THE CULTIVATED OASES 41 



Hence the valles are by no means wholly productive. 

 The oases represent only a limited portion of them. 

 It would be impossible to imagine a more striking 

 contrast than that of the freshness and life of the oases 

 compared with the surrounding desert. Screens of 

 poplars shelter them from the zonda. The water runs 

 along trenches paved with round pebbles under the 

 spreading vines, at the foot of which, to economize 

 water and space, lucerne is sown. Each garden feeds 

 a family. Near the raw-brick houses there are large 

 earthenware vessels, as tall as a man, in which the 

 corn is kept. The hammering of the cooper fills the 

 air. 



In places the oasis is watered by a stream. In those 

 cases there is on each side of the bed of the stream a 

 narrow fringe, a continuous ribbon, of smiling gardens, 

 which hide the path. Above and below Santa Maria 

 a trench is opened every mile in the wet sands of the 

 Rio. The water rises in it and fills it, and is directed 

 by it toward one of the banks, where it is jealously 

 collected and distributed. The water which flows from 

 the irrigated fields and returns to the river, as well as 

 that which the porous side of the trench has permitted 

 to escape, goes to fill another trench and supply other 

 fields farther on. The region of Los Sauces, in the 

 northern part of the province of La Rioja, to the south 

 of Tinogasta, shows a different type of irrigated cultiva- 

 tion, on account of the sandy course of the stream. 

 The fields follow the feeding artery for about fifty 

 miles. It is bled at the beginning of each bend, the 

 waters remaining underground like hidden wealth. 



In most cases however, the valle has no running 

 water. What reaches it from the lateral quehradas is 

 lost in the alluvial beds accumulated at the point 

 where the quebrada enters the valle. In order to make 

 use of it the cultivated areas are grouped on the cone of 

 deposition ; at least, that is the position in the great 

 majority of the oases. A cosfa is a line of separate 



