﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  

  

  III 
  

  

  thickness 
  in 
  each, 
  and 
  the 
  two 
  dippmg 
  toward 
  one 
  another, 
  this 
  sup- 
  

   position 
  seems 
  improbable 
  in 
  high 
  degree. 
  There 
  seems 
  no 
  direct 
  

   evidence 
  for 
  it 
  and 
  much 
  against 
  it. 
  

  

  The 
  other 
  alternative 
  is 
  that 
  the 
  structure 
  here 
  is 
  anticlinal 
  in- 
  

   stead 
  of 
  synclinal. 
  This 
  is 
  a 
  possible 
  interpretation 
  of 
  it 
  in 
  spite 
  

   of 
  the 
  fact 
  that 
  the 
  two 
  limestones 
  dip 
  toward 
  one 
  another. 
  Long 
  

   continued 
  and 
  severe 
  compression 
  may 
  so 
  closely 
  compress 
  rock 
  

   folds 
  as 
  to 
  cause 
  them 
  to 
  pass 
  into 
  the 
  fan 
  fold 
  type 
  as 
  illustrated 
  

   in 
  figure 
  8. 
  Such 
  folds 
  are 
  so 
  pinched 
  that 
  vertical 
  dips 
  prevail 
  

   centrally, 
  along 
  the 
  axes, 
  and 
  the 
  dips 
  farther 
  away 
  converge 
  

  

  toward 
  the 
  axis 
  in 
  the 
  anticlines, 
  ^,,-' 
  -^^ 
  

  

  instead 
  of 
  in 
  the 
  synclines 
  as 
  in 
  the 
  , 
  /"" 
  ^^^ 
  ^'\ 
  

  

  previous 
  case. 
  In 
  that 
  also 
  the 
  dips 
  / 
  ''' 
  ^n^ 
  \ 
  

  

  flatten 
  in 
  the 
  vicinity 
  of 
  the 
  axis 
  of 
  ' 
  ,' 
  ,---v, 
  ^ 
  \ 
  

  

  the 
  fold, 
  and 
  pass 
  from 
  one 
  direc- 
  ', 
  ; 
  /' 
  ■. 
  / 
  ; 
  

  

  tion 
  to 
  the 
  other 
  through 
  the 
  hori- 
  

   zontal, 
  instead 
  of 
  through 
  the 
  ver- 
  

   tical, 
  as 
  in 
  the 
  f-an 
  fold. 
  In 
  repeated 
  

   instances, 
  and 
  in 
  many 
  localities, 
  in 
  

   the 
  Grenville 
  rocks 
  of 
  northern 
  Ne^v 
  

   York, 
  the 
  writer 
  has 
  observed 
  that 
  

   change 
  in 
  dip 
  has 
  taken 
  place 
  

   through 
  the 
  vertical 
  instead 
  of 
  

   through 
  the 
  horizontal, 
  and 
  this 
  

   seems 
  to 
  imply 
  a 
  condition 
  of 
  very 
  close 
  folding 
  in 
  

   \'ille 
  rocks 
  at 
  many 
  and 
  widely 
  distributed 
  

   especial 
  case 
  the 
  dips 
  change 
  from 
  the 
  northwest 
  to 
  the 
  

   southeast 
  through 
  the 
  vertical 
  in 
  the 
  schists 
  northeast 
  of 
  Mill- 
  

   site 
  lake, 
  but 
  with 
  some 
  comparatively 
  flat 
  dips 
  in 
  the 
  inter- 
  

   banded 
  quartzites 
  north 
  of 
  the 
  lake. 
  At 
  the 
  same 
  time 
  the 
  schists 
  

   become 
  greatly 
  contorted 
  and 
  puckered. 
  Millsite 
  lake 
  seems 
  to 
  lie 
  

   closely 
  along 
  the 
  axis 
  of 
  the 
  fold. 
  The 
  section 
  shown 
  in 
  figure 
  9 
  

   was 
  sketched 
  from 
  an 
  exposure 
  j4 
  rnile 
  northeast 
  of 
  ^lillsite 
  lake. 
  

  

  Fig. 
  8 
  Section 
  similar 
  to 
  the 
  previous, 
  

   surface 
  outcrops, 
  dips 
  and 
  scale 
  the 
  same, 
  

   on 
  the 
  assumption 
  of 
  fan 
  fold 
  structure 
  

  

  the 
  Gren- 
  

   points. 
  In 
  this 
  

  

  •Fig. 
  9 
  Exposure 
  of 
  Grenville 
  rocks 
  J 
  mile 
  northeast 
  of 
  Millsite 
  lake, 
  showing 
  sharply- 
  

   folded 
  quartzite 
  q-q, 
  with 
  a 
  pinched 
  in 
  thin 
  limestone 
  between 
  the 
  quartzite 
  limbs, 
  1, 
  the 
  

   quartzite 
  succeeded 
  on 
  the 
  left 
  by 
  hornblende 
  schists, 
  s, 
  and 
  very 
  schistose 
  mica 
  schist 
  

   ms, 
  the 
  dip 
  being 
  vertical 
  or 
  nearly 
  so 
  throughout 
  

  

  