﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  

  

  69 
  

  

  worn 
  away 
  by 
  the 
  spray 
  generated 
  by 
  the 
  falHng 
  water, 
  thus 
  under- 
  

   mining 
  the 
  resistant 
  layer. 
  Such 
  undermining 
  may 
  be 
  seen 
  in 
  the 
  

   Cave 
  of 
  the 
  Winds. 
  In 
  course 
  of 
  time 
  this 
  undermining 
  progresses 
  

   so 
  far 
  that 
  the 
  projecting 
  portion 
  of 
  the 
  capping 
  stratum 
  breaks 
  

   down 
  for 
  want 
  of 
  support, 
  and 
  the 
  crest 
  Hne 
  of 
  the 
  fall 
  becomes 
  

   abruptly 
  altered. 
  The 
  fallen 
  fragments 
  accumulate 
  at 
  the 
  foot 
  of 
  

   the 
  fall, 
  where 
  they 
  will 
  remain 
  if 
  the 
  force 
  of 
  the 
  water 
  is 
  unable 
  

   to 
  move 
  them, 
  as 
  illustrated 
  by 
  the 
  rock 
  masses 
  lying 
  at 
  the 
  foot 
  

   of 
  the 
  American 
  fall. 
  If, 
  however, 
  the 
  force 
  of 
  the 
  falling 
  water 
  is 
  

   great 
  as 
  at 
  the 
  Horseshoe 
  falls, 
  these 
  blocks 
  will 
  be 
  moved 
  about, 
  

   perhaps 
  even 
  spun 
  about, 
  and 
  so 
  made 
  to 
  dig 
  a 
  deep 
  channel 
  below 
  

   the 
  falls. 
  In 
  the 
  soft 
  rocks 
  which 
  lie 
  at 
  the 
  foot 
  of 
  the 
  Horseshoe 
  

   falls 
  a 
  channel 
  probably 
  not 
  less 
  than 
  200 
  feet 
  in 
  depth 
  has 
  been 
  

   dug 
  in 
  this 
  manner. 
  (Fig. 
  15) 
  

  

  :i 
  . 
  j 
  t^ 
  

  

  

  ^^m^i'^jm^ 
  ( 
  ^!|gi 
  ^ 
  ,,. 
  

  

  Fig. 
  15 
  Sectional 
  view 
  of 
  the 
  Horseshoe 
  falls 
  showing 
  arrangement 
  of 
  strata, 
  and 
  depth 
  of 
  water 
  

   below 
  falls. 
  (After 
  Gilbert) 
  The 
  numbering 
  of 
  b3ds 
  corresponds 
  with 
  that 
  of 
  table. 
  

  

  When 
  we 
  consider 
  the 
  Niagara 
  gorge 
  in 
  detail 
  we 
  find 
  it 
  to 
  be 
  

   much 
  more 
  complex 
  than 
  would 
  at 
  first 
  appear. 
  The 
  first 
  ab- 
  

   normal 
  feature 
  which 
  presents 
  itself 
  in 
  a 
  map 
  view 
  of 
  the 
  entire 
  

   gorge 
  is 
  the 
  bi-crescentic 
  character 
  of 
  its 
  course, 
  with 
  the 
  rectan- 
  

   gular 
  turn 
  at 
  the 
  whirlpool, 
  a 
  course 
  very 
  different 
  from 
  that 
  which 
  

   we 
  are 
  accustomed 
  to 
  find 
  in 
  large 
  rivers 
  whose 
  direction 
  of 
  flow 
  

  

  