THE BORDER VALLEYS OF THE EASTERN ANDES 71 



of steep ravines are cultivated by distant owners who also till 

 parts of the larger fans on the main valley floors. Between the 

 fans of the valley bottoms and the smooth slopes of the high 

 plateaus are the unoccupied lands — the steep canyon walls. Only 

 in the most highly favored places where a small bench or a patch 

 of alluvium occurs may one find even an isolated dwelling. The 

 stair-like trails, in some places cut in solid rock, zigzag up the 

 rocky slopes. An ascent of a thousand feet requires about an 

 hour's travel with fresh beasts. The valley people are therefore 

 walled in. If they travel it is surely not for pleasure. Even busi- 

 ness trips are reduced to the smallest number. The prosperity 

 and happiness of the valley people are as well known among the 

 plateau people as is their remarkable bread. Their climate has a 

 combination of winter rain and winter cold with light frosts that 

 is as favorable for good wheat as the continuous winter cold and 

 snow cover of our northern Middle West. The colder grainfields 

 of the plateau are sowed to barley chiefly, though there is also 

 produced some wheat. Urubamba wheat and bread are exported 

 in relatively large quantities, and the market demands greater 

 quantities than the valley can supply. Oregon and Washington 

 flour are imported at Cuzco, two days' muleback journey from the 

 wheat fields of Urubamba. 



Such are the conditions in the upper Urubamba Valley. The 

 lower valley, beginning at Huadquma, is 8,000 feet (2,440 m.) 

 above sea level and extends down to the two-thousand-foot con- 

 tour at Eosalina and to one thousand feet (305 m.) at Pongo de 

 Mainique. The upper and lower sections are only a score of miles 

 (30 km.) apart between Huadquina and Torontoy, but there is a 

 difference in elevation of three thousand feet (915 m.) at just the 

 level where the maximum contrasts are produced. The cold tim- 

 ber line is at 10,500 feet (3,200 m.). 2 ' Winter frosts are common 



2 Reference to the figures in this chapter will show great variation in the level 

 of the timber line depending upon insolation as controlled by slope exposure and 

 upon moisture directly as controlled largely by exposure to winds. In some places 

 these controls counteract each other; in other places they promote each other's 

 effects. The topographic and climatic cross-sections and regional diagrams else- 

 where in this book also emphasize the patchiness of much of the woodland and scrub, 

 some noteworthy examples occurring in the chapter on the Eastern Andes. Two of 



