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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  So 
  far 
  as 
  the 
  ancient 
  glaciations 
  are 
  concerned, 
  the 
  distribution 
  of 
  

   the 
  ice 
  is 
  still 
  a 
  matter 
  of 
  uncertainty, 
  because 
  obviously 
  only 
  a 
  

   relatively 
  small 
  part 
  of 
  the 
  glacial 
  deposits 
  and 
  ice 
  pavements 
  

   could 
  have 
  been 
  preserved, 
  in 
  accessible 
  positions, 
  from 
  such 
  long- 
  

   distant 
  times. 
  These 
  ancient 
  glaciations, 
  too, 
  add 
  greatly 
  to 
  the 
  

   complexity 
  of 
  the 
  problem 
  because 
  of 
  characteristics 
  peculiar 
  to 
  

   themselves. 
  For 
  example, 
  in 
  South 
  Africa, 
  and 
  perhaps 
  also 
  in 
  

   Brazil, 
  the 
  movement 
  of 
  the 
  Permian 
  ice 
  vs^as 
  from 
  north 
  to 
  south, 
  

   from 
  the 
  Equator 
  poleward, 
  the 
  opposite 
  of 
  what 
  we 
  should 
  have 
  

   expected 
  it 
  to 
  be. 
  Furthermore, 
  the 
  enormous 
  thickness 
  of 
  the 
  

   bowlder 
  beds, 
  1,000 
  feet 
  or 
  more, 
  called 
  the 
  Dwyka 
  conglomerate, 
  

   fairly 
  staggers 
  the 
  imagination 
  when 
  one 
  compares 
  it 
  with 
  Pleisto- 
  

   cene 
  moraines. 
  The 
  occurrence 
  of 
  great 
  bowlder 
  beds 
  in 
  penin- 
  

   sular 
  India, 
  so 
  near 
  the 
  Equator, 
  is 
  a 
  very 
  puzzling 
  circumstance, 
  

   vfhich 
  some 
  climatologists 
  believe 
  can 
  be 
  explained 
  only 
  by 
  a 
  shifting 
  

   of 
  the 
  earth's 
  poles. 
  

  

  Because 
  of 
  those 
  uncertainties, 
  it 
  will 
  be 
  advantageous 
  to 
  confine 
  

   our 
  attempts 
  at 
  explaining 
  glacial 
  climates 
  to 
  the 
  Pleistocene, 
  be- 
  

   cause 
  the 
  evidence 
  is 
  still 
  so 
  very 
  extensively 
  and 
  perfectly 
  preserved, 
  

   that 
  the 
  distribution 
  of 
  the 
  Pleistocene 
  ice 
  sheets 
  and 
  mountain 
  

   glaciers 
  can 
  be 
  determined 
  with 
  a 
  certainty 
  which 
  can 
  not 
  be 
  attained 
  

   in 
  the 
  more 
  ancient 
  periods 
  of 
  ice 
  action. 
  If 
  we 
  can 
  find 
  a 
  satis- 
  

   factory 
  explanation 
  of 
  the 
  climatic 
  phenomena 
  of 
  the 
  Pleistocene, 
  

   we 
  shall 
  not 
  have 
  far 
  to 
  seek 
  for 
  an 
  explanation 
  of 
  the 
  more 
  ancient 
  

   ice 
  periods. 
  

  

  There 
  would 
  seem 
  to 
  have 
  been 
  no 
  glaciation 
  on 
  a 
  continental 
  

   scale 
  between 
  the 
  Permian 
  and 
  the 
  Pleistocene. 
  Throughout 
  the 
  

   Mesozoic 
  and 
  most 
  of 
  the 
  Tertiary 
  periods 
  indications 
  of 
  climatic 
  

   zones 
  are 
  obscure 
  and 
  doubtful, 
  and 
  there 
  can 
  have 
  been 
  no 
  great 
  

   accumulation 
  of 
  ice 
  and 
  snow 
  at 
  the 
  poles. 
  The 
  Jurassic 
  sand- 
  

   stones 
  of 
  the 
  now 
  utterly 
  desolate 
  Antarctic 
  Continent 
  have 
  yielded 
  

   Cycad 
  leaves 
  much 
  like 
  those 
  of 
  contemporary 
  Great 
  Britain, 
  and 
  

   the 
  Arctic 
  fossil 
  floras 
  of 
  Greenland 
  and 
  Alaska 
  clearly 
  demon- 
  

   strate 
  that, 
  so 
  late 
  as 
  the 
  Eocene 
  at 
  least, 
  these 
  polar 
  lands 
  had 
  

   luxuriant 
  forests 
  of 
  large 
  trees 
  of 
  the 
  kinds 
  familiar 
  to 
  us 
  in 
  tem- 
  

   perate 
  latitudes 
  — 
  a 
  fact 
  which 
  indisputably 
  proves 
  the 
  prevalence 
  

   of 
  much 
  milder 
  climates. 
  That 
  the 
  Arctic 
  regions 
  were 
  cooler 
  than 
  

   the 
  area 
  now 
  covered 
  by 
  the 
  United 
  States 
  is 
  indicated 
  by 
  the 
  absence 
  

   of 
  large 
  reptiles, 
  of 
  palms 
  and 
  other 
  subtropical 
  forms 
  from 
  the 
  far 
  

   north, 
  while 
  they 
  occur 
  from 
  Idaho 
  and 
  Montana 
  southward; 
  and 
  

   the 
  Eocene 
  flora 
  of 
  the 
  southeastern 
  coastal 
  plain, 
  so 
  beautifully 
  

   reconstructed 
  by 
  Professor 
  Berry, 
  demonstrates 
  a 
  far 
  warmer 
  cli- 
  

   mate 
  than 
  that 
  of 
  to-day, 
  though 
  not 
  properly 
  to 
  be 
  called 
  tropical. 
  

  

  