﻿266 
  

  

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

  

  The 
  Niagara 
  Gorge. 
  

  

  In 
  his 
  admirable 
  paper 
  

   Prof. 
  Spencer 
  presents 
  fi\ 
  

  

  

  A 
  

  

  

  

  1 
  1 
  1 
  IV. 
  

  

  

  A 
  

  

  loo 
  

  

  100_ 
  

  

  

  

  Niagara-'---' 
  

  

  { 
  J 
  

  

  

  

  Clinton— 
  "^^ 
  

  

  hi 
  J 
  

  

  

  ^k~ 
  -¥ 
  

  

  . 
  , 
  . 
  _-_-_-. 
  

  

  z-m 
  \ 
  

  

  

  _-_-.-Ar 
  rl 
  

  

  -20 
  

  

  -_-_-_ 
  

  

  y?r:-A 
  / 
  

  

  

  

  T 
  , 
  1 
  , 
  

  

  S00 
  I0QO 
  

  

  on 
  the 
  "Duration 
  of 
  Niagara 
  Falls," 
  

   e 
  cross 
  sections 
  of 
  the 
  Niagara 
  gorge. 
  

   A 
  close 
  comparison 
  of 
  them 
  is 
  so 
  

   instructive 
  that 
  I 
  have 
  reproduced 
  

   them 
  in 
  a 
  single 
  cut. 
  Some 
  of 
  the 
  

   details 
  of 
  his 
  drawings 
  are 
  omitted. 
  

   The 
  significance 
  of 
  the 
  difference 
  

   between 
  C 
  and 
  D 
  and 
  E 
  was 
  suffi- 
  

   ciently 
  explained 
  in 
  the 
  paper 
  on 
  the 
  

   second 
  Lake 
  Algonquin. 
  The 
  con- 
  

   clusion 
  then 
  reached 
  was, 
  that 
  con- 
  

   sidering 
  the 
  uniformity 
  of 
  the 
  geo- 
  

   logical 
  structure 
  it 
  must 
  be 
  admitted 
  

   that 
  if 
  D 
  and 
  E 
  were 
  made 
  by 
  the 
  

   great 
  cataract, 
  C 
  could 
  not 
  have 
  

   been, 
  but 
  must 
  have 
  been 
  made 
  by 
  

   a 
  stream 
  of 
  much 
  less 
  volume. 
  That 
  

   stream 
  was 
  the 
  Erigan 
  river, 
  drain- 
  

   ing 
  only 
  Lake 
  Erie, 
  which 
  did 
  not 
  

   then 
  receive 
  the 
  discharge 
  of 
  the 
  

   upper 
  lakes. 
  Prof. 
  Spencer's 
  ex- 
  

   planation, 
  that 
  C 
  was 
  made 
  while 
  

   the 
  great 
  cataract 
  had 
  a 
  sheer 
  fall 
  

   of 
  420 
  feet 
  was 
  shown 
  to 
  be 
  incon- 
  

   sistent 
  with 
  the 
  obvious 
  fact 
  that 
  

   the 
  Erigan 
  section 
  of 
  the 
  gorge 
  is 
  

   much 
  shallower 
  than 
  the 
  wider 
  sec- 
  

   tion 
  above. 
  

  

  If 
  this 
  explanation 
  of 
  the 
  origin 
  

   of 
  the 
  Erigan 
  gorge, 
  which 
  is 
  repre- 
  

   sented 
  by 
  C, 
  is 
  valid, 
  then 
  the 
  same 
  

   argument 
  applies 
  to 
  the 
  lower 
  sec- 
  

   tion 
  of 
  the 
  gorge 
  which 
  is 
  repre- 
  

   sented 
  by 
  B 
  and 
  A. 
  These 
  sections 
  

   must 
  have 
  been 
  made 
  by 
  the 
  great 
  

   cataract 
  and 
  not 
  by 
  the 
  Erigan 
  Fall. 
  

   For 
  A 
  and 
  B 
  are 
  almost 
  exactly 
  the 
  

  

  Note 
  to 
  -Fig. 
  2. 
  — 
  These 
  cross-sections 
  are 
  situated 
  as 
  follows 
  beginning 
  at 
  

   the 
  north 
  or 
  lower 
  end 
  of 
  the 
  gorge. 
  A, 
  half 
  a 
  mile 
  above 
  lower 
  end 
  ; 
  B, 
  at 
  

   Foster's 
  Flat; 
  C, 
  at 
  "Whirlpool 
  rapids 
  just 
  below 
  the 
  railroad 
  bridges; 
  D, 
  at 
  

   Johnson's 
  Ridge 
  about 
  one 
  mile 
  above 
  the 
  bridges 
  ; 
  E, 
  at 
  the 
  Horseshoe 
  Fall. 
  

   The 
  top 
  of 
  the 
  sections 
  is 
  hard 
  Niagara 
  limestone. 
  Then 
  comes 
  softer, 
  shaley 
  

   layers 
  with 
  the 
  harder 
  Medina 
  below. 
  00, 
  level 
  of 
  Lake 
  Ontario 
  ; 
  rr, 
  river 
  level 
  ; 
  

   m, 
  level 
  of 
  Iroquois 
  marine 
  water 
  during 
  middle 
  of 
  Erigan 
  epoch 
  ; 
  bb, 
  probable 
  

   bottom 
  of 
  gorge 
  (about 
  75 
  feet 
  below 
  rr). 
  Both 
  scales 
  in 
  feet. 
  The 
  strata 
  are 
  

   substantially 
  the 
  same 
  on 
  both 
  sides 
  of 
  the 
  gorge. 
  These 
  sections 
  are 
  copied 
  

   from 
  Prof. 
  J. 
  W. 
  Spencer's 
  cuts 
  in 
  his 
  paper 
  in 
  this 
  Journal 
  for 
  December 
  1894, 
  

   with 
  some 
  omissions 
  and 
  also 
  with 
  some 
  additions. 
  Note 
  the 
  shallowness 
  of 
  C 
  

   (bottom 
  about 
  at 
  bb) 
  and 
  narrowness 
  at 
  top 
  as 
  compared 
  with 
  A, 
  B, 
  D 
  or 
  E. 
  

  

  5~Q0 
  1000 
  

  

  