﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  65 
  

  

  great 
  lakes 
  as 
  well 
  as 
  for 
  the 
  maritime 
  species 
  of 
  plants 
  found 
  in 
  the 
  

   lake 
  district. 
  It 
  must 
  however 
  be 
  borne 
  in 
  mind 
  that 
  this 
  marine 
  

   invasion 
  was 
  not 
  till 
  after 
  the 
  time 
  of 
  Lake 
  Iroquois, 
  for 
  fresh-water 
  

   fossils 
  have 
  been 
  found 
  in 
  the 
  beaches 
  of 
  this 
  lake. 
  

  

  The 
  tilting 
  of 
  the 
  land, 
  which 
  is 
  recorded 
  in 
  the 
  deformed 
  beaches, 
  

   has 
  not 
  yet 
  ceased, 
  as 
  recent 
  investigations 
  in 
  the 
  lake 
  regions 
  

   clearly 
  prove. 
  Mr 
  Gilbert 
  has 
  made 
  an 
  extended 
  study 
  of 
  this 
  prob- 
  

   lem; 
  and 
  he 
  has 
  been 
  led 
  to 
  the 
  assumption 
  ''that 
  the 
  whole 
  lake 
  

   region 
  is 
  being 
  lifted 
  on 
  one 
  side 
  or 
  depressed 
  on 
  the 
  other, 
  so 
  that 
  

   its 
  plane 
  is 
  bodily 
  canted 
  toward 
  the 
  southsouthwest, 
  and 
  that 
  the 
  

   rate 
  of 
  change 
  is 
  such 
  that 
  the 
  two 
  ends 
  of 
  a 
  line 
  lOO 
  miles 
  long 
  and 
  

   lying 
  in 
  a 
  southsouthwest 
  direction 
  are 
  relatively 
  displaced 
  .4 
  of 
  a 
  

   foot 
  in 
  100 
  years 
  ". 
  From 
  this 
  it 
  follows 
  that 
  " 
  the 
  waters 
  of 
  each 
  

   lake 
  are 
  gradually 
  rising 
  on 
  the 
  southern 
  and 
  western 
  shores 
  or 
  

   falling 
  on 
  the 
  northern 
  or 
  eastern 
  shores, 
  or 
  both 
  ". 
  This 
  implies 
  of 
  

   course 
  a 
  drowning 
  of 
  the 
  lower 
  courses 
  of 
  all 
  streams 
  entering 
  these 
  

   lakes 
  from 
  the 
  southwest 
  and 
  an 
  extension 
  of 
  those 
  entering 
  

   from 
  the 
  northeast. 
  Assuming 
  that 
  the 
  rate 
  and 
  character 
  of 
  

   change 
  will 
  be 
  constant 
  in 
  the 
  future, 
  the 
  following 
  interesting 
  re- 
  

   sults 
  have 
  been 
  predicted 
  by 
  Mr 
  Gilbert. 
  The 
  waters 
  of 
  Lake 
  Michi- 
  

   gan 
  at 
  Chicago 
  are 
  rising 
  at 
  the 
  rate 
  of 
  9 
  or 
  10 
  inches 
  a 
  century; 
  and 
  

   " 
  eventually, 
  unless 
  a 
  dam 
  is 
  erected 
  to 
  prevent, 
  Lake 
  Michigan 
  will 
  

   again 
  overflow 
  to 
  the 
  Illinois 
  river, 
  its 
  discharge 
  occupying 
  the 
  

   channel 
  carved 
  by 
  the 
  outlet 
  of 
  a 
  Pleistocene 
  glacial 
  lake. 
  . 
  . 
  

   Evidently 
  the 
  first 
  water 
  to 
  overflow 
  will 
  be 
  that 
  of 
  some 
  high 
  stage 
  

   of 
  the 
  lake 
  and 
  the 
  discharge 
  may 
  at 
  first 
  be 
  intermittent. 
  Such 
  

   high 
  water 
  discharge 
  will 
  occur 
  in 
  five 
  hundred 
  or 
  six 
  hundred 
  years. 
  

   For 
  a 
  mean 
  lake 
  stage 
  such 
  a 
  discharge 
  will 
  begin 
  in 
  about 
  one 
  

   thousand 
  years, 
  and 
  after 
  one 
  thousand 
  five 
  hundred 
  years 
  there 
  will 
  

   be 
  no 
  interruption. 
  In 
  about 
  two 
  thousand 
  years 
  the 
  IlHnois 
  river 
  

   and 
  the 
  Niagara 
  will 
  carry 
  equal 
  portions 
  of 
  the 
  surplus 
  water 
  of 
  the 
  

   great 
  lakes. 
  In 
  two 
  thousand 
  five 
  hundred 
  years 
  the 
  discharge 
  of 
  

   the 
  Niagara 
  will 
  be 
  intermittent, 
  falling 
  at 
  low 
  stages 
  of 
  the 
  lake, 
  

   and 
  in 
  three 
  thousand 
  five 
  hundred 
  years 
  there 
  will 
  be 
  no 
  Niagara. 
  

   The 
  basin 
  of 
  Lake 
  Erie 
  will 
  then 
  be 
  tributary 
  to 
  Lake 
  Huron, 
  the 
  

   current 
  being 
  reversed 
  in 
  the 
  Detroit 
  and 
  St 
  Clair 
  channels."^ 
  

  

  ^Gilbert, 
  G. 
  K. 
  Recent 
  earth 
  movements 
  in 
  the 
  great 
  lake 
  region. 
  i8th 
  

   an. 
  rep't 
  U. 
  S. 
  geol. 
  sur. 
  1896-97. 
  pt 
  2. 
  

  

  