Caratteristiche geomorfologiche dell’Isola di Pianosa.

Pianosa Island belongs to the Tuscany Archipelago; it has an extension of 10 km2, 18 km of coastal development and a max altitude of 29 m a.s.l. The island is made up of neogenic and quaternary sediments; pelitic Miocene sediments outcrops at the base of the cliff in the south-western coast, while the bio-calcarenitic Pliocene sediments cover most part of the island. Quaternary deposits are established by biodetrital shore sediments of Tyrrhenian age and by Late Pleistocene colluvial deposits. The island is characterized by cliffs in the western and southern sector, by plain surfaces and by a small beach in the east side. Cliffs have been distinguished in 3 different types. In the first type is always present a developing wave notch. When the coast is not characterized by cliff we can found erosion plains (at maximum level of approximately 4 m) formed during the Tyrrhenian high stand (Isotopic stage 5e). These erosion planes can be suspended and sub-horizontal (when the layers of the pliocenic substrate dip towards inland), or gently tilted towards sea (when the layers of the pliocenic substrate dip towards sea). On these various erosion planes are always present rock pools characterized by different shape and dimension, besides rare fossiliferous shore deposits (Panchina). In these sediments have been recognized, between others: Strombus bubonius, Patella ferruginea and Conus testudinarius, dating Tyrrhenian age. On the island we can found three different order of erosion planes at 2-4 m, 8 m and 25 m a.s.l. Karst process produced erosion epigean micro-landforms, such us dissolutional flutes, dissolutional groves and dissolutional pans (kamenitza), macro-landforms represented by E-W karst oval basin depressions, enlarged hundred meters and few meters deep. The same process left isolated rock promontory residual of the tyrrhenian cliffs coast lines. Much diffused are hypogean karst shape such as caves and conduits that, sometimes, are opened on the cliff and are visible only by the sea. In some of these caves, characterized by speleothemes, we discovered, at a quote of 7 m a.s.l., marine deposits and litodomes holes probably of Tyrrhenian age. Frequently is the founding of breccias breeded by collapse of caves and conduits. Surface karst landforms are widening covered by high agricoltural activity developed in the last two centuries due to the presence of the agricoltural penal colony.