Alps, the name applied to the most important mountain chain in Europe. Physically the Alps cannot be separated from the Apennines on the one hand, from the mountains of Istria, etc., on the other. Thus, the limits of the chain itself, as well as its subdivisions, are rather arbitrary. It may be roughly separated from the Apennines by a line joining Turin with Mentone; from the Julian Alps by the watershed between the Isonzo and the Save. The chain sweeps round the great plain of northern Italy, by the head of the Adriatic, to the plain of Hungary, and it inosculates with the mountain region on the eastern shore of the Adriatic; the length measured along the watershed being roughly 790 miles, with a maximum breadth of about 200 miles. The highest peak is Mont Blanc (15,781 ft.), but many peaks exceed 10,000 ft., even the crest of a range not falling below this for a considerable distance. Thus, there are many large snowflelds and glaciers. The Alps occupy part of the territory of the following nationalities: Austria, Bavaria, Switzerland, France, and Italy.
Subdivisioxs. - Geographers differ as to the subdivisions of the Alps; the following correspond nearly with those adopted by one of tiie best authorities.
(1) The Maritime Alps. These are divided from the Apennines, as stated above, and extend to the Col de Longet, south-east of the Viso. The chain here is single, with ramifying valleys, the highest peak being the Aiguille de Chambeyron (11,155 ft.). (2) The Cottian Alps. From the Col de Longet to the Col del Carro (joining the valley of the Arc in Savoy with that of the Orco in Piedmont), and limited on the west by the Col de Galibier. The chain is now becoming more complicated in structure. The highest peak in the Cottian Alps is Monte Viso (12,643 ft.). The most important road passes are the Mont Genevre (6,102 ft.), and the Mont Cenis (6,772 ft.); near the latter a railway is carried through the range by a tunnel eight miles long. (3) The Dauphine Alps. These are composed of a great spur extending westward from the main range (arbitrarily limited at the Col de Galibier, connecting the upper waters of the Durance with those of the Arc), and a huge offshoot from it towards the south, linked on by the Col du Lautarat (6,740 ft.), which is crossed by the carriage road from Grenoble to Briancon. In the former section only one peak just overtops 11,500 ft., in the latter the Pointe des Ecrins is 13,462 ft., and several exceed 12,000 ft. The structure of the chain is now becoming yet more complicated, and gives indications of being composed of parallel ranges. (4) The Graian Alps include the whole chain as far as the Little St. Bernard Pass (about 7,200 ft.), together with the great spur which runs out eastward and is cut off from the Pennine Alps by the valley of the Dora Baltea. Its highest peak is the Grand Paradis (13,300 ft.), that of the main mass is the Grande Casse (12,780 ft.). (5) The Pennine Alps. To these may be assigned the district north of the Graians, and on the left bank of the Rhone, though by some the western part of this is distinguished as the Savoy Alps, the eastern limit being the Simplon Pass (6,595 ft.). This division includes the most elevated part of the chain, from Mont Blanc, with its Aiguilles (or adjacent peaks) on the west, to the group of great peaks around Monte Rosa (15,217 ft.) on the east. Up to the Simplon no carriage road crosses the main range, but the Great St. Bernard, a mule track (8,131 ft.), has been made famous by its hospice. (6) The Bernese Alps run parallel with the Pennines from the valley of the Rhone to that of the Reuss. The range is generally lofty, the highest summit being the Finster Aarhorn (14,026 ft.); one of its glaciers, the Gross Aletsch, is the largest in the Alps. This range is continued east of the Reuss by the (7) North Swiss Alps, an extensive but less elevated region, the highest peak, the Todi, only attaining 11,887 ft. In like way the Pennine Range is continued east of the Simplon Pass by the (8) Lepontine Alps, of which the Splugen Pass (6,945 ft.) may be taken as the eastern boundary. Here the peaks are lower, the highest point, Monte Leone (11,696 ft.), being close to the Simplon road. The range is crossed by the St. Gothard Pass (6,936 ft.), and pierced by a railway which passes through a tunnel 9-1/4 miles long (9) The Rhaetian Alps include the district east of the last up to the Vorarlberg Pass (now crossed by a railway) on the north; on the eastern side they are limited by the Inn as far as a line joining that river with the head waters of the Adige, and then by the right bank of that river. The highest peak is the Bernina (13,294 ft.). In this division is the Stelvio Pass, the highest carriage road in the Alps (9,177 ft.). (10) The Vindelican Alps include the northern range from the Lake of Constance to the neighbourhood of Vienna, the highest peak being the Zug Spitz (9,716 ft,). By some the part east of the Inn is called the North Noric Alps. (11) The Central Tyrol Alps. These are limited by the right bank of the upper Inn, and extend eastward as far as a rather irregular line passing through Gmund and Villach, the highest peak being the Gross Glockner, 12,455 ft, They are crossed by the Brenner Pass (4,588 ft.) road and railway; east of these are (12) The Styrian Alps. (13) The South Tyrol and Venetian Alps extend from the east bank of the Adige to the Sexten Thal, the highest peak being the Marmolata (11,020 ft.), and are followed by (14) The South-eastern Alps.
