﻿130 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Jan. 
  20, 
  

  

  § 
  7. 
  Conclusion. 
  

  

  The 
  opinion 
  that 
  many 
  of 
  the 
  phenomena 
  attending 
  the 
  surface- 
  

   geology 
  of 
  a 
  large 
  portion 
  of 
  North 
  America 
  were 
  caused 
  by 
  glacial 
  

   ice, 
  appears 
  to 
  be 
  gradually 
  gaining 
  ground 
  among 
  American 
  geolo- 
  

   gists. 
  First 
  enunciated 
  by 
  Professor 
  Louis 
  Agassiz 
  *, 
  it 
  received 
  

   the 
  sanction, 
  wholly 
  or 
  in 
  part, 
  of 
  some 
  well-known 
  geologists. 
  In 
  

   a 
  recent 
  paper 
  by 
  Dr. 
  Newberry, 
  it 
  is 
  stated 
  that 
  " 
  in 
  this 
  ' 
  glacial 
  

   epoch' 
  all 
  the 
  Lake-country 
  was 
  covered 
  with 
  ice, 
  by 
  which 
  the 
  rocky 
  

   surface 
  was 
  planed 
  down 
  and 
  furrowed, 
  and 
  left 
  precisely 
  in 
  the 
  con- 
  

   dition 
  of 
  that 
  beneath 
  modern 
  moving 
  glaciers 
  in 
  mountain 
  -valle3 
  r 
  s"t. 
  

  

  Dana 
  considers 
  " 
  the 
  glacial 
  theory 
  the 
  most 
  satisfactory, 
  but 
  

   the 
  iceberg-theory 
  required, 
  in 
  some 
  cases, 
  for 
  the 
  borders 
  of 
  con- 
  

   tinents 
  "J. 
  

  

  Sir 
  William 
  Logan, 
  when 
  speaking 
  of 
  the 
  innumerable 
  lakes 
  

   scattered 
  over 
  the 
  Laurentian 
  region 
  of 
  Canada, 
  says, 
  in 
  his 
  ' 
  Geo- 
  

   logy 
  of 
  Canada', 
  just 
  published, 
  " 
  The 
  rock 
  which 
  is 
  most 
  charac- 
  

   teristic 
  of 
  the 
  depressions 
  is 
  the 
  comparatively 
  soft 
  crystalline 
  lime- 
  

   stones 
  of 
  the 
  series 
  ; 
  and 
  it 
  appears 
  probable 
  that 
  one 
  of 
  the 
  main 
  

   erosive 
  forces 
  has 
  been 
  glacial 
  action." 
  

  

  Also, 
  with 
  reference 
  to 
  the 
  great 
  Lake-basins, 
  he 
  says, 
  " 
  These 
  

   great 
  Lake-basins 
  are 
  depressions, 
  not 
  of 
  geological 
  structure, 
  but 
  

   of 
  denudation 
  ; 
  and 
  the 
  grooves 
  on 
  the 
  surfaces 
  of 
  the 
  rocks, 
  which 
  

   descend 
  under 
  the 
  water, 
  appear 
  to 
  point 
  to 
  glacial 
  action 
  as 
  one 
  of 
  

   the 
  great 
  causes 
  which 
  have 
  produced 
  these 
  depressions" 
  ||. 
  

  

  I 
  have 
  great 
  satisfaction 
  in 
  observing 
  that 
  the 
  views 
  which 
  I 
  

   published 
  in 
  1859 
  %, 
  respecting 
  the 
  origin 
  of 
  the 
  great 
  American 
  

   lakes 
  and 
  other 
  glacial 
  phenomena 
  in 
  North 
  America, 
  are 
  con- 
  

   tinually 
  receiving 
  additional 
  support 
  from 
  various 
  sources; 
  and 
  I 
  

   venture 
  to 
  think 
  that 
  it 
  is 
  not 
  unreasonable 
  to 
  suppose 
  that 
  we 
  shall 
  

   find 
  in 
  North 
  America 
  the 
  parallel 
  of 
  that 
  widespread 
  work 
  of 
  

   ancient 
  glaciers 
  in 
  Europe, 
  which 
  has 
  been 
  so 
  ably 
  described 
  before 
  

   the 
  Society 
  by 
  its 
  distinguished 
  President, 
  Professor 
  Eamsay. 
  

  

  2. 
  Notes 
  on 
  the 
  Drift-deposits 
  of 
  the 
  Valley 
  of 
  the 
  Severn, 
  in 
  the 
  

   Neighbourhood 
  of 
  Coalbrook 
  Dale 
  and 
  Bridgnorth. 
  By 
  George 
  

   Maw, 
  F.S.A., 
  F.L.S., 
  &c. 
  

  

  [Communicated 
  by 
  Sir 
  C. 
  Lyell, 
  F.E.S., 
  V.P.G.S.] 
  

   The 
  general 
  subject 
  of 
  the 
  drift- 
  deposits 
  distributed 
  so 
  abundantly 
  

   throughout 
  the 
  counties 
  of 
  Gloucester, 
  Worcester, 
  Shropshire, 
  and 
  

  

  * 
  Lake 
  Superior 
  : 
  its 
  Physical 
  Character, 
  Vegetation, 
  and 
  Animals, 
  &c. 
  1850. 
  

  

  t 
  Notes 
  on 
  the 
  Surface-geology 
  of 
  the 
  Basin 
  of 
  the 
  Great 
  Lakes. 
  

  

  % 
  Dana's 
  ' 
  Manual 
  of 
  Geology,' 
  18G3, 
  p. 
  546. 
  

  

  || 
  Geological 
  Survey 
  of 
  Canada, 
  18(>3, 
  page 
  889. 
  

  

  ■([ 
  See 
  Reports 
  of 
  the 
  Assinniboine 
  and 
  Saskatchewan 
  Expedition. 
  In 
  1855 
  

   I 
  read 
  a 
  paper 
  before 
  the 
  Canadian 
  Institute, 
  Toronto, 
  " 
  On 
  the 
  Origin 
  of 
  the 
  

   Basins 
  of 
  the 
  Great 
  Lakes." 
  advocating 
  the 
  view 
  that 
  they 
  had 
  been 
  excavated 
  

   bj 
  means 
  of 
  ice. 
  

  

  