﻿lxxxvi 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [May 
  l8Q7 
  r 
  

  

  concludes 
  by 
  saying 
  : 
  ' 
  With 
  every 
  desire 
  to 
  follow 
  the 
  interpretation 
  

   of 
  my 
  late 
  chief, 
  I 
  criticized 
  minutely 
  each 
  detail 
  of 
  the 
  work 
  upon 
  

   the 
  ground; 
  but 
  I 
  found 
  the 
  evidence 
  altogether 
  overwhelming 
  

   against 
  the 
  upward 
  succession 
  which 
  Murchison 
  believed 
  to 
  exist 
  

   in 
  Eriboll 
  from 
  the 
  base 
  of 
  the 
  Silurian 
  strata 
  into 
  an 
  upper 
  

   conformable 
  series 
  of 
  schists 
  and 
  gneisses 
  ' 
  (p. 
  30). 
  Since 
  that 
  time 
  

   the 
  districts 
  about 
  Loch 
  Maree, 
  Gairloch, 
  Auchnasheen, 
  and 
  Loch 
  

   Carron 
  have 
  been 
  surveyed 
  by 
  the 
  officers 
  of 
  the 
  Geological 
  Survey,. 
  

   and 
  in 
  their 
  report 
  for 
  1895 
  (p. 
  19) 
  it 
  is 
  stated 
  that 
  ' 
  in 
  the 
  area 
  

   mapped 
  between 
  Auchnasheen 
  and 
  Loch 
  Alsh, 
  evidence 
  has 
  been 
  

   obtained 
  of 
  the 
  alternations 
  of 
  strips 
  of 
  recognizable 
  Lewisian 
  Gneiss 
  

   with 
  schists 
  of 
  the 
  true 
  Moine 
  type 
  . 
  . 
  . 
  Some 
  of 
  the 
  cores 
  and 
  

   lenticles 
  of 
  gneiss, 
  almost 
  certainly 
  Lewisian, 
  attain 
  a 
  considerable 
  

   size. 
  Thus, 
  to 
  the 
  south 
  of 
  Auchnasheen, 
  a 
  tract 
  of 
  hornblendic 
  

   gneiss 
  covers 
  an 
  area 
  of 
  perhaps 
  more 
  than 
  50 
  square 
  miles.' 
  It 
  

   is 
  but 
  right 
  to 
  state 
  that 
  Prof. 
  Bonney 
  and 
  I 
  called 
  particular 
  

   attention 
  to 
  what 
  we 
  considered 
  the 
  re-appearance 
  of 
  the 
  older 
  

   gneisses 
  in 
  these 
  areas 
  in 
  1883, 
  and 
  therefore 
  far 
  to 
  the 
  east 
  of 
  any 
  

   areas 
  in 
  which 
  they 
  had 
  previously 
  been 
  described, 
  and 
  the 
  following 
  

   passage 
  occurs 
  in 
  my 
  paper 
  of 
  1883: 
  — 
  'The 
  presence 
  of 
  a 
  group 
  

   of 
  gneisses 
  of 
  so 
  old-looking 
  a 
  character, 
  and 
  with 
  a 
  crystalline 
  

   condition, 
  as 
  shown 
  in 
  microscopical 
  sections, 
  not 
  to 
  be 
  distin- 
  

   guished 
  from 
  the 
  oldest 
  gneisses 
  of 
  the 
  Loch 
  Maree 
  type, 
  reaching 
  

   to 
  the 
  crest 
  of 
  a 
  mountain 
  of 
  over 
  2300 
  feet 
  in 
  height, 
  in 
  an 
  area 
  

   regarded 
  as 
  containing 
  the 
  so-called 
  newer 
  Silurian 
  metamorphic 
  

   rocks 
  only, 
  and 
  east 
  of 
  the 
  limestone 
  series, 
  is 
  a 
  fact 
  of 
  enormous 
  

   importance, 
  especially 
  as 
  we 
  are 
  told 
  by 
  Murchison 
  and 
  Geikie 
  that 
  

   the 
  rocks 
  found 
  in 
  this 
  area 
  are 
  newer 
  than 
  the 
  limestone 
  

   series 
  of 
  Loch 
  Kishorn, 
  and 
  that 
  they 
  repose 
  conformably 
  upon 
  the 
  

   latter.' 
  l 
  Since 
  the 
  rocks 
  of 
  these 
  areas 
  were 
  described 
  by 
  us 
  in 
  

   1883, 
  views 
  as 
  to 
  the 
  origin 
  of 
  the 
  gneisses 
  and 
  of 
  some 
  of 
  the 
  

   crystalline 
  schists 
  have 
  undergone 
  a 
  considerable 
  change, 
  and 
  it 
  is 
  

   now 
  generally 
  admitted 
  that 
  the 
  massive 
  gneisses 
  are 
  in 
  the 
  main 
  

   igneous 
  rocks 
  which 
  had 
  been 
  crumpled, 
  crushed, 
  and 
  deformed 
  in 
  

   pre-Cambrian 
  times. 
  Facts 
  bearing 
  on 
  these 
  questions 
  have 
  been 
  

   worked 
  out 
  with 
  great 
  care 
  by 
  the 
  officers 
  of 
  the 
  Geological 
  Survey 
  

   in 
  several 
  areas 
  in 
  Scotland. 
  

  

  At 
  the 
  Meeting 
  of 
  the 
  British 
  Association 
  in 
  1891 
  an 
  important 
  

   announcement 
  was 
  made 
  by 
  Sir 
  A. 
  Geikie 
  of 
  the 
  discovery 
  of 
  Lower 
  

   Cambrian 
  fossils 
  by 
  the 
  officers 
  of 
  the 
  Geological 
  Survey 
  in 
  rocks 
  

   overlying 
  unconformably 
  the 
  Torridon 
  Sandstone 
  in 
  the 
  North- 
  west 
  

   Highlands. 
  The 
  Torridon 
  Sandstone, 
  which 
  attains 
  a 
  thickness 
  

   1 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  toI. 
  xxxix. 
  p. 
  151. 
  

  

  