Rivers

Of the many rivers rising in the Appenines, the most significant are the rivers Arno, Tiber, and Volturno. They have their sources on the western slopes, and all drain into the Tyrrhenian Sea.

Geology

The northern Apennines, extending about 370 km/239 mi from the Maritime Alps to the headwaters of the Tiber near the Trabaria Pass, are chiefly weak sandstones and clays. The central Apennines, running for about 320 km/199 mi to the Calore River and the Benevento depression, are wider, more complex, and dominated by high massive limestone groups. The southern Apennines, characterized by smaller limestone blocks set in a matrix of clays and sands, extend for another 190 km/118 mi to Monte Pollino, where they continue unbroken into the granites and gneiss of the Calabrian Apennines. The central and southern Appennines have mineral springs and volcanoes, of which two (Vesuvius and Etna) are still active.

Northern Apennines

The northern range runs almost east-west across the peninsula, rising at Monte Cimone to 2,165 m/7,105 ft, and is drained mainly northwards to the plain of Emilia by a series of straight parallel streams. The largest of these is the Reno; around its headwaters a number of passes provide relatively low crossings, conveniently connecting Florence and Bologna. To the east, river basins are a feature of the mountain range, continuing as far south as Calabria. These basins in the north (Mugello, Casantinio, Arezzo, and Valdarno) are united and drained by the Arno.

Central Apennines

Running northwest-southeast, the central range includes the highest and wildest parts of the system. Peaks include Gran Sasso, which has a small glacier; La Maiella (2,793 m/9,167 ft); Monte Velino (2,487 m/8,159 ft); Monte Vettore (Sibillini) (2,476 m/8,126 ft); Terminillo (2,216 m/7,273 ft); and La Matese (2,050 m/6,728 ft). The River Tiber links a group of elongated depressions, and some of the many other enclosed basins are drained through gorges by eastward flowing streams.

Southern Apennines

In the south the limestone massifs are close to the west coast and the eastern part of the range is occupied by clay and sandstone ridges, apart from the extinct volcano of Monte Vulture. South of Monte Pollino (2,248 m/7,378 ft) the limestone and enclosed basins are replaced by steep-sided rolling plateaus of ancient impermeable rocks, running north-south through the plateau of La Sila (1,928 m/6,328 ft) to Aspromonte (1,955 m/6,416 ft).

Passes

The Apennines, despite their complex relief, form a continuous barrier to road and rail. Only at Genoa and at Benevento, near Naples, do relatively easy, low-level crossings connect the two sides of the country. Many tortuous roads and railways use the mountain passes and gorges. The complexity of the structure and the prevalence of intermontane basins has encouraged the development of longitudinal routes within the mountains, such as the Perugia-Terni-L'Aquila road or the Autostrada del Sole, south of Salerno.

Economy

The once heavily forested slopes of the Appenines have been greatly reduced by human activity. Despite attempts at conservation and reforestation, the forests been replaced by scrubby woods of oak, chestnut, and beech. The clays and sands of the northern and southern parts of the Apennines are plagued by landslips and badlands (deeply eroded barren areas), inhibiting good soil formation and agriculture, but many of the intermontane basins, fed by perennial springs and seepage from the permeable limestone, are remarkably productive. The high pastures of the central Apennines were traditionally used as summer grazing for flocks of sheep moved up from the lowlands, but the practice, known as transhumance, has largely declined since World War II. There are also many hydroelectric plants, located mainly along the western slopes.