﻿Chapter 
  6 
  

  

  CENOZOIC 
  HISTORY 
  

  

  TERTIARY 
  PERIOD 
  

  

  Rock 
  formations 
  and 
  life 
  of 
  the 
  Tertiary 
  The 
  Mesozoic 
  closed 
  

   and 
  the 
  Cenozoic 
  opened 
  with 
  the 
  uplift 
  of 
  the 
  great 
  Cretacic 
  pene- 
  

   plain. 
  Before 
  the 
  uplift, 
  the 
  sea 
  spread 
  over 
  the 
  Long 
  and 
  Staten 
  

   Islands 
  region, 
  but 
  for 
  a 
  time 
  after 
  the 
  uplift 
  the 
  land 
  was 
  there 
  

   high 
  enough 
  to 
  exclude 
  the 
  sea 
  and 
  New 
  York 
  State 
  was 
  wholly 
  

   above 
  sea 
  level. 
  This 
  we 
  know 
  because 
  the 
  lowest 
  (earliest) 
  Ter- 
  

   tiary 
  deposits 
  do 
  not 
  occur 
  on 
  Long 
  or 
  Staten 
  Islands 
  or 
  in 
  northern 
  

   New 
  Jersey, 
  and 
  hence 
  the 
  region 
  must 
  have 
  been 
  above 
  water. 
  

   The 
  subdivisions 
  of 
  the 
  Tertiary, 
  from 
  oldest 
  to 
  youngest, 
  are 
  

   known 
  as 
  Eocene, 
  Miocene, 
  and 
  Pliocene. 
  The 
  early 
  Eocene 
  de- 
  

   posits 
  are 
  missing 
  from 
  the 
  northern 
  Atlantic 
  Coastal 
  plain, 
  and 
  

   on 
  Long 
  and 
  Staten 
  Islands 
  we 
  have 
  no 
  evidence 
  that 
  any 
  of 
  the 
  

   Eocene 
  is 
  present 
  which 
  thus 
  leads 
  to 
  the 
  conclusion 
  that 
  all 
  south- 
  

   eastern 
  New 
  York 
  was 
  dry 
  land 
  during 
  the 
  whole 
  of 
  the 
  Eocene. 
  

   During 
  the 
  Miocene 
  there 
  was 
  enough 
  sinking 
  to 
  allow 
  the 
  sea 
  to 
  

   encroach 
  over 
  the 
  Long 
  and 
  Staten 
  Islands 
  districts 
  as 
  well 
  as 
  the 
  

   whole 
  northern 
  Coastal 
  plain. 
  Except 
  for 
  very 
  slight 
  oscillations 
  

   of 
  level 
  which 
  we 
  shall 
  here 
  disregard, 
  the 
  region 
  remained 
  sub- 
  

   merged 
  under 
  shallow 
  sea 
  water 
  during 
  all 
  the 
  Miocene 
  and 
  Plio- 
  

   cene, 
  or 
  till 
  the 
  close 
  of 
  the 
  Tertiary 
  period. 
  The 
  Tertiary 
  deposits 
  

   were 
  sands, 
  gravels, 
  and 
  clays 
  which 
  formed 
  layer 
  upon 
  layer 
  in 
  

   the 
  shallow 
  sea 
  along 
  the 
  margin 
  of 
  the 
  continent 
  (see 
  figure 
  22), 
  

   but 
  on 
  Long 
  and 
  Staten 
  Islands 
  they 
  are 
  seldom 
  seen 
  because 
  of 
  

   the 
  more 
  recent 
  covering 
  of 
  glacial 
  deposits. 
  They 
  are 
  finely 
  

   exposed 
  in 
  the 
  Coastal 
  plain 
  of 
  New 
  Jersey. 
  

  

  The 
  Tertiary 
  period 
  is 
  generally 
  called 
  the 
  " 
  Age 
  of 
  Mammals 
  " 
  

   because, 
  although 
  mammals 
  began 
  in 
  a 
  small 
  way 
  in 
  the 
  Mesozoic, 
  

   they 
  became 
  the 
  dominant 
  feature 
  of 
  life 
  for 
  the 
  first 
  time 
  in 
  the 
  

   Tertiary. 
  In 
  the 
  early 
  Tertiary 
  the 
  mammals 
  were 
  very 
  different 
  in 
  

   appearance 
  from 
  those 
  of 
  the 
  present, 
  a 
  common 
  form 
  then 
  being 
  

   a 
  generalized 
  or 
  ancestral 
  type 
  (for 
  example, 
  Phenacodus) 
  about 
  

   the 
  size 
  of 
  a 
  dog 
  and 
  having 
  five 
  toes. 
  Many 
  of 
  our 
  modern 
  mam- 
  

   mals 
  have 
  descended 
  from 
  this 
  type. 
  During 
  the 
  Tertiary 
  the 
  

   mammals 
  developed 
  very 
  rapidly 
  so 
  that 
  by 
  the 
  close 
  of 
  the 
  period 
  

   they 
  were 
  very 
  much 
  as 
  they 
  are 
  today 
  except 
  that 
  man, 
  the 
  highest 
  

  

  [77] 
  

  

  