﻿334 
  T. 
  E. 
  JAMIESON 
  ON 
  THE 
  LAST 
  STAGE 
  OF 
  

  

  of 
  snow 
  would 
  be 
  melted 
  before 
  the 
  ice 
  in 
  the 
  central 
  trough 
  of 
  the 
  

   valley 
  broke 
  up, 
  so 
  that 
  heavy 
  floods 
  of 
  turbid 
  water 
  would 
  be 
  let 
  loose 
  

   over 
  the 
  surface 
  of 
  the 
  frozen 
  rivers 
  and 
  thus 
  rise 
  to 
  great 
  heights 
  

   along 
  their 
  banks. 
  The 
  thick 
  solid 
  ice 
  occupying 
  the 
  bed 
  of 
  the 
  

   stream 
  would 
  take 
  longer 
  to 
  melt, 
  but 
  would 
  gradually 
  break 
  up, 
  

   rising 
  to 
  the 
  surface 
  in 
  great 
  masses, 
  and 
  bringing 
  with 
  it 
  stones 
  and 
  

   pebbles 
  from 
  the 
  bottom. 
  These 
  masses 
  of 
  ice 
  would 
  float 
  down 
  the 
  

   stream, 
  dropping 
  the 
  boulders 
  here 
  and 
  there 
  as 
  they 
  dissolved. 
  

   "When 
  the 
  Straits 
  of 
  Dover 
  were 
  dry 
  land 
  and 
  the 
  rivers 
  wandered 
  

   away 
  down 
  far 
  below 
  the 
  present 
  coast-line, 
  it 
  is 
  probable 
  that 
  during 
  

   the 
  winter 
  season 
  the 
  Seine, 
  the 
  Somme, 
  the 
  Thames, 
  &c. 
  would 
  be 
  

   completely 
  frozen 
  along 
  what 
  are 
  now 
  the 
  lower 
  reaches 
  of 
  these 
  

   rivers, 
  and 
  at 
  the 
  break 
  up 
  of 
  the 
  snow 
  in 
  summer 
  these 
  frozen 
  

   masses 
  would 
  cause 
  the 
  river-floods 
  to 
  rise 
  to 
  heights 
  which 
  now 
  

   appear 
  very 
  marvellous. 
  

  

  Mr. 
  Prestwich 
  has 
  discussed 
  this 
  subject 
  in 
  an 
  excellent 
  manner 
  

   in 
  the 
  « 
  Philosophical 
  Transactions 
  ' 
  for 
  1864, 
  p. 
  286 
  ; 
  and 
  I 
  would 
  

   only 
  suggest 
  that 
  he 
  has 
  perhaps 
  not 
  sufficiently 
  allowed 
  for 
  the 
  

   unmelted 
  ice 
  in 
  the 
  bottom 
  of 
  the 
  valley, 
  forcing 
  the 
  floods 
  to 
  reach 
  

   a 
  height 
  they 
  could 
  not 
  otherwise 
  do. 
  

  

  The 
  underground 
  ice 
  of 
  Siberia 
  may 
  have 
  been 
  buried 
  in 
  this 
  way 
  

   by 
  the 
  rivers 
  flooding 
  it 
  and 
  flinging 
  down 
  beds 
  of 
  mud 
  on 
  it 
  before 
  

   it 
  had 
  time 
  to 
  melt 
  and 
  become 
  detached 
  from 
  the 
  bottom. 
  

  

  § 
  8. 
  Comparative 
  Olaciation 
  of 
  East 
  and 
  West 
  Coasts. 
  

  

  I 
  have 
  often 
  been 
  struck 
  with 
  the 
  remarkable 
  intensity 
  of 
  the 
  

   glacial 
  action 
  displayed 
  on 
  the 
  rocks 
  of 
  the 
  west 
  side 
  of 
  Scotland 
  

   compared 
  with 
  the 
  east, 
  and 
  in 
  a 
  former 
  paper 
  * 
  I 
  threw 
  out 
  the 
  

   suggestion 
  that 
  the 
  precipitation 
  of 
  snow 
  along 
  the 
  west 
  Highlands 
  

   had 
  probably 
  much 
  exceeded 
  what 
  fell 
  on 
  the 
  eastern 
  slope 
  of 
  the 
  

   island, 
  just 
  as 
  takes 
  place 
  now 
  in 
  regard 
  to 
  the 
  rainfall. 
  Thanks 
  to 
  

   the 
  Meteorological 
  Society 
  of 
  Scotland, 
  we 
  have 
  now 
  accurate 
  data 
  

   concerning 
  the 
  rain 
  ; 
  and 
  Mr. 
  Buchan's 
  excellent 
  papers 
  on 
  the 
  

   subject 
  show 
  us 
  what 
  an 
  immense 
  excess 
  there 
  is 
  in 
  the 
  quantity 
  

   that 
  falls 
  on 
  the 
  west 
  side 
  of 
  the 
  country 
  compared 
  with 
  the 
  east. 
  

   There 
  are 
  several 
  stations 
  in 
  the 
  west 
  Highlands 
  where 
  the 
  annual 
  

   rainfall 
  exceeds 
  100 
  inches, 
  whereas 
  along 
  the 
  east 
  coast 
  it 
  ranges 
  

   generally 
  from 
  25 
  to 
  30 
  ; 
  and 
  it 
  is 
  interesting 
  to 
  note 
  that 
  the 
  gla- 
  

   ciation 
  of 
  the 
  rocks 
  corresponds 
  in 
  intensity 
  with 
  the 
  present 
  excess 
  

   of 
  the 
  rainfall, 
  showing 
  that 
  the 
  precipitation 
  of 
  snow 
  had 
  been 
  

   similarly 
  distributed 
  ; 
  and 
  is 
  it 
  not 
  the 
  case 
  generally 
  that 
  the 
  marks 
  

   of 
  ancient 
  glaciers 
  are 
  most 
  decided 
  where 
  the 
  rainfall 
  is 
  now 
  

   heaviest 
  ? 
  

  

  The 
  prevailing 
  wind 
  in 
  Scotland 
  is 
  the 
  south-west, 
  which, 
  sweeping 
  

   up 
  the 
  moisture 
  from 
  the 
  Atlantic, 
  is 
  cooled 
  as 
  it 
  rises 
  over 
  the 
  

   mountain-tops 
  of 
  the 
  west 
  coast 
  and 
  throws 
  down 
  its 
  burden 
  in 
  

   copious 
  showers 
  on 
  those 
  hills, 
  so 
  that 
  before 
  it 
  reaches 
  the 
  eastern 
  

   side 
  of 
  the 
  island 
  it 
  is 
  a 
  comparatively 
  dry 
  wind. 
  Tbis 
  is 
  well 
  seen 
  

   * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  xix. 
  p. 
  258, 
  1863. 
  

  

  