﻿8 
  W. 
  Zfpham 
  — 
  Champlain 
  Subsidence 
  and 
  

  

  Lake 
  Algonquin* 
  — 
  When 
  the 
  glacial 
  melting 
  and 
  retreat 
  

   at 
  length 
  permitted 
  an 
  outflow 
  from 
  the 
  St. 
  Lawrence 
  basin 
  

   over 
  a 
  lower 
  pass, 
  which 
  was 
  through 
  central 
  New 
  York 
  to 
  the 
  

   Mohawk 
  and 
  Hudson, 
  the 
  water 
  surface 
  of 
  the 
  basins 
  of 
  Lakes 
  

   Michigan, 
  Huron, 
  and 
  Superior, 
  fell 
  only 
  some 
  50 
  or 
  75 
  feet, 
  

   from 
  the 
  latest 
  and 
  lowest 
  stage 
  of 
  Lake 
  Warren 
  to 
  its 
  short- 
  

   lived 
  successor, 
  Lake 
  Algonquin. 
  This 
  lake 
  appears 
  to 
  have 
  

   been 
  ice-dammed 
  only 
  at 
  low 
  places 
  on 
  its 
  east 
  end, 
  as 
  at 
  or 
  

   near 
  the 
  heads 
  of 
  the 
  Trent 
  and 
  Mattawa 
  rivers, 
  lying 
  respect- 
  

   ively 
  east 
  of 
  Lakes 
  Simcoe 
  and 
  Nipissing, 
  where 
  otherwise 
  its 
  

   w 
  T 
  aters 
  must 
  have 
  been 
  somewhat 
  further 
  lowered 
  to 
  outflow 
  

   by 
  these 
  passes. 
  Careful 
  study 
  and 
  comparison 
  of 
  the 
  work 
  of 
  

   Spencer 
  in 
  tracing 
  the 
  Algonquin 
  beach 
  about 
  the 
  southern 
  

   part 
  of 
  Lake 
  Huron 
  and 
  Georgian 
  bay, 
  and 
  of 
  Taylor 
  in 
  ex- 
  

   ploration 
  of 
  his 
  " 
  Nipissing 
  beach 
  " 
  from 
  Duluth 
  east 
  along 
  the 
  

   south 
  coast 
  of 
  Lake 
  Superior 
  and 
  the 
  north 
  side 
  of 
  Lake 
  Huron 
  

   and 
  Georgian 
  bay 
  to 
  Lake 
  Nipissing, 
  convince 
  me 
  that 
  these 
  

   beaches 
  were 
  of 
  contemporaneous 
  formation, 
  marking 
  respect- 
  

   ively 
  the 
  southern 
  and 
  northern 
  shores 
  of 
  Lake 
  Algonquin, 
  and 
  

   therefore 
  both 
  to 
  be 
  known 
  by 
  the 
  name 
  Algonquin 
  beach 
  of 
  

   Spencer, 
  according 
  to 
  the 
  law 
  of 
  priority. 
  The 
  earliest 
  and 
  

   principal 
  stage 
  of 
  Lake 
  Algonquin 
  is 
  shown 
  by 
  these 
  beaches 
  

   to 
  have 
  coincided 
  closely 
  in 
  area 
  w 
  T 
  ith 
  Lakes 
  Michigan 
  and 
  

   Superior, 
  but 
  to 
  have 
  been 
  considerably 
  more 
  extensive 
  east- 
  

   ward 
  than 
  the 
  present 
  Lake 
  Huron 
  and 
  Georgian 
  bay. 
  It 
  

   held 
  a 
  level 
  which 
  now 
  by 
  subsequent 
  differential 
  epeirogenic 
  

   movements 
  is 
  left 
  probably 
  wholly 
  below 
  the 
  level 
  of 
  Lake 
  

   Michigan 
  by 
  a 
  vertical 
  amount 
  ranging 
  from 
  almost 
  nothing 
  to 
  

   about 
  40 
  feet. 
  Its 
  shores 
  were 
  nearly 
  coincident 
  with 
  the 
  

   western 
  shore 
  of 
  Lake 
  Huron, 
  but 
  eastward 
  they 
  are 
  now 
  

   elevated 
  mostly 
  150 
  to 
  200 
  feet 
  above 
  that 
  lake 
  and 
  Georgian 
  

   bay 
  ; 
  and 
  in 
  the 
  Lake 
  Superior 
  basin 
  they 
  vary 
  from 
  about 
  50 
  

   feet 
  above 
  Lake 
  Superior 
  at 
  its 
  mouth, 
  and 
  along 
  its 
  north- 
  

   eastern 
  and 
  northern 
  shores, 
  to 
  25 
  feet 
  at 
  Houghton, 
  and 
  to 
  a 
  

   few 
  feet 
  or 
  none 
  at 
  Duluth. 
  

  

  The 
  Algonquin 
  beach 
  at 
  the 
  south 
  end 
  of 
  Lake 
  Huron 
  coin- 
  

   cides 
  very 
  closely 
  with 
  the 
  land 
  surface 
  there 
  and 
  with 
  the 
  

  

  Chicago 
  to 
  the 
  Des 
  Plaines 
  and 
  Mississippi 
  rivers 
  so 
  lately 
  as 
  about 
  1,500 
  years 
  

   ago, 
  when 
  the 
  Niagara 
  river 
  had 
  cut 
  back 
  its 
  gorge 
  to 
  the 
  Johnson 
  ridge, 
  about 
  

   a 
  mile 
  north 
  of 
  the 
  present 
  site 
  of 
  the 
  falls. 
  This 
  would 
  have 
  formed 
  a 
  beach 
  10 
  

   to 
  15 
  feet 
  above 
  Lakes 
  Michigan 
  and 
  Huron, 
  and 
  about 
  20 
  to 
  25 
  feet 
  above 
  Lake 
  

   Erie, 
  around 
  all 
  their 
  shores; 
  and 
  the 
  absence 
  of 
  such 
  a 
  modern 
  and 
  still 
  horizon- 
  

   tal 
  shore 
  line, 
  slightly 
  higher 
  than 
  the 
  present 
  lake 
  levels, 
  upon 
  all 
  this 
  large 
  

   area, 
  forbids 
  an 
  acceptance 
  of 
  this 
  hypothesis. 
  

  

  * 
  J. 
  W. 
  Spencer, 
  "Deformation 
  of 
  the 
  Algonquin 
  Beach, 
  and 
  Birth 
  of 
  Lake 
  

   Huron," 
  this 
  Journal, 
  III, 
  vol. 
  xli, 
  pp. 
  12-21, 
  with 
  map, 
  Jan.. 
  1891; 
  and 
  other 
  

   papers 
  before 
  cited. 
  G. 
  K. 
  Gilbert, 
  F. 
  B. 
  Taylor, 
  and 
  Warren 
  Upham, 
  as 
  before 
  

   cited 
  for 
  Lake 
  Warren. 
  G. 
  F. 
  Wright, 
  Bulletin 
  Geol. 
  Soc. 
  Am., 
  vol. 
  iv, 
  pp. 
  423- 
  

   5 
  ; 
  with 
  ensuing 
  discussion 
  by 
  Dr. 
  Robert 
  Bell, 
  pp. 
  425-7. 
  

  

  