﻿352 
  Spencer— 
  Origin 
  and 
  Age 
  of 
  the 
  Ontario 
  Shore-Line. 
  

  

  Fig. 
  1. 
  

  

  Fig. 
  1. 
  Map 
  and 
  chart 
  in 
  the 
  vicinity 
  of 
  

   Toronto, 
  showing 
  soundings, 
  etc. 
  (After 
  

   Chipman 
  and 
  Powers' 
  maps.) 
  

  

  *Bull. 
  Geol. 
  Soc. 
  Am., 
  vol. 
  xxvii, 
  

  

  due 
  to 
  the 
  scour 
  of 
  its 
  

   outlet 
  had 
  not 
  been 
  in- 
  

   vestigated. 
  Between 
  

   1911-1914, 
  I 
  found 
  that 
  

   the 
  terraces 
  at 
  about 
  15 
  

   feet* 
  and 
  5 
  feet 
  recur 
  

   from 
  one 
  end 
  of 
  the 
  lake 
  

   to 
  the 
  other, 
  thus 
  show- 
  

   ing 
  that 
  the 
  deformation 
  

   had 
  ceased 
  when 
  the 
  

   waters 
  were 
  at 
  these 
  

   levels. 
  But, 
  as 
  stated 
  

   before, 
  the 
  water 
  level 
  

   had 
  been 
  more 
  than 
  200 
  

   feet 
  lower 
  than 
  now 
  be- 
  

   fore 
  the 
  deformation 
  

   which 
  barricaded 
  the 
  

   basin, 
  thereby 
  causing 
  

   the 
  lake 
  to 
  rise 
  again. 
  

  

  The 
  banks 
  of 
  the 
  St. 
  

   Lawrence 
  River, 
  except 
  

   at 
  some 
  of 
  the 
  rapids, 
  

   are 
  composed 
  of 
  drift 
  

   seldom 
  rising 
  higher 
  

   than 
  20 
  feet, 
  with 
  broad 
  

   plains 
  beyond 
  formerly 
  

   covered 
  by 
  a 
  pre-Ontario 
  

   lake. 
  Where 
  rocky 
  isl- 
  

   ands, 
  in 
  the 
  upper 
  part 
  

   of 
  the 
  river, 
  rise 
  higher, 
  

   deep 
  channels 
  occur 
  be- 
  

   tween 
  them. 
  These 
  are 
  

   pre-Gl 
  acial 
  features, 
  

   while 
  the 
  modern 
  river 
  

   was 
  first 
  established 
  

   when 
  it 
  was 
  confined 
  by 
  

   the 
  terrace 
  about 
  15 
  feet 
  

   above 
  the 
  present 
  sur 
  

   face, 
  such 
  as 
  may 
  be 
  seen 
  

   at 
  Gananoque, 
  carved 
  

   out 
  of 
  banks 
  of 
  drift. 
  

   This 
  terrace 
  is 
  especially 
  

   well-defined 
  at 
  Mill 
  

   Haven 
  (12 
  miles 
  west 
  of 
  

   Kingston), 
  being 
  there 
  

   carved 
  out 
  of 
  shaly 
  rock 
  ; 
  

   so 
  that 
  the 
  term 
  Mill 
  

   Haven 
  Terrace 
  m 
  a 
  y 
  

   approximately 
  be 
  given 
  

   p. 
  79, 
  1916 
  (abstract). 
  

  

  