Chapter XV · —Mountain Barriers And Their Passes

Man as part of the mobile envelope of the earth.

Inaccessibility of mountains.

Mountains as transit regions.

Such mountain regions attain independent historical importance when their population increases enough to form the nucleus of a state, and to acquire additional territory about the highland base either by conquest or voluntary union, while they utilize their naturally protected location and their power to grant safe transit to their allies, as means to secure their political autonomy. Therefore to mountain regions so often falls the rôle of buffer states. Such were medieval Burgundy and modern Savoy, which occupied part of the same territory, Navarre which in the late Middle Ages controlled the important passway around the western end of the Pyrenees, and Switzerland which commands the passes of the central Alps. The position of such mountain states is, however, always fraught with danger, owing to the weakness inherent in their small area and yet smaller allowance of productive soil, to their diverse ethnic elements, and the forces working against political consolidation in their deeply dissected surface. Political solidarity has a hard, slow birth in the mountains.

Transition forms of relief between highlands and lowlands.

In view of the barrier character of mountains, a fact of immense importance to the distribution of man and his activities is the rarity of abrupt, ungraded forms of relief on the earth's surface. The physiographic cause lies in the elasticity of the earth's crust and the leveling effect of weathering and denudation. Everywhere mountains are worn down and rounded off, while valleys broaden and fill up to shallow trough outlines. Transition forms of relief abound. Human intercourse meets therefore few absolute barriers on the land; but these few reveal the obstacles to historical movement in perpendicular reliefs. The mile-high walls of the Grand Cañon of the Colorado are an insuperable obstacle to intercourse for a stretch of three hundred miles. The glacier-crowned ridge of the Bernese Alps is crossed by no wagon road between the Grimsel Pass and the upper Rhone highway around their western end, a distance of 100 kilometers (62 miles). The Pennine Alps have no pass between the Great St. Bernard and the Simplon, a distance of 90 kilometers (54 miles).

Importance of transition slopes.

Gentle transition slopes or terrace lands facilitate almost everywhere access to the lowest, most habitable and therefore, from the human standpoint, most important section of mountains. They combine the ease of intercourse characteristic of plains with many advantages of the mountains, and especially in warm climates they unite in a narrow zone both tropical and temperate vegetation. The human value of these transition slopes holds equally of single hills, massive mountain systems, and continental reliefs. The earth as a whole owes much of its habitability to these gently graded slopes. Continents and countries in which they are meagerly developed suffer from difficulty of intercourse, retarded development and poverty of the choicest habitable areas. This is one disadvantage of South Africa, emphasized farther by a poor coastline. The Pacific face of Australia would gain vastly in historical importance, if the drop from the highlands to the ocean were stretched out into a broad slope, like that which links our Atlantic coastal plain with the Appalachian highlands. There each river valley shows three characteristic anthropo-geographical sub-divisions—the active seaports and tide-water tillage of its lower course, the contrasted agriculture of its hilly course, the upland farms, waterpower industries and mines of its headstream valleys, each landscape giving its population distinctive characteristics. The same natural features, with the same effect upon human activities and population, appear in the long seaward slopes of France, Germany and northern Italy.

Piedmont belts as boundary zones.

Density of population in piedmont belts.

Mineral wealth or waterpower in the mountains serves to collect an urban and industrial population along their rim, as we see it about the base of the Erz Mountains in Saxony, the Riesen range in Silesia, the coal-bearing Pennine Mountains of northwestern England, and the highlands of southern Wales, all which piedmont zones show a density of over 150 to the square kilometer (385 to the square mile). Hence the original Swiss Confederation, which included only the mountain cantons of Schwyz, Uri and Unterwalden, was greatly strengthened by the accession of the piedmont cantons of Lucerne, Zurich, Zug and Bern in the early fourteenth century, as later by St. Gall, Aargau and Geneva. These marginal cantons to-day show a density of population exceeding 385 to the square mile, and rising to 1356 in the canton of Geneva.

Piedmont towns and roads.

Piedmont termini of transmontane routes.

Cities of coastal piedmonts.

