GEOGRAPHY OF THE PO VALLEY

The Po Valley is often regarded as a syncline, or dip in the crust due to compression at the edges. Regardless of whether this concept accurately describes its geology, the valley is manifestly a sediment-filled trough, or virtual syncline, continuous with the deeps of the Adriatic Sea. The surface terrain is therefore divided into two overall types of landform: the plain, or flat surface of the fill, and the anticline at the edges, taking the form of hilly country in which the outcrops of the original rock are visible along with alluvial fans formed from the outwash of the more severe anticlinal terrain; that is, the Apennines and the Alps. The valley is broadly divided into an upper, drier part, often not particularly suited for agriculture, and a lower, very fertile, and well irrigated section, known in Lombardy and western Emilia as la Bassa, "the low (plain)".

The upper areas of the Po valley take local names which reflect in their meanings their being modestly suited for farming. So we have the Piedmontese vaude and baragge, the Lombard brughiere and Groane, or, exiting from the Po valley proper, the Friulian magredi, areas remote from easily reachable water tables and covered with dense woods or dry soils. This specific meaning for "lower plain" derive from a geologic feature called the fontanili ("spring") line or zone, a band of springs around the Val Po, heaviest on the north, on the lowermost slopes of the anticline. It varies from a few kilometres to as much as wide. The fontanili line is the outcrop, or intersection, of the anticline's water table with the surface at the edge of the bassa. The rock above the line is porous. Surface water in the intermittent streams of the mountains tends to disappear below ground only to spring out again in the spring zone. The spring zone is often called "the middle valley." Surface runoff water (the Po and its affluents) is not of much value to the valley's dense population for drinking and other immediate uses, being unreliable, often destructive and heavily polluted by sewage and fertilizers.

Its main anthropic value is for hydro-electric power, irrigation and industrial transport. The cost of purifying it for human consumption makes that process less feasible. The fresh drinking water comes from hundreds of thousands of wells concentrated especially in the fontanili zone. The major settlements therefore are also in that zone, which has become the center of economic development and industry in Italy, and now is an almost continuous megalopolis stretching from Turin to Trieste. The bassa Padana was settled and farmed earliest, in Etruscan and Roman times, and has been completely devoted to agriculture since the Middle Ages, when efforts from monastic orders, feudal lords and free communes converged. The older and smaller cities deriving from ancient times are still located there.