﻿THE 
  GEOLOGICAL 
  HISTORY 
  OF 
  NEW 
  YORK 
  STATE 
  37 
  

  

  plastic 
  masses 
  when 
  subjected 
  to 
  any 
  great 
  lateral 
  pressure 
  within 
  

   the 
  earth. 
  1 
  

  

  Rocks 
  at 
  the 
  surface 
  of 
  the 
  earth, 
  subjected 
  to 
  the 
  same 
  lateral 
  

   pressure, 
  would 
  be 
  broken 
  or 
  fractured 
  instead 
  of 
  bent 
  or 
  folded. 
  

   It 
  is 
  not 
  the 
  present 
  purpose 
  to 
  discuss 
  the 
  origin 
  of 
  such 
  pressure 
  

   within 
  the 
  earth, 
  but 
  suffice 
  it 
  to 
  say 
  that 
  it 
  is 
  somehow 
  due 
  to 
  the 
  

   shrinkage 
  of 
  the 
  interior 
  portion 
  of 
  the 
  earth, 
  and 
  the 
  tendency 
  of 
  

   the 
  exterior 
  (or 
  crust) 
  to 
  accommodate 
  itself 
  to 
  the 
  shrinking 
  in- 
  

   terior, 
  thus 
  producing 
  lateral 
  thrust 
  (pressure) 
  in 
  this 
  exterior 
  

   portion. 
  

  

  We 
  are 
  now 
  ready 
  to 
  discuss 
  the 
  first 
  known 
  uplift 
  of 
  the 
  whole 
  

   Adirondack 
  region 
  above 
  sea 
  level, 
  or 
  what 
  we 
  may 
  call 
  the 
  

   birth 
  of 
  the 
  first 
  known 
  Adirondack 
  mountains. 
  As 
  we 
  have 
  just 
  

   learned, 
  the 
  very 
  character 
  and 
  structure 
  of 
  the 
  rocks 
  now 
  exposed 
  

   in 
  the 
  region, 
  show 
  conclusively 
  that 
  they 
  were 
  at 
  one 
  time 
  deeply 
  

   buried 
  under 
  thousands 
  of 
  feet 
  of 
  overlying 
  materials, 
  and 
  the 
  

   inference 
  is 
  perfectly 
  plain 
  that 
  those 
  materials 
  must 
  have 
  been 
  

   removed 
  by 
  erosion. 
  Extensive 
  erosion 
  of 
  any 
  land 
  mass 
  means 
  

   that 
  the 
  land 
  must 
  be 
  above 
  sea 
  level 
  and 
  thus 
  we 
  come 
  to 
  the 
  

   important 
  conclusion 
  that 
  the 
  great 
  mass 
  of 
  Grenville 
  sediments 
  

   were 
  upraised 
  well 
  above 
  sea 
  level. 
  Just 
  when 
  the 
  great 
  uplift 
  oc- 
  

   curred 
  can 
  not 
  be 
  positively 
  stated, 
  but 
  if 
  it 
  was 
  not 
  during, 
  or 
  after 
  

   the 
  igneous 
  intrusions, 
  it 
  must 
  have 
  been 
  shortly 
  before 
  them. 
  It 
  is 
  

   quite 
  reasonable 
  to 
  believe 
  that 
  the 
  same 
  great 
  force 
  which 
  caused 
  a 
  

   welling 
  up 
  of 
  so 
  much 
  liquid 
  rock 
  might 
  easily 
  have 
  caused 
  a 
  decided 
  

   uplift 
  of 
  the 
  whole 
  region. 
  Again, 
  it 
  is 
  quite 
  plausible 
  that 
  there 
  

   may 
  have 
  been 
  no 
  great 
  uplift 
  until 
  the 
  development 
  of 
  the 
  lateral 
  

   pressure 
  which 
  caused 
  the 
  metamorphism 
  of 
  the 
  rocks. 
  Still 
  another 
  

   view 
  is 
  that 
  a 
  lateral 
  pressure, 
  once 
  started, 
  first 
  caused 
  a 
  welling 
  up, 
  

   at 
  different 
  times, 
  of 
  igneous 
  rock 
  and 
  then, 
  after 
  the 
  cessation 
  of 
  

   the 
  igneous 
  activity, 
  the 
  same 
  force 
  continued 
  to 
  compress, 
  fold 
  

   and 
  metamorphose 
  the 
  rocks. 
  Whatever 
  the 
  actual 
  history 
  may 
  

   have 
  been, 
  it 
  is 
  at 
  least 
  true 
  that 
  the 
  sum 
  total 
  of 
  all 
  effects, 
  as 
  we 
  

   now 
  observe 
  them, 
  harmonizes 
  well 
  with 
  the 
  view 
  last 
  expressed. 
  

   The 
  intense 
  folding 
  and 
  tilting 
  of 
  the 
  strata 
  show 
  that 
  the 
  amount 
  

   of 
  uplift 
  must 
  have 
  been 
  very 
  considerable 
  as 
  is 
  the 
  case 
  in 
  all 
  typi- 
  

   cal 
  mountain 
  ranges. 
  W 
  r 
  e 
  can 
  not, 
  however, 
  even 
  state 
  the 
  approxi- 
  

   mate 
  height 
  of 
  those 
  very 
  ancient 
  Adirondack 
  mountains. 
  The 
  fact 
  

  

  1 
  Professor 
  Adams 
  of 
  McGill 
  University, 
  Montreal, 
  has 
  recently 
  proved 
  

   experimentally 
  that 
  rocks, 
  under 
  great 
  pressure, 
  flow 
  like 
  plastic 
  matter. 
  

  

  