpretation of multi-temporal sets of air photographs allowed to identify some 50 instability events along the coast, and to analyze their spatial distribution and temporal evolution as well. Some of the events have directly affected the Grotte della Poesia caves, the recent most on December 2003. This highlights the hazard for the archaeological site and even for tourists, since the area is very populated during the summer season, due to natural beauty of the coastline and the sea. Eventually, an attempt to reconstruct the geomorphological evolution of the karst system is presented, starting from the onset of the speleogenesis, through sinkhole development, up to the present phase, with the recent detachment of rock falls. To this latter regard, some suggestions about the more likely sistemation works are also given.