﻿THEORY 
  OF 
  LAKE-BASINS. 
  489 
  

  

  Prof. 
  Ramsay 
  was 
  glad 
  to 
  find 
  that 
  the 
  author 
  was 
  gradually- 
  

   coming 
  round 
  towards 
  his 
  own 
  views, 
  as 
  he 
  now 
  admitted 
  that 
  

   glaciers 
  may 
  have 
  excavated 
  some 
  lake-basins. 
  He 
  argued 
  that 
  

   the 
  valleys 
  originated 
  before 
  they 
  were 
  eovered 
  with 
  a 
  thick 
  coating 
  

   of 
  ice 
  ; 
  but 
  he 
  maintained 
  that 
  at 
  its 
  origin 
  the 
  ice 
  would 
  have 
  great 
  

   weight 
  and 
  excavating 
  power. 
  

  

  Rev. 
  J. 
  F. 
  Blake 
  thought 
  that 
  if 
  the 
  slope 
  of 
  the 
  bottom 
  of 
  the 
  

   glacier 
  changed, 
  its 
  excavating 
  power 
  would 
  be 
  increased. 
  ' 
  

  

  Mr. 
  Koch 
  had 
  sounded 
  many 
  lakes, 
  and 
  found 
  great 
  circular 
  

   cavities, 
  which 
  he 
  thought 
  could 
  hardly 
  be 
  due 
  to 
  ice-action. 
  In 
  

   winter 
  glaciers 
  move 
  very 
  slightly, 
  and 
  would 
  be 
  able 
  to 
  perform 
  

   very 
  little 
  work. 
  

  

  Mr. 
  Bonney, 
  in 
  reply, 
  remarked 
  that 
  he 
  had 
  in 
  no 
  way 
  come 
  

   round 
  to 
  Professor 
  Ramsay's 
  views; 
  for 
  he 
  had 
  never 
  denied 
  that 
  

   certain 
  tarns 
  might 
  be 
  the 
  result 
  of 
  ice-action. 
  Ice-denudation 
  is 
  

   different 
  from 
  aqueous 
  denudation. 
  A 
  glacier 
  planes 
  and 
  could 
  not 
  

   cut 
  out 
  a 
  notch. 
  He 
  said 
  that 
  he 
  could 
  only 
  admit 
  the 
  smaller 
  

   lakelets 
  in 
  special 
  positions 
  as 
  the 
  result 
  of 
  glacier-action. 
  He 
  did 
  

   not 
  think 
  there 
  was 
  satisfactory 
  evidence 
  of 
  the 
  existence 
  of 
  an 
  ice- 
  

   sheet 
  all 
  over 
  Switzerland. 
  He 
  urged 
  that 
  it 
  is 
  not 
  always 
  safe 
  to 
  

   argue 
  from 
  small 
  phenomena 
  to 
  large 
  ones. 
  

  

  Q. 
  J. 
  G. 
  8. 
  No. 
  120. 
  2 
  m 
  

  

  