﻿Reelevation 
  of 
  the 
  St. 
  Lawrence 
  river 
  basin. 
  13 
  

  

  cally. 
  From 
  the 
  lower 
  and 
  mam 
  Lundy 
  beach 
  the 
  water 
  fell 
  

   about 
  4S0 
  feet 
  to 
  the 
  earliest 
  stage 
  of 
  Lake 
  Iroquois 
  when 
  the 
  

   Toronto 
  fossil 
  shells 
  lived 
  in 
  the 
  edge 
  of 
  that 
  lake, 
  excepting 
  

   that 
  here 
  again 
  some 
  undetermined 
  amount 
  must 
  be 
  subtracted 
  

   to 
  compensate 
  the 
  concurrent 
  rise 
  of 
  the 
  land. 
  Adding 
  these 
  

   vertical 
  intervals 
  together, 
  we 
  have 
  635 
  feet, 
  which 
  probably 
  

   may 
  be 
  reduced 
  100 
  feet, 
  more 
  or 
  less, 
  for 
  the 
  effects 
  of 
  the 
  

   accompanying 
  epeirogenic 
  uplift. 
  We 
  have 
  left 
  some 
  500 
  or 
  

   550 
  feet, 
  to 
  be 
  subtracted 
  from 
  the 
  altitude 
  of 
  the 
  old 
  Chicago 
  

   outlet 
  of 
  Lake 
  Warren, 
  believed 
  to 
  have 
  been 
  then 
  approxi- 
  

   mately 
  as 
  now, 
  590 
  feet 
  above 
  the 
  sea, 
  to 
  give 
  the 
  earliest 
  alti- 
  

   tude 
  of 
  the 
  Koine 
  outlet. 
  It 
  thus 
  appears, 
  as 
  I 
  concluded 
  from 
  

   a 
  similar 
  computation 
  four 
  years 
  ago, 
  that 
  the 
  Rome 
  outlet 
  

   was 
  at 
  first 
  only 
  50 
  or 
  100 
  feet 
  above 
  the 
  sea 
  level.* 
  It 
  was 
  

   gradually 
  uplifted, 
  participating 
  in 
  the 
  differential 
  rise 
  of 
  the 
  

   whole 
  Ontario 
  basin, 
  to 
  about 
  300 
  feet 
  above 
  the 
  sea 
  while 
  the 
  

   outflow 
  continued 
  here, 
  and 
  to 
  probably 
  350 
  feet 
  or 
  more, 
  lack- 
  

   ing 
  less 
  than 
  100 
  feet 
  of 
  its 
  present 
  height, 
  by 
  the 
  time 
  when 
  

   the 
  much 
  farther 
  retreat 
  of 
  the 
  ice 
  permitted 
  the 
  extension 
  of 
  

   the 
  sea 
  to 
  Ogdensburgh 
  and 
  Brockville, 
  on 
  the 
  St. 
  Lawrence 
  

   river 
  near 
  the 
  mouth 
  of 
  Lake 
  Ontario. 
  Intermediate 
  between 
  

   Lake 
  Iroquois 
  and 
  the 
  Cham 
  plain 
  incursion 
  of 
  the 
  sea, 
  the 
  

   glacial 
  Lake 
  St. 
  Lawrence, 
  into 
  which 
  Lake 
  Iroquois 
  was 
  

   merged 
  by 
  the 
  retreat 
  of 
  the 
  ice-sheet 
  from 
  the 
  northern 
  side 
  

   of 
  the 
  Adirondacks, 
  filled 
  the 
  Lake 
  Ontario 
  basin 
  for 
  a 
  con- 
  

   siderable 
  time 
  at 
  levels 
  below 
  the 
  Iroquois 
  beaches. 
  

  

  As 
  the 
  area 
  of 
  Lake 
  Warren 
  was 
  being 
  differentially 
  much 
  

   elevated 
  during 
  the 
  earlier 
  existence 
  of 
  that 
  lake, 
  and 
  as 
  the 
  

   area 
  of 
  Lake 
  Algonquin 
  was 
  similarly 
  uplifted 
  in 
  part 
  or 
  

   wholly 
  contemporaneously 
  with 
  the 
  Iroquois 
  basin, 
  so 
  this 
  

   region 
  was 
  being 
  rapidly 
  raised 
  and 
  tilted 
  upward 
  to 
  the 
  north 
  

   and 
  east 
  while 
  the 
  lake 
  level, 
  held 
  constantly 
  without 
  import- 
  

   ant 
  downward 
  cutting 
  at 
  the 
  Rome 
  outlet, 
  inscribed 
  many 
  

   shore 
  lines 
  on 
  the 
  slowly 
  moving 
  land. 
  All 
  the 
  movement 
  

   throughout 
  the 
  whole 
  region 
  probably 
  was 
  upward 
  ; 
  but 
  the 
  

   position 
  of 
  Rome, 
  and 
  its 
  greater 
  rise 
  than 
  western 
  parts 
  of 
  the 
  

   basin 
  during 
  the 
  existence 
  of 
  Lake 
  Iroquois, 
  caused 
  the 
  old 
  

   beaches 
  westward 
  to 
  have 
  now 
  declining 
  gradients. 
  

  

  Lake 
  Hudson- 
  Charwplain.\ 
  — 
  The 
  absence 
  of 
  marine 
  fossils 
  

  

  * 
  Bulletin 
  Geol. 
  Soc. 
  Am., 
  vol, 
  ii, 
  pp. 
  260-r262. 
  

  

  f 
  Warren 
  T7pham. 
  Bulletin 
  Geol. 
  Soc. 
  Am., 
  vol. 
  i. 
  p. 
  566; 
  vol. 
  ii, 
  p. 
  265; 
  vol. 
  

   iii, 
  pp. 
  484-487 
  (first 
  using 
  this 
  name). 
  C. 
  H. 
  Hitchcock, 
  Geology 
  of 
  Vermont, 
  

   1861. 
  vol. 
  i, 
  pp. 
  93-167, 
  with 
  map. 
  J. 
  S. 
  Xewoerry, 
  Pop. 
  Sci. 
  Monthly, 
  vol. 
  xiii, 
  

   1879, 
  pp. 
  641-660. 
  F. 
  J. 
  H. 
  Merrill, 
  this 
  Journal. 
  Ill, 
  vol. 
  xli, 
  pp. 
  460-466, 
  June, 
  

   1891. 
  W. 
  M. 
  Davis. 
  Proc. 
  Boston 
  Soc. 
  Xat. 
  Hist., 
  vol. 
  xxv, 
  1891, 
  pp. 
  318-334. 
  

   S. 
  Prentiss 
  Baldwin, 
  " 
  Pleistocene 
  History 
  of 
  the 
  Champlain 
  Valley," 
  Am. 
  Geolo- 
  

   gist, 
  vol. 
  xiii, 
  pp. 
  170-184, 
  with 
  map, 
  March, 
  1894. 
  Baron 
  de 
  Geer, 
  as 
  cited 
  for 
  

   Lake 
  Iroquois. 
  

  

  