﻿THE 
  GEOLOGICAL 
  HISTORY 
  OF 
  NEW 
  YORK 
  STATE 
  IOQ. 
  

  

  by 
  ice 
  erosion, 
  and 
  during 
  the 
  Algonquin-Iroquois 
  stage 
  of 
  the 
  

   Great 
  Lakes 
  history, 
  we 
  have 
  learned 
  that 
  these 
  lakes 
  discharged 
  

   through 
  the 
  Mohawk 
  valley 
  and 
  across 
  the 
  Little 
  Falls 
  divide. 
  It 
  

   was 
  the 
  passage 
  of 
  this 
  great 
  volume 
  of 
  water 
  over 
  the 
  divide 
  

   which 
  caused 
  the 
  cutting 
  of 
  most 
  of 
  the 
  gorge 
  as 
  we 
  now 
  find 
  it, 
  

   except 
  for 
  the 
  narrow 
  trench 
  in 
  the 
  hard, 
  underlying 
  Precambric 
  

   rock 
  which 
  is 
  no 
  doubt 
  due 
  to 
  postglacial 
  erosion. 
  During 
  the 
  

   Iroquois 
  stage 
  an 
  arm 
  of 
  the 
  lake 
  extended 
  along 
  the 
  valley 
  from 
  

   Rome 
  to 
  Little 
  Falls. 
  All 
  the 
  streams 
  from 
  north 
  and 
  south 
  which 
  

   entered 
  this 
  arm 
  of 
  the 
  lake 
  were 
  heavily 
  charged 
  with 
  debris 
  from 
  

   the 
  newly 
  drift-covered 
  regions 
  and, 
  the 
  current 
  not 
  being 
  strong 
  

   enough 
  to 
  carry 
  away 
  the 
  debris, 
  the 
  valley 
  from 
  Rome 
  to 
  Little 
  

   Falls 
  was 
  built 
  up 
  (aggraded) 
  to 
  such 
  an 
  extent 
  that, 
  after 
  the 
  dis- 
  

   appearance 
  of 
  Lake 
  Iroquois, 
  -the 
  drainage 
  from 
  Rome 
  was 
  able 
  to 
  

   continue 
  eastward. 
  Thus 
  we 
  have 
  here 
  a 
  very 
  fine 
  example 
  of 
  

   exact 
  reversal 
  of 
  drainage 
  directly 
  due 
  to 
  glaciation 
  and 
  by 
  this 
  

   means 
  the 
  upper 
  waters 
  of 
  the 
  Mohawk 
  were 
  added 
  to 
  the 
  pre- 
  

   glacial 
  Mohawk. 
  

  

  Closely 
  associated 
  with 
  the 
  above 
  is 
  the 
  postglacial 
  history 
  of 
  

   West 
  Canada 
  creek 
  and 
  the 
  famous 
  chasm 
  at 
  Trenton 
  Falls. 
  The 
  

   preglacial 
  West 
  Canada 
  creek 
  flowed 
  from 
  Prospect 
  (upper 
  end 
  

   of 
  Trenton 
  chasm) 
  past 
  Holland 
  Patent, 
  through 
  the 
  valley 
  of 
  the 
  

   present 
  Nine 
  Mile 
  creek, 
  and 
  into 
  the 
  Rome 
  river 
  opposite 
  the 
  

   village 
  of 
  Oriskany. 
  This 
  channel 
  was 
  completely 
  blocked 
  by 
  

   glacial 
  drift 
  at 
  Prospect 
  so 
  that 
  the 
  creek 
  was 
  forced 
  to 
  find 
  a 
  new 
  

   course 
  southward 
  over 
  the 
  limestone 
  at 
  Trenton 
  Falls, 
  and 
  thence 
  

   southeastward 
  to 
  its 
  present 
  mouth 
  at 
  Herkimer. 
  The 
  gorge, 
  be- 
  

   tween 
  Prospect 
  and 
  Trenton 
  Falls 
  villages, 
  is 
  2^ 
  miles 
  long 
  and 
  

   from 
  100 
  to 
  200 
  feet 
  deep, 
  and 
  has 
  been 
  cut 
  into 
  the 
  Trenton 
  lime- 
  

   stone 
  by 
  the 
  postglacial 
  stream. 
  It 
  contains 
  five 
  or 
  six 
  waterfalls 
  

   ranging 
  in 
  height 
  from 
  10 
  to 
  126 
  feet, 
  the 
  total 
  drop 
  of 
  the 
  water 
  

   in 
  the 
  2^ 
  miles 
  of 
  the 
  gorge 
  being 
  360 
  feet 
  (see 
  plates 
  43 
  and 
  44). 
  

  

  In 
  the 
  southeastern 
  Adirondacks; 
  the 
  upper 
  waters 
  of 
  the 
  Hudson 
  

   river 
  present 
  some 
  very 
  interesting 
  examples 
  of 
  drainage 
  changes. 
  

   In 
  fact, 
  it 
  is 
  not 
  too 
  much 
  to 
  say 
  that 
  the 
  larger 
  drainage 
  features 
  

   of 
  that 
  region 
  have 
  been 
  well 
  nigh 
  revolutionized 
  as 
  a 
  result 
  of 
  

   glaciation. 
  The 
  accompanying 
  sketch 
  map 
  (fig. 
  37) 
  gives 
  a 
  fair 
  idea 
  

   of 
  the 
  changes, 
  but 
  reference 
  to 
  the 
  State 
  geologic 
  map 
  and 
  to 
  the 
  

   topographic 
  maps 
  of 
  the 
  region 
  is 
  greatly 
  to 
  be 
  desired. 
  The 
  State 
  

   geologic 
  map 
  shows 
  two 
  distinct 
  embayments 
  of 
  Paleozoic 
  rocks 
  

   forming 
  valleys 
  which 
  extend 
  northward, 
  one 
  to 
  Northville 
  and 
  

   the 
  other 
  to 
  Corinth, 
  and 
  into 
  the 
  mass 
  of 
  Precambric 
  rocks 
  of 
  the 
  

  

  