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 thousand to four thousand feet and the mountain flanks at eight thousand feet where the mountain pastures begin. It is substantially a barren region. While, as we have seen, there are tracts of scrub which depend upon natural subirrigation and occasional scattered patches of bushes and thorny plants along the ravines, the nakedness of the desert, its exceedingly thin plant cover, is the outstanding feature. And so barren is the desert pampa outside the borders of the oases that even a pastoral occupation is denied the inhabitants. If they raise flocks they must forage on the cultivated plants of the garden farms—alfalfa, millet, and the like—or be driven to the moun- tain pastures at elevations above eight and ten thousand feet. In some parts of the desert, as we shall see in the country between Copiapé and Vallenar, at the southern end of Ata- cama, occasional showers make possible a temporary range for flocks and herds, when grasses spring up and carpet the otherwise barren surface with green, but the dryness of the Desert of Tarapacd is so great that not even this temporary range comes into being. Beyond the oases there is nothing upon which man can depend, and access to the exceedingly thin mountain pastures is denied over much of the year by the extreme scarcity of springs and streams to which shep- herds can drive their flocks to drink. Otherwise there is noth- ing except in some underdeveloped oasis where poorly watered marginal tracts, rarely more than a few square miles in extent, often salt-incrusted, support a wild growth of temporary grasses and perennial shrubs which for a short time bear a certain amount of succulent foliage.

The Desert of Tarapaca contains rich nitrate deposits that have been worked for half a century and upon which is based the prosperity of the city of Iquique and several neighboring ports engaged in the nitrate business. Before the discovery of nitrate it was an almost uninhabited region. Towns, rail- ways, and nitrate works have been made out-of-hand. They were built almost entirely by foreign capital and run by