﻿100 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  By 
  successive 
  stages, 
  due 
  to 
  a 
  complete 
  removal 
  of 
  ice 
  from 
  

   central 
  New 
  York 
  and 
  a 
  draining 
  of 
  the 
  glacial 
  lake 
  in 
  the 
  Mo- 
  

   hawk 
  valley, 
  the 
  waters 
  dropped 
  to 
  below 
  Warren 
  level 
  until 
  Lake 
  

   Iroquois 
  was 
  formed 
  (see 
  figure 
  33). 
  The 
  old 
  beach 
  line 
  of 
  this 
  

   lake 
  is 
  still 
  plainly 
  visible 
  in 
  New 
  York 
  and 
  with 
  some 
  slight 
  inter- 
  

   ruptions 
  has 
  been 
  traced 
  from 
  near 
  the 
  mouth 
  of 
  Niagara 
  river 
  to 
  

   just 
  north 
  of 
  Rochester, 
  past 
  Syracuse, 
  along 
  the 
  south, 
  east, 
  and 
  

   north 
  sides 
  of 
  Oneida 
  lake, 
  and 
  thence 
  along 
  the 
  western 
  base 
  of 
  

   the 
  Tug 
  Hill 
  plateau 
  to 
  near 
  Watertown. 
  The 
  well-known 
  ridge 
  

   road 
  between 
  Niagara 
  river 
  and 
  Rochester 
  is 
  built 
  on 
  the 
  old 
  

  

  Fig. 
  33 
  The 
  Algonquin-Iroquois 
  stage 
  of 
  Great 
  Lakes 
  history 
  when 
  the 
  

   ice 
  had 
  retreated 
  far 
  enough 
  to 
  open 
  the 
  outlet 
  through 
  the 
  Mohawk 
  valley. 
  

  

  After 
  Taylor 
  

  

  Iroquois 
  beach 
  deposit. 
  Lake 
  Iroquois 
  covered 
  somewhat 
  more 
  

   than 
  the 
  present 
  area 
  of 
  Lake 
  Ontario, 
  *and 
  the 
  distinctly 
  lower 
  

   water 
  level 
  here 
  than 
  in 
  the 
  Erie 
  basin 
  allowed 
  the 
  modern 
  Niagara 
  

   river 
  to 
  begin 
  its 
  history 
  by 
  flowing 
  northward 
  over 
  the 
  limestone 
  

   plain 
  near 
  Buffalo. 
  Meantime 
  the 
  waters 
  of 
  the 
  upper 
  lake 
  basins 
  

   had 
  merged 
  to 
  form 
  Lake 
  Algonquin 
  which 
  at 
  first 
  probably 
  dis- 
  

   charged 
  past 
  Detroit 
  through 
  the 
  Erie 
  basin 
  and 
  into 
  Lake 
  Iroquois 
  

   by 
  way 
  of 
  Niagara 
  river. 
  Later, 
  however, 
  when 
  the 
  ice 
  had 
  with- 
  

   drawn 
  a 
  little 
  farther 
  northward, 
  a 
  lower 
  outlet 
  was 
  opened 
  through 
  

   the 
  Trent 
  river 
  by 
  which 
  Lake 
  Algonquin 
  drained 
  into 
  Lake 
  

  

  