THE VALLE OF SANTA MARIA, NORTH-WEST OF MOUNT ACONCAGUA. 



At the bottom of the valle one can see the sandy bed of the river as a white line in the fore- 

 ground. Zone of torrential terraces, which follows the edge of the valle. 



Photograph by the Author. 



"" 1 



m^^~' 



Plate VI 



THE OASIS OF ANDALGALA. 



At the wzstern foot of Aconcagua, the snowy crest of which can be seen. 



Photograph by the Author. 



To face p, 70, 



