﻿F. 
  B. 
  Taylor 
  — 
  Niagara 
  and 
  the 
  Great 
  Lakes. 
  269 
  

  

  sion 
  of 
  the 
  Erigan 
  gorge 
  thus 
  covers 
  the 
  duration 
  of 
  the 
  first 
  

   Lake 
  Algonquin, 
  Warren 
  Gulf, 
  and 
  the 
  second 
  Lake 
  Algonquin.* 
  

   If 
  this 
  is 
  a 
  true 
  statement 
  of 
  the 
  order 
  and 
  character 
  of 
  the 
  

   changes, 
  we 
  should 
  expect 
  to 
  find 
  the 
  strongest 
  confirmation 
  

   of 
  it 
  in 
  the 
  most 
  recent 
  beaches 
  with 
  confirmations 
  less 
  and 
  

   less 
  distinctly 
  marked 
  as 
  we 
  go 
  backward 
  in 
  time. 
  And 
  so 
  it 
  is. 
  

   In 
  the 
  article 
  on 
  the 
  second 
  Lake 
  Algonquin 
  are 
  detailed 
  the 
  

   facts 
  which 
  seem 
  to 
  show 
  the 
  existence 
  and 
  boundaries 
  of 
  that 
  

   lake, 
  and 
  that 
  it 
  filled 
  the 
  epoch 
  of 
  lake 
  history 
  immediately 
  

   preceding 
  the 
  present. 
  In 
  the 
  present 
  paper 
  have 
  been 
  stated 
  

   facts 
  in 
  support 
  of 
  the 
  view 
  that 
  the 
  Chippewa 
  beach 
  marks 
  

   the 
  climax 
  of 
  a 
  great 
  marine 
  invasion 
  which 
  formed 
  Warren 
  

   Gulf, 
  and 
  facts 
  which 
  show 
  with 
  less 
  distinctness, 
  but 
  with 
  

   some 
  degree 
  of 
  force, 
  the 
  existence 
  of 
  the 
  first 
  Lake 
  Algonquin. 
  

   To 
  this 
  it 
  may 
  be 
  added 
  that 
  if 
  we 
  accept 
  the 
  enlarged 
  gorge 
  

   below 
  the 
  Whirlpool 
  as 
  evidence 
  of 
  a 
  pre-Erigan 
  discharge 
  of 
  

   the 
  whole 
  lake 
  system 
  by 
  the 
  Niagara 
  river, 
  it 
  will 
  necessarily 
  

   follow 
  that 
  between 
  that 
  stage 
  and 
  the 
  Warren 
  Gulf 
  epoch 
  

   there 
  must 
  have 
  existed 
  a 
  first 
  Lake 
  Algonquin 
  marking 
  

   the 
  transition 
  from 
  the 
  first 
  Niagara 
  lakes 
  to 
  the 
  Warren 
  

   Gulf 
  epoch, 
  just 
  as 
  the 
  second 
  Lake 
  Algonquin 
  marked 
  the 
  

   transition 
  from 
  the 
  Warren 
  Gulf 
  epoch 
  back 
  to 
  the 
  second 
  

   Niagara 
  system. 
  

  

  Chronological 
  Conspectus. 
  

  

  At 
  its 
  maximum 
  the 
  great 
  Laurentide 
  glacier 
  covered 
  the 
  

   whole 
  area 
  of 
  the 
  Great 
  Lakes. 
  By 
  a 
  correlation 
  of 
  the 
  aban- 
  

   doned 
  shore 
  lines, 
  moraines 
  and 
  outlets, 
  and 
  the 
  gorges, 
  recently 
  

   submerged 
  shores 
  and 
  rivers 
  of 
  this 
  region 
  the 
  following 
  order 
  

   of 
  events 
  is 
  made 
  out 
  for 
  the 
  post-glacial 
  history 
  of 
  the 
  Great 
  

  

