﻿78 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  tion 
  in 
  volume 
  would 
  lead 
  to 
  a 
  great 
  decrease 
  in 
  cutting 
  power, 
  and 
  

   that 
  the 
  resultant 
  gorge 
  would 
  hence 
  be 
  much 
  narrower 
  and 
  shal- 
  

   lower 
  than 
  the 
  one 
  cut 
  when 
  the 
  water 
  supply 
  was 
  as 
  large 
  as 
  at 
  

   present. 
  The 
  Nipissing-Mattawa 
  outlet 
  was 
  finally 
  closed, 
  as 
  we 
  

   have 
  seen, 
  by 
  the 
  elevation 
  of 
  the 
  land 
  on 
  the 
  north, 
  and 
  the 
  upper 
  

   lakes 
  assumed 
  their 
  modern 
  outlet 
  by 
  way 
  of 
  Port 
  Huron. 
  As 
  a 
  

   result 
  the 
  water 
  supply 
  of 
  Niagara 
  was 
  greatly 
  increased, 
  and 
  the 
  

   broad 
  and 
  deep 
  gorge, 
  which 
  extends 
  from 
  south 
  of 
  the 
  railwa}r 
  

   bridges 
  to 
  the 
  present 
  falls, 
  was 
  cut 
  by 
  a 
  cataract 
  of 
  the 
  size 
  of 
  the 
  

   present 
  Horseshoe 
  falls, 
  which 
  in 
  addition 
  carried 
  the 
  water 
  now 
  

   passing 
  over 
  the 
  American 
  falls. 
  This 
  correlation 
  between 
  change 
  

   in 
  drainage 
  of 
  the 
  upper 
  lakes 
  and 
  change 
  in 
  size 
  of 
  the 
  gorge 
  of 
  

   Niagara 
  is 
  certainly 
  very 
  suggestive, 
  and 
  seems 
  admirably 
  to 
  ac- 
  

   count 
  for 
  many 
  features 
  observed 
  in 
  the 
  gorge. 
  For 
  example, 
  it 
  

   .explains 
  satisfactorily 
  the 
  sudden 
  widening 
  of 
  the 
  gorge 
  just 
  before 
  

   reaching 
  the 
  whirlpool, 
  forming 
  what 
  Taylor 
  has 
  called 
  the 
  Eddy 
  

   basin, 
  from 
  the 
  strong 
  eddy 
  which 
  characterizes 
  this 
  portion 
  of 
  the 
  

   river. 
  This 
  wider 
  part 
  of 
  the 
  gorge 
  Taylor 
  believes 
  was 
  formed 
  by 
  

   the 
  same 
  large-volume 
  river 
  which 
  cut 
  out 
  the 
  broad 
  channel 
  north 
  

   of 
  the 
  whirlpool, 
  and 
  he 
  farther 
  thinks, 
  that 
  the 
  sudden 
  change 
  from 
  

   this 
  broad 
  channel 
  to 
  the 
  narrow 
  one 
  of 
  the 
  whirlpool 
  rapids 
  marks- 
  

   the 
  reduction 
  in 
  volume 
  of 
  water 
  on 
  the 
  opening 
  of 
  the 
  Nipissing- 
  

   Mattawa 
  channel, 
  which 
  had 
  hitherto 
  been 
  blocked 
  by 
  the 
  remnant 
  

   of 
  the 
  Laurentian 
  glacier. 
  There 
  are 
  however 
  several 
  features- 
  

   which 
  must 
  be 
  satisfactorily 
  explained 
  before 
  this 
  theory 
  (which 
  

   Upham 
  rejects 
  on 
  grounds 
  already 
  stated) 
  can 
  be 
  accepted. 
  It 
  is 
  

   highly 
  probable 
  that 
  the 
  gorge 
  of 
  St 
  Davids 
  was 
  worn 
  back 
  beyond 
  

   the 
  whirlpool. 
  From 
  the 
  great 
  depth 
  of 
  the 
  whirlpool 
  basin, 
  and 
  

   the 
  presence 
  of 
  the 
  quartzose 
  sandstone 
  bed 
  at 
  the 
  Inlet 
  to 
  it, 
  it 
  

   seems 
  probable 
  that 
  a 
  fall 
  existed 
  here 
  in 
  the 
  ancient 
  stream 
  which 
  

   carved 
  the 
  St 
  Davids 
  channel. 
  That 
  channel 
  has 
  probably 
  a 
  depth 
  

   similar 
  to 
  or 
  greater 
  than 
  that 
  of 
  the 
  part 
  now 
  constituting 
  the 
  

   whirlpool 
  basin. 
  Now, 
  if, 
  as 
  we 
  have 
  reason 
  to 
  believe, 
  this 
  old 
  

   channel 
  was 
  formed 
  by 
  an 
  obsequent 
  stream 
  of 
  moderate 
  volum 
  i. 
  

   flowing 
  northward 
  to 
  the 
  Ontario 
  lowland, 
  it 
  can 
  hardly 
  be 
  assumed 
  

   that 
  there 
  was 
  but 
  one 
  continuous 
  fall 
  of 
  from 
  four 
  hundred 
  to 
  five 
  

  

  