. A MULE-BACK JOURNEY 337 



limit of the subtropical forest zone. This type of forest 

 grows on the eastern slopes only of the Bolivian Andes; 

 a section directly eastward would, therefore, take us through 

 this zone and possibly enable us to find the solution to the 

 problem. It was not intended to cover the entire one hun- 

 dred and ten miles from Samaipata to Santa Cruz, but only 

 to go far enough to secure the desired information. 



The mountain range breaks down rapidly east of Samai- 

 pata, but the road to Santa Cruz is, nevertheless, neither 

 an easy nor a level one. There are still four steep ridges 

 to cross, called Cuevas, Negra, Herradura, and Guitara; 

 between them lie small, well-watered valleys, planted in 

 cane and fruits, and settled by Bolivians of Spanish ex- 

 traction. There are no more Quechuas, nor is their lan- 

 guage spoken ; after many months we were once again in a 

 Spanish-speaking world. 



The trail, at least during the second day's travel, lies 

 near the course of the Rio Piray, and the scenery flanking 

 this watercourse is among the most picturesque found in 

 the Bolivian Andes. There is a bewildering succession of 

 dome-shaped peaks, unscalable cliffs and overhanging 

 precipices, all of red sandstone. Many of the formations 

 are spotlessly clean and smooth, as if scoured, or cut with 

 a knife. The river laves the base of the rugged chain, and 

 dark caverns worn into the frowning battlement open al- 

 luringly to tempt the adventurous spirit to explore their 

 unknown depths. 



Vermejo is the name given to a fertile region that may 

 be called yungas, between the Negra and Herradura ridges. 

 Several houses are scattered along the trail; the inhabitants 

 grow maize, potatoes, and large quantities of cane that is 

 used in making chancaca (brown sugar) and molasses. The 

 people also make bread and a peculiar "food-drink" called 

 somo to sell to passers-by. Somo is made of boiled maize 

 that has been left standing until fermentation sets in, and 

 is taken with molasses. To us, the taste was very disagree- 

 able, but the natives were fond of it and purchased a bowl- 



