﻿GEOLOGY 
  OF 
  THE 
  NORTH 
  CREEK 
  QUADRANGLE 
  47 
  

  

  of 
  the 
  newly 
  cooled 
  magma 
  and 
  also 
  that 
  the 
  molten 
  masses, 
  in 
  all 
  

   these 
  cases, 
  broke 
  through 
  the 
  Grenville 
  along 
  very 
  straight 
  or 
  regu- 
  

   lar 
  lines 
  often 
  for 
  miles. 
  Both 
  of 
  these 
  assumptions 
  are 
  out 
  of 
  

   harmony 
  with 
  well-known 
  observations 
  in 
  other 
  regions. 
  

  

  The 
  very 
  common 
  dip 
  of 
  the 
  Grenville 
  downward 
  against 
  the 
  

   faults 
  is 
  due 
  to 
  the 
  fact 
  that 
  most 
  of 
  the 
  prominent 
  fault 
  scarps 
  

   face 
  the 
  west 
  while 
  the 
  prevailing 
  dip 
  of 
  the 
  Grenville 
  is 
  toward 
  

   the 
  east. 
  

  

  Among 
  the 
  more 
  positive 
  criteria 
  for 
  the 
  recognition 
  of 
  the 
  faults 
  

   are 
  the 
  following: 
  (i) 
  actual 
  steep 
  to 
  vertical 
  scarps, 
  often 
  in 
  hard, 
  

   perfectly 
  homogeneous 
  rock, 
  and 
  frequently 
  in 
  such 
  positions 
  as 
  to 
  

   preclude 
  the 
  possibility 
  of 
  their 
  having 
  been 
  formed 
  by 
  ice 
  or 
  stream 
  

   erosion; 
  (2) 
  the 
  distinct 
  tilting 
  of 
  the 
  earth 
  blocks 
  gradually 
  down- 
  

   ward 
  away 
  from 
  the 
  scarps; 
  (3) 
  the 
  frequent 
  presence 
  of 
  actual 
  

   crushed, 
  sheared, 
  or 
  brecciated 
  fault 
  zones; 
  and 
  (4) 
  the 
  long, 
  

   straight 
  contact 
  lines 
  between 
  the 
  Grenville 
  and 
  the 
  igneous 
  rocks, 
  

   with 
  the 
  latter 
  rising 
  abruptly 
  high 
  above 
  the 
  former. 
  

  

  What 
  is 
  the 
  age 
  of 
  the 
  faulting? 
  That 
  some, 
  at 
  least, 
  occurred 
  

   during 
  Precambric 
  time 
  has 
  been 
  pretty 
  well 
  established 
  but, 
  so 
  tar 
  

   as 
  known, 
  such 
  faults 
  are 
  of 
  minor 
  importance 
  and 
  certainly 
  have 
  

   no 
  appreciable 
  influence 
  upon 
  existing 
  topography. 
  But 
  a 
  single 
  

   case 
  of 
  such 
  very 
  ancient 
  faulting 
  has 
  come 
  under 
  the 
  writer's 
  

   notice 
  within 
  the 
  area 
  of 
  the 
  quadrangle 
  and 
  this 
  occurs 
  along 
  the 
  

   road 
  three-fifths 
  of 
  a 
  mile 
  southwest 
  of 
  Sullivan 
  pond. 
  A 
  fault, 
  

   plainly 
  visible 
  for 
  12 
  feet, 
  there 
  passes 
  across 
  a 
  glaciated 
  ledge 
  of 
  

   quartz 
  syenite. 
  On 
  the 
  east 
  side, 
  for 
  a 
  width 
  of 
  7 
  or 
  8 
  feet, 
  the 
  

   whole 
  mass 
  is 
  a 
  fault 
  breccia. 
  This 
  breccia 
  is 
  fine 
  at 
  the 
  fault 
  and 
  

   coarser, 
  with 
  fragments 
  up 
  to 
  1 
  V 
  2 
  feet 
  across, 
  away 
  from 
  the 
  fault. 
  

   The 
  fault 
  strikes 
  north 
  30 
  east 
  and 
  is 
  in 
  no 
  way 
  related 
  to 
  existing 
  

   topography. 
  

  

  There 
  is 
  good 
  reason 
  to 
  think 
  that 
  considerable 
  faulting 
  occurred 
  

   during 
  the 
  Paleozoic 
  era 
  after 
  the 
  deposition 
  of 
  the 
  Ordovicic 
  sedi- 
  

   ments 
  because 
  rocks 
  of 
  that 
  age 
  are 
  involved 
  in 
  the 
  faulting 
  along 
  

   the 
  eastern 
  and 
  southern 
  borders 
  of 
  the 
  Adirondacks. 
  Cushing 
  has 
  

   suggested 
  that 
  the 
  faulting 
  may 
  have 
  been 
  initiated 
  at 
  the 
  time 
  of 
  

   the 
  Taconic 
  revolution 
  when 
  the 
  rocks 
  immediately 
  eastward 
  were 
  

   so 
  greatly 
  disturbed, 
  but 
  he 
  says 
  •} 
  " 
  The 
  great 
  earth 
  disturbance 
  

   (Appalachian 
  revolution) 
  which 
  prevailed 
  in 
  the 
  Appalachian 
  zone 
  

   toward 
  the 
  close 
  of 
  the 
  Paleozoic 
  would 
  seem 
  more 
  likely 
  to 
  have 
  

   brought 
  about 
  the 
  major 
  faulting 
  of 
  the 
  region." 
  We 
  know 
  that 
  

  

  1 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  95, 
  p. 
  405. 
  

  

  