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  -':**.'- 
  

  

  'imW: 
  

  

  w 
  

  

  -yj 
  u 
  

  

  Plate 
  4. 
  — 
  Mountain 
  agriculture 
  in 
  Peru. 
  Top: 
  Ancient 
  terraces, 
  some 
  still 
  

   used, 
  in 
  Colca 
  Valley. 
  (Courtesy 
  James 
  Sawders.) 
  Bottom: 
  Valley 
  floor 
  culti- 
  

   vation. 
  (Courtesy 
  Truman 
  Bailey.) 
  

  

  