82 TUCUMAN and MENDOZA 



The oases of San Juan and San Rafael spread evenly 

 over the most suitable parts of the alluvial talus, but 

 the oasis of Mendoza has a peculiar shape which can 

 only be explained by historical causes. The cultivated 

 belt is a narrow strip along the Tunuyan, for more than 

 sixty miles, as far as the heart of the plain, out of 

 sight of the Cordillera. It is one instance, out of a 

 thousand, of the influence of traffic on colonization, 

 As a matter of fact, the road from Mendoza to the coast, 

 by which the cattle convoys of San Luis went to the 

 invernadas, passes along the Tunuyan. The estates 

 grew up by the side of it. The villages of Santa Rosa, 

 Las Catitas, and La Paz, which mark the various 

 stages of it, are all of ancient origin. Strangers are 

 rarely found there. One still sees in them very old 

 houses, built before the railway was made, dating from 

 the days of the carril or waggon-road. The importance 

 of this line of water across the desert is clearly seen on 

 the Woodbine Parish map. 



The use of irrigation in this district raised different 

 technical problems from those of the north-western 

 provinces. In this latitude the torrents of the Andes 

 are formidable when the snows meet, at the beginning 

 of summer. The flood is all the greater and more 

 sudden as the heat is late. From all the ravines of 

 the mountains the muddy waters then converge toward 

 the valley. The flood scours the bed of the river, 

 erodes its banks, and threatens to find a way amongst 

 the estates. Even the towns of Mendoza and San 

 Juan have more than once been in danger. The fear 

 of diverting the flood and of bringing it upon themselves 

 compelled them to be content with raising only light 

 and frail dams in the path of the torrent. At San 

 Juan they used, for a long time, the waters of the 

 Arroyo del Eestero, a small brook fed by infiltration 

 from the Valle de Zenda, and it was some time before 

 they ventured to draw upon the river itself. 



Another problem, which the smaller oases of the 



