﻿60 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  very 
  existence 
  is 
  due 
  to 
  the 
  fact 
  that, 
  as 
  a 
  result 
  of 
  the 
  folding 
  and 
  

   subsequent 
  erosion, 
  the 
  great 
  sheet 
  of 
  hard 
  and 
  resistant 
  conglom- 
  

   erate 
  has 
  been 
  left 
  as 
  a 
  protective 
  cap 
  over 
  the 
  soft 
  Hudson 
  river 
  

   (Ordovicic) 
  shales 
  (see 
  figure 
  19). 
  In 
  the 
  Rosendale 
  cement 
  

   region 
  the 
  effects 
  of 
  the 
  folding 
  are 
  also 
  1 
  evident 
  (see 
  figure 
  10 
  and 
  

   plate 
  33). 
  The 
  folds 
  in 
  the 
  Siluric 
  and 
  Devonic 
  strata 
  of 
  Skunne- 
  

   munk 
  mountain 
  were 
  also 
  produced 
  at 
  this 
  time. 
  Of 
  course 
  the 
  

   whole 
  lower 
  Hudson 
  valley 
  was 
  subjected 
  to 
  this 
  mild 
  compressive 
  

   force 
  but, 
  since 
  all 
  the 
  rocks 
  older 
  than 
  the 
  Siluric 
  were 
  already 
  

   so 
  greatly 
  disturbed, 
  it 
  is 
  often 
  impossible 
  to 
  see 
  the 
  effects 
  of 
  the 
  

   Appalachian 
  disturbance. 
  Thus 
  we 
  see 
  that 
  mountain-building 
  

   forces 
  have 
  affected 
  the 
  rocks 
  of 
  the 
  Highlands-of-the-Hudson 
  at 
  

   least 
  three 
  times 
  (Precambric, 
  Taconic 
  revolution, 
  and 
  Appalachian 
  

   revolution) 
  ; 
  Cambric 
  and 
  Ordovicic 
  strata 
  of 
  the 
  lower 
  Hudson 
  

   valley 
  twice 
  (Taconic 
  and 
  Appalachian 
  revolutions) 
  ; 
  and 
  the 
  

   Siluric 
  and 
  Devonic 
  strata 
  but 
  once 
  (Appalachian 
  revolution). 
  

  

  The 
  extensive 
  faulting 
  or 
  'fracturing 
  of 
  the 
  eastern 
  Adirondack 
  

   and 
  Mohawk 
  valley 
  regions 
  is 
  a 
  matter 
  of 
  no 
  small 
  importance 
  in 
  

   our 
  discussion 
  of 
  the 
  physical 
  history 
  of 
  the 
  State, 
  because 
  the 
  

   present 
  major 
  topographic 
  features 
  of 
  those 
  regions 
  are 
  largely 
  

   dependent 
  upon 
  the 
  faulting. 
  It 
  is 
  generally 
  believed 
  that 
  much 
  

   of 
  this 
  faulting 
  occurred 
  toward 
  the 
  close 
  of 
  the 
  Paleozoic 
  era, 
  and 
  

   most 
  likely 
  at 
  the 
  time 
  of 
  the 
  Appalachian 
  revolution, 
  but 
  since 
  

   considerable 
  faulting 
  certainly 
  occurred 
  later 
  than 
  that 
  time, 
  it 
  is 
  

   thought 
  best 
  to 
  discuss 
  this 
  whole 
  subject 
  toward 
  the 
  close 
  of 
  the 
  

   next 
  chapter. 
  

  

  