﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  S^ 
  

  

  From 
  

  

  1842 
  

  

  to 
  

  

  The 
  American 
  falls 
  

   1875 
  

  

  Feet 
  a 
  year 
  

  

  •74 
  

  

  

  1875 
  

  

  u 
  

  

  1886 
  

  

  .11 
  

  

  *^ 
  T 
  r^:i+"o 
  rvi 
  tn 
  rv 
  

  

  1886 
  

  

  ii 
  

  

  1890 
  

  

  1.65 
  

  

  averaging^ 
  

  

  From 
  

  

  1842 
  

  

  to 
  

  

  1890 
  

   The 
  Horseshoe 
  falls 
  

  

  .64 
  

  

  From 
  

  

  1842 
  

  

  to 
  

  

  1875 
  

  

  2.01 
  

  

  

  1875 
  

  

  a 
  

  

  1886 
  

  

  1.86 
  

  

  

  1886 
  

  

  a 
  

  

  1890 
  

  

  5.01 
  

  

  averaging 
  

  

  

  

  

  

  From 
  

  

  1842 
  

  

  to 
  

  

  1890 
  

  

  2.18 
  

  

  This 
  shows 
  a 
  most 
  rapid 
  increase 
  in 
  the 
  rate 
  of 
  recession 
  during 
  

   the 
  four 
  years 
  between 
  the 
  last 
  two 
  surveys. 
  From 
  this 
  we 
  may 
  

   assume 
  that 
  the 
  mean 
  recession 
  of 
  a 
  cataract 
  combining 
  the 
  volumes 
  

   of 
  both 
  American 
  and 
  Horseshoe 
  falls, 
  such 
  as 
  existed 
  throughout 
  

   the 
  greater 
  period 
  of 
  gorge 
  excavation, 
  is 
  at 
  least 
  three 
  feet 
  a 
  year 
  

   and 
  may 
  be 
  as 
  high 
  as 
  four 
  or 
  even 
  five 
  feet 
  a 
  year. 
  

  

  The 
  first 
  to 
  make 
  use 
  of 
  this 
  known 
  rate 
  of 
  recession 
  in 
  estimat- 
  

   ing 
  the 
  age 
  of 
  the 
  gorge 
  was 
  Dr 
  Julius 
  Pohlman. 
  He 
  considered 
  

   that 
  the 
  gorge 
  of 
  the 
  whirlpool 
  rapids 
  and 
  other 
  portions 
  of 
  the 
  

   present 
  gorge 
  were 
  of 
  preglacial 
  origin, 
  and 
  so 
  reduced 
  the 
  length 
  

   of 
  post-glacial 
  time 
  to 
  3500 
  years. 
  Since 
  that 
  time 
  numerous 
  esti- 
  

   mates 
  of 
  the 
  age 
  of 
  the 
  gorge 
  have 
  been 
  made, 
  the 
  results 
  often 
  

   varying 
  widely, 
  owing 
  to 
  different 
  interpretations 
  given 
  to 
  the 
  nar- 
  

   row 
  portions 
  of 
  the 
  gorge. 
  It 
  is 
  perfectly 
  evident 
  that, 
  if 
  Niagara 
  

   was 
  deprived 
  of 
  seven 
  eighths 
  of 
  its 
  water 
  supply, 
  for 
  the 
  period 
  of 
  

   time 
  during 
  which 
  the 
  gorge 
  of 
  the 
  whirlpool 
  rapids 
  was 
  excavated 
  

   a 
  very 
  slow 
  rate 
  of 
  recession 
  must 
  have 
  obtained, 
  and 
  hence 
  the 
  age 
  

   of 
  the 
  gorge 
  is 
  greatly 
  increased. 
  Upham, 
  who 
  does 
  not 
  believe 
  

   in 
  the 
  withdrawal 
  of 
  the 
  waters, 
  makes 
  the 
  age 
  of 
  the 
  gorge 
  be- 
  

   tween 
  5000 
  and 
  10,000 
  years. 
  Spencer 
  and 
  Taylor 
  are 
  ardent 
  ad- 
  

   vocates 
  of 
  the 
  reduction 
  of 
  the 
  volume 
  of 
  water 
  during 
  a 
  prolonged 
  

   period, 
  when 
  the 
  supply 
  from 
  the 
  upper 
  Great 
  lakes 
  was 
  cut 
  off. 
  

  

  