The Po-Venetian Plain
This is the principal Italian plain, extending for circa 42 sq km to the south of the Alpine arc and having its other border with the northern Apennines and the Adriatic where it merges into a coast that is low and sandy on the Romagna shore and ringed by lagoons on the Venetian shore. The Po River cuts across the centre of the plain and, over the past two thousand years, has created a huge delta on the edge of the Adriatic Sea. In this it has been assisted by many Alpine and Apennine tributaries, as well as by other watercourses descending directly to the sea from the Venetian pre-Alps (Adige, Brenta, Piave, Tagliamento and Isonzo) and the northern Apennines (Reno, Lamone and Marecchia). The Po-Venetian Plain has a mean altitude of circa 50 m, while in the marginal belt at the foot of the pre-Alps and the Alps it exceeds 200 m. This is the point at which it is possible to distinguish a high (gravel and sand) from a low (mainly mud and clay) plain, separated by a row of springs that have had an important influence in the development of the plain's agricultural economy (cultivation of the rice fields, water etc.). This plain also has an extremely important economic and social role. Though it forms only a seventh part of the national territory it contains about a third of the Italian population.
Almost the whole southern side of this great mountainous system belongs to Italy, covering as it does a length of circa 110 km from the mouth of the Rhône to the mid-Danube plains and varying in width from circa 150 to 250 km. This southern side contains many longitudinal (Valle d'Aosta, Valtellina, Val Venosta and Val Pusteria) and transversal valleys (Val di Susa, Val d'Ossola, Val Camonica and Valle dell'Adige). It can be divided in three sectors: western, central and eastern Alps. The first two of mainly crystalline rocks and the third of sedimentary rocks. Their traditional groupings are still in use: western sector of Ligurian, Maritime, Cottian and Graian Alps; central sector of Pennine, Lepontine and Rhaetian Alps; and eastern sector of Adige, Carnic and Julian Alps. The first two groups contain the highest peaks, often exceeding 4,000 m. (Gran Paradiso, Mont Blanc, Cervino, Rosa and Bernina). The pre-Alpine belt is mainly formed of sedimentary rocks. It stretches from the mouth of the Valle d'Aosta to the Valle dell'Isonzo and is particularly disjointed, especially in two zones: the Lombard pre-Alps, where the landscape of valleys is enlivened by large glacially excavated lakes (Orta, Maggiore, Lugano, Como, Iseo and Garda); and the Venetian pre-Alps, which contain numerous plateaux (Lessini, Sette Comuni and Cansiglio).
· 1 decade ago