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]

[Sidenote:  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]

[Sidenote:  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