EASTERN ANDES: CORDILLERA VILCAPAMPA 



207 



Scale of Mile 



O 1 



PANTA MT.p (8623 



lira, and an unnamed valley farther south at an elevation of 

 11,500 feet (3,500 m.). A mile below Choquetira a second moraine 

 appears, elevation 12,000 feet (3,658 m.), and immediately above 

 the village a third at 12,800 (3,900 m.). The lowermost moraine 

 is well dissected, the second is ravined and broken but topo- 

 graphically distinct, the third is sharp-crested and regular. A 

 fourth though minor stage is represented by the moraine at the 

 snout of the living glacier 

 and still less important 

 phases are represented in 

 some valleys — possibly the 

 record of post-glacial 

 changes of climate. Each 

 main moraine is marked by 

 an important amount of 

 outwash, the first and third 

 moraines being associated 

 with the greatest masses. 

 The material in the moraines 

 represents only a part of 

 that removed to form the 

 successive steps in the valley 

 profile. The lowermost one 

 has an enormous volume, 

 since it is the oldest and 

 was built at a time when the valley was full of waste. It is fronted 

 by a deep fill, over the dissected edge of which one may descend 

 800 feet in half an hour. It is chiefly alluvial in character, whereas 

 the next higher one is composed chiefly of bowlders and is fronted 

 by a pronounced bowlder train, which includes a remarkable 

 perched bowlder of huge size. Once the valley became cleaned 

 out the ice would derive its material chiefly by the slower 

 process of plucking and abrasion, hence would build much smaller 

 moraines during later recessional stages, even though the stages 

 were of equivalent length. 



There is a marked difference in the degree of dissection of the 



111 



m 



tr * 



WM 



^PfjI^^P'f 16178" vtfc^gS 



Fig. 136 — Glacial sculpture on the south- 

 western flank of the Cordillera Vileapampa. 

 Flat-floored valleys and looped terminal mo- 

 raines below and glacial steps and hanging 

 valleys are characteristic. The present snow- 

 fields and glaciers are shown by dotted contours. 



