﻿GEOLOGY 
  OF 
  THE 
  NORTH 
  CREEK 
  QUADRANGLE 
  1 
  5 
  

  

  unsatisfactory 
  than 
  if 
  we 
  were 
  dealing 
  with 
  a 
  great 
  thickness 
  of 
  

   unaltered 
  fossiliferous 
  strata. 
  However, 
  because 
  of 
  the 
  excellence 
  

   and 
  frequency 
  of 
  the 
  exposures 
  in 
  most 
  of 
  the 
  Grenville 
  areas, 
  

   some 
  unusually 
  good 
  results 
  have 
  been 
  obtained 
  though 
  it 
  should 
  

   not 
  be 
  understood 
  that 
  the 
  statements 
  or 
  conclusions 
  here 
  given 
  

   are 
  always 
  regarded 
  as 
  thoroughly 
  established. 
  Much 
  detailed 
  

   work 
  on 
  the 
  adjoining 
  areas 
  will 
  have 
  to 
  be 
  carried 
  on 
  before 
  

   such 
  statements 
  can 
  possibly 
  be 
  made. 
  

  

  So 
  far 
  as 
  can 
  be 
  made 
  out 
  from 
  a 
  study 
  of 
  all 
  the 
  Grenville 
  

   sections, 
  the 
  order 
  of 
  succession 
  of 
  the 
  strata 
  appears 
  to 
  be: 
  

  

  5 
  Dark 
  gray 
  biotite-garnet 
  gneiss. 
  Thickness 
  unknown. 
  

  

  4 
  Dark 
  hornblende 
  gneiss. 
  Thickness 
  at 
  least 
  2000 
  feet. 
  

  

  3 
  Crystalline 
  limestone. 
  Thickness 
  of 
  some 
  10,000 
  or 
  12,000 
  feet, 
  

   but 
  frequently 
  interbedded 
  with 
  more 
  or 
  less 
  hornblende 
  or 
  

   pyroxene 
  gneisses 
  or 
  quartzite. 
  

  

  2 
  Quartzite. 
  Thickness 
  of 
  about 
  3000 
  feet 
  and 
  generally 
  

   pure 
  except 
  for 
  very 
  thin 
  layers 
  of 
  biotite 
  gneiss. 
  

  

  1 
  Gray, 
  banded 
  biotite-garnet 
  gneiss. 
  Thickness 
  unknown. 
  

  

  Some 
  Grenville 
  rocks 
  which 
  are 
  more 
  locally 
  well 
  developed 
  are 
  

   not 
  included 
  in 
  the 
  above 
  list 
  because 
  their 
  stratigraphic 
  positions 
  

   are 
  wholly 
  unknown. 
  Among 
  such 
  rocks 
  are 
  the 
  graphite 
  schist, 
  

   the 
  white 
  gneiss, 
  and 
  the 
  sillimanite 
  gneiss. 
  

  

  The 
  best 
  extensive 
  section 
  within 
  the 
  quadrangle 
  is 
  shown 
  by 
  

   figure 
  1 
  which 
  represents 
  the 
  succession 
  of 
  strata 
  along 
  a 
  north- 
  

   east-southwest 
  line 
  through 
  the 
  Grenville 
  area 
  between 
  Oven 
  moun- 
  

   tain 
  and 
  Wevertown. 
  The 
  position 
  of 
  the 
  section 
  is 
  indicated 
  by 
  

   the 
  line 
  EE 
  on 
  the 
  geologic 
  map. 
  This 
  is 
  by 
  no 
  means 
  a 
  perfectly 
  

   continuous 
  section, 
  but 
  the 
  outcrops 
  are 
  numerous 
  enough 
  so 
  that 
  

   the 
  condition 
  of 
  things 
  shown 
  in 
  the 
  figure 
  can 
  not 
  be 
  far 
  wrong. 
  

   A 
  total 
  of 
  from 
  18,000 
  to 
  20,000 
  feet 
  of 
  Grenville 
  strata 
  appears 
  

   to 
  be 
  shown 
  in 
  this 
  section. 
  The 
  dip 
  and 
  strike 
  of 
  the 
  strata 
  are 
  

   pretty 
  constant 
  the 
  whole 
  length 
  of 
  the 
  section, 
  and 
  though 
  the 
  

   Oven 
  mountain 
  fault 
  probably 
  passes 
  across 
  the 
  section 
  it 
  is 
  not 
  

   thought 
  materially 
  to 
  affect 
  the 
  position 
  and 
  thickness 
  of 
  the 
  strata. 
  

   The 
  hornblende 
  gneiss 
  toward 
  the 
  top 
  of 
  the 
  section 
  forms 
  the 
  

   prominent 
  ridge 
  which 
  extends 
  northward 
  to 
  the 
  Hudson 
  river. 
  

  

  Figure 
  2 
  represents 
  an 
  east-west 
  section 
  across 
  the 
  valley 
  one- 
  

   third 
  of 
  a 
  mile 
  south 
  of 
  Daggett 
  pond 
  where 
  there 
  is 
  an 
  almost 
  

   unbroken 
  succession 
  of 
  nearly 
  pure 
  limestone 
  whose 
  total 
  thick- 
  

   ness 
  is 
  something 
  like 
  3000 
  feet. 
  On 
  the 
  west 
  side, 
  and 
  dipping 
  

   under 
  the 
  limestone, 
  are 
  some- 
  beds 
  of 
  hornblende-garnet 
  gneiss. 
  

  

  