These minor ranges, excepting the Zenta, are separated from the Andean masses by comparatively low depressions and are usually described as distinct ranges; topographically, however, they seem to form a continuation of the ranges running southward from the Santa Victoria and forming the eastern rampart of the great central plateau of which the Puna de Atacama covers a large part.
More recently, the extensive deposits of borates (chiefly, however, of calcium; see Colemanite) in the Mohave desert on the borders of California and Nevada, and in the Atacama desert in South America, have been the chief commercial sources of boron compounds.
Thus we have in the northern hemisphere the Sahara desert, the deserts of Arabia, Iran, Turan, Takla Makan and Gobi, and the desert regions of the Great Basin in North America; and in the southern hemisphere the Kalahari desert in Africa, the desert of Australia, and the desert of Atacama in South America.
It was formerly capital of the Bolivian department of Atacama and the only port possessed by Bolivia, but the seizure of that department in 1879 by Chile and the construction of the Antofagasta and Oruro railway deprived it of all importance, and its population, estimated at 6000 in 1858, has fallen to less than 500.
When the attempt was made to mark this boundary the commissioners were unable to agree on a line across the Puna de Atacama in the north, where parallel ranges enclosing a high arid plateau without any clearly defined drainage to the Atlantic or Pacific, gave an opportunity for conflicting claims. In the south the broken character of the Cordillera, pierced in places by large rivers flowing into the Pacific and having their upper drainage basins on the eastern side of the line of highest crests, gave rise to unforeseen and very difficult questions.
Extensive deposits of the salt (called caliche in its crude, impure state) in the provinces of Tacna, Tarapaca, Antofagasta and Atacama owe their existence to the rainless character of the climate.
Before 1842, when guano began to attract notice as an exportable product, Atacama was considered as Bolivian territory, and Coquimbo the extreme northern province of Chile.
The province of Coquimbo, which lies between those of Aconcagua and Atacama and extends from the Pacific inland to the Argentine frontier, has an area of 13, 4 61 sq.
Communications.-Railway construction in Chile dates from 1850, when work was begun on a short line between Copiapo and the port of Caldera, in the Atacama desert region.
The question of the Puna de Atacama was referred to a tribunal composed of the United States minister to Argentina and of one Argentine and one Chilean delegate; that of the southern frontier in Patagonia to the British crown.