Note illustrative alla carta geomorfologica della Tavoletta Menfi (Sicilia occidentale)

The present note is to describe the morphogenetic processes and the relative landforms that were recognized in the area represented by the 1: 25,000 scale IGMI topographic map named Tavoletta Menfi (Serie 25/V F. 266 IV NO). The geomorphological map was realized by using the classic methodology based on direct geological and geomorphological field surveys, integrating the acquired data with the analysis of 1:18,000 scale aerial photos taken in 1997. From the geological point of view the examined area is characterized by the outcropping of carbonate and terrigenous sediments. The great part of the territory is affected by landslide phenomena, of different sizes and activity degree, that show recurring phases of reactivation when the more intense rainfall events happen or when earth tremors occur; the present spatial distribution of landslide phenomena was analyzed and described by means of field surveys. Landslide and water erosion phenomena affect large sectors of the studied area, with a geographical variability that is strictly linked to the outcropping of the highly diffused clayey sediments; the temporal evolution of the mass movements is typically slow, so the relative risk is quite low; nevertheless, the frequent occurrence of the slope movements, their activity degree and evolutionary trends have to be taken into careful consideration during the phases of territorial planning. In particular, the carried out study highlighted how the outcropping of lithologies characterized by a different lithotechnical behavior, produced a landscape highly differentiated between the areas in which clayey deposits are present and those in which carbonate and arenaceous deposits outcrop; in the first sectors landforms given by gravity prevail, while along the main fluvial axes, the Carboj river and the right tributaries of the Belice river, erosive and depositional landforms produced by the flowing water are recognizable; in the zones where the carbonate and arenaceous terrains outcrop the most diffuse landforms are those shaped by planation processes and the ones strictly linked to the stratigraphical-structural setting, as scarps and structural surfaces.