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

  

  But 
  the 
  age 
  of 
  the 
  lake 
  itself 
  is 
  somewhat 
  older 
  — 
  its 
  surface 
  

   having 
  been 
  lowered 
  a 
  few 
  feet, 
  while 
  the 
  St. 
  Lawrence 
  was 
  

   deepening 
  its 
  channel, 
  but 
  there 
  is 
  no 
  direct 
  measurement 
  

   derivable 
  from 
  the 
  St. 
  Lawrence 
  River 
  itself. 
  

  

  Researches, 
  relating 
  to 
  the 
  great 
  accession 
  of 
  water 
  to 
  the 
  

   Niagara 
  River, 
  show 
  that 
  the 
  terrestrial 
  tilting 
  about 
  the 
  north- 
  

   eastern 
  angle 
  of 
  Lake 
  Huron 
  occurred 
  as 
  late 
  as 
  some 
  3,500 
  

   years 
  ago. 
  This 
  earth 
  movement 
  extending 
  to 
  the 
  St. 
  Law- 
  

   rence 
  River 
  was 
  that 
  which 
  gave 
  birth 
  to 
  the 
  great 
  modern 
  

   river 
  itself. 
  No 
  appreciable 
  deformation 
  has 
  since 
  occurred. 
  

   Consequently, 
  Lake 
  Ontario 
  is 
  found 
  to 
  be 
  some 
  3,500 
  years 
  

   old. 
  The 
  difference 
  between 
  this 
  figure 
  and 
  2,000 
  years 
  for 
  

   the 
  age 
  of 
  the 
  Ontario 
  Beach 
  seems 
  ample 
  for 
  the 
  lowering 
  of 
  

   the 
  lake 
  level 
  from 
  the 
  Mill 
  Haven 
  to 
  the 
  present 
  shore-line. 
  

  

  New 
  Results. 
  — 
  Lake 
  Ontario 
  and 
  the 
  St. 
  Lawrence 
  River 
  

   date 
  only 
  from 
  the 
  time 
  when 
  the 
  discharge 
  was 
  first 
  confined 
  

   to 
  the 
  river 
  channel, 
  since 
  lowered 
  some 
  15 
  feet 
  by 
  current 
  

   scour. 
  The 
  former 
  earth 
  movements 
  of 
  some 
  3,500 
  years 
  ago 
  

   have 
  disappeared 
  in 
  the 
  higher 
  and 
  present 
  Ontario 
  shore-lines. 
  

   The 
  age 
  of 
  the 
  Ontario 
  Beach 
  is 
  satisfactorily 
  determined 
  at 
  

   about 
  2,000 
  years, 
  while 
  the 
  age 
  of 
  the 
  lake 
  itself, 
  and 
  that 
  of 
  

   the 
  St. 
  Lawrence 
  River, 
  is 
  3,500 
  years 
  or 
  perhaps 
  slightly 
  less, 
  

   as 
  based 
  upon 
  the 
  data 
  so 
  far 
  discovered, 
  without 
  any 
  great 
  

   probable 
  variation 
  indicated. 
  

  

  Speculations 
  relating 
  to 
  the 
  Age 
  of 
  Lake 
  Ontario 
  and 
  Post- 
  

   Glacial 
  Tbne. 
  

  

  To 
  close 
  this 
  study 
  and 
  not 
  analyze 
  the 
  speculations 
  would 
  

   leave 
  the 
  subject 
  in 
  confusion, 
  as 
  few 
  have 
  the 
  available 
  data 
  

   or 
  opportunities 
  for 
  investigation. 
  Furthermore, 
  a 
  discussion 
  

   introduces 
  other 
  important 
  features. 
  A 
  notable 
  attempt 
  to 
  

   find 
  the 
  time 
  value 
  for 
  the 
  Ontario 
  Beach 
  has 
  been 
  made 
  by 
  

   Prof. 
  A. 
  P. 
  Coleman,* 
  who 
  based 
  his 
  estimate 
  on 
  beach 
  

   accumulations 
  artificially 
  obstructed 
  by 
  the 
  canal 
  piers 
  crossing 
  

   the 
  beach 
  at 
  Toronto 
  Island 
  (see 
  fig. 
  3) 
  ; 
  and 
  according 
  to 
  his 
  

   assumed 
  rate 
  of 
  deposit 
  and 
  the 
  gross 
  quantity 
  of 
  sand 
  under 
  

   Toronto 
  Island 
  he 
  concluded 
  that 
  the 
  age 
  of 
  the 
  Ontario 
  shore 
  

   is 
  8,000 
  years. 
  Plausible 
  as 
  this 
  method 
  might 
  seem, 
  such 
  

   assumptions 
  are 
  contrary 
  to 
  the 
  observations 
  and 
  mechanics 
  of 
  

   wave 
  action, 
  as 
  well 
  as 
  the 
  mass 
  of 
  sand, 
  being 
  derived 
  from 
  

   one 
  source. 
  

  

  In 
  transportation, 
  the 
  wave-action 
  varies 
  as 
  the 
  sixth 
  power 
  

   of 
  velocity. 
  Reduce 
  the 
  velocity 
  one-half 
  and 
  the 
  transporta- 
  

   tion 
  power 
  is 
  reduced 
  to 
  one 
  sixty-fourth. 
  Thus, 
  a 
  slight 
  

   obstruction 
  will 
  cause 
  a 
  deposition 
  of 
  the 
  wave-carried 
  sand, 
  

  

  * 
  Estimate 
  of 
  Post-Glacial 
  Time, 
  by 
  A. 
  P. 
  Coleman. 
  Trans. 
  International 
  

   Geol. 
  Congress, 
  for 
  1913, 
  pp. 
  455-472. 
  

  

  