﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  II3 
  

  

  and 
  to 
  a 
  certain 
  extent 
  at 
  least 
  is 
  due 
  to 
  the 
  pivotal 
  situation 
  of 
  the 
  

   region 
  with 
  respect 
  to 
  the 
  early 
  Paleozoic 
  warpings, 
  as 
  has 
  already 
  

   been 
  shown. 
  In 
  general 
  the 
  rocks 
  lie, 
  in 
  nearly 
  flat 
  attitude, 
  on 
  the 
  

   worn 
  surface 
  of 
  the 
  sharply 
  folded 
  Precambric 
  rocks. 
  Over 
  most 
  

   of 
  the 
  district 
  a 
  low, 
  southwesterly 
  dip 
  prevails; 
  locally, 
  however, 
  

   the 
  dip 
  steepens 
  to 
  5° 
  or 
  more, 
  and 
  dips 
  occur 
  in 
  all 
  compass 
  direc- 
  

   tions. 
  A 
  strong 
  westerly 
  dip 
  in 
  the 
  rocks 
  along 
  the 
  Black 
  river 
  

   just 
  above 
  the 
  bridge 
  at 
  Brownville 
  is 
  well 
  shown 
  in 
  plate 
  28, 
  and 
  

   the 
  dip 
  is 
  to 
  the 
  north, 
  into 
  the 
  bank, 
  as 
  well, 
  rock 
  layers 
  on 
  the 
  

   south 
  side 
  of 
  the 
  river 
  lying 
  some 
  10 
  feet 
  higher 
  than 
  their 
  

   equivalents 
  on 
  the 
  north 
  bank. 
  In 
  plate 
  24 
  a 
  rather 
  steep 
  north- 
  

   erly 
  dip 
  in 
  the 
  Black 
  River 
  limestone 
  at 
  Watertown 
  is 
  shown, 
  and 
  

   in 
  plate 
  21 
  a 
  similar 
  easterly 
  dip 
  in 
  the 
  same 
  formation 
  at 
  another 
  

   locality. 
  These 
  are 
  samples 
  of 
  what 
  is 
  a 
  matter 
  of 
  common 
  oc- 
  

   currence 
  all 
  over 
  the 
  district. 
  The 
  areal 
  mapping 
  plainly 
  brings 
  

   out 
  the 
  presence 
  of 
  a 
  series 
  of 
  folds 
  which 
  trend 
  somewhat 
  to 
  the 
  

   east 
  of 
  north. 
  It 
  also 
  shows 
  that 
  the 
  present 
  stream 
  valleys 
  of 
  the 
  

   region 
  in 
  large 
  part 
  trend 
  with 
  these 
  folds 
  and 
  chiefly 
  follow 
  the 
  

   anticlines, 
  while 
  the 
  synclines 
  constitute 
  the 
  higher 
  ground 
  be- 
  

   tween.^ 
  Examples 
  are 
  the 
  valleys 
  running 
  south 
  from 
  Theresa 
  and 
  

   from 
  Evans 
  Mills 
  on 
  the 
  Theresa 
  sheet 
  ; 
  the 
  French 
  creek 
  valley 
  

   and 
  the 
  Chaumont 
  valley 
  on 
  the 
  Clayton 
  sheet; 
  and 
  the 
  Clear 
  lake- 
  

   Butterfield 
  lake-Black 
  creek 
  valley 
  on 
  the 
  Alexandria 
  sheet; 
  but 
  

   there 
  are 
  many 
  others 
  of 
  minor 
  importance. 
  

  

  In 
  addition 
  to 
  these 
  nearly 
  north-south 
  folds 
  there 
  is 
  a 
  second 
  

   set, 
  about 
  at 
  right 
  angles 
  to 
  the 
  first, 
  trending 
  somewhat 
  to 
  the 
  

   north 
  of 
  west, 
  in 
  parallelism 
  with 
  the 
  Frontenac 
  axis 
  which 
  is 
  

   itself 
  a 
  ■ 
  fold 
  of 
  this 
  group, 
  the 
  axia,l 
  and 
  most 
  prominent 
  one. 
  

   Though 
  mostly 
  of 
  minor 
  importance, 
  these 
  folds 
  are 
  likely 
  earlier 
  

   than 
  the 
  others, 
  and 
  in 
  part 
  at 
  least 
  owe 
  their 
  existence 
  to 
  the 
  

   warpings 
  and 
  tiltings 
  of 
  the 
  region 
  in 
  early 
  Paleozoic 
  times, 
  when 
  

   it 
  oscillated 
  up 
  and 
  down^ 
  with 
  tipping 
  now 
  to 
  the 
  east 
  and 
  now 
  

   to 
  the 
  west. 
  The 
  Frontenac 
  axis 
  appears 
  to 
  be 
  the 
  major 
  warp 
  

   of 
  this 
  ser^'es, 
  and 
  the 
  others 
  are 
  minor 
  corrugations, 
  grouped 
  

   about 
  it 
  and 
  diminishing 
  in 
  importance 
  with 
  recession 
  from 
  it. 
  

  

  1 
  An 
  anticline 
  is 
  the 
  upward 
  folding 
  of 
  rock 
  layers 
  into 
  a 
  long 
  and 
  rela- 
  

   tively 
  narrow 
  arch 
  ; 
  a 
  syncline, 
  the 
  downfolding 
  into 
  a 
  similar 
  trough. 
  

   Where 
  erosion 
  has 
  removed 
  the 
  upper 
  portion 
  of 
  such 
  folds 
  a 
  worn 
  off 
  

   anticline 
  is 
  readily 
  recognized 
  on 
  an 
  areal 
  map 
  since 
  it 
  will 
  show 
  an 
  older 
  

   ^ock 
  centrally, 
  followed 
  by 
  successively 
  younger 
  rocks 
  in 
  the 
  same 
  order 
  on 
  

   each 
  side; 
  while 
  an 
  eroded 
  syncline 
  will 
  show 
  a 
  younarer 
  rock 
  in 
  the 
  center, 
  

   followed 
  by' 
  successively 
  ol(|er 
  rocks 
  on 
  each* 
  side:. 
  Thus 
  the 
  French 
  creek 
  

   valley, 
  south, 
  of 
  Clayton, 
  shows 
  Precambric 
  rocks 
  centrally, 
  ^adjoined 
  by 
  

   Potsdam 
  on 
  'each 
  side, 
  Potsdam 
  adjoined 
  by 
  Theresa 
  and' 
  that 
  by 
  Pamelia 
  

   Hmestone, 
  and 
  the 
  structure 
  there 
  i§ 
  anticlinal. 
  

  

  