﻿TO 
  THE 
  OEDOV1CIAN 
  EOCKS 
  OP 
  THE 
  NOETHEEN 
  HIGHLANDS. 
  117 
  

  

  or 
  even 
  trebled, 
  the 
  question 
  would 
  not 
  be 
  materially 
  affected, 
  since, 
  

   in 
  these 
  shore-deposits, 
  great 
  accumulations 
  may 
  be 
  formed 
  in 
  a 
  few 
  

   millenniums. 
  The 
  overlying 
  quartzo-calcareous 
  series 
  nowhere, 
  I 
  

   believe, 
  reaches 
  a 
  maximum 
  of 
  500 
  feet, 
  the 
  great 
  prominence 
  which 
  

   it 
  assumes 
  in 
  the 
  lofty 
  mass 
  of 
  Ben 
  More 
  of 
  Assynt 
  being 
  due 
  to 
  

   frequent 
  repetitions 
  by 
  faulting 
  and 
  folding. 
  Accepting 
  an 
  extreme 
  

   estimate, 
  the 
  united 
  sandstone 
  and 
  quartzite 
  will 
  hardly 
  exceed 
  the 
  

   thickness 
  of 
  the 
  Arenigs 
  of 
  Shropshire, 
  which, 
  composed 
  mainly 
  of 
  

   shales 
  and 
  fine-grained 
  flags, 
  must 
  have 
  been 
  accumulated 
  with 
  much 
  

   less 
  rapidity 
  ; 
  and 
  the 
  Highland 
  groups 
  must 
  fall 
  short 
  of 
  the 
  Arenigs 
  

   of 
  South 
  Wales, 
  which 
  Dr. 
  Hicks 
  calculates 
  at 
  nearly 
  4000 
  feet. 
  

   There 
  would 
  therefore 
  appear 
  to 
  be 
  no 
  sufficient 
  reason 
  for 
  sepa- 
  

   rating 
  the 
  Torridon 
  Sandstone 
  from 
  the 
  Ordovician 
  system. 
  

  

  Discussion. 
  

  

  Mr. 
  Hudleston 
  said 
  that 
  Dr. 
  Heddle 
  maintained 
  the 
  unconformity 
  

   of 
  the 
  quartzites 
  with 
  the 
  Torridon 
  Sandstone, 
  and 
  he 
  was 
  extremely 
  

   well 
  acquainted 
  with 
  the 
  district. 
  This 
  was 
  a 
  question 
  of 
  evidence 
  

   which 
  could 
  hardly 
  be 
  brought 
  before 
  the 
  meeting 
  ; 
  but 
  as 
  regards 
  

   the 
  age 
  of 
  the 
  sandstone 
  it 
  was 
  possible 
  that 
  the 
  limestones 
  over 
  

   the 
  quartzites 
  were 
  not 
  of 
  the 
  same 
  age 
  as 
  the 
  Durness 
  Lime- 
  

   stone 
  ; 
  the 
  old 
  statements 
  as 
  to 
  fossils 
  having 
  been 
  found 
  in 
  the 
  

   limestone 
  and 
  quartzite 
  group 
  did 
  not 
  seem 
  to 
  have 
  been 
  sub- 
  

   stantiated. 
  The 
  chemical 
  composition 
  of 
  the 
  two 
  differed; 
  the 
  

   fossiliferous 
  limestone 
  of 
  Durness 
  was 
  not 
  dolomitic, 
  the 
  others 
  

   were, 
  containing 
  sometimes 
  48 
  per 
  cent, 
  of 
  carbonate 
  of 
  magnesia 
  ; 
  

   if 
  these 
  are 
  different 
  the 
  theories 
  built 
  upon 
  their 
  supposed 
  identity 
  

   fall 
  to 
  the 
  ground. 
  

  

  Mr. 
  Deew 
  asked 
  if 
  Dr. 
  Callaway 
  had 
  visited 
  the 
  same 
  section 
  

   that 
  Sir 
  Roderick 
  Murchison 
  had 
  described. 
  

  

  Dr. 
  Hicks 
  said 
  that 
  he 
  thought 
  if 
  Dr. 
  Callaway 
  had 
  carried 
  his 
  

   sections 
  farther 
  south 
  he 
  would 
  have 
  seen 
  unconformity. 
  In 
  the 
  

   neighbourhood 
  of 
  Loch 
  Maree 
  the 
  Torridon 
  Sandstone 
  was 
  nearly 
  

   4000 
  feet 
  thick, 
  and 
  the 
  quartzite 
  within 
  a 
  very 
  short 
  distance 
  

   rested 
  directly 
  upon 
  the 
  gneiss, 
  so 
  that 
  an 
  unconformity 
  was 
  needed. 
  

   He 
  could 
  not 
  agree, 
  however, 
  with 
  the 
  views 
  of 
  Dr. 
  Heddle 
  as 
  to 
  

   the 
  non-identity 
  of 
  the 
  limestone 
  of 
  Durness 
  with 
  that 
  of 
  the 
  other 
  

   districts. 
  He 
  thought 
  that 
  the 
  Torridon 
  Sandstone 
  represented 
  the 
  

   Lower 
  Cambrian, 
  and 
  the 
  quartzite 
  series, 
  which 
  contains 
  evidences 
  

   of 
  worm-tracks, 
  some 
  part 
  of 
  the 
  Lower 
  Silurian. 
  

  

  Prof* 
  Bonnet 
  said 
  he 
  agreed 
  with 
  Dr. 
  Hicks 
  in 
  thinking 
  that 
  the 
  

   Loch-Maree 
  quartzites 
  were 
  unconformable 
  with 
  the 
  Torridon 
  Sand- 
  

   stone 
  ; 
  at 
  the 
  same 
  time 
  he 
  was 
  prepared 
  to 
  believe 
  there 
  was 
  con- 
  

   formity 
  further 
  north. 
  He 
  believed, 
  from 
  microscopic 
  examination, 
  

   that 
  the 
  limestone 
  in 
  Glen 
  Laggan 
  was 
  dolomitic, 
  and 
  thought 
  that 
  

   Prof. 
  Heddle's 
  solution 
  of 
  the 
  question 
  was 
  the 
  right 
  one. 
  He 
  

   could 
  not 
  think 
  the 
  Torridon 
  Sandstone 
  Ordovician 
  ; 
  at 
  any 
  rate, 
  if 
  

   it 
  were, 
  Dr. 
  Callaway 
  must 
  accept 
  the 
  following 
  dilemma, 
  either 
  

  

  