﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  I43 
  

  

  relation 
  as 
  that 
  which 
  initiated 
  the 
  Black 
  valley. 
  The 
  only 
  features 
  

   which 
  are 
  not 
  in 
  harmony 
  with 
  the 
  above 
  theory 
  are 
  the 
  southward 
  

   course 
  of 
  a 
  section 
  of 
  the 
  Indian 
  river, 
  above 
  Evans 
  Mills, 
  and 
  of 
  

   the 
  Oswegatchie 
  above 
  Oxbow. 
  These 
  are 
  probably 
  due 
  to 
  glacial 
  di- 
  

   version, 
  similar 
  to 
  that 
  of 
  the 
  Black 
  below 
  Great 
  Bend, 
  but 
  for 
  

   better 
  knowledge 
  we 
  must 
  await 
  the 
  topographic 
  sheets. 
  

  

  Professor 
  Gushing 
  suggests 
  that 
  north 
  from 
  Felts 
  Mills 
  the 
  pre- 
  

   glacial 
  divide 
  might 
  have 
  swung 
  west 
  from 
  the 
  present 
  course, 
  pass- 
  

   ing 
  south 
  of 
  Perch 
  lake, 
  through 
  Depauville 
  and 
  south 
  of 
  St 
  Law- 
  

   rence 
  corners. 
  The 
  wider 
  valley 
  of 
  the 
  Ghaumont 
  north 
  of 
  Depau- 
  

   ville 
  and 
  the 
  northward 
  course 
  of 
  French 
  creek 
  favor 
  this 
  view. 
  

   It 
  is 
  quite 
  possible 
  that 
  Prewisconsin 
  glacial 
  erosion 
  has 
  caused 
  a 
  

   northward 
  migration 
  of 
  the 
  portion 
  of 
  the 
  divide 
  that 
  was 
  trans- 
  

   verse 
  to 
  the 
  ice 
  flow, 
  but 
  the 
  latest 
  ice 
  work 
  seems 
  to 
  have 
  been 
  

   too 
  weak. 
  We 
  may 
  not 
  appeal 
  to 
  forced 
  stream 
  flow 
  during 
  the 
  

   last 
  ice 
  recession, 
  as 
  the 
  region 
  was 
  then 
  buried 
  under 
  Iroquois 
  

   waters. 
  The 
  northward 
  uptilting 
  of 
  the 
  area 
  tends 
  of 
  course 
  to 
  

   divert 
  sluggish 
  drainage 
  into 
  southward 
  flow, 
  but 
  alone 
  this 
  could 
  

   not 
  be 
  a 
  very 
  effective 
  factor. 
  

  

  Passing 
  now 
  to 
  certain 
  specific 
  data 
  and 
  features 
  connected 
  with 
  

   very 
  recent 
  history, 
  the 
  reader 
  should 
  note 
  again 
  the 
  intimate 
  rela- 
  

   tion 
  and 
  parallelism 
  of 
  Black 
  river 
  to 
  its 
  northward 
  flowing 
  neigh- 
  

   bors 
  [pi. 
  43], 
  after 
  which 
  a 
  glance 
  at 
  plate 
  44 
  will 
  show 
  the 
  cause 
  

   of 
  the 
  separation 
  and 
  the 
  character 
  of 
  the 
  barrier. 
  At 
  Great 
  Bend 
  

   and 
  Felts 
  Mills 
  the 
  river 
  has 
  cut 
  into 
  the 
  south 
  side 
  of 
  its 
  own 
  

   delta, 
  that 
  was 
  built 
  in 
  Lake 
  Iroquois. 
  Along 
  much 
  of 
  that 
  stretch 
  

   rock 
  is 
  seen 
  in 
  the 
  bed 
  of 
  the 
  river, 
  beneath 
  the 
  steep 
  wall 
  of 
  the 
  

   delta 
  deposits. 
  North 
  of 
  the 
  delta 
  the 
  ground 
  is 
  100 
  feet 
  or 
  more 
  

   lower 
  than 
  the 
  river, 
  and 
  all 
  draining 
  northward. 
  At 
  Felts 
  Mills 
  

   the 
  river 
  has 
  an 
  altitude 
  of 
  580 
  feet, 
  while 
  only 
  1I/2 
  miles 
  north, 
  

   and 
  simply 
  across 
  the 
  delta 
  divide, 
  is 
  Pleasant 
  creek, 
  a 
  tributary 
  

   of 
  Indian 
  river, 
  at 
  only 
  520 
  feet 
  altitude. 
  The 
  fall 
  from 
  Black 
  

   river 
  to 
  Indian 
  river 
  by 
  Pleasant 
  creek 
  is 
  200 
  feet 
  in 
  about 
  6 
  miles. 
  

   Further 
  up 
  stream, 
  at 
  Great 
  Bend 
  the 
  river 
  has 
  a 
  large 
  meander 
  in 
  

   the 
  delta 
  and 
  the 
  facility 
  for 
  northward 
  flow 
  may 
  be 
  even 
  better 
  

   than 
  at 
  Felts 
  Mills, 
  but 
  the 
  topographic 
  survey 
  has 
  not 
  covered 
  the 
  

   district. 
  

  

  The 
  suggestion 
  is 
  natural 
  that 
  possibly 
  a 
  rock 
  barrier 
  is 
  buried 
  

   under 
  the 
  delta, 
  which 
  would 
  be 
  an 
  effective 
  barrier 
  to 
  north 
  escape 
  

   of 
  the 
  river 
  if 
  the 
  delta 
  were 
  removed. 
  Fortunately 
  we 
  have 
  

   specific 
  data. 
  Mr 
  F. 
  A. 
  Hinds, 
  the 
  well 
  known 
  hydraulic 
  engineer 
  

   of 
  Watertown, 
  has 
  pointed 
  out 
  the 
  important 
  fact 
  that 
  the 
  drainage 
  

  

  