AN of the Southern Alps, which form the great arch that encloses the Po Valley, some crystalline massifs and stretches of the more northern Pennidic and Austroalpine areas fall within the Italian territory. Here the main watershed has moved from inside the building to the outside, via a series of catches of the waterways. Simultaneously with these the Würm glacial phenomena acted. The Canavese, Insubrica, Giudicarie and Pusteria lines are the transition to the Southern Alps where, between Ticino and Sarca, an alpine and subalpine environment with glacial modeling is manifested. The Val d’Adige is a sharply engraved transversal furrow, a consequence of the play of the trans; fluences of the Pleistocene glaciers. AE dell’Adige, in the Venetian Pre-Alps, there are glacio-karst elements in the summit areas, sinkholes, karst basins, canyons and dry valleys. N of the Prealps, between the Adige and the Piave, the peculiar landscape of the Dolomites is due to the different degradability of the dolomitic cliffs and plateaus compared to the pyroclastic, arenaceous and marly bands, to which they are interspersed. The Italian Alpine district is concluded by the Julian Alps, formed by attenuated reliefs, sloping down towards the Adriatic, in contact with which the Trieste Karst stretches, from the numerous sinkholes (from 20 to 50, on average, for each km which are interspersed. The Italian Alpine district is concluded by the Julian Alps, formed by attenuated reliefs, sloping down towards the Adriatic, in contact with which the Trieste Karst stretches, from the numerous sinkholes (from 20 to 50, on average, for each km which are interspersed. The Italian Alpine district is concluded by the Julian Alps, formed by attenuated reliefs, sloping down towards the Adriatic, in contact with which the Trieste Karst stretches, from the numerous sinkholes (from 20 to 50, on average, for each km2).
The Po Valley and the adjacent hill systems still in the Quaternary period constituted a marine gulf; the filling took place through the alluvial contributions of the rivers and glacial and fluvioglacial contributions. With its 46,000 km 2, the plain is the largest and most important in Italy. To the west, the Piedmontese sector is interspersed with hilly reliefs. The central sector corresponds to the Lombard and Emilian plains, divided by the course of the Po and bordered, to the North, by the moraines bordering the pre-alpine lakes towards the S. To these is connected the high plain, separated from the low, adjacent to the Po by the upper limit of the springs (fountains). The succession is repeated, simplified and inverted, in the Emilian plain. A blanket of wind sediments (Löss) deposited throughout the basin, almost 2 m thick in the Piacentino area. In the Veneto section the plain is limited to the East by the Adriatic coastal arc, which alternates lagoons and evolving delta formations: the Po delta, extended for 730 km 2, as a result of subsidence movements still in progress, for the most part it is located below sea level (even −3 m).
The Northern Apennines consists of a series of ridges with a NW-SE direction, arranged to climb from the Tyrrhenian to the Adriatic sector and characterized, in the upper parts, by gentle and slightly bumpy shapes, demolished by erosive processes. The hydrographic network is asymmetrical: the Adriatic side has transversal valleys, almost straight, the Tyrrhenian one is rich in longitudinal segments, many of which originally were lake basins (Casentino, Mugello, Valdarno, Valle Tiberina etc.). The traces of Pleistocene glacialism are much less evident than in the Alps.
The Central Apennines is the highest section of the chain (2912 m asl in the Gran Sasso of Italy), characterized by the great diffusion and power of limestone, and by massifs fractured and displaced horizontally or vertically by tectonic movements, with an evolution very different morphology in the various parts. Inside the chain there are numerous intermontane basins, mostly of tectonic origin. Along the Lazio-Abruzzo section, four morphotectonic units can be distinguished: Tyrrhenian Antiappennino; Internal Apennines; External Apennines (Gran Sasso and Maiella); Adriatic foreland. Karst forms are widespread: karst basins and plains of the polje type, sinkholes, sinkholes. Quaternary glacialism has left its mark since the Riss.
