﻿F. 
  B. 
  Taylor 
  — 
  Niagara 
  and 
  the 
  Great 
  Lakes. 
  267 
  

  

  same 
  as 
  D 
  and 
  E, 
  the 
  differences 
  being 
  no 
  greater 
  than 
  those 
  

   which 
  may 
  arise 
  from 
  the 
  action 
  of 
  a 
  river 
  of 
  constant 
  volume. 
  

   The 
  argument 
  for 
  difference 
  of 
  volume 
  is 
  as 
  strong 
  by 
  the 
  

   comparison 
  of 
  A 
  and 
  B 
  with 
  C 
  as 
  in 
  the 
  other 
  two 
  sections. 
  

   It 
  seems 
  certain 
  that 
  the 
  upper 
  lakes 
  did 
  not 
  drain 
  through 
  

   the 
  St. 
  Clair 
  river 
  during 
  the 
  making 
  of 
  the 
  Erigan 
  section. 
  

   The 
  great 
  cataract 
  has 
  therefore 
  had 
  two 
  independent 
  periods 
  

   of 
  activity 
  separated 
  by 
  the 
  Erigan 
  period. 
  This 
  much 
  seems 
  

   clear 
  from 
  an 
  examination 
  of 
  the 
  gorge 
  alone. 
  

  

  The 
  level 
  of 
  the 
  water 
  in 
  the 
  Ontario 
  basin 
  has 
  undergone 
  

   several 
  changes 
  during 
  the 
  making 
  of 
  the 
  gorge. 
  At 
  the 
  

   beginning 
  of 
  the 
  first 
  Niagara 
  period 
  the 
  water 
  probably 
  stood 
  

   higher 
  than 
  now 
  at 
  Lewiston, 
  but 
  not 
  long 
  above 
  the 
  Iroquois 
  

   level. 
  Then 
  it 
  gradually 
  fell 
  away 
  to 
  a 
  level 
  80 
  to 
  100 
  feet 
  

   lower 
  than 
  to-day. 
  All 
  this 
  was 
  during 
  the 
  first 
  Niagara 
  

   period. 
  The 
  great 
  cataract 
  stopped 
  either 
  at 
  Foster's 
  Flat 
  or 
  

   at 
  the 
  upper 
  side 
  of 
  the 
  Whirlpool. 
  There 
  is 
  still 
  some 
  doubt 
  

   on 
  this 
  point, 
  with 
  probability, 
  it 
  now 
  seems 
  to 
  me, 
  in 
  favor 
  of 
  

   the 
  latter 
  place. 
  

  

  From 
  the 
  Whirlpool 
  up 
  to 
  a 
  point 
  a 
  few 
  rods 
  above 
  the 
  

   cantilever 
  bridge 
  the 
  gorge 
  is 
  narrow 
  and 
  shallow, 
  and 
  the 
  

   latter 
  character 
  continues 
  also 
  below 
  the 
  Whirlpool 
  to 
  the 
  

   lower 
  end 
  of 
  Foster's 
  Flat. 
  It 
  was 
  presumably 
  about 
  at 
  the 
  

   middle 
  of 
  the 
  Erigan 
  period 
  that 
  the 
  Iroquois 
  beach 
  was 
  made 
  

   at 
  Lewiston, 
  135 
  feet 
  above 
  present 
  lake 
  level. 
  The 
  water 
  at 
  

   that 
  time 
  stood 
  in 
  the 
  gorge 
  at 
  a 
  level 
  slightly 
  higher 
  than 
  the 
  

   water 
  level 
  at 
  the 
  foot 
  of 
  the 
  present 
  falls. 
  This, 
  with 
  the 
  

   smallness 
  of 
  'the 
  Erigan 
  Fall, 
  explains 
  why 
  this 
  part 
  of 
  the 
  

   gorge 
  is 
  shallow. 
  After 
  that 
  the 
  water 
  fell 
  away 
  again 
  to 
  80 
  

   or 
  100 
  feet 
  below 
  its 
  present 
  level 
  during 
  the 
  early 
  part 
  of 
  the 
  

   present 
  period 
  of 
  the 
  cataract 
  and 
  then 
  more 
  recently 
  was 
  

   raised 
  again 
  to 
  its 
  present 
  level 
  by 
  the 
  Champlain 
  uplift 
  which 
  

   elevated 
  the 
  outlet 
  of 
  Lake 
  Ontario. 
  These 
  changes, 
  with 
  the 
  

   harder 
  quality 
  and 
  higher 
  level 
  of 
  the 
  Medina 
  rocks 
  in 
  the 
  

   bottom 
  of 
  the 
  gorge, 
  explain 
  its 
  salient 
  peculiarities 
  below 
  the 
  

   Whirlpool, 
  and 
  the 
  changes 
  in 
  the 
  volume 
  of 
  the 
  river 
  find 
  

   their 
  correlatives 
  in 
  the 
  history 
  of 
  the 
  upper 
  lakes. 
  

  

  The 
  Succession 
  of 
  the 
  Lake 
  Stages. 
  

  

  In 
  the 
  paper 
  on 
  the 
  second 
  Lake 
  Algonquin 
  it 
  was 
  shown 
  

   that 
  the 
  whole 
  interval 
  from 
  the 
  present 
  day 
  back 
  to 
  the 
  time 
  

   of 
  Warren 
  Gulf 
  is 
  completely 
  filled 
  by 
  the 
  series 
  of 
  events 
  

   there 
  described. 
  The 
  gorge 
  of 
  Niagara 
  from 
  the 
  falls 
  to 
  the 
  

   cantilever 
  bridge 
  suggests 
  no 
  change 
  or 
  variation 
  in 
  the 
  volume 
  

   of 
  the 
  river. 
  But 
  at 
  and 
  below 
  the 
  bridge 
  th 
  gorge 
  grows 
  

   narrow 
  and 
  shallow. 
  Considering 
  the 
  uniformity 
  of 
  the 
  geolog- 
  

  

  