Where mountains drop off into a desert, as these Central Asiatic ranges do, their piedmont cities are confined to a narrow zone between mountains and arid waste. Bordering two transit regions of scant population and through travel, they become natural outfitting points, centers of exchange rather than production. Where mountains drop off into the sea and the piedmont therefore becomes a coastal belt, again it borders two transit regions; but here the ports of the desert are replaced by maritime ports, which command the world thoroughfare of the ocean. They therefore tend to concentrate population and commerce wherever a good harbor coincides with the outlet of a transmontane route, as in Genoa and Bombay.

Piedmonts as colonial or backwoods frontiers.

Mountain carriers.

Power of mountain barriers to block or deflect.

If the historical movement slackens its pace at the piedmont slope, higher up the mountain it comes to a halt. Only when human invention has greatly improved communication across the barrier are its obstacles in part overcome. The great highland wall stretching across southern Europe from the Bay of Biscay to the Black Sea long cut off the solid mass of the continent from the culture of the Mediterranean lands. Owing to these mountains Central Europe came late into the foreground of history, not till the Middle Ages. Even the penetrating civilization of Greece reached it only by long detours around the ends of the mountain barrier; by Massilia and the Rhone, by Istria and the Danube, Greek commerce trickled through to the interior of the continent.

Significance of mountain valleys.

Longitudinal valleys.

Passes in mountain barriers.

Breadth of mountain barriers.

Mountains folded into a succession of parallel ranges are greater obstructions than a single range like the Erz, Black Forest, and Vosges, or a narrow, compact system like the Western Alps, which can be crossed by a single pass. Owing to this simple structure the Western Alps were traversed by four established routes in the days of the Roman Empire. These were: I. The Via Aurelia between the Maritime Alps and the sea, where now runs the Cornice Road. II. The Mons Matrona (Mont Genevre Pass, 6080 feet or 1854 meters [Transcriber's Note: printer's error incorrectly printed as kilometers]) between the headstream of the Dora Riparia and that of the Durance, which was the best highway for armies. III. The Little St. Bernard (7075 feet or 2157 meters), from Aosta on the Dora Baltea over to the Isère and down to Lugdunum (Lyons). IV. The Great St. Bernard (8109 feet or 2472 meters) route, which led northward from Aosta over the Pennine Alps to Octodurus at the elbow of the upper Rhone, where Martigny now stands. Across the broad double rampart of the Central Alps the Roman used chiefly the Brenner route, which by a low saddle unites the deep reëntrant valleys of the Adige and Inn rivers, and thus surmounts the barrier by a single pass. However, a short cut northward over the Chalk Alps by the Fern Pass made closer connection with Augusta Vindelicorum (Augsburg). The Romans seem to have been ignorant of the St. Gotthard, which, though high, is the summit of an unbroken ascent from Lake Maggiore up the valley of the Ticino on one side, and from Lake Lucerne up the Reuss on the other.

Circuitous routes through folded mountains.

Dominant trans-montane routes.

Brenner route.

The Pass of Dariel, owing to its situation in a retarded Brenner corner of Asia, has never attained the historical importance which attaches to the deep saddle of the Brenner Pass (4470 feet) in the Central Alps. Uniting the reëntrant valleys of the Inn and Adige rivers only 2760 feet above the Inn's exit from the mountains upon the Bavarian plateau, it forms a low, continuous line of communication across the Central Alps. The Brenner was the route of the Cimbri invading the Po Valley, and later of the Roman forces destined for frontier posts of the Empire on the upper Danube. In the Middle Ages it was the route for the armies of the German Emperors who came to make good their claim to Italy. By this road came the artists and artisans of the whole north country to learn the arts and crafts of beauty-loving Venice. From the Roman road-makers to the modern railroad engineer, with the concomitant civilization of each, the Brenner has seen the march of human progress.

Pass of Belfort.

Mohawk route.

