Opposed to the _valle_ is the eroded ravine, carved out by water, the _quebrada_. It opens upon a _valle_ with a V-shaped mouth, which widens out at the top, and one can recognise at sight the various slopes and the successive stages of erosion. Narrow and winding, a level bed of shingle filling the entire base of the valley, it rises rapidly toward the mountains and provides a route from the _valle_ to the _puna_. These _valles_, _quebradas_ and _puna_ are the three inhabited zones of the Andes. The first is the richest. The inhabitant of the _valle_, proud of his comparative comfort, has for his neighbour in the _quebrada_ or the _puna_--the _coyada_--a contempt such as one finds the inhabitants of the good land in Europe feeling for the people in poorer districts. The narrower the _valle_, the less rain there is. The observations give 112 millimetres of rain per year at Tinogasta, 290 at Andalgala, and 200 at Santa Maria. Salta and Jujuy have a much moister climate, and have no less than 570 and 740 millimetres of rain annually. This is because the eastern chain of the Andes, which stretches from the Sierra de Santa Victoria on the Bolivian frontier to Aconcagua, sinks lower at the latitude of Salta, and lets in the moisture of the Chaco to the heart of the zone of the Andes. The rains of Salta and Jujuy are suspended during the winter, but they are so heavy during the summer months (November to March) that maize, which needs only the summer rain, can be cultivated without irrigation. But when we follow the Valle de Lerma southward from Salta the maize harvest becomes more and more uncertain, and it is no longer sown in dry soil when we get to about twenty miles from Salta, in the latitude of the confluence of the Arias and the Juramento. However, the summer rains, which are good for maize, are very injurious to the vine; they spoil the grapes. Thus the southern limit of the cultivation of maize in dry soil almost coincides with the northern limit of the vine. At that point we have the real beginning of the typical scenery of the _valles_. [Illustration: THE PATAGONIAN ANDES. _Mount Tronador (11,500 feet) on the Chilean frontier, dominating the road from Lake Nahuel Huapi to Chile. The glaciers still reach the bottom of the valley, which they filled at one time. A burnt forest in the foreground._ PLATE III. To face p. 38.]