In the eastern part of the Alps the chain is obviously composed of three ranges, parted by long troughs occupied by important rivers, the central one being the watershed. This structure becomes rather less distinct near the head waters of the Inn, and the watershed appears to cross to the southern range. It is, however, more probable that the latter disappears by denudation, and the Lepontine and Pennine Alps are orographically continuous with the Central Tyrol Alps. South of Mont Blanc the above-named structure exists, but is difficult to trace.
Geoloqy. - The "foundation stones" of the Alps consist of crystalline rocks - granites, gneisses, schists, etc., of unknown but very great geological age. The oldest fossiliferous rocks are of Silubian and Devonian age; they occur in the Eastern Alps, between the Northern and Central range. Rocks of Caeboniferous age are recognised here and there in many parts of the Alps. These prove that a region hilly, if not mountainous, then existed. Permian times saw great volcanic activity in the South Tyrol region. After this came subsidence, and here extensive masses of dolomite were formed. In some districts land remained above water till the end of the Trias, but at last the whole area became submerged, and continued to receive sediment till near the end of the Eocene period. Then began a great epoch of mountain-making.
The crust of the earth was folded, outlining the dominant features of the chain. Rivers, precursors of those still running, brought down sand and gravel and poured it over the lowlands or into the sea on either side of the chain. The Miocene period, roughly speaking, was closed by another epoch of mountain-making. This, in Switzerland, raised the pebble-beds in the Rigi and the Speer some 6,000 ft. above the sea. It left this chain much as it is at present, though vast masses of rock have been since removed. After a long interval, the climate of Europe, from some unknown causes, became much colder, the glaciers of the Alps increased enormously in size; they occupied the mountain valleys, debouched on the Italian plain, covered the lowland of Switzerland, and welled up on the flanks of the Jura to a height of about 2,000 ft. above the lake of Neufchatel. Here blocks of Alpine rocks remain to mark their limit. On the Italian plain the moraines (q.v.) are like ranges of hills. Some geologists have credited glaciers with the excavation of the lake basins; these, however, are regarded by others as due to differential movements in the beds of pre-existing valleys.
The earth-movements have left their mark in extraordinary flexures of the rocks, beds being bent into S-like curves or even folded back. Sometimes these folds are fractured and one part is thrust over another; thus the order of succession is locally inverted. By pressure, clays have been converted into slates, massive crystalline rocks have become foliated, while ancient foliated rocks have received a new structure.
Hydrography. - The main rivers, the Mur, the Save and the Drave, draining the eastern part of the chain, run east towards the Danube, but the Salza, also its tributary, turns to the north and cuts through the northern range. The south face of the southern range is drained by minor rivers flowing to the head of the Adriatic, the most important being the Piave. Farther west the drainage of the south side of the central range is carried through the southern range by the Adige or Etsch, its principal affluents being parted from the Drave on the east and the Inn on the west by comparatively low watersheds. The last river rises in the southern range on the Maloya Pass (5,942 ft.), seemingly cuts the central range; then, after flowing eastward between this and the northern range, severs the latter and debouches on the Bavarian plain on its way to the Danube.
