THE KARREN LANDSCAPES IN THE EVAPORITIC ROCKS OF SICILY.

The karren in the evaporitic rocks of Sicily show wide distribution and variety of shapes relating to the large extension of the rocky outcrops, to the different lithofacies and to the climate. Karren features are largely present in all kinds of evaporites: macrocrystalline selenitic gypsum, detritic gypsum with various grain size, microcrystalline gypsum and in salts such as halite and kainite. Both the origin and the evolution of the karren are controlled by the dynamics of several processes such as solution and recrystallization, granular disintegration, carbonation, and phenomena linked to biological activity. The karren features have different dimensions, ranging from the nano- and the micro-forms to very large forms, and develop both on the exposed surfaces and under permeable covers. Karren are present on extensive outcrops, such as denuded slopes and hilly summits, and even on the exposed faces of little stones and isolated blocks. Peculiar environments where some specific types of karren have been recognized are the fluvial and coastal geo-ecosystems, some artificial and semi-artificial geo-ecosystems such as quarries, the dumps of mines and dry walls. Generally several analogies can be drawn between the gypsum karren in Sicily and limestone karren, despite important differences.