of the Cuzco Valley, Peru. 41 



14,235 feet; but between Ollantaytambo and Torontoy, 40 

 miles northwest of Cuzco, "well-developed terminal moraines 

 at least 400 feet bigh stand but 8,500 feet (aneroid) above 

 sea level." 18 



Unpublished topographic maps of the Peruvian Expeditions 

 of 1911 to 1914 give trustworthy figures for the position of 

 the present glaciers and of Pleistocene moraines at Salcantay, 

 in latitude 13° 20' south. On the north side of this mountain 

 group the ends of the glaciers rest at 14,500 feet and the lowest 

 moraine lies at 11,100 feet; for the east side the corresponding 

 figures are 14,300 and 11,200 feet, and for the south side 

 14,300 and 12,200 feet. 



Glacial Features North of the Cuzco Valley Axis. 



The east-west trend of the Cuzco Valley gives to its opposite 

 sides unequal exposure to the rays of the sun. It is, there- 

 fore, to be expected that northward-facing slopes in this lat- 

 itude should present less evidence of glaciation than slopes 

 facing southward. When the highlands forming the valley 

 rim are examined, this assumption is found to be in accord with 

 the facts. 



Along the north rim of the Cuzco Valley the evidence of 

 ice action is unmistakable and glacial features retain their 

 original expression with only slight modification. Streams 

 flowing from Seneca, Fortaleza, and Catunga-Machu head in 

 cirques and flow between stretches of lateral moraines 1,000 

 to 2,000 feet long and 10 to 50 feet high. On the southwest 

 slope of Seneca cirques between 13,500 and 14,000 feet are 

 plainly visible from the valley below. In the upper reaches 

 of the Rio Muyo-Oryco, where the direction of ice movement 

 is at right angles to the strike of jointed sandstone, a flight 

 of four steps was noted with risers 5 feet to 60 feet in height. 

 The largest tread has an area of about 1 acre ; the smallest, 

 of 300 square feet. Two of the treads are overdeepeneel and 

 retain ponds on their striated floors. A series of terminal 

 moraines, the lowest at about 13,500 feet, are trenched by the 

 northern tributaries of the upper Huatanay, and ground mo- 

 raines with uneven surface occupy interstream spaces. The 

 projecting ledges of sandstone as well as of limestone are 

 poorly adapted to retain strise, and the effect of glacial scour 

 on dividing ridges is scarcely perceptible. A remarkable 



18 Bowman : The Geological Relations of the Cuzco Remains, this 

 Journal, xxxiii, p. 317, 1912. 



