﻿I40 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  From 
  the 
  Iroquois 
  to 
  the 
  Gilbert 
  levels 
  the 
  waters 
  fell 
  with 
  

   comparative 
  rapidity 
  by 
  the 
  removal 
  of 
  the 
  ice 
  dam. 
  The 
  apparent 
  

   lowering 
  of 
  the 
  Gilbert 
  waters 
  was 
  on 
  the 
  contrary 
  by 
  the 
  very 
  

   slow 
  uplifting 
  of 
  the 
  land 
  out 
  of 
  the 
  sea-level 
  waters. 
  This 
  rising 
  

   of 
  the 
  land 
  must 
  have 
  been 
  so 
  slow 
  as 
  to 
  give 
  opportunity 
  to 
  the 
  

   waves 
  at 
  all 
  minor 
  levels 
  to 
  produce 
  shore 
  line 
  phenomena, 
  and 
  

   many 
  such 
  are 
  found. 
  However, 
  such 
  proofs 
  of 
  the 
  presence 
  of 
  

   standing 
  waters 
  are 
  missing 
  over 
  long 
  stretches 
  of 
  even 
  the 
  summit 
  

   plane, 
  which 
  emphasizes 
  the 
  well 
  recognized 
  fact 
  that 
  absence 
  of 
  

   clear 
  wave 
  work 
  does 
  not 
  necessarily 
  prove 
  the 
  absence 
  of 
  standing 
  

   waters. 
  

  

  But 
  while 
  beach 
  phenomena 
  may 
  be 
  lacking 
  or 
  Aveak 
  over 
  wide 
  

   stretches 
  we 
  find 
  other 
  evidences 
  of 
  the 
  waters. 
  Either 
  by 
  the 
  

   lowering 
  of 
  the 
  Iroquois 
  Avaters 
  over 
  the 
  higher 
  ground 
  or 
  by 
  the 
  

   lifting 
  of 
  the 
  lower 
  ground 
  through 
  the 
  Gilbert 
  waters 
  all 
  the 
  

   land 
  surfaces 
  have 
  been 
  brought 
  into 
  the 
  zone 
  of 
  wave 
  action 
  and 
  

   subjected 
  to 
  erosion 
  or 
  deposition 
  by 
  the 
  agitated 
  waters. 
  In 
  

   consequence 
  the 
  steep 
  slopes, 
  the 
  projecting 
  rock 
  masses, 
  tables 
  

   and 
  knobs, 
  have 
  been 
  more 
  or 
  less 
  cleared 
  of 
  their 
  drift 
  and 
  

   specially 
  of 
  the 
  finer 
  material, 
  which 
  has 
  been 
  shifted 
  to 
  lower 
  

   levels. 
  The 
  broader 
  plateaus 
  and 
  plains 
  have 
  been 
  smoothed 
  

   and 
  the 
  lower 
  grounds, 
  valleys, 
  basins 
  and 
  hollows, 
  have 
  been 
  

   more 
  or 
  less 
  filled 
  or 
  silted 
  with 
  the 
  detritus, 
  sand 
  or 
  clay, 
  washed 
  

   from 
  the 
  higher 
  ground. 
  This 
  action 
  explains 
  two 
  striking 
  

   characters 
  of 
  the 
  region, 
  the 
  areas 
  of 
  bare 
  rocks 
  and 
  the 
  silt- 
  

   filled 
  basins, 
  which 
  will 
  be 
  discussed 
  later. 
  

  

  Conclusive 
  proof 
  that 
  the 
  lower 
  waters 
  were 
  confluent 
  with 
  

   the 
  sea 
  would 
  be 
  the 
  finding 
  of 
  marine 
  fossils. 
  Such 
  have 
  not 
  

   yet 
  been 
  found 
  in 
  the 
  Ontario 
  basin, 
  though 
  they 
  are 
  abundant 
  

   in 
  the 
  Champlain 
  and 
  St 
  Lawrence 
  valleys, 
  and 
  marine 
  shells 
  

   have 
  been 
  found 
  as 
  far 
  west 
  as 
  Ogdensburg. 
  

  

  Atmospheric 
  erosion. 
  The 
  whole 
  region, 
  above 
  the 
  Ontario 
  

   level, 
  has 
  long 
  been 
  subjected 
  to 
  a 
  renewal 
  of 
  the 
  atmospheric 
  

   agencies. 
  The 
  length 
  of 
  time 
  is 
  unknown, 
  but 
  is 
  not 
  equal 
  for 
  all 
  

   the 
  area. 
  For 
  the 
  lower 
  plains, 
  near 
  the 
  present 
  lake, 
  the 
  time 
  must 
  

   somewhat 
  exceed 
  the 
  life 
  of 
  Ontario; 
  while 
  for 
  the 
  higher 
  ground, 
  

   above 
  the 
  Gilbert 
  levels, 
  the 
  time 
  must 
  cover 
  not 
  only 
  the 
  life 
  of 
  

   Ontario 
  but 
  also 
  that 
  of 
  Gilbert 
  gulf. 
  If 
  we 
  estimate 
  the 
  life 
  of 
  

   each 
  of 
  these 
  water 
  bodies 
  as 
  10,000 
  years 
  it 
  may 
  give 
  some 
  fair 
  

   conception 
  of 
  the 
  duration 
  in 
  years. 
  For 
  lands 
  above 
  the 
  reach 
  

   of 
  Lake 
  Iroquois 
  its 
  length 
  of 
  life 
  must 
  be 
  added 
  to 
  the 
  time 
  of 
  

   exposure, 
  at 
  least 
  another 
  10,000 
  years. 
  It 
  is 
  likely 
  that 
  these 
  fig- 
  

   ures 
  are 
  too 
  small 
  rather 
  than 
  too 
  large. 
  

  

  