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  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1929 
  

  

  concerning 
  the 
  changes 
  in 
  that 
  environment 
  through 
  changes 
  of 
  climate 
  

   during 
  historic 
  times; 
  and 
  in 
  his 
  treatment 
  of 
  the 
  subject 
  of 
  the 
  effects 
  

   of 
  these 
  changes 
  on 
  its 
  history. 
  

  

  Briefly 
  stated 
  his 
  main 
  argument 
  is 
  that 
  there 
  is 
  evidence 
  of 
  the 
  

   recurrence 
  of 
  changes 
  of 
  cHmate 
  in 
  Central 
  Asia 
  during 
  historic 
  times, 
  

  

  and 
  that 
  some 
  measure 
  of 
  these 
  changes 
  is 
  furnished 
  by 
  the 
  variations 
  

   in 
  the 
  level 
  of 
  the 
  Caspian 
  Sea. 
  The 
  evidence 
  as 
  to 
  the 
  variations 
  in 
  

   the 
  climatic 
  conditions 
  of 
  other 
  places 
  in 
  Asia 
  confirms 
  that 
  concerning 
  

   the 
  variations 
  in 
  the 
  level 
  of 
  the 
  Caspian. 
  He 
  maintains 
  that, 
  while 
  

  

  