﻿THE 
  GLACIAL 
  PERIOD 
  IN 
  NORTH 
  BRITAIN. 
  335 
  

  

  along 
  the 
  line 
  of 
  the 
  Caledonian 
  Canal. 
  Fort 
  William 
  (at 
  its 
  south- 
  

   west 
  extremity) 
  is 
  one 
  of 
  the 
  wettest 
  places 
  in 
  Scotland, 
  while 
  Cul- 
  

   loden 
  (at 
  the 
  north-east 
  end) 
  is 
  one 
  of 
  the 
  driest 
  — 
  86 
  inches 
  of 
  rain 
  

   falling 
  at 
  the 
  one, 
  to 
  25 
  at 
  the 
  other 
  ; 
  while 
  in 
  the 
  Clen 
  Quoich, 
  near 
  

   the 
  summit 
  level 
  of 
  the 
  canal, 
  102 
  inches 
  are 
  recorded 
  in 
  the 
  course 
  

   of 
  a 
  year. 
  

  

  Can 
  we 
  doubt 
  that 
  in 
  the 
  Glacial 
  period 
  a 
  similar 
  inequality 
  must 
  

   have 
  existed 
  in 
  the 
  fall 
  of 
  snow 
  ? 
  and 
  must 
  not 
  the 
  glaciers 
  fed 
  by 
  

   three 
  times 
  the 
  quantity 
  of 
  snow 
  have 
  been 
  much 
  heavier 
  and 
  more 
  

   erosive 
  than 
  those 
  in 
  the 
  eastern 
  valleys 
  ? 
  Braemar, 
  at 
  the 
  head 
  of 
  the 
  

   river 
  Dee, 
  in 
  Aberdeenshire, 
  although 
  embosomed 
  among 
  the 
  highest 
  

   mountains 
  in 
  Scotland, 
  has 
  a 
  rainfall 
  of 
  only 
  33 
  inches 
  in 
  the 
  year, 
  

   while 
  some 
  of 
  the 
  Argyleshire 
  glens 
  have 
  more 
  than 
  a 
  hundred. 
  

  

  The 
  absence 
  of 
  erratic 
  phenomena 
  along 
  the 
  Ural 
  chain 
  and 
  Siberia 
  

   generally 
  may 
  perhaps 
  be 
  traced 
  to 
  the 
  well-known 
  dryness 
  of 
  the 
  

   air 
  and 
  lack 
  of 
  snow 
  in 
  that 
  region. 
  

  

  Many 
  of 
  the 
  singular 
  features 
  in 
  the 
  glaciation 
  of 
  the 
  British 
  

   Islands 
  seem 
  to 
  be 
  due 
  to 
  excessive 
  falls 
  of 
  snow 
  along 
  the 
  western 
  

   hills 
  and 
  valleys, 
  in 
  the 
  localities 
  probably 
  where 
  the 
  heaviest 
  rains 
  

   now 
  occur. 
  The 
  phenomena 
  of 
  the 
  Parallel 
  Eoads 
  of 
  Glen 
  Roy, 
  for 
  

   example, 
  if 
  we 
  are 
  to 
  explain 
  them 
  by 
  the 
  agency 
  of 
  glaciers, 
  require 
  

   us 
  to 
  suppose 
  that 
  the 
  ice 
  was 
  much 
  more 
  developed 
  on 
  Ben 
  Nevis 
  

   and 
  the 
  region 
  to 
  the 
  west 
  of 
  the 
  Caledonian 
  Canal 
  than 
  in 
  the 
  hilly 
  

   district 
  around 
  the 
  sources 
  of 
  the 
  Spey. 
  But 
  the 
  mountain-ridge 
  

   that 
  lies 
  between 
  Loch 
  Laggan 
  and 
  Loch 
  Spey 
  is 
  quite 
  as 
  lofty 
  as 
  the 
  

   hills 
  which 
  encircle 
  Loch 
  Arkaig, 
  if 
  not 
  more 
  so 
  — 
  four 
  of 
  the 
  

   summits 
  exceeding 
  3000 
  feet, 
  and 
  one 
  of 
  them 
  being 
  no 
  less 
  than 
  

   3700. 
  Yet 
  it 
  is 
  evident 
  the 
  glaciers 
  proceeding 
  from 
  this 
  ridge 
  were 
  

   much 
  smaller 
  and 
  waned 
  sooner 
  than 
  those 
  that 
  blocked 
  the 
  

   mouths 
  of 
  Glen 
  Gluoy 
  and 
  Glen 
  Spean 
  ; 
  otherwise 
  they 
  would 
  have 
  

   occupied 
  the 
  watersheds 
  or 
  cols 
  and 
  also 
  the 
  top 
  of 
  Glen 
  Boy 
  at 
  

   the 
  time 
  the 
  terraces 
  show 
  that 
  these 
  places 
  were 
  clear 
  of 
  ice. 
  Now 
  

   what 
  we 
  know 
  regarding 
  the 
  rainfall 
  of 
  the 
  district 
  harmonizes 
  re- 
  

   markably 
  with 
  these 
  results. 
  We 
  have 
  the 
  records 
  of 
  three 
  gauges 
  

   in 
  the 
  neighbourhood 
  of 
  Ben 
  Nevis 
  and 
  Loch 
  Arkaig 
  — 
  namely, 
  one 
  at 
  

   Fort 
  William, 
  another 
  at 
  Glen 
  Quoich, 
  and 
  a 
  third 
  at 
  Inverie 
  near 
  

   Loch 
  Nevis 
  ; 
  and 
  the 
  annual 
  rainfall 
  at 
  each 
  of 
  these 
  places 
  is 
  86, 
  

   102, 
  and 
  82 
  inches 
  respectively, 
  being 
  an 
  average 
  of 
  90 
  inches 
  in 
  

   the 
  year, 
  whereas 
  at 
  Laggan, 
  near 
  the 
  head 
  of 
  the 
  Spey, 
  the 
  annual 
  

   amount 
  of 
  rain 
  is 
  only 
  46 
  inches, 
  or 
  just 
  about 
  half 
  of 
  this. 
  

  

  Again, 
  there 
  seems 
  reason 
  to 
  believe 
  that 
  the 
  upper 
  reach 
  of 
  the 
  

   Moray 
  Firth 
  was 
  at 
  one 
  time 
  occupied 
  by 
  a 
  large 
  glacier 
  composed 
  

   of 
  the 
  united 
  ice-streams 
  issuing 
  from 
  all 
  the 
  glens 
  of 
  Ross-shire 
  

   and 
  Inverness, 
  which 
  now 
  pour 
  their 
  waters 
  into 
  the 
  Moray 
  and 
  

   Dornoch 
  Firths. 
  This 
  great 
  glacier 
  seems 
  not 
  only 
  to 
  have 
  occupied 
  

   the 
  top 
  of 
  the 
  Moray 
  Firth, 
  but 
  to 
  have 
  spread 
  eastward 
  past 
  Nairn 
  

   and 
  Elgin 
  to 
  near 
  Speymouth, 
  as 
  if 
  the 
  glaciers 
  descending 
  from 
  the 
  

   district 
  lying 
  to 
  the 
  east 
  of 
  Inverness 
  (now 
  remarkable 
  for 
  its 
  dry 
  

   climate 
  and 
  small 
  amount 
  of 
  rain) 
  were 
  comparatively 
  so 
  small 
  as 
  to 
  

   be 
  overborne 
  and 
  pressed 
  aside 
  by 
  the 
  heavier 
  ice 
  issuing 
  from 
  the 
  

  

  