In the Southern Apennines the Campania and Basilicata sections have an axis shifted to the Tyrrhenian side. The morphotectonic evolution derives from the association of distinct units: the calcareous massifs incarsated in the Tyrrhenian frame (Matese, Monti Picentini etc.), arid, not very hospitable, but which act as a water reservoir for large areas; the Fossa Bradanica, a sinking area located between the Calabrian buttress and the Murge, filled with Plio-Quaternary deposits; the Adriatic plateaus, part of the Apulian Apennines, marked by a remarkable complexity of landscapes and complicated by recent volcanism phenomena (Vulture). This section of the chain was affected, in the Quaternary, by strong upheavals accompanied by tension tectonics, an expression of which was the catastrophic earthquake of Irpinia (1980).
The Calabrian-Peloritan Apennines correspond to the outcrop of the pre-Triassic crystalline base, fractured into clods and extremely altered on the surface. The tectonic structure consists of longitudinal blocks (Coastal Range, Sila, Aspromonte) alternating with longitudinal pits. The whole arc is subject to intense neotectonic lifting movements. The geomorphological resultant of these processes is a flat structure, evident in the Aspromonte, arranged in steps from 1300-1200 m up to 300-250 m of altitude. The whole area is subject to erosion phenomena of exceptional intensity, both for the characteristics of the climate, with short and intense rains, and for the superficial alteration of the lithologies, and, to a decisive extent, for the uplift in progress. Similar geomorphological characters present the Peloritani Mountains,
The Antiappennino develops in several formations. AS of the Arno are the heights of the Volterrano, the Metalliferous Hills, the Sienese, affected in the Plio-Pleistocene by a series of transgressive cycles and marked by badlands. The Tosco-Lazio Antiappennino is mainly the result of recent volcanism: in the Pleistocene, along a system of extending faults, the volcanic activity of the Volsini, Cimini, Sabatini and Colli Albani settles. In southern Lazio the anti-Apennine reliefs continue with the limestone spurs of the Lepini, Ausoni and Aurunci, which the tectonic furrow in which the Sacco-Liri flows separates from the Abruzzese Apennines. In Campania, Vesuvius follows the extinct volcano of Roccamonfina to the south. On the Adriatic side, the Antiappennino almost coincides with the Apulian region, and is made up of the Gargano and the Murge, divided by the alluvial plain of the Tavoliere and the Salento Peninsula. This whole area was subjected to an uplift which gave rise to particularly intense erosive phenomena. The lithological nature of the reliefs (limestone) and the recent and still current tectonic activity have produced karst landscapes: from the tectocarsic forms of the Gargano to the soft sinkholes of the Murge, to the caves (Castellana), to the karst springs of Salento.
At the beginning of the Pliocene of Sicily, the Sicilian Apennines emerged, to the NE, and the Iblei Mountains, to the SE; the rest will emerge during the Pliocene and Pleistocene regressive phases. The Nebrodi Mountains have landscapes similar to those of the Northern Apennines, while the Madonie, with their incarsite plateaus, recall the Tyrrhenian frame of the Campania Apennines. Eastern Sicily is dominated by Etna, an active volcano that rises on a base of sedimentary rocks, a thousand meters high above the sea. In the SE of the island develops the Hyblean plateau, which dominates the rift valleys of Catania and Gela. From the clastic-evaporitic formations of central Sicily, arid hills subject to intense erosion, we pass to the mountains of western Sicily, a mosaic of rigid blocks, intersected by active faults, sloping down towards the coast with a succession of terraced shelves. The main reliefs of Sardinia, in the eastern sector of the island, belong to the Sardinian-Corsican massif. The extreme south-western edge, separated from the Campidano rift valley, is formed by the rounded mountains of the Iglesiente, where the most ancient sedimentary rocks of Italy (Cambrian, Silurian). The mountain ranges are separated and isolated by plateaus or plains. Superficial and deep karst manifestations are very common. The forms of wind erosion are quite peculiar, in particular in the Gallura granites. it is formed by the rounded mountains of the Iglesiente, where the most ancient sedimentary rocks of Italy (Cambrian, Silurian). The mountain ranges are separated and isolated by plateaus or plains. Superficial and deep karst manifestations are very common. The forms of wind erosion are quite peculiar, in particular in the Gallura granites. it is formed by the rounded mountains of the Iglesiente, where the most ancient sedimentary rocks of Italy (Cambrian, Silurian). The mountain ranges are separated and isolated by plateaus or plains. Superficial and deep karst manifestations are very common. The forms of wind erosion are quite peculiar, in particular in the Gallura granites.
