﻿THE 
  GEOLOGICAL 
  HISTORY 
  OF 
  NEW 
  YORK 
  STATE 
  75 
  

  

  At 
  the 
  close 
  of 
  the 
  Paleozoic, 
  and 
  as 
  a 
  result 
  of 
  the 
  Appalachian 
  

   uplift, 
  the 
  region 
  of 
  New 
  York 
  State 
  was 
  raised 
  well 
  above 
  sea 
  

   level, 
  with 
  the 
  greatest 
  uplift 
  toward 
  the 
  north 
  as 
  shown 
  by 
  the 
  

   general 
  south 
  to 
  southwesterly 
  dip 
  (tilt) 
  of 
  the 
  Paleozoic 
  strata 
  

   (see 
  figures 
  3 
  and 
  5). 
  At 
  that 
  time 
  those 
  strata 
  lapped 
  over 
  much 
  

   of 
  what 
  is 
  now 
  the 
  Precambric 
  rock 
  area 
  of 
  the 
  Adirondacks. 
  The 
  

   Appalachian 
  folds 
  of 
  the 
  Hudson 
  valley 
  region, 
  as 
  well 
  as 
  the 
  high- 
  

   lands 
  (of 
  earlier 
  origin) 
  in 
  general 
  along 
  the 
  eastern 
  border 
  of 
  

   the 
  State, 
  must 
  have 
  prevented 
  any 
  important 
  eastward 
  drainage. 
  

   Thus, 
  in 
  the 
  writer's 
  belief, 
  the 
  strongest 
  evidence 
  suggests 
  that 
  the 
  

   principal 
  streams 
  of 
  the 
  early 
  Mesozoic 
  era 
  flowed 
  in 
  general 
  

   southwesterly 
  courses 
  upon 
  the 
  surface 
  of 
  the 
  newly 
  upraised 
  

   Paleozoic 
  strata 
  and 
  away 
  from 
  the 
  highlands 
  of 
  the 
  eastern 
  border 
  

   of 
  the 
  State. 
  1 
  

  

  If 
  this 
  be 
  the 
  correct 
  interpretation 
  (for 
  others 
  are 
  certainly 
  pos- 
  

   sible) 
  of 
  the 
  early 
  Mesozoic 
  drainage, 
  it 
  must 
  follow 
  that 
  no 
  river 
  

   at 
  all 
  comparable 
  in 
  length 
  and 
  position 
  to 
  the 
  present 
  Hudson 
  

   could 
  have 
  existed 
  along 
  the 
  eastern 
  side 
  of 
  the 
  State, 
  and 
  no 
  large 
  

   rivers, 
  like 
  the 
  Susquehanna 
  and 
  Delaware, 
  then 
  had 
  southeasterly 
  

   courses 
  across 
  the 
  Appalachian 
  mountains. 
  

  

  During 
  the 
  long 
  Mesozoic 
  era, 
  the 
  area 
  of 
  the 
  State 
  was 
  pro- 
  

   foundly 
  eroded, 
  as 
  already 
  proved. 
  In 
  the 
  midst 
  of 
  this 
  era 
  trie 
  

   ruggedness 
  of 
  Mesozoic 
  relief 
  reached 
  its 
  maximum 
  and, 
  in 
  accord- 
  

   ance 
  with 
  well-known 
  principles, 
  the 
  valleys 
  must 
  have 
  formed 
  

   along 
  the 
  belts 
  of 
  softer 
  rock, 
  while 
  the 
  harder 
  rocks 
  stood 
  out 
  to 
  

   form 
  the 
  highlands 
  or 
  ridges. 
  At 
  this 
  time 
  the 
  edges 
  of 
  the 
  Paleo- 
  

   zoic 
  strata 
  had 
  sufficiently 
  retreated 
  (by 
  erosion) 
  on 
  all 
  sides 
  from 
  

   the 
  central 
  Adirondacks 
  so 
  that 
  a 
  considerable 
  area 
  of 
  Precambric 
  

   rocks 
  had 
  already 
  become 
  exposed 
  in 
  northern 
  New 
  York. 
  During 
  

   this 
  retreat 
  of 
  the 
  Paleozoic 
  strata 
  there 
  was 
  a 
  tendency 
  to 
  form 
  

   important 
  valleys, 
  especially 
  along 
  the 
  western 
  and 
  southern 
  bor- 
  

   ders 
  of 
  the 
  Adirondacks, 
  because 
  whenever 
  the 
  harder 
  rock 
  forma- 
  

   tions 
  were 
  encountered 
  they 
  would 
  stand 
  out 
  as 
  escarpments, 
  while 
  

   the 
  softer 
  rocks 
  would 
  be 
  worn 
  down 
  into 
  valleys. 
  It 
  is 
  in 
  accord- 
  

   ance 
  with 
  these 
  principles 
  that 
  the 
  Mohawk 
  and 
  Black 
  river 
  valleys 
  

   were 
  formed, 
  though 
  it 
  does 
  not 
  necessarily 
  follow 
  that 
  these 
  older 
  

   valleys 
  occupied 
  the 
  same 
  positions 
  as 
  the 
  present 
  ones 
  because 
  of 
  

   the 
  gradual 
  retreat 
  of 
  these 
  depressions 
  away 
  from 
  the 
  Adirondack 
  

   region. 
  

  

  1 
  It 
  should 
  be 
  stated 
  that 
  the 
  Great 
  Lakes 
  were 
  not 
  then 
  in 
  existence, 
  those 
  

   bodies 
  of 
  water 
  not 
  having 
  been 
  formed 
  till 
  late 
  in 
  the 
  Cenozoic 
  era 
  (see 
  

   chapter 
  6). 
  

  

  