﻿

  THE 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [THIRD 
  SERIES. 
  1 
  

  

  Art. 
  I. 
  — 
  Late 
  Glacial 
  or 
  Champlain 
  Subsidence 
  and 
  Reeleva- 
  

   tion 
  of 
  the 
  St. 
  Lawrence 
  river 
  basin 
  / 
  by 
  Warren 
  Upham. 
  

   (With 
  Plate 
  I.) 
  

  

  The 
  accompanying 
  map 
  (Plate 
  I) 
  shows 
  the 
  maximum 
  area 
  

   covered 
  by 
  the 
  ice-sheet 
  in 
  the 
  St. 
  Lawrence 
  basin 
  and 
  adjoin- 
  

   ing 
  portions 
  of 
  the 
  United 
  States 
  and 
  southern 
  Canada, 
  with 
  

   approximate 
  outlines 
  of 
  the 
  glacial 
  boundary 
  at 
  successive 
  

   stages 
  of 
  its 
  retreat. 
  The 
  Champlain 
  epoch 
  or 
  part 
  of 
  the 
  

   Pleistocene 
  period 
  including 
  these 
  stages 
  of 
  glacial 
  recession 
  

   was 
  begun 
  and 
  ended, 
  respectively, 
  by 
  downward 
  and 
  upward 
  

   epeirogenic 
  movements. 
  It 
  comprised 
  the 
  time 
  of 
  departure 
  

   of 
  the 
  ice-sheet, 
  with 
  many 
  small 
  and 
  large 
  glacial 
  lakes 
  tem- 
  

   porarily 
  formed 
  by 
  its 
  receding 
  barrier, 
  and 
  with 
  marine 
  sub- 
  

   mergence 
  to 
  hundreds 
  of 
  feet 
  above 
  the 
  present 
  shore 
  lines. 
  

   The 
  Late 
  Glacial 
  subsidence 
  appears 
  to 
  have 
  been 
  principally 
  

   completed 
  before 
  the 
  retreat 
  of 
  the 
  ice 
  and 
  deposition 
  of 
  the 
  

   Champlain 
  lacustrine 
  and 
  marine 
  beds 
  ; 
  but 
  the 
  following 
  

   uplift 
  was 
  in 
  progress, 
  advancing 
  as 
  fast 
  as 
  the 
  ice 
  receded, 
  

   from 
  the 
  beginning 
  to 
  the 
  end 
  of 
  Champlain 
  time.* 
  Indeed, 
  

   considerable 
  parts 
  of 
  the 
  glaciated 
  areas 
  of 
  North 
  America 
  

   and 
  Scandinavia 
  are 
  still 
  undergoing 
  small 
  and 
  slow 
  oscillatory 
  

   movements, 
  not 
  having 
  yet, 
  during 
  the 
  short 
  Postglacial 
  period, 
  

   fully 
  reached 
  isostatic 
  repose. 
  

  

  * 
  For 
  a 
  discussion 
  of 
  the 
  part 
  of 
  this 
  movement 
  reelevating 
  the 
  upper 
  Missis- 
  

   sippi 
  region, 
  the 
  area 
  of 
  the 
  glacial 
  Lake 
  Agassiz 
  in 
  the 
  basin 
  of 
  the 
  Red 
  river 
  

   of 
  the 
  North 
  and 
  Lake 
  Winnipeg, 
  and 
  the 
  country 
  surrounding 
  Hudson 
  Bay, 
  see 
  

   the 
  Journal 
  of 
  Geology, 
  vol. 
  ii, 
  pp. 
  383-395, 
  May-June, 
  1894. 
  The 
  dynamic 
  

   causes 
  of 
  epeirogenic 
  movements, 
  and 
  their 
  relations 
  to 
  the 
  Glacial 
  period 
  as 
  the 
  

   probable 
  causes 
  of 
  both 
  its 
  beginning 
  and 
  end, 
  are 
  partly 
  considered 
  in 
  that 
  

   paper, 
  but 
  more 
  fully 
  in 
  an 
  appendix 
  of 
  Wright's 
  Ice 
  Age 
  in 
  North 
  America, 
  

   1889, 
  pp. 
  573-595, 
  this 
  Journal, 
  III, 
  vol. 
  xlvi, 
  pp. 
  114-121, 
  Aug., 
  1893, 
  and 
  the 
  

   G-eol. 
  Magazine, 
  IV, 
  vol. 
  i, 
  pp. 
  340-349, 
  Aug., 
  1894. 
  

  

  Am. 
  Jouk. 
  Sci.— 
  Third 
  Series, 
  Vol. 
  XLIX, 
  No. 
  289.— 
  Jan., 
  1895. 
  

  

  1 
  

  

  