﻿Ray 
  — 
  Ages 
  of 
  Pleistocene 
  Deposits. 
  ' 
  361 
  

  

  Art. 
  XXIV. 
  — 
  On 
  the 
  Relative 
  Ages 
  of 
  certain 
  Pleistocene 
  

   Deposits; 
  by 
  Oliver 
  P. 
  Hay. 
  

  

  The 
  writer 
  accepts 
  the 
  conclusions 
  of 
  those 
  glaciol- 
  

   ogists 
  who 
  hold 
  that 
  there 
  occurred 
  during 
  the 
  Pleisto- 
  

   cene 
  epoch 
  four 
  or 
  five 
  glacial 
  stages, 
  each 
  of 
  which 
  was 
  

   followed 
  by 
  a 
  stage 
  of 
  mild 
  climate. 
  As 
  a 
  result 
  of 
  great 
  

   extremes 
  of 
  climate 
  and 
  of 
  alternate 
  reduction 
  and 
  expan- 
  

   sion 
  of 
  the 
  habitable 
  areas 
  one 
  might 
  expect 
  that, 
  as 
  the 
  

   glacial 
  epoch 
  passed 
  on, 
  obvious 
  changes 
  in 
  the 
  faunas 
  

   would 
  show 
  themselves 
  through 
  both 
  extinctions 
  and 
  

   modifications. 
  As 
  to 
  the 
  development 
  of 
  new 
  species 
  

   during 
  the 
  part 
  of 
  the 
  Pleistocene 
  known 
  to 
  us, 
  this 
  might 
  

   be 
  hard 
  to 
  prove. 
  As 
  a 
  matter 
  of 
  fact, 
  it 
  would 
  now 
  be 
  

   hazardous 
  to 
  assert 
  that 
  any 
  particular 
  existing 
  species 
  

   had 
  not 
  been 
  present, 
  either 
  here 
  or 
  in 
  Asia, 
  early 
  in 
  the 
  

   Pleistocene. 
  As 
  to 
  extinctions, 
  these 
  stand 
  out 
  clearly. 
  

   I 
  have 
  a 
  list 
  of 
  over 
  600 
  species 
  of 
  vertebrates 
  which 
  

   have 
  been 
  reported 
  from 
  our 
  Pleistocene 
  deposits 
  ; 
  and 
  

   of 
  these 
  about 
  60 
  per 
  cent 
  are 
  extinct. 
  

  

  As 
  is 
  shown 
  in 
  and 
  near 
  the 
  glacial 
  region, 
  many 
  

   species, 
  mostly 
  conspicuous 
  because 
  of 
  their 
  size, 
  as 
  

   elephants, 
  the 
  American 
  mastodon, 
  the 
  giant 
  beaver, 
  the 
  

   existing 
  beaver, 
  and 
  Megalonyx 
  jeffersonii, 
  lived 
  on 
  from 
  

   the 
  first 
  interglacial 
  stage 
  to 
  the 
  post-Wisconsin. 
  A 
  con- 
  

   siderable 
  number 
  of 
  other 
  species, 
  as 
  the 
  long-horned 
  

   bisons, 
  at 
  least 
  one 
  species 
  of 
  horse, 
  the 
  tapirs, 
  saber- 
  

   tooth 
  tigers, 
  and 
  mylodon, 
  no 
  longer 
  appear 
  after 
  the 
  

   Wisconsin 
  stage, 
  but 
  did 
  exist 
  during 
  the 
  interval 
  between 
  

   the 
  Illinoian 
  and 
  the 
  Wisconsin. 
  Other 
  mammals, 
  again, 
  

   as 
  Elephas 
  imperator, 
  the 
  camels, 
  and 
  many 
  species 
  of 
  

   horses, 
  are 
  not 
  found 
  after 
  the 
  second 
  glacial 
  epoch, 
  the 
  

   Kansan. 
  Hence, 
  in 
  the 
  glaciated 
  region, 
  we 
  may 
  for 
  the 
  

   present 
  recognize 
  three 
  Pleistocene 
  faunas, 
  an 
  early, 
  a 
  

   middle, 
  and 
  a 
  late. 
  Did 
  these 
  faunas 
  have 
  the 
  same 
  his- 
  

   tory 
  in 
  the 
  nonglaciated 
  region 
  as 
  in 
  the 
  glaciated; 
  or 
  

   did 
  the 
  early 
  fauna 
  continue 
  on 
  in 
  the 
  southern 
  States 
  

   virtually 
  unchanged 
  up 
  to 
  the 
  end 
  of 
  the 
  Pleistocene? 
  

   There 
  are 
  those 
  who 
  take 
  the 
  view 
  last 
  mentioned. 
  Some 
  

   of 
  these 
  base 
  their 
  opinions 
  on 
  the 
  geological 
  structure 
  

   of 
  the 
  Pleistocene 
  part 
  of 
  the 
  coastal 
  plain 
  ; 
  others 
  on 
  the 
  

   fact 
  that 
  in 
  certain 
  localities 
  the 
  animal 
  remains 
  are 
  

   associated 
  with 
  relics 
  of 
  man. 
  It 
  must 
  be 
  granted 
  that 
  

  

  