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 Added to the effects of dryness and increasing altitude as we go southward from western Bolivia tothe Puna de Atacama in northwestern Argentina is the effect of increasing latitude. In short, we have a culmination of four unfavorable condi- tions: first, a broacd| mountain zone; second, a dryness so great as to be self-stimulating in its effects; third, the effect of in- creasing altitude; fourth, the increasing cold of increasing latitude. These causes combine to make the Puna without exception the most inhospitable part of the entire Andean section of South America below the level of permanent snow, whether we consider the winter or the summer season. What the summers gain in temperature they lose in the violence and frequency of the wind, and what the winter lacks of violent local tempest is made up for by the increasing risk from heavy snowfall that covers the whole surface and fills the passes and ravines with impassable drifts.

Unlike the shepherds of Peru and Bolivia, who pasture their flocks the whole year round at the highest elevations because they arc able to endure the few weeks of cold weather at the height of the winter season, most of the shepherds of the Puna de Atacama are driven out for an entire season. It would be impossible for them to live the whole year through at most of their camp sites in the high mountain belt. When they come to the lower valleys they must come, not as vagrants but as owners, with rights; else their migratory system would be impossible. They customarily leave a part of the community, consisting chiefly of boys and old women, at the lower stations to guard their fixed property, while they drive their flocks to the high pastures, and especially to care for the fields and the limited crops. When the winter cold sets in the shepherds return from their tiny corrals perched on the mountain sides and come down to the lower valleys, where the fattened flocks graze upon the scant herbage of the valley floor and the dried stalks of desert grasses.

The settlements of the Puna de Atacama are governed from the town of San Antonio de los Cobres, which is the capital of