The central portion of the Alps is drained by the Rhine, the Reuss (its tributary), and the Rhone. These rise in the northern face of the Lepontine Alps; the first runs for a considerable distance eastward, the third in like manner westward, till they turn northward, and run roughly parallel with the second. Hence the head waters of these three rivers lie in a kind of trough interrupted by the Oberalp Pass between the Rhine and the Reuss, and the Furka Pass between the Reuss and the Rhone. The Aar is fed by the glaciers of the Bernese Alps, the Limmat issues from the North Swiss Alps.
South of Mont Blanc the Isere, Arc, and Romanche carry the drainage of the western portion of the chain, by zigzagging courses, to the Rhone; but parts of the Dauphine and the Cottian Alps are drained by the Durance, which also ultimately reaches the Rhone. Parts of the Maritime Alps discharge their waters direct to the Gulf of Lyons by less important streams. West of the Adige, all the water from the inner side of the great loop of the Alpine chain makes its way to the Po.
Lakes. - The lakes of the Alps are numerous. The most important are those of the Salzkammergut and the Konigsee in the North Noric Alps, the Lakes of Constance, Zurich, Lucerne, Thun, Brienz, and Geneva, wholly or in part, in Switzerland; of Garda, Iseo, Corno, Lugano, Maggiore, mainly in Italy, with those of Annecy and Bourget in France.
Climate. - As the Alps extend over about four degrees of latitude and the summits vary so much in elevation, no general statement can be made. The mean temperature of the Swiss Lowland differs but little from that of England, the summer being rather warmer, the winter rather colder. The mean at Berne is 49.5° F., Lucerne 47.5°, Geneva 49.5°, Montreux 50.9°, the summer temperature at Berne being 72° and the winter 31.8°. The mean temperature at the St. Bernard is 28.12°. The rainfall here is 6.6 ft. per annum. The snow-line varies according to locality; 8,000 feet may be taken as a rough average. Much snow falls everywhere in the winter months. This slips from the great slopes of the mountains in the form of avalanches, which often are very destructive. Occasionally also portions of the steeper glaciers break away. The scenery of the Alps is varied and beautiful. In the more distant views lakes, pasturage, and woodlands form a foreground to snowy masses; in the heart of the ranges the traveller is surrounded by pine-clad slopes, grand precipices, rushing torrents, great glaciers, and snow-clad peaks. The Italian lakes are exceptionally lovely. The grandest outlooks over crag, snowfield, and glacier are to be obtained on the range of Mont Blanc, in the region about Monte Rosa, and in the Bernese Oberland. In the less frequented regions the Aiguilles of Dauphine and the dolomite crags of the S.E. Tyrol are remarkably fine. But to appreciate the scenery of the Upper Alps their fastnesses must be scaled. This of late years has become a favourite pastime, so that the Alps have been called "The playground of Europe." Now not a peak of importance is untrodden, and the glacier plains which have been traversed may be counted by hundreds.
Fauna. - The fauna of the Alps obviously depends on the climate. In the lower parts it is that of Central Europe; higher up the wolf, lynx, and bear are occasionally found, with the hare (Lepus variabilis); the marmot is common near the edge of the snows, the chamois is not seldom seen among the higher peaks, the steinbock (Capra Ibex) is rare and appears to be now restricted to the Eastern Graians. The most distinctive Alpine birds are the lammergeyer (Gypaetus barbatus), the brown eagle, the ptarmigan, the Alpine chough, and the Alpine swift. Reptiles do not ascend very high. Butterflies of mountain species are common, and have been seen fluttering about peaks more than 12,000 ft. high. Higher than about 3,500 ft. to 5,500 ft. (according to the locality) corn is seldom cultivated; the slopes are occupied by pastures or great pine woods to between 6,000 and 7,000 feet, and the former extend yet higher. These pastures afford ample food in summer to cattle, sheep, and goats, the animals and their attendants being sheltered in huts of wood or stone, called chalets.