The natural depression of the Mohawk Valley, only 445 feet (136 meters) above sea level, is the only decided break across the entire width of the long Appalachian system. This fact, together with its ready accessibility from the Hudson on the east and Lake Ontario on the west, lent it importance in the early history of the colonies, as well as in the later history of New York. It was an easy line of communication with the Great Lakes, and gave the colonists access to the fur trade of the Northwest, then in the hands of the French. So when French and English fought for supremacy in the New World, the Mohawk and Hudson valleys were their chief battleground; elsewhere the broad Appalachian barrier held them apart. Again in the Revolution, control of the Mohawk-Hudson route was the objective of the British armies mobilized on the Canadian frontier, because it alone would enable them to co-operate with the British fleet blockading the coast cities of the colonies. In the War of 1812, it was along this natural transmontane highway that supplies were forwarded to the remote frontier, to support Perry's fight for control of the Great Lakes. The war demonstrated the strategic necessity of a protected, wholly American line of water communication between the Hudson and our western frontier, while the commercial and political advantage was obvious. Hence a decade after the conclusion of the war, this depression was traced by the Erie Canal, through which passed long lines of boats to build up the commercial greatness of New York City.

Height in mountain barriers.

Contrasted accessibility of opposite slopes.

Mountains are seldom equally accessible from all sides. Rarely does the crest of a system divide it symmetrically. This means a steep, difficult approach to the summit from one direction, and a longer, more gradual, and hence easier ascent from the other. It means also in general a wide zone of habitation and food supply on the gentler slope, a better commissary and transport base whence to make the final ascent, whether in conquest, trade or ethnic growth. Mountain boundaries are therefore rarely by nature impartial. They do not umpire the great game of expansion fairly. They lower the bars to the advancing people on one side, and hold them relentlessly in place to the other. To the favored slope they give the strategic advantage of a swift and sudden descent beyond the summit down the opposite side. The political boundary of France along the watershed of the Vosges Mountains is backed by a long, gradual ascent from the Seine lowland and faces a sharp drop to the rift valley of the middle Rhine, Its boundary along the crest of the Alps from Mont Blanc to the Mediterranean brings over two-thirds of the upheaved area within the domain of France, and gives to that country great advantages of approach to the Alpine passes at the expense of Italy. With the exception of the ill-matched conflict between the civilized Romans and the barbarian Gauls, it is a matter of history that from the days of Hannibal to Napoleon III, the campaigns over the Alps from the north have succeeded, while those from the steep-rimmed Po Valley have miscarried. The Brenner route favored alike the Cimbri hordes in 102 B.C. and later the medieval German Emperors invading Italy from the upper Danube. The drop from the Brenner Pass to Munich is 2800 feet; to Rovereto, an equally distant point on the Italian side, the road descends 3770 feet.

Its ethnic effects.

Persistence of barrier nature.

Mountains influence the life of their inhabitants and their neighbors fundamentally and variously, but always reveal their barrier nature. For the occupants of one slope they provide an abundant rainfall, hold up the clouds, and rob them of their moisture; to the leeward side they admit dry winds, and only from the melting snow or the precipitation on their summits do they yield a scanty supply of water. The Himalayas are flanked by the teeming population of India and the scattered nomadic tribes of Tibet. Mountains often draw equally clear cut lines of cleavage in temperature. The Scandinavian range concentrates upon Norway the warm, soft air of the Atlantic westerlies, while just below the watershed on the eastern side Sweden feels all the rigor of a sub-Arctic climate. In history, too, mountains play the same part as barriers. They are always a challenge to the energies of man. Their beauty, the charm of the unknown beyond tempts the enterprising spirit; the hardships and dangers of their roads daunt or baffle the mediocre, but by the great ones whose strength is able to dwarf these obstacles is found beyond a prize of victory. Such were Hannibal, Napoleon, Suvaroff, Genghis Khan, and those lesser heroes of the modern work-a-day world who toiled across the Rockies and Sierras in the feverish days of '49, or who faced the snows of Chilkoot Pass for the frozen gold-fields of the Yukon.

Importance of mountain passes.

