Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/453

 GEOGRAPHY.] ITALY 435 Central and Southern Italy, though, in general use among geographers, and convenient for descriptive purposes, do not correspond to any natural divisions of the great Italian peninsula. 1. Nort/terii Italy. By far the larger portion of Northern Italy is occupied by the basin of the Po, which comprises the whole of the broad plain extending from the foot of the Apennines to that of the Alps, together with the valleys and slopes on both sides of i:. Throughout its whole course indeed, from its source in Monte Viso to its outflow into the Adriatic -a distance of more than 5 degrees of longitude, or 220 miles in a direct line the Po receives all the waters that flow from the Apennines northwards, and all those that descend from the Alps towards the south, till one comes to the Adige, which, after pursuing a parallel course with the Po for a considerable distance, enters the Adriatic by a separate mouth. There is no other instance in Europe of a basin of similar extent equally clearly characterized, the perfectly level character of the plain being as striking as the boldness with which the lower slopes of the mountain ranges begin 1 to rise on each side of it. This is most clearly marked on the side of the Apennines, where the great Emilian Way, which has been the high road from the time of the Romans to our own, preserves an unbroken straight line from Rimini to Piacenza, a distance of more than 150 miles, during which the underfalls of the mountains continually approach it on the left, without once crossing the line of road. On the side of the Alps the boundary is more varied and broken, the great projecting masses of those mountains being inter sected by large rivers, which produce valleys of consider able extent running far up into the mountains. But still, from whatever point the traveller approaches the Alps, he will be struck by the manner in which the unbroken alluvial plain extends quite up to the foot of the actual mountains or their immediate offshoots, presenting in this respect a striking contrast with the broken, hilly country which is found on the north side of the Alps both in Switzerland and in Austria. The only exception to this uniform level occurs in the Monferrat region, which consists principally of hills of moderate elevation and of Tertiary formation, projecting to the north from the Ligurian Apennines, and occupying a breadth of about 50 miles from the neighbourhood of Turin to that of Alessandria, around which the Po is com pelled to form a great bend between Turin and Valenza, leaving, however, a broad strip of plain (from 15 to 30 miles across) between its north bank and the foot of the Alps. The detached group of the Euganean hills, within sight of the Adriatic, though separated from the nearest Alps by a very narrow strip of plain, is wholly independent of that great chain, and forms a separate and isolated mass of volcanic origin. The geography of Northern Italy will be best described by following the course of the Po. That mighty stream has its origin as a mountain torrent descending from two little dark lakes on the north flank of Monte Viso, at a height of more than 6000 feet above the sea ; and after a course of less than 20 miles it enters the plain at Saluzzo, between which and Turin, a distance of only 30 miles, it receives three considerable tributaries, the Clusone on its left bank, bringing down the waters from the valley of Fenestrelle, and the Varaita and Maira on the south, con tributing those of two valleys of the Alps immediately south of that of the Po itself. Between Turin and Valenza it receives no affluent of importance on its right bank, but a few miles below the latter town it is joined by the Tanaro, a large stream, which brings with it the united waters of the Stura, the Bormida, and several minor rivers. All these have their sources on the northern flank or reverse of the Maritime Alps, where the chain bends round towards Savona, and being fed by the snows of those lofty mountains are greatly superior in volume to the rivers that descend from the Apennines farther east. But far more important are the great rivers that descend from the main chain of the Graian and Pennine Alps, and join the Po on its left bank. Of these the Dora (called for distinction s sake Dora Riparia), which unites with the greater river just below Turin, has its source in the Mont Genevre, and flows past Susa at the foot of the Mont Cenis. Next comes the Stura, which rises in the glaciers of the Roche Melon ; then the Oreo, flowing through the Val di Locana ; and then the Dora Baltea, one of the greatest of all the Alpine tributaries of the Po, which has its source in the glaciers of Mont Blanc, above Courmayeur, and thence descends through the Val d Aosta for about 70 miles till it enters the plain at Ivrea, and after flowing about 20 miles more joins the Po a few miles below Chivasso. This great valley one of the most considerable on the southern side of the Alps has attracted more especial attention, in ancient as well as modern times, from its leading to two of the most frequented passes across the great mountain chain, the Great and the Little St Bernard, the former diverging at Aosta, and crossing the main ridges to the north into the valley of the Rhone, the other following a more westerly direction into Savoy. In its course below Aosta also the Dora Baltea receives several considerable tributaries, which descend from the range of glaciers between Mont Blanc and Monte Rosa. About 25 miles below its confluence with the Dora, the Po receives the waters of the Sesia, also a large river, which has its source above Alagna at the southern foot of Monte Rosa, and after flowing by Varallo and Vercelli falls into the Po about 14 miles below the latter city. About 30 miles east of this confluence, in the course of which the Po makes a great bend south to Valenza, and then returns again to the northward, it is joined by the Ticino, a large and rapid river, which brings with it the outflow of the great lake called the Lago Maggiore, and all the accumulated waters that flow into it. Of these the Ticino itself has its source about 10 miles above Airolo at the foot of the St Gotthard, and after flowing above 36 miles through the Val Leventina to Bellinzona, where it is joined by the Moesa bringing down the waters of the Val Misocco, enters the lake through a marshy plain at Magadino, about 10 miles distant. On the west side of the lake the Toccia or Tosa descends from the pass of the Gries nearly due south to Domo d Ossola, where it receives the waters of the Doveria from the Simplon, and a few miles lower down those of the Val Anzasca, from the foot of Monte Rosa, and 12 miles farther has its outlet into the lake between Baveno and Pallanza. Besides these two great streams the Lago Maggiore is the receptacle of the waters of two minor but considerable lakes the Lago di Lugano on the east and the Lago d Orta on the west. The Ticino has a course of above 50 miles from Sesto Calende, where it issues from the lake, through the level plain, till it joins the Po just below the city of Pavia. The next great affluent of the Po, the Adda, forms in like manner the outflow of a great lake the Lake of Como, and has also its sources far away in the Alps, above Bormio, from whence it flows through the broad and fertile valley of the Val Tellina for a distance of more than 65 miles till it enters the lake near Colico. The Adda in this part of its course has a direction almost due east to west ; but at the same point where it reaches the lake, another river, the Lira, descends the valley of S. Giacomo, which runs nearly north and south from the pass of the Spliigen, thus affording one of the most direct lines of communication across the Alps. The Adda flows out of