﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  69 
  

  

  mere 
  upper 
  part 
  of 
  the 
  whole, 
  the 
  giving 
  of 
  a 
  local 
  name 
  seems 
  

   justified, 
  and 
  in 
  Pamelia 
  township 
  the 
  entire 
  thickness 
  is 
  exposed. 
  

   As 
  has 
  been 
  shown 
  there 
  is 
  plain 
  evidence 
  of 
  an 
  erosion 
  interval 
  

   between 
  this 
  and 
  the 
  Theresa, 
  indicative 
  of 
  uplift 
  to 
  above 
  sea 
  

   level 
  and 
  of 
  erosion 
  on 
  this 
  land 
  surface. 
  As 
  will 
  be 
  later 
  shown 
  

   this 
  is 
  an 
  important 
  and 
  widespread 
  break. 
  The 
  comparatively 
  

   slight 
  amount 
  of 
  erosion 
  is 
  indicative 
  of 
  low 
  altitude 
  for 
  this 
  land 
  

   surface. 
  

  

  The 
  renewed 
  depression 
  which 
  initiated 
  Pamelia 
  deposition 
  

   came 
  in 
  from 
  the 
  southwest 
  instead 
  of 
  from 
  the 
  east, 
  involving 
  

   change 
  in 
  the 
  direction 
  of 
  slope 
  of 
  the 
  surface. 
  

  

  The 
  formation 
  consists 
  essentially 
  of 
  limestone, 
  though 
  much 
  

   of 
  it 
  is 
  not 
  pure 
  limestone. 
  It 
  is 
  conveniently 
  separable 
  into 
  

   lower 
  and 
  upper 
  divisions 
  which, 
  differ 
  in 
  lithologic 
  character. 
  

   The 
  lower 
  division 
  has 
  always 
  a 
  sandy 
  base, 
  followed 
  by 
  alterna- 
  

   tions 
  of 
  black 
  limestone, 
  blue 
  limestone 
  and 
  gray 
  (somewhat 
  

   magnesian) 
  limestone, 
  often 
  with 
  shaly 
  partings 
  between 
  the 
  

   beds. 
  The 
  upper 
  division 
  contains 
  much 
  whitish, 
  earthy 
  lime- 
  

   stone, 
  with 
  interbedded 
  dove 
  limestone 
  and 
  gray 
  magnesian 
  

   limestone. 
  The 
  black 
  limestone 
  characterizes 
  the 
  lower, 
  and 
  the 
  

   earthy 
  and 
  dove 
  limestones 
  the 
  upper 
  division. 
  

  

  In 
  the 
  western 
  portion 
  of 
  the 
  Theresa 
  quadrangle 
  the 
  forma- 
  

   tion 
  has 
  a 
  thickness 
  of 
  150 
  feet 
  or 
  more. 
  Traced 
  eastward' 
  

   across 
  the 
  quadrangle 
  it 
  thins 
  considerably, 
  and 
  on 
  the 
  eastern 
  

   margin 
  appears 
  to 
  have 
  less 
  than 
  half 
  this 
  thickness 
  though 
  here 
  

   the 
  drift 
  is 
  so 
  heavy, 
  and 
  exposures 
  so 
  poor, 
  that 
  no 
  good 
  

   measurements 
  can 
  be 
  obtained. 
  However, 
  60 
  feet 
  seems 
  a 
  generous 
  

   allowance 
  for 
  the 
  thickness 
  here, 
  and 
  it 
  is 
  the 
  beds 
  of 
  the 
  lower 
  

   division 
  which 
  have 
  disappeared. 
  

  

  Following 
  the 
  formation 
  westward, 
  across 
  the 
  Clayton 
  quad- 
  

   rangle 
  to 
  its 
  disappearance 
  beneath 
  the 
  river, 
  the 
  belt 
  of 
  outcrop 
  

   swerves 
  somewhat 
  to 
  the 
  north, 
  and 
  the 
  formation 
  thins 
  somewhat 
  

   in 
  this 
  direction 
  also. 
  If 
  it 
  could 
  be 
  followed 
  due 
  west 
  across 
  the 
  

   quadrangle 
  it 
  would 
  no 
  doubt 
  hold 
  its 
  thickness 
  or 
  even 
  perhaps 
  

   increase. 
  It 
  is 
  the 
  northward 
  shift 
  that 
  causes 
  the 
  thinning. 
  A 
  thick- 
  

   ness 
  of 
  at 
  least 
  80 
  feet 
  is 
  maintained 
  to 
  the 
  river 
  however, 
  and 
  the 
  

   formation 
  passes 
  across 
  into 
  Canada 
  with 
  this 
  amount 
  not 
  materially 
  

   reduced. 
  The 
  shore 
  lines 
  of 
  this 
  depositional 
  basin 
  then 
  lay 
  not 
  far 
  

   distant 
  to 
  the 
  east 
  and 
  north 
  of 
  the 
  district 
  and 
  the 
  invasion 
  of 
  the 
  

   sea 
  must 
  have 
  come 
  from 
  the 
  opposite 
  direction. 
  

  

  In 
  the 
  immediate 
  district 
  the 
  formation 
  rests 
  everywhere 
  on 
  the 
  

   sandy 
  dolomites 
  of 
  the 
  Tlieresa. 
  In 
  the 
  district 
  about 
  Kingston 
  it 
  

  

  