52 



H. E. Gregory — A Cfeologic Eeconnaissance 



a flight of three terraces was seen. The lowest step, 8 feet 

 above the stream, is cut in rock; the other two are developed 

 on gravel at elevations of 12 to 20 feet and 50 to 60 feet 

 respectively above the valley floor. At the mouth of the 



Fig. 33. 



Fig. 33. Group of terraces at Ttancarpata. 



Huatanay the terrace 12 feet above the stream again appears. 

 The terraced bank of the Huatanay below the mouth of the 

 Huancaro is shown in fig. 32. At this locality the flat floor 

 of the lowest terrace is practically undissected ; the second ter- 

 race is trenched by quebradas. The material of both terraces 

 is lacustrine in origin, and the foot of the upper terrace is 



