﻿128 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  on 
  the 
  Alexandria 
  sheet, 
  as 
  we 
  have 
  just 
  seen. 
  This' 
  parallel, 
  

   but 
  northerly-flowing 
  Theresa 
  valley 
  plainly 
  heads 
  several 
  miles 
  

   south 
  of 
  the 
  original 
  line 
  - 
  of 
  the 
  divide, 
  in 
  other 
  words 
  has 
  

   pushed 
  it 
  south 
  out 
  of 
  line 
  by 
  headward 
  cutting 
  of 
  its 
  valley. 
  

   Its 
  ability 
  to 
  do 
  this 
  w^as 
  no 
  doubt 
  conditioned 
  upon 
  the 
  weak 
  

   resistance 
  of 
  the 
  Grenville 
  limestone 
  belt 
  there. 
  Once 
  the 
  Pots- 
  

   dam 
  was 
  cut 
  through, 
  rapid 
  headward 
  cutting 
  of 
  the 
  stream 
  would 
  

   be 
  possible. 
  From 
  the 
  present 
  valley 
  head 
  a 
  shallow 
  valley 
  runs 
  

   southwest 
  to 
  Perch 
  lake, 
  and 
  it 
  seems 
  clear 
  that 
  formerly 
  this 
  

   valley 
  headed 
  along 
  the 
  old 
  divide, 
  and 
  was 
  diverted, 
  bit 
  by 
  bit, 
  

   by 
  the 
  more 
  advantageously 
  situated 
  stream 
  flowing 
  the 
  other 
  

   way. 
  The 
  minor 
  tributary 
  valleys 
  from 
  the 
  east 
  and 
  west, 
  

   between 
  Theresa 
  and 
  the 
  north 
  margin 
  of 
  the 
  sheet, 
  are 
  southerly 
  

   trending 
  valleys, 
  southeast 
  or 
  southwest, 
  and 
  hence 
  adjusted 
  to 
  

   a 
  southerly, 
  rather 
  than 
  a 
  northerly 
  flowing 
  stream. 
  The 
  north- 
  

   erly 
  flowing 
  stream 
  slowly 
  captured 
  and 
  rei'ersed 
  the 
  headwaters 
  

   of 
  the 
  south 
  stream, 
  extending 
  its 
  capture 
  through 
  a 
  distance 
  of 
  

   from 
  4 
  to 
  5 
  miles. 
  

  

  Northeastward 
  from 
  Theresa 
  are 
  a 
  number 
  of 
  valleys 
  heading 
  

   sharply 
  against 
  the 
  Potsdam 
  mass 
  which 
  there 
  forms 
  the 
  divide, 
  

   and 
  leading 
  away 
  from 
  it 
  to 
  the 
  southwest. 
  These 
  are 
  located 
  on 
  

   belts 
  of 
  Grenville 
  limestone, 
  or 
  of 
  weak 
  schist, 
  and 
  therefore 
  are 
  

   broader 
  and 
  less 
  ravinelike 
  than 
  most 
  of 
  such 
  valleys 
  in 
  the 
  dis- 
  

   trict. 
  They 
  are, 
  however, 
  comparatively 
  narrow, 
  distinctly 
  rock 
  

   vvalled, 
  and 
  with 
  present 
  flat-bottomed 
  floors 
  owing 
  to 
  drift 
  

   deposits. 
  

  

  Here, 
  in 
  the 
  northeast 
  corner 
  of 
  the 
  Theresa 
  sheet, 
  the 
  divide 
  

   runs 
  off 
  our 
  maps 
  to 
  the 
  east, 
  and 
  with 
  maps 
  of 
  that 
  district 
  

   not 
  yet 
  available, 
  its 
  further 
  course 
  can 
  not 
  be 
  traced. 
  It, 
  today, 
  

   rises 
  steadily 
  in 
  altitude 
  in 
  that 
  direction, 
  and 
  is, 
  as 
  in 
  Tertiary 
  

   times, 
  the 
  divide 
  between 
  waters 
  flowing 
  north 
  to 
  the 
  St 
  Law- 
  

   rence 
  and 
  west 
  to 
  the 
  Ontario 
  valley. 
  

  

  The 
  Indian 
  river 
  of 
  today, 
  from 
  Theresa 
  south 
  to 
  the 
  great 
  

   bend 
  north 
  of 
  Evans 
  ]\Iills, 
  is 
  flowing 
  in 
  reversed 
  direction 
  

   through 
  AA^hat 
  was 
  then 
  the 
  valley 
  of 
  a 
  small 
  stream 
  heading 
  

   near 
  Theresa 
  and 
  flowing 
  south. 
  Wilson's 
  view 
  is 
  that 
  at 
  the 
  

   bend 
  it 
  was 
  tributary 
  to 
  a 
  southwest 
  stream, 
  occupying 
  the 
  

   valley 
  now 
  foUoAved 
  by 
  Indian 
  river 
  above 
  the 
  bend; 
  and 
  that 
  

   their 
  combined 
  Avaters 
  floAved 
  south 
  through 
  the 
  present 
  West 
  

   creek 
  valley 
  to 
  the 
  Black 
  river. 
  With 
  our 
  disbelief 
  in 
  the 
  pres- 
  

   ence 
  of 
  the 
  Black 
  riA^er 
  there 
  at 
  that 
  time, 
  coupled 
  AA^th 
  the 
  fact 
  

   that 
  the 
  West 
  <:reek 
  valley 
  seems 
  both 
  to 
  Aviden, 
  and 
  to 
  deepen, 
  

  

  