﻿46 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  and 
  mapping 
  of 
  these 
  faults 
  well 
  within 
  the 
  Precambric 
  area. 
  The 
  

   North 
  Creek 
  quadrangle, 
  which 
  lies 
  in 
  the 
  midst 
  of 
  this 
  eastern 
  

   Adirondack 
  faulted 
  region, 
  is 
  literally 
  cut 
  to 
  pieces 
  by 
  faults. 
  On 
  

   the 
  accompanying 
  geologic 
  map 
  the 
  writer 
  has 
  indicated 
  the 
  posi- 
  

   tions 
  of 
  over 
  forty 
  faults, 
  most 
  of 
  which 
  show 
  unmistakable 
  evi- 
  

   dences 
  of 
  their 
  presence, 
  while 
  the 
  others, 
  shown 
  on 
  the 
  map 
  by 
  the 
  

   heavy 
  broken 
  lines, 
  are 
  more 
  or 
  less 
  certainly 
  present. 
  

  

  The 
  faults 
  are 
  all 
  of 
  the 
  normal 
  type 
  with 
  fault 
  planes 
  vertical 
  

   or 
  very 
  steep. 
  Because 
  of 
  the 
  character 
  and 
  structure 
  of 
  the 
  rock 
  

   masses 
  and 
  the 
  lack 
  of 
  any 
  well-defined 
  stratigraphic 
  relations, 
  it 
  

   is 
  practically 
  impossible 
  to 
  determine 
  the 
  actual 
  amounts 
  of 
  dis- 
  

   placement, 
  though 
  in 
  many 
  cases 
  minimum 
  approximations 
  can 
  be 
  

   made. 
  Such 
  minimum 
  figures 
  commonly 
  range 
  from 
  a 
  few 
  hundred 
  

   to 
  a 
  thousand 
  feet 
  or 
  more. 
  One 
  feature 
  worthy 
  of 
  special 
  mention 
  

   is 
  the 
  frequent 
  rapid 
  diminution 
  of 
  throw 
  within 
  very 
  short 
  dis- 
  

   tances. 
  Thus 
  in 
  many 
  respects 
  the 
  North 
  Creek 
  faults 
  are 
  much 
  

   like 
  those 
  of 
  the 
  Mohawk 
  and 
  Champlain 
  valleys, 
  which 
  is 
  to 
  be 
  

   expected 
  as 
  the 
  faults 
  of 
  this 
  whole 
  eastern 
  Adirondack 
  region 
  were 
  

   all 
  produced 
  at 
  the 
  same 
  time 
  or 
  times. 
  With 
  regard 
  to 
  the 
  strike, 
  

   however, 
  the 
  North 
  Creek 
  faults 
  are 
  rather 
  exceptional 
  because 
  the 
  

   general 
  trend 
  of 
  the 
  Adirondack 
  faults 
  is 
  north-northeast 
  by 
  south- 
  

   southwest, 
  while 
  within 
  the 
  North 
  Creek 
  quadrangle 
  this 
  trend 
  is 
  

   the 
  rule 
  only 
  in 
  its 
  northern 
  portion. 
  

  

  As 
  a 
  rule, 
  faults 
  within 
  the 
  Precambric 
  area 
  are 
  difficult 
  to 
  locate 
  

   and 
  trace 
  with 
  any 
  great 
  degree 
  of 
  accuracy 
  and 
  certainty 
  because 
  

   of 
  the 
  general 
  similarity 
  of 
  the 
  rocks 
  and 
  the 
  lack 
  of 
  ordinary 
  fos- 
  

   siliferous 
  strata. 
  In 
  the 
  North 
  Creek 
  region, 
  however, 
  the 
  condi- 
  

   tions 
  are 
  particularly 
  favorable 
  for 
  locating 
  faults 
  both 
  because 
  of 
  

   the 
  unusual 
  excellence 
  of 
  exposures 
  and 
  the 
  large 
  amount 
  of 
  widely 
  

   distributed 
  weak 
  Grenville 
  strata. 
  

  

  Frequently 
  the 
  line 
  of 
  contact 
  between 
  the 
  syenite 
  or 
  granite 
  and 
  

   the 
  Grenville 
  is 
  very 
  regular 
  and 
  sharp, 
  the 
  Grenville 
  often 
  seeming 
  

   to 
  dip 
  under 
  the 
  igneous 
  rock 
  with 
  the 
  latter 
  rising 
  abruptly 
  and 
  

   to 
  a 
  great 
  height 
  above 
  the 
  Grenville. 
  Among 
  the 
  best 
  examples 
  of 
  

   such 
  phenomenon 
  are 
  the 
  southern 
  sides 
  of 
  Huckleberry, 
  Crane, 
  and 
  

   Little 
  mountains, 
  and 
  the 
  western 
  sides 
  of 
  Oven, 
  Prospect, 
  Birch, 
  

   and 
  Potter 
  mountains. 
  There 
  are 
  only 
  two 
  possible 
  explanations 
  

   of 
  this 
  phenomenon, 
  namely, 
  either 
  that 
  the 
  igneous 
  rocks 
  were 
  in- 
  

   truded 
  into 
  the 
  positions 
  which 
  they 
  now 
  occupy 
  or 
  that 
  faulting 
  

   has 
  occurred. 
  If 
  this 
  is 
  to 
  be 
  explained 
  simply 
  on 
  the 
  basis 
  of 
  in- 
  

   trusion, 
  then 
  we 
  are 
  forced 
  to 
  assume 
  a 
  remarkably 
  irregular 
  surface 
  

  

  