For migrating, warring and trading humanity therefore, the interest of the mountains is centered in the passes. These are only dents or depressions in the great up-lifted crest, or gaps carved out by streams, or deeper breaches in the mountain wall; but they point the easiest pathway to the ultramontane country, and for this reason focus upon themselves the travel that would cut across the grain of the earth's wrinkled crust. Their influence reaches far. The Brenner, by its medieval trade, made the commercial greatness of Augsburg, Ratisbon, Nuremberg, and Leipzig to the north, and promoted the growth of Venice to the south. The Khaibar Pass and the Gates of Herat in Afghanistan have for long periods dominated the Asiatic policy of Russia and British India. The Mohawk depression and Cumberland Gap for decades gave direction to the streams of population moving westward into the Mississippi basin in the early history of the Republic. Where Truckee Pass (7017 feet) makes a gash in the high ridge of the Sierra Nevada, the California Trail in 1844 sought the line of least resistance across the barrier mass, and deposited its desert-worn immigrants about the Sacramento Valley and San Francisco Bay. There they made a nucleus of American population in Mexican California, and in 1846 became the center of American revolt.

Persistent influence of passes.

Geographic factors in the historical importance of passes.

The historical importance of passes tends to increase with the depth of the depression, since the lowest gap in a range relegates the others to only occasional or local use; and with their rarity, in consequence of which intercourse between opposite slopes is concentrated upon one or two defiles. The low dips of the Central American Cordilleras to 262 feet (80 meters) at Panama, 151 feet (46 meters) in the Nicaraguan isthmus, and 689 feet (210 meters) at Tehuantepec, present a striking contrast both orographically and historically to the South American Andes, where from the equator to the Uspallata or Bermejo Pass (12,562 feet or 3842 meters) back of Valparaiso, a stretch measuring 33 degrees of latitude, the passes all reach or exceed 10,000 feet or 3000 meters. The southern or Pennine range of the Alps, stretching as a snow-wrapped barrier from Mont Blanc 90 miles to the central Alpine dome of the St. Gotthard, is notched only by the Great St. Bernard and Simplon passes, which have therefore figured conspicuously in war and trade, since very early times. The Pass of Thermopylæ, as the only route southward along the flank of the Pindus system, figures in every land invasion of Greece from Xerxes to the Greek war of independence. All movements back and forth across the Caucasus wall have been confined to the Pass of Dariel and the far lower Pass of Derbent, or Pylæ Albaniæ; of the ancients, which lies between the Caspian and the last low spurs of the mountains as they drop down to the sea. The latter, as the easier of the two passes, has had a longer and richer history. It alone enabled the ancient Persians temporarily to force a wedge of conquest to the northern foot of the Caucasus, and it has been in all ages a highway for peoples entering Persia and Georgia from the north. It has so far been the only practicable route for a railway from the Russian steppes to the southern base of the Caucasus. While Vladicaucas and Tiflis have direct connection by the military highway over the Pass of Dariel, the railroad between these two points makes a detour of 300 miles to the east.

Intermarine mountains.

Intermarine mountains as a rule offer the easiest passways where they sink to meet the flanking seas. The Pyrenees are crossed by only two railroads, the Bayonne-Burgos line, along the shore of the Bay of Biscay, and the Narbonne-Barcelona line, overlooking the Mediterranean. Between these extremities the passes are very high and only two are practicable for carriages, the Col de la Perche (5280 feet or 1610 meters) between the valleys of the Tet and the upper Segre, and the Port de Canfranc (7502 feet or 2288 meters) on the old Roman road from Saragossa to Oloron. The coastal road around the eastern end of the Cheviot Hills has been the great intermediary between England and Scotland. It was the avenue for early Teutonic expansion into the Scotch Lowlands, the thoroughfare for all those armies which for centuries made Berwick a chronic battleground.

