﻿126 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Jail. 
  20, 
  

  

  sistible 
  agent 
  which 
  picked 
  up 
  the 
  materials 
  composing 
  the 
  Blue 
  

   Clay, 
  and 
  then 
  melting, 
  left 
  them 
  in 
  their 
  present 
  position, 
  have 
  been 
  

   largely 
  instrumental 
  in 
  excavating 
  the 
  basins 
  of 
  the 
  great 
  Canadian 
  

   lakes 
  ? 
  " 
  * 
  

  

  And, 
  in 
  1860, 
  in 
  a 
  'Narrative 
  of 
  the 
  Canadian 
  Expeditions,' 
  I 
  re- 
  

   marked, 
  " 
  The 
  widespread 
  phenomena 
  exhibiting 
  the 
  greater 
  or 
  

   less 
  action 
  of 
  ice, 
  such 
  as 
  grooved, 
  polished, 
  and 
  embossed 
  rocks, 
  the 
  

   excavation 
  of 
  the 
  deep 
  lakes 
  of 
  the 
  St. 
  Lawrence 
  basin, 
  the 
  forced 
  

   arrangement 
  of 
  drift, 
  the 
  ploughing-up 
  of 
  large 
  areas, 
  and 
  the 
  

   extraordinary 
  amount 
  of 
  denudation 
  at 
  different 
  levels, 
  without 
  the 
  

   evidence 
  of 
  beaches, 
  all 
  point 
  to 
  the 
  action 
  of 
  glacial 
  ice 
  previous 
  to 
  

   the 
  operations 
  of 
  floating 
  ice 
  in 
  the 
  grand 
  phenomena 
  of 
  the 
  Drift." 
  t 
  

  

  § 
  3. 
  The 
  Driftless 
  Area 
  in 
  Wisconsin. 
  

  

  In 
  a 
  recent 
  Report 
  on 
  the 
  Geological 
  Survey 
  of 
  the 
  State 
  of 
  

   Wisconsin, 
  by 
  the 
  distinguished 
  American 
  geologists, 
  Professors 
  

   James 
  Hall 
  and 
  J. 
  D. 
  Whitney, 
  the 
  remarkable 
  view 
  is 
  advanced 
  by 
  

   the 
  latter, 
  that 
  there 
  is 
  an 
  area 
  of 
  more 
  than 
  3000 
  square 
  miles 
  in 
  

   extent 
  (long. 
  90° 
  W., 
  lat. 
  42° 
  50' 
  N.) 
  which 
  has 
  never 
  been 
  overflowed 
  

   since 
  the 
  Upper 
  Silurian 
  epoch. 
  Mr. 
  Whitney 
  says 
  i, 
  " 
  If 
  we 
  con- 
  

   sider 
  the 
  magnitude 
  and 
  universality 
  of 
  the 
  drift-deposits 
  in 
  the 
  

   Northern 
  United 
  States, 
  and 
  especially 
  in 
  Northern 
  Wisconsin, 
  we 
  

   shall 
  be 
  the 
  more 
  astonished 
  to 
  learn 
  that 
  throughout 
  nearly 
  the 
  

   whole 
  Lead-region, 
  and 
  over 
  a 
  considerable 
  extent 
  of 
  territory 
  to 
  the 
  

   north 
  of 
  it, 
  no 
  trace 
  of 
  transported 
  materials, 
  boulders, 
  or 
  drift 
  can 
  

   be 
  found 
  ; 
  and 
  what 
  is 
  more 
  curious, 
  to 
  the 
  east, 
  south, 
  and 
  west, 
  

   the 
  limit 
  of 
  the 
  productive 
  Lead-region 
  is 
  almost 
  exactly 
  the 
  limit 
  of 
  

   the 
  area 
  thus 
  marked 
  by 
  the 
  absence 
  of 
  Drift." 
  

  

  The 
  conclusions 
  to 
  which 
  Mr. 
  Whitney 
  has 
  been 
  led 
  by 
  the 
  study 
  

   of 
  this 
  driftless 
  region 
  are 
  briefly 
  as 
  follow 
  : 
  — 
  

  

  1. 
  That 
  since 
  the 
  Upper 
  Silurian 
  period 
  this 
  portion 
  of 
  Wisconsin 
  

   has 
  not 
  been 
  submerged, 
  and 
  that 
  its 
  surface 
  has, 
  consequently, 
  never 
  

   been 
  covered 
  by 
  Drift. 
  

  

  2. 
  That 
  the 
  denudation 
  it 
  has 
  undergone 
  has 
  been 
  effected 
  by 
  the 
  

   simple 
  agency 
  of 
  rain 
  and 
  frost. 
  

  

  3. 
  That 
  a 
  large 
  portion 
  of 
  the 
  superficial 
  detritus 
  of 
  the 
  West 
  

   must 
  have 
  had 
  its 
  origin 
  in 
  the 
  subaerial 
  destruction 
  of 
  the 
  rocks, 
  

   the 
  soluble 
  portion 
  of 
  them 
  having 
  been 
  gradually 
  removed 
  by 
  the 
  

   percolating 
  water. 
  

  

  4. 
  The 
  entire 
  absence 
  of 
  terraces 
  indicates 
  that 
  the 
  region 
  in 
  

   question 
  has 
  not 
  been 
  submerged 
  in 
  recent 
  times. 
  No 
  organic 
  

   remains 
  other 
  than 
  those 
  belonging 
  to 
  palaeozoic 
  times, 
  except 
  those 
  

   of 
  land 
  animals 
  and 
  plants, 
  have 
  been 
  found 
  in 
  the 
  Lead-region. 
  

  

  On 
  the 
  railway 
  between 
  Milwaukie 
  (Lake 
  Michigan) 
  and 
  Prairie 
  du 
  

   Chien 
  on 
  the 
  Mississippi, 
  there 
  is 
  no 
  point 
  which 
  rises 
  higher 
  than 
  950 
  

   feet 
  above 
  the 
  sea-level 
  ; 
  and 
  the 
  towns 
  of 
  Galena, 
  Menomonee, 
  and 
  

   Dunlieth, 
  in 
  the 
  Lead-region, 
  are 
  below 
  the 
  level 
  of 
  Lake 
  Michigan. 
  

  

  * 
  Op. 
  cit. 
  (Toronto), 
  p. 
  122. 
  

  

  t 
  Narrative 
  of 
  the 
  Canadian 
  Expeditions 
  of 
  1847 
  and 
  1858, 
  vol. 
  ii. 
  p. 
  254. 
  

   Longmans, 
  1860. 
  % 
  Vol. 
  i. 
  p. 
  116. 
  

  

  