﻿306 
  W. 
  TJpham 
  — 
  Epochs 
  and 
  Stages 
  of 
  the 
  Glacial 
  Period. 
  

  

  of 
  the 
  interglacial 
  stage 
  from 
  the 
  now 
  buried 
  channel 
  which 
  

   appears 
  to 
  have 
  been 
  then 
  eroded 
  by 
  the 
  Mississippi 
  river 
  a 
  

   few 
  miles 
  west 
  of 
  the 
  present 
  gorge 
  below 
  these 
  falls.* 
  

  

  Adopting 
  the 
  helpful 
  new 
  nomenclature 
  proposed 
  by 
  Cham- 
  

   berlin,f 
  we 
  may 
  provisionally 
  formulate 
  the 
  minor 
  time 
  divis- 
  

   ions 
  of 
  the 
  Glacial 
  and 
  Champlain 
  epochs 
  as 
  follows. 
  The 
  

   order 
  is 
  stratigraphic, 
  so 
  that 
  for 
  the 
  advancing 
  sequence 
  in 
  

   time 
  it 
  should 
  be 
  read 
  upward. 
  

  

  Champlain 
  Epoch. 
  — 
  (Land 
  depression 
  ; 
  disappearance 
  of 
  

   the 
  ice-sheet 
  ; 
  partial 
  reelevation 
  of 
  the 
  land.) 
  

  

  Wisconsin 
  stage. 
  — 
  (Progressing 
  reelevation.) 
  Moderate 
  

   reelevation 
  of 
  the 
  land, 
  advancing 
  as 
  a 
  permanent 
  wave 
  

   from 
  south 
  to 
  north 
  and 
  northeast 
  ; 
  continued 
  retreat 
  of 
  

   the 
  ice 
  along 
  most 
  of 
  its 
  extent, 
  but 
  its 
  maximum 
  advance 
  

   in 
  southern 
  New 
  England, 
  with 
  fluctuations 
  and 
  the 
  for- 
  

   mation 
  of 
  prominent 
  moraines 
  ; 
  great 
  glacial 
  lakes 
  on 
  the 
  

   northern 
  borders 
  of 
  the 
  United 
  States 
  ; 
  slight 
  glacial 
  oscil- 
  

   lations, 
  with 
  temperate 
  climate 
  nearly 
  as 
  now, 
  at 
  Toronto 
  

   and 
  Scarboro', 
  Ont. 
  ; 
  the 
  sea 
  finally 
  admitted 
  to 
  the 
  St. 
  

   Lawrence, 
  Champlain, 
  and 
  Ottawa 
  valleys 
  ; 
  uplift 
  to 
  the 
  

   present 
  height 
  completed 
  soon 
  after 
  the 
  departure 
  of 
  the 
  ice. 
  

   (The 
  great 
  Baltic 
  glacier, 
  and 
  European 
  marginal 
  moraines.) 
  

  

  Champlain 
  subsidence. 
  — 
  Depression 
  of 
  the 
  ice-covered 
  

  

  area 
  from 
  its 
  high 
  Glacial 
  elevation 
  ; 
  retreat 
  of 
  the 
  ice 
  

  

  from 
  its 
  former 
  Iowan 
  limits 
  ; 
  abundant 
  deposition 
  of 
  loess. 
  

  

  Glacial 
  Epoch. 
  — 
  (Ice 
  accumulation, 
  due 
  to 
  the 
  culmination 
  

  

  of 
  the 
  Lafayette 
  epeirogenic 
  uplift.) 
  

  

  Iowan 
  stage. 
  — 
  Renewed 
  ice 
  accumulation 
  covering 
  the 
  

   forest 
  beds 
  and 
  extending 
  south 
  nearly 
  to 
  its 
  early 
  bound- 
  

   ary. 
  (Third 
  European 
  glacial 
  stage.) 
  

  

  Interglacial 
  stage. 
  — 
  Extensive 
  glacial 
  recession 
  in 
  the 
  

   upper 
  part 
  of 
  the 
  Mississippi 
  basin 
  ; 
  cool 
  temperate 
  climate 
  

   and 
  coniferous 
  forests 
  up 
  to 
  the 
  waning 
  ice-border; 
  much 
  

   erosion 
  of 
  the 
  early 
  drift. 
  

  

  Kansan 
  stage. 
  — 
  Maximum 
  extent 
  of 
  the 
  ice-sheet 
  in 
  the 
  

   interior 
  of 
  North 
  America, 
  and 
  also 
  eastward 
  in 
  northern 
  

   New 
  Jersey. 
  (Maximum 
  glaciation 
  in 
  Europe.) 
  

  

  Undetermined 
  stages 
  of 
  fluctuation 
  in 
  the 
  general 
  growth 
  

   of 
  the 
  ice-sheet. 
  — 
  Including 
  an 
  early 
  glacial 
  recession 
  

   and 
  readvance 
  shown 
  by 
  layers 
  of 
  interglacial 
  lignite 
  on 
  

   branches 
  of 
  the 
  Moose 
  and 
  Albany 
  rivers, 
  southwest 
  of 
  

   James 
  bay. 
  (First 
  glacial 
  stage 
  in 
  the 
  Alps.) 
  

  

  * 
  Am. 
  Geologist, 
  vol. 
  x, 
  pp. 
  69-80, 
  with 
  three 
  plates 
  (sections 
  and 
  map), 
  Aug., 
  

   1892. 
  

  

  •f 
  In 
  two 
  chapters 
  (pp. 
  724-775, 
  with 
  maps 
  forming 
  plates 
  xiv 
  and 
  xv) 
  of 
  J. 
  

   Geikie's 
  "The 
  Great 
  Ice 
  Age," 
  third 
  edition, 
  1894, 
  Prof. 
  T. 
  C. 
  Chamberlin 
  pro- 
  

   poses 
  a 
  chronologic 
  classification 
  of 
  the 
  North 
  American 
  drift 
  under 
  three 
  forma- 
  

   tions, 
  named 
  in 
  the 
  order 
  of 
  their 
  age, 
  beginning 
  with 
  the 
  earliest, 
  the 
  Kansan, 
  

   East 
  Iowan, 
  and 
  East 
  Wisconsin 
  formations. 
  

  

  