I geomorfositi dell\'area pedemontana dei monti Billiemi (Palermo): contributi idrogeologici e geofisici

Abstract

En The Mesozoic carbonatic relieves surrounding the Palermo Plain are characterized by notable morphologic structures that belong to the cultural heritage of Sicily. These apes,relevant to the eustatic Pleistocene oscillations and modelled by the sea, are represented by terraces, seacliffs, wave-cut notches, old shores, karst cavities. They can be considered, for their conformation and appreciable state of conservation, among the most important morphologic outlines in Sicily. Important karst evidences occur in the foothills of the Billiemi mountainous range, West of the Palermo Plain. The Montagnola di Santa Rosalia is a carbonatic isolated block, encircled by steep rock walls; it is recognizable for the wide and marked sea terrace, delimited by high and very sharp seacliffs in which various cavities are developed. The Contrada Petrazzi shows also interesting karst features, with the Grotta della Molara and the Grotta del Coniglio Morto. The Falesia di Malatacca-Benfratelli, in the Northern sector of the Billiemi mounts, is characterized by a group of cavities, notably degraded by the human intervention. The studied, remarkably interested by noteworthy morphologic, paleontological and archaeological structures, assumes an important role for the history and the development of the geological and historical events of the Palermo Plain (Conca d’Oro). Consequently, in this sector of the town, the Montagnola di Santa Rosalia and the Falesia di Malatacca-Benfratelli could be classified like geomorphosites, namely typical localities with relevant geomorphological features. In the last twenty years, the activity of rock quarries and the indiscriminate and wild expansion of the peripheries have interested, almost incessantly, the coastal as well as the hilly zones of Palermo. As an example, the presence of a great pit has abruptly interrupted the morphologic continuity of the Montagnola di Santa Rosalia and the Falesia di Malatacca-Benfratelli, the protection of which is urgent. This has contributed to hinder the opportune creation of a larger entire area of inestimable naturalistic value. Only the Contrada Petrazzi is now protected, by moreover constituting a safeguard example for the above mentioned ruined areas, that appear unfortunately directed towards a dramatic destiny of irreversible degradation. The here discussed localities are included in a research project on the aquifer vulnerability and pollution danger of groundwaters, recently launched out in the metropolitan area of Palermo. Integrated methodologies have contributed to recognize in the investigated area a high hydrogeological risk, completing the deterioration picture of this part of the Palermo area.