  * 
  An 
  idea 
  of 
  the 
  probable 
  slowness 
  of 
  the 
  recession 
  of 
  the 
  Erigan 
  Fall 
  and 
  the 
  

   time 
  required 
  to 
  make 
  its 
  gorge 
  may 
  be 
  gathered 
  from 
  the 
  following 
  words 
  of 
  

   Mr. 
  G. 
  K. 
  Gilbert 
  (Letter 
  in 
  Nature 
  for 
  May 
  17, 
  1894). 
  After 
  mentioning 
  the 
  

   several 
  accurate 
  surveys 
  that 
  have 
  been 
  made 
  of 
  the 
  Palls, 
  he 
  says 
  : 
  " 
  It 
  has 
  

   thus 
  become 
  known, 
  first, 
  that 
  in 
  the 
  middle 
  of 
  the 
  Horseshoe 
  Fall, 
  where 
  the 
  

   principal 
  body 
  of 
  water 
  descends, 
  the 
  brink 
  retrogrades 
  at 
  the 
  rate 
  of 
  four 
  or 
  five 
  

   feet 
  per 
  annum 
  ; 
  second, 
  that 
  the 
  American 
  Fall, 
  carrying 
  a 
  much 
  thinner 
  sheet 
  

   of 
  water, 
  retrogrades 
  so 
  slowly 
  that 
  its 
  rate 
  is 
  concealed 
  by 
  errors 
  of 
  survey." 
  

   Speaking 
  of 
  the 
  post-glacial 
  period 
  when 
  the 
  upper 
  lakes 
  had 
  their 
  outlet 
  in 
  some 
  

   other 
  direction 
  and 
  Niagara 
  was 
  fed 
  only 
  by 
  Lake 
  Krie, 
  he 
  says: 
  " 
  During 
  that 
  

   epoch 
  the 
  volume 
  of 
  the 
  river 
  was 
  so 
  small 
  that 
  canon-cutting 
  was 
  affected 
  only 
  

   by 
  the 
  feeble 
  process 
  now 
  illustrated 
  by 
  the 
  American 
  Fall." 
  This 
  was 
  the 
  

   Erigan 
  epoch. 
  (See 
  also 
  Mr 
  Gilbert's 
  " 
  History 
  of 
  Niagara 
  River," 
  Smithsonian 
  

   Report, 
  189o) 
  The 
  brink 
  of 
  the 
  American 
  Fall 
  is 
  to-day 
  almost 
  exactly 
  in 
  line 
  

   with 
  the 
  brink 
  of 
  the 
  canon 
  wall 
  above 
  and 
  below. 
  While 
  the 
  Horseshoe 
  Fall 
  

   has 
  receded 
  from 
  the 
  center 
  of 
  the 
  American 
  Fall 
  (about 
  3000 
  feet) 
  the 
  American 
  

   Fall 
  has 
  receded 
  at 
  most 
  not 
  more 
  than 
  100 
  feet 
  and 
  probably 
  less 
  than 
  50 
  feet, 
  

   and 
  it 
  still 
  strikes 
  at 
  its 
  foot 
  upon 
  rock 
  ledges 
  and 
  bowlders 
  which 
  it 
  has 
  not 
  yet 
  

   been 
  able 
  to 
  remove. 
  From 
  the 
  measured 
  difference 
  between 
  the 
  volume 
  of 
  the 
  

   St. 
  Clair 
  and 
  Niagara 
  rivers 
  it 
  is 
  found 
  that 
  the 
  contribution 
  of 
  Lake 
  Erie 
  is 
  about 
  

   three-elevenths 
  of 
  the 
  whole, 
  and 
  this, 
  as 
  Spencer 
  states, 
  is 
  almost 
  the 
  same 
  as 
  the 
  

   present 
  volume 
  of 
  the 
  American 
  Fall. 
  (See 
  also 
  L. 
  Y. 
  Schermerhorn, 
  this 
  Jour- 
  

   nal 
  vol. 
  xxxiii, 
  April 
  1887.) 
  The 
  true 
  Erigan 
  section 
  of 
  the 
  gorge 
  is 
  probably 
  

   about 
  three-fourths 
  of 
  a 
  mile 
  long. 
  

  

  