﻿GEOLOGY 
  OF 
  THE 
  NORTH 
  CREEK 
  QUADRANGLE 
  jj 
  

  

  After 
  the 
  intrusions 
  the 
  whole 
  region 
  was 
  subjected 
  to 
  intense 
  

   compression 
  and 
  metamorphism 
  when 
  the 
  gneissic 
  or 
  foliated 
  

   structure 
  of 
  all 
  the 
  rocks 
  so 
  far 
  mentioned 
  was 
  developed. 
  This 
  

   structure 
  is 
  now 
  shown 
  in 
  the 
  rocks 
  at 
  the 
  earth's 
  surface; 
  but, 
  

   since 
  such 
  a 
  structure 
  can 
  develop 
  only 
  in 
  rock 
  masses 
  which 
  are 
  

   deeply 
  buried, 
  we 
  know 
  that 
  at 
  the 
  time 
  of 
  the 
  compression 
  the 
  

   present 
  surface 
  rocks 
  were 
  deeply 
  covered. 
  

  

  The 
  rocks 
  represented 
  by 
  the 
  coarse 
  grained 
  pegmatite 
  dikes 
  of 
  

   the 
  quadrangle 
  were 
  intruded 
  after 
  this 
  period 
  of 
  intense 
  com- 
  

   pression 
  because 
  they 
  lack 
  the 
  gneissic 
  structure, 
  and 
  before 
  the 
  

   diabase 
  because 
  the 
  latter 
  rock 
  cuts 
  the 
  pegmatite. 
  

  

  The 
  great 
  elevation 
  of 
  the 
  region, 
  above 
  referred 
  to, 
  inaugurated 
  

   a 
  long 
  period 
  of 
  erosion 
  to 
  be 
  measured 
  by 
  at 
  least 
  some 
  millions 
  

   of 
  years, 
  and 
  extending 
  into 
  the 
  early 
  Paleozoic 
  era. 
  

  

  After 
  the 
  removal, 
  by 
  erosion, 
  of 
  some 
  thousands 
  of 
  feet 
  of 
  

   rock 
  materials, 
  the 
  last 
  igneous 
  activity 
  of 
  the 
  region 
  occurred 
  

   when 
  the 
  molten 
  diabase 
  was 
  forced 
  through 
  narrow 
  fissures 
  in 
  

   the 
  earth 
  to 
  cool 
  in 
  the 
  form 
  of 
  dikes. 
  The 
  utter 
  lack 
  of 
  meta- 
  

   morphism 
  and 
  the 
  fact 
  that 
  they 
  cut 
  all 
  the 
  other 
  rocks 
  show 
  that 
  

   this 
  diabase 
  is 
  the 
  youngest 
  of 
  the 
  intrusives. 
  That 
  it 
  must 
  have 
  

   cooled 
  rather 
  close 
  to 
  the 
  earth's 
  surface 
  is 
  evidenced 
  by 
  the 
  fine 
  

   grained 
  to 
  even 
  glassy 
  texture. 
  

  

  As 
  a 
  result 
  of 
  the 
  vast 
  erosion, 
  the 
  whole 
  area 
  was 
  worn 
  down 
  

   to 
  near 
  sea 
  level 
  and 
  presented 
  only 
  a 
  moderate 
  relief. 
  Then 
  a 
  

   gradual 
  sinking 
  took 
  place 
  when 
  the 
  sea 
  steadily 
  encroached 
  upon 
  

   the 
  old 
  land 
  from 
  the 
  east, 
  and 
  the 
  early 
  Paleozoic 
  sediments 
  were 
  

   deposited 
  upon 
  the 
  old 
  land 
  surface. 
  As 
  the 
  nearby 
  outliers 
  show, 
  

   the 
  first 
  sediment 
  to 
  cover 
  the 
  area 
  of 
  the 
  quadrangle 
  was 
  the 
  upper 
  

   Cambric 
  (Potsdam) 
  sandstone, 
  followed 
  in 
  turn 
  by 
  the 
  Theresa 
  

   passage 
  beds 
  and 
  the 
  Little 
  Falls 
  dolomite 
  which 
  are 
  also 
  of 
  Cam- 
  

   bric 
  age. 
  

  

  Recent 
  studies 
  have 
  shown 
  that, 
  toward 
  the 
  close 
  of 
  the 
  Cam- 
  

   bric, 
  there 
  was 
  a 
  gentle 
  upward 
  movement 
  of 
  the 
  Adirondack 
  region 
  

   to 
  above 
  sea 
  level 
  after 
  which 
  some 
  erosion 
  took 
  place. 
  Then, 
  early 
  

   in 
  the 
  Ordovicic 
  period, 
  the 
  Champlain 
  and 
  Mohawk 
  valley 
  regions 
  

   sank 
  below 
  the 
  ocean 
  surface 
  when 
  the 
  thick 
  limestones 
  and 
  shales 
  

   of 
  that 
  period 
  were 
  laid 
  down. 
  It 
  is 
  highly 
  probable 
  that 
  the 
  North 
  

   Creek 
  area 
  was 
  also 
  submerged 
  under 
  the 
  Ordovicic 
  sea, 
  though 
  

   positive 
  evidence 
  is 
  lacking. 
  At 
  any 
  rate 
  we 
  have 
  no 
  reason 
  to 
  

   think 
  that 
  this 
  area, 
  or 
  in 
  fact 
  any 
  of 
  the 
  Adirondack 
  region 
  outside 
  

   of 
  the 
  immediate 
  Champlain 
  and 
  St 
  Lawrence 
  valleys, 
  was 
  ever 
  

   again 
  below 
  sea 
  level 
  after 
  the 
  Ordovicic 
  period. 
  

  

  