﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  79 
  

  

  hundred 
  feet 
  in 
  hight, 
  with 
  such 
  a 
  pronounced 
  alternation 
  of 
  hard 
  

   and 
  soft 
  layers. 
  We 
  must 
  rather 
  assume 
  that 
  a 
  separate 
  fall 
  existed 
  

   over 
  each 
  hard 
  layer, 
  and 
  that, 
  as 
  in 
  the 
  other 
  streams 
  flowing 
  north- 
  

   ward 
  over 
  these 
  same 
  strata, 
  these 
  falls 
  were 
  separated 
  from 
  one 
  

   another 
  by 
  considerable 
  distances. 
  If 
  then, 
  as 
  is 
  clearly 
  indicated 
  

   by 
  the 
  quartzose 
  sandstone 
  ledge 
  at 
  the 
  inlet 
  to 
  the 
  whirlpool, 
  the 
  

   lowest 
  of 
  these 
  falls 
  was 
  at 
  that 
  place, 
  the 
  other 
  two 
  or 
  three 
  must 
  

   have 
  been 
  at 
  some 
  distances 
  up 
  stream, 
  and 
  in 
  thai 
  case 
  it 
  is 
  not 
  too 
  

   much 
  to 
  assume 
  with 
  Pohlman, 
  that 
  the 
  upper 
  old 
  falls 
  over 
  the 
  

   Lockport 
  limestone 
  were 
  somewhere 
  near 
  where 
  the 
  gorge 
  is 
  now 
  

   spanned 
  by 
  the 
  railway 
  bridges. 
  Taylor, 
  however, 
  does 
  not 
  en- 
  

   counter 
  this 
  difiliculty, 
  for 
  he 
  assumes 
  that 
  the 
  St 
  Davids 
  gorge 
  was 
  

   iormed 
  by 
  an 
  interglacial 
  Niagara, 
  the 
  great 
  cataract 
  of 
  wdiich, 
  just 
  

   before 
  its 
  cessation 
  (probably 
  through 
  a 
  southward 
  diversion 
  of 
  the 
  

   drainage) 
  plunged 
  as 
  a 
  single 
  fall 
  over 
  the 
  cliff 
  into 
  the 
  basin 
  now 
  

   holding 
  the 
  whirlpool. 
  To 
  this 
  view 
  it 
  may 
  be 
  objected 
  that 
  the 
  

   old 
  St 
  Davids 
  gorge 
  is 
  not 
  such 
  as 
  would 
  be 
  formed 
  by 
  a 
  single 
  

   great 
  cataract, 
  since 
  it 
  flares 
  out 
  northward, 
  having 
  a 
  width 
  at 
  St 
  

   Davids 
  of 
  perhaps 
  twO' 
  miles. 
  Such 
  a 
  form 
  is 
  more 
  readily 
  ac- 
  

   counted 
  for 
  if 
  one 
  assumes 
  that 
  the 
  valley 
  was 
  made 
  by 
  the 
  headward 
  

   gnawing 
  of 
  an 
  obsequent 
  stream 
  and 
  its 
  various 
  branches. 
  Taylor 
  

   meets 
  this 
  objection 
  by 
  invoking 
  the 
  action 
  of 
  readvancing 
  ice 
  to 
  

   broaden 
  the 
  gorge, 
  but, 
  unless 
  the 
  last 
  ice 
  advance 
  was 
  from 
  a 
  very 
  

   different 
  direction 
  from 
  that 
  indicated 
  by 
  the, 
  striae 
  of 
  this 
  region, 
  

   this 
  hypothesis 
  will 
  scarcely 
  hold. 
  That 
  directiop, 
  as 
  already 
  noted, 
  

   is 
  30° 
  west 
  of 
  south, 
  while 
  the 
  direction 
  of 
  the 
  old 
  gorge 
  is 
  almost 
  

   due 
  northwest. 
  Why 
  may 
  we 
  not 
  assume 
  that 
  only 
  a 
  portion, 
  the 
  

   southern 
  one 
  of 
  the 
  gorge 
  of 
  the 
  whirlpool 
  rapids, 
  was 
  carved 
  by 
  

   the 
  Niagara 
  during 
  the 
  time 
  that 
  its 
  volume 
  was 
  diminished, 
  and 
  

   that 
  the 
  greater 
  portion 
  of 
  this 
  gorge 
  was 
  preglacial? 
  This 
  would 
  

   greatly 
  reduce 
  the 
  length 
  of 
  time 
  during 
  which 
  the 
  upper 
  lakes 
  dis- 
  

   charged 
  by 
  way 
  of 
  the 
  Nipissing-Mattawa 
  river, 
  though 
  probably 
  

   leaving 
  time 
  enough 
  for 
  the 
  waters 
  from 
  these 
  lakes 
  to 
  produce 
  all 
  

   the 
  erosion 
  features 
  found 
  in 
  this 
  ancient 
  stream 
  channel. 
  This 
  

   would 
  still 
  leave 
  the 
  Eddy 
  basin 
  to 
  be 
  accounted 
  for, 
  a 
  difficulty 
  

   which 
  may 
  perhaps 
  be 
  diminished 
  by 
  assuming 
  that 
  the 
  second 
  of 
  

  

  