﻿68 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  given. 
  Thus, 
  toward 
  the 
  end 
  of 
  the 
  Mesozoic 
  era 
  all 
  the 
  area 
  of 
  

   New 
  York 
  State 
  had 
  been 
  reduced 
  to 
  a 
  vast, 
  monotonous, 
  feature- 
  

   less 
  plain 
  {peneplain) 
  except 
  for 
  the 
  mountain 
  masses 
  of 
  very 
  

   moderate 
  elevation 
  in 
  the 
  east-central 
  Adirondack, 
  and 
  possibly 
  

   also 
  the 
  Catskill, 
  regions. 
  As 
  Professor 
  Berkey 
  says 
  : 
  " 
  The 
  con- 
  

   tinent 
  stood 
  much 
  lower 
  than 
  now. 
  Portions 
  that 
  are 
  now 
  moun- 
  

   tain 
  tops 
  and 
  the 
  crests 
  of 
  ridges 
  were 
  then 
  constituent 
  parts 
  of 
  the 
  

   rock 
  floor 
  of 
  the 
  peneplain 
  not 
  much 
  above 
  sea 
  level. 
  This 
  rock 
  

   floor 
  was 
  probably 
  thickly 
  covered 
  with 
  alluvial 
  deposits 
  (flood 
  

   plain) 
  not 
  very 
  different 
  in 
  character 
  from 
  the 
  alluvial 
  matter 
  of 
  

   portions 
  of 
  the 
  lower 
  Mississippi 
  valley 
  of 
  today. 
  Upon 
  such 
  a 
  

   surface 
  the 
  principal 
  rivers 
  of 
  that 
  time 
  flowed, 
  sluggishly 
  

   meandering 
  over 
  alluvial 
  sands 
  and 
  taking 
  their 
  courses 
  toward 
  

   the 
  sea 
  (the 
  Atlantic) 
  in 
  large 
  part 
  free 
  from 
  influence 
  by 
  the 
  

   underlying 
  rock 
  structure. 
  The 
  ridges 
  and 
  valleys, 
  the 
  hills, 
  moun- 
  

   tains 
  and 
  gorges 
  of 
  the 
  present 
  were 
  not 
  in 
  existence, 
  except 
  poten- 
  

   tially 
  in 
  the 
  hidden 
  differences 
  of 
  hardness 
  of 
  rock 
  structure. 
  Such 
  

   conditions 
  prevailed 
  over 
  a 
  very 
  large 
  region, 
  certainly 
  all 
  of 
  the 
  

   eastern 
  portion 
  of 
  the 
  United 
  States." 
  1 
  

  

  In 
  the. 
  western 
  part 
  of 
  the 
  United 
  States 
  the 
  Mesozoic 
  era 
  was 
  

   brought 
  to 
  a 
  close 
  by 
  what 
  must 
  take 
  rank 
  as 
  one 
  of 
  the 
  greatest 
  

   mountain 
  upheavals 
  in 
  the 
  history 
  of 
  North 
  America. 
  This 
  is 
  

   known 
  as 
  the 
  Rocky 
  Mountain 
  revolution 
  because 
  the 
  great 
  Rocky 
  

   Mountain 
  system 
  was 
  chiefly 
  formed 
  at 
  this 
  time. 
  At 
  the 
  same 
  

   time 
  in 
  the 
  eastern 
  part 
  of 
  the 
  United 
  States 
  the 
  Mesozoic 
  was 
  

   closed 
  by 
  an 
  important 
  physical 
  disturbance 
  though 
  on 
  a 
  far 
  less 
  

   grand 
  scale 
  than 
  that 
  of 
  the 
  west. 
  This 
  1 
  disturbance 
  produced 
  an 
  

   upwarp 
  of 
  the 
  vast 
  Cretacic 
  peneplain 
  with 
  maximum 
  uplift 
  of 
  from 
  

   two 
  to 
  three 
  thousand 
  feet 
  following 
  the 
  general 
  trend 
  of 
  the 
  

   Appalachians 
  and 
  thence 
  through 
  northern 
  New 
  York. 
  This 
  up- 
  

   ward 
  movement 
  was 
  unaccompanied 
  by 
  any 
  renewed 
  folding 
  of 
  

   the 
  strata, 
  and 
  the 
  effect 
  was 
  to 
  produce 
  a 
  broad 
  dome 
  sloping 
  

   eastward 
  and 
  westward, 
  and 
  northward 
  to 
  the 
  Gulf 
  of 
  St 
  Lawrence 
  

   and 
  southward 
  to 
  the 
  Gulf 
  of 
  Mexico. 
  

  

  A 
  prominent 
  effect 
  of 
  this 
  great 
  uplift 
  was 
  to 
  revive 
  the 
  activity 
  

   of 
  the 
  streams 
  so 
  that 
  they 
  once 
  more 
  became 
  active 
  agents 
  of 
  

   erosion. 
  We 
  are 
  now 
  prepared 
  to 
  make 
  the 
  important 
  statement 
  

   that 
  the 
  present 
  major 
  topographic 
  features 
  of 
  New 
  York 
  State, 
  as 
  

   well 
  as 
  western 
  New 
  England 
  and 
  the 
  whole 
  Appalachian 
  region, 
  

   have 
  largely 
  been 
  produced 
  by 
  the 
  erosion 
  or 
  dissection 
  of 
  this 
  up- 
  

  

  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  146, 
  p. 
  67. 
  

  

  