﻿Il6 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  length 
  of 
  the 
  gorge 
  is 
  7 
  miles, 
  and 
  if 
  we 
  consider 
  the 
  rate 
  of 
  reces- 
  

   sion 
  to 
  have 
  been 
  always 
  5 
  feet 
  a 
  year, 
  the 
  length 
  of 
  time 
  necessary 
  

   to 
  cut 
  Niagara 
  gorge 
  would 
  be 
  something 
  over 
  7000 
  years. 
  But 
  

   the 
  problem 
  is 
  not 
  so 
  simple, 
  since 
  we 
  know 
  that 
  at 
  the 
  time 
  of, 
  or 
  

   shortly 
  after, 
  the 
  beginning 
  of 
  the 
  river, 
  the 
  upper 
  lakes 
  drained 
  

   out 
  through 
  the 
  Trent 
  river, 
  and 
  then 
  still 
  later 
  through 
  the 
  Ottawa 
  

   river. 
  So 
  it 
  is 
  evident 
  that, 
  for 
  a 
  good 
  part 
  of 
  the 
  time 
  since 
  the 
  

   ice 
  retreated 
  from 
  the 
  Niagara 
  region, 
  the 
  volume 
  of 
  water 
  passing 
  

   over 
  the 
  falls 
  was 
  notably 
  diminished, 
  and 
  hence 
  the 
  length 
  of 
  time 
  

   for 
  the 
  gorge 
  cutting 
  increased. 
  The 
  best 
  estimates 
  for 
  the 
  length 
  

   of 
  time 
  since 
  the 
  ice 
  retreated 
  from 
  the 
  Niagara 
  region 
  vary 
  from 
  

   7000 
  to 
  50,000 
  years, 
  an 
  average 
  being 
  about 
  25,000 
  years. 
  In 
  a 
  

   similar 
  way 
  the 
  time 
  based 
  upon 
  the 
  recession 
  of 
  St 
  Anthony's 
  

   falls, 
  Minnesota, 
  range 
  from 
  about 
  10,000 
  to 
  16,000 
  years. 
  While 
  

   closer 
  estimates 
  are 
  practically 
  impossible, 
  it 
  is 
  at 
  least 
  certain 
  that 
  

   the 
  time 
  since 
  the 
  Ice 
  age 
  is 
  far 
  less 
  than 
  its 
  duration, 
  and 
  that, 
  

   for 
  the 
  region 
  of 
  New 
  York 
  State, 
  the 
  final 
  ice 
  retreat 
  occurred 
  

   only 
  a 
  very 
  short 
  time 
  ago. 
  

  

  When 
  we 
  consider 
  the 
  slight 
  amount 
  of 
  weathering 
  and 
  erosion 
  

   of 
  the 
  latest 
  glacial 
  drift, 
  we 
  are 
  also 
  forced 
  to 
  conclude 
  that 
  the 
  

   time 
  since 
  the 
  close 
  of 
  the 
  Ice 
  age 
  in 
  New 
  York 
  is 
  to 
  be 
  measured 
  

   only 
  by 
  some 
  thousands 
  of 
  years. 
  Thus 
  kames, 
  drumlins, 
  extinct 
  

   lake 
  deltas, 
  and 
  moraines 
  with 
  their 
  kettle 
  holes 
  have 
  generally 
  

   been 
  very 
  little 
  affected 
  by 
  ice 
  erosion 
  since 
  their 
  formation. 
  

  

  Champlain 
  subsidence 
  and 
  recent 
  elevation 
  of 
  New 
  York 
  

   State. 
  We 
  have 
  already 
  shown 
  that 
  at 
  about 
  the 
  beginning 
  of 
  

   the 
  glacial 
  epoch 
  the 
  region 
  of 
  New 
  York 
  State, 
  especially 
  along 
  

   the 
  eastern 
  side, 
  was 
  much 
  higher 
  than 
  it 
  is 
  today, 
  positive 
  proof 
  

   for 
  this 
  being 
  afforded 
  by 
  the 
  submerged 
  Hudson 
  river 
  channel 
  

   which 
  must 
  have 
  been 
  cut 
  when 
  the 
  land 
  was 
  higher. 
  Toward 
  the 
  

   close 
  of 
  the 
  Ice 
  age 
  and 
  shortly 
  after 
  (Champlain 
  epoch), 
  we 
  know- 
  

   that 
  the 
  land 
  had 
  subsided 
  to 
  a 
  level 
  even 
  lower 
  than 
  that 
  of 
  today. 
  

   It 
  was 
  during 
  this 
  period 
  of 
  subsidence 
  that 
  the 
  lower 
  Hudson 
  and 
  

   St 
  Lawrence 
  channels 
  were 
  submerged 
  and 
  the 
  sea 
  coast 
  was 
  

   transferred 
  to 
  more 
  nearly 
  its 
  present 
  position. 
  But 
  as 
  the 
  land 
  

   was 
  even 
  lower 
  than 
  now, 
  the 
  lowlands 
  of 
  Long 
  island 
  and 
  in 
  the 
  

   vicinity 
  of 
  New 
  York 
  City 
  were 
  under 
  water 
  and 
  a 
  narrow 
  arm. 
  

   of 
  the 
  sea 
  extended 
  through 
  the 
  Hudson 
  and 
  Champlain 
  valleys 
  

   to 
  join 
  a 
  broad 
  arm 
  of 
  the 
  sea 
  which 
  reached 
  up 
  the 
  St 
  Lawrence 
  

   valley 
  and 
  even 
  into 
  the 
  Ontario 
  basin 
  (see 
  figure 
  34). 
  This 
  Cham- 
  

   plain 
  sea 
  existed 
  at 
  the 
  time 
  of 
  the 
  Nipissing 
  Great 
  Lakes 
  already 
  

   described. 
  Champlain 
  sea 
  beaches, 
  containing 
  marine 
  shells 
  and 
  

  

  