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strata which, in the more attractive valleys, have been obliterated or overlaid by later invasions of peoples and cultures. Ignoring this temporary attraction of population to protected mountain locations in ages of persistent warfare, we find that a comparison of many countries reveals a decreasing food supply and decreasing density of population, with every increase of height above a certain altitude, except in favored mining regions and in some tropical lands, where better climatic conditions and freedom from malaria distribute settlements far above the steaming and forest-choked lowlands. The density of population in mountains is influenced also by the composition of the soil, which affects its fertility; by the grade and exposure of the slopes, which determine the ease and success of tillage; by the proximity of the highlands to teeming centers of lowland population, and by the general economic development of the people.

In Great Britain, the sparsest population is found in the sterile highland moors of Scotland, where the county of Sutherland has only 11 inhabitants to the square mile, Inverness only 20.1262 These figures reveal also the remoteness of a far northern location. In the southern half of the island the sparsest populations are found in the Welsh county of Radnor, with 49 to the square mile, and in English Westmoreland with 85, both of them mountain regions, but reflecting in their larger figures their close proximity to the teeming industrial centers of South Wales and Lancashire respectively. In France the most thinly settled départements are Basses-Alpes with 43 to the square mile and Hautes-Alpes with 50, which again owe even these figures in part to their situation on the margin of the densely populated valley of the middle Rhone. [See map page 559.] Norway, almost wholly a mountain country, averages only 18 souls to the square mile. Less than a thousand square miles of its territory are under cultivation, and these are distributed in small deltas at the heads of the fiords, in low strips here and there along its western coasts, or in the openings of its mountain valleys to the southeast. Here too is massed the larger part of its inhabitants. A barren granitic soil, unfavorable zonal location, excessive rainfall, paucity of level land, leaving the "upright farm" predominant, and remoteness from any thickly settled areas, together with the resulting enormous emigration, have combined to keep down Norway's population.

Sparsity of population in the Alps.

If we turn to Switzerland, a country poor in the resources of its land but rich in the resourcefulness of its people, we find a high average density, 218 to the square mile; but this is due to the surprising industrial development of the marginal plains, which show in the Canton of Geneva 1356 to the square mile, and in Canton Zurich 705, while the rugged upland of Graubünden (Grisons) shows only 38 to the square mile, Uri only 48, and Wallis (Valais) only 59. How limited is the food supply of the country is evident from the fact that only 2400 square miles, or fifteen per cent. of its area, can be ranked as arable land, fit for garden, orchard or grain field, while a larger proportion, or twenty-eight per cent. is made wholly useless by watercourses, glaciers, rock and detritus. One half of the entire country lies above the region where agriculture is possible. In the Cantons of Uri and Valais, more than half the area is absolutely unproductive, scarcely less in the Grisons, and a third even in sunny Ticino.1263 The three strictly Alpine provinces of Austria, Tyrol, Salzburg and Carinthia, reproduce approximately these geographic conditions. Nearly half of their area is uninhabited, and only one-seventh consists of arable land. In consequence they support only 75 inhabitants to the square mile, while just outside the mountains, in the piedmont or Alpine foreland, this density is doubled.1264 Many tracts of the Carpathians, especially about the sources of the Theiss and Pruth and the wooded mountain borders of Transylvania, are among the most sparsely inhabited parts of Europe.1265 Japan, ridged by steep volcanic ranges, drenched by mountain-born rains, strewn with detritus from plunging torrents, can cultivate only 15.7 per cent. of its area, and is forced to leave 59 per cent. in forest reserves.1266

Terrace agriculture.

These figures tell of the hard conditions of life characteristic of most mountain regions. Population under normal circumstances settles in the narrow valleys between the ranges and along the borders of their drainage stream. Soon, however, the food supply becomes inadequate for the growing numbers, so that artificial means have to be employed to expand the area of arable land. The soil on the mountain slopes is so thin that it yields only a scanty return to the labor of tillage. Moreover, under the operations of ploughing and harrowing, it is exposed to the danger of washing; so that after a few croppings the underlying rock of the mountain side may be laid bare, and all that was valuable in the quondam field deposited in the valley as silt or swept away to enrich the distant delta of the nearest trunk river.

To obviate this difficulty and to secure the desired increase of arable land, mountain peoples the world over have resorted to terrace agriculture. This means hand-made fields. Parallel walls, one above the other, are constructed on horizontal lines across the face of the steep slopes, and the intervals between are filled with earth, carried thither in baskets on the peasants' backs. The soil must be constantly renewed and enriched by manure in the same way, and the masonry of the retaining walls kept in repair. Whenever possible these costly terraced fields are located by preference on southward facing slopes, where the tilt of the land makes the fields catch the rays of the sun almost at right angles and thus counteracts the chill of the higher altitude, while the mountain behind protects the growing crops from cold northern winds. Good arable land, being limited in amount, commands a high price; and especially do choice terraced fields in vine-growing countries, since they make the best vineyards. Such fields in Switzerland will bring from $300 to $2,000 an acre, and are estimated to produce annually two bottles of wine for every square foot.1267

Geographical distribution.