For purposes of trade these intermarine mountains are less serious barriers, because they can be avoided by an easier and cheaper sea route. Hence on each side of such ranges grow up active ports, like Narbonne and Barcelona, Bayonne and Bilbao with San Sebastian, on the piedmont seaboard of the Pyrenees; Petrovsk and Baku on the Caspian rim of the Caucasus, balancing the Crimean ports and Poti with Trebizond on the Black Sea. Analogous is the position of Genoa and Marseilles in relation to the Maritime Alps. Such ports are inevitably the object of attack in time of hostilities. In the Peninsular War almost the first act of the French was to seize Barcelona, San Sebastian and Bilbao; and throughout the seven years of the conflict these points were centers of battle, blockade and siege. If Russia ever tries to wrench the upper Euphrates Valley from Turkey, Trebizond will repeat the history of Barcelona in the Peninsular War.

Pass roads between regions of contrasted production

As the world's roads are used primarily for commerce, pass routes rank in importance according to the amount of trade which they forward; and this in turn is decided by the contrast in the lands which they unite. The passes of the Alps and the Pass of Belfort have been busy thoroughfares from the early Middle Ages, because they facilitate exchanges between the tropical Mediterranean and the temperate regions of Central Europe. Or the contrast may be one of economic and social development. The Mohawk depression forwards the grain of the agricultural Northwest in return for the manufactured wares of the Atlantic seaboard. The passes of the Asiatic ranges connect the industrial and agricultural lowlands of India and China with the highland pastures of Mongolia, Tibet, Afghanistan and Russian Turkestan. Hence they forward the wool, skins, felts, cloth and carpets of the wandering shepherds in exchange for the food stuffs and industrial products of the fertile, crowded lowlands. Where passes open a highway for inland countries to the sea, their sphere of influence is greatly increased. San Francisco, New York, Marseilles, Genoa, Venice, Beirut and Bombay are seaports which owe their importance in no small degree to dominant pass routes into their hinterland.

Passes determine transmontane roads.

In plains and lowlands highways may run in any direction expediency suggests, but in mountain regions the pass points the road. In very high ranges there is no appeal from this law; but in lower systems and especially in old mountains which have been rounded and worn down by ages of denudation, economic and social considerations occasionally transcend orographical conditions in fixing the path of highways. Scarcely less important than pass or gap is the avenue of approach to the same. This is furnished by lateral or transverse valleys of erosion. The deeper their reentrant angles cut back into the heart of the highlands, the more they facilitate intercourse and lend historical importance to the pass route. The Alpine passes which are approached by a single valley from each side are those crossed by railroads to-day,—Mont Cenis, Simplon, St. Gotthard and the Brenner. The Alpine chain is trenched on its inner or southern side by a series of transverse erosion valleys, such as the Dora Baltea, Sesia, Tosa, Ticino, Adda, Adige, and Tagliamento, which carry roads up to the chief Alpine passes. The coincidence of the Roman and medieval roads over the Alps with the modern railroads is striking, except in the single point of elevation. Railroads tend to follow lower levels. Modern engineering skill enables them to tunnel the crest, to cut galleries in the perpendicular walls of gorges, and to embank mountain torrents against the spring inundation of the roadbed, where it drops to the valley floor.

Navigable river approaches to passes.

Types of settlements in the valley approaches.

Lower settlements.

Farther down the transverse valley the type of settlement changes where side valleys, leading down from other passes, converge and help build up a distributing center for a considerable highland area. Such a point is Chiavenna in northern Italy, located above the head of Lake Como at the junction of the Mera and Liro valleys, which lead respectively to the Splügen and Maloja passes. It lies at an altitude of 1090 feet (332 meters) and has a population of 4000. Such a point is Aosta (1913 feet or 583 meters elevation) in the Dora Baltea Valley, commanding the Italian approaches to the Great St. Bernard Pass, and the less important Col de Fenêtre leading to the upper Rhone, the Little St. Bernard highway to the valley of the Isère, and Col de la Seigne path around the Mont Blanc range to the valley of the Arve. Aosta was an important place in the Roman period and has to-day a population of about 8000. Kokan, in the upper Sir-Daria Valley in Russian Turkestan, commands the approach to the passes of the western Tian Shan and the northern Pamir. Its well-stocked bazaars, containing goods from Russia, Persia and India, testify to its commercial location.

Pass cities and their markets.

Pass peoples.

Transit duties.

Strategic power of pass states.

NOTES TO CHAPTER XV