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 valie. 



Photograph by the Author. 



THE OASIS OF ANDALGALA. 



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



Photograph by the Author. 

 PLATE VI. To face p. 70. 