Terrace agriculture, rare in new countries, in the more densely populated Old World is widely distributed in mountainous areas. In Germany, where it is nearly identical with the culture of the vine, it is found along the steep slopes overlooking the valley of the Moselle and the Rhine; also in the Vosges Mountains, the Black Forest and the Swabian Jura, to the limited altitude in which the vine will flourish in these northern regions. In the Alps it is widespread, and not confined to the culture of the vine. The traveler passing along the upper Rhone through the sunny Canton of Valais follows these terraced fields almost as far as Fiesch (altitude 3458 feet), beyond which agriculture proper becomes more and more restricted on account of the elevation, and passes rapidly into the mere hay-making of a pastoral community. Between Leak and Sierre, not only the mountain sides, but also the steep gravel hills constituting the old terminal moraine deposited by the receding Rhone glacier across the valley floor, are terraced to their very tops.

Terrace cultivation prevails in the mountains of Italy; it is utilized not only for the vine, but for olives, maize, oats, hemp, rye and flax. On the gentler declivities of the Apennines, the terraced walls are wider apart and lower than on the steep slopes of the Ligurian Apennines and along the Riviera of the Maritime Alps, where the mountains rise abruptly from the margin of the sea.1268 Careful and laborious terrace cultivation has produced in Italy a class of superior gardeners. The Genoese are famous for their skill in this sort of culture. The men from the Apennine plateau of the Abruzzi readily find positions in the lowlands as expert gardeners.1269

Terrace culture of the Saracens.

The Saracens of Spain in the tenth century converted every mountain slope into a succession of green terraces. They built walls of heavy masonry, and brought water, loam, and fertilizing materials from great distances. The slopes of Granada back of Malaga and Almeria were covered with vineyards. Every foot of land susceptible of cultivation was turned to account, every drop of water from the ill-timed winter rains was conserved for the growing season. The application of intelligence and labor to tillage enabled the Hispano-Arab provinces to support a dense population.1270 These Saracen cultivators had come from the severest training school in all Eurasia. Where the arid tableland of Arabia is buttressed on the southwestern front by high coast ranges (6000 to 10,500 feet or 2000 to 3200 meters) is Yemen, rich in its soil of disintegrated trap rock, adequately watered by the dash of the southwest monsoons against its towering ridges; but practically the whole country is atilt. Consequently the mountains have been terraced from the base often up to 6000 feet. The country presents the aspect of vast agricultural amphitheaters, in which the narrow paths of ancient paving zigzag up and up through successive zones of production. Here is a wide range of fruits—oranges, lemons, figs, dates, bananas and coffee; then apricots, apples, plums, grapes, quinces, peaches, together with grains of various zonal distribution, such as millet, maize, wheat and barley. The terrace walls are from five to eight feet high, but toward the top of the mountains they often increase to fifteen feet. Though laid without mortar, they are kept in perfect repair. Reservoirs filled with water from the two rainy seasons, supply the irrigation channels.1271 In the narrow valleys of the Nejd plateau in central Arabia and on the mountain slopes of Oman are found the same irrigated gardens and terraced plantations. This laborious tillage underlay the prosperity of the ancient Sabaean monarchy of Yemen, as it explains the population of 35,000 souls who occupy the modern capital of Sanaa, located at an altitude of 7600 feet (2317 meters).1272

In the Himalayas.

Turning eastward, we find terrace agriculture widely distributed in Himalayan lands. The steep mountain sides of the Vale of Kashmir are cultivated thus to a considerable height. The terraces are irrigated by contour channels constructed along the hillsides, which bring the water for miles from distant snow-fed streams. Their shelf-like fields are green with fruit orchards and almond groves, with vineyards and grain fields.1273 The terraced slopes about the Himalayan hill-station of Simla (elevation 7100 to 8000 feet) feed the summer population of English, who there take refuge from the deadly heat of the plains. The mountain sections of the native states of Nepal and Bhutan present the view of slopes cut into gigantic stairs, each step a field of waving rice kept saturated by irrigating streams from abundant mountain springs. Farther north, where Himalayas and Hindu Kush meet, terrace agriculture is combined with irrigation in the high Gilgit valleys, and farther still along that mere gash running down from the Pamir dome, called the Hunza Valley. Here live the once lawless robber tribes of the Hunzas and Nagaris, whose conquest cost the British a dangerous and expensive campaign in 1892, but whose extensive terraces of irrigated fields and evidences of skillful tillage gave the whole country an appearance of civilization strangely at variance with the barbarous character of its inhabitants.1274

In Tibet and China.

North of the outer Himalayan range, near the sources of the Indus and Sutlej rivers in Ladak or Western Tibet, this same form of cultivation has been resorted to by the retarded and

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