﻿228 
  J. 
  W. 
  JUDD 
  ON 
  THE 
  SECONDARY 
  KOCKS 
  OE 
  SCOTLAND. 
  

  

  (2) 
  Masses 
  of 
  vegetable 
  matter, 
  at 
  times 
  containing 
  recognizable 
  

   trunks 
  and 
  branches 
  of 
  trees, 
  in 
  some 
  cases 
  converted 
  by 
  the 
  heat 
  of 
  

   the 
  overflowing 
  lava 
  into 
  a 
  kind 
  of 
  charcoal, 
  and 
  at 
  others 
  constituting 
  

   beds 
  of 
  lignite 
  or 
  coal, 
  which 
  are 
  often 
  of 
  fair 
  quality 
  and 
  considerable 
  

   thickness, 
  but 
  seldom 
  of 
  great 
  extent 
  or 
  very 
  constant 
  character, 
  

   are 
  by 
  no 
  means 
  of 
  unfrequent 
  occurrence 
  between 
  the 
  sheets 
  of 
  

   Tertiary 
  lava. 
  Such 
  relics 
  of 
  the 
  vegetation 
  of 
  the 
  periods 
  during 
  

   which 
  the 
  great 
  sheets 
  of 
  basaltic 
  lava 
  were 
  formed 
  have 
  been 
  found 
  

   at 
  many 
  points 
  in 
  Ireland 
  — 
  also 
  in 
  the 
  Isle 
  of 
  Mull, 
  near 
  Carsaig, 
  

   at 
  Loch 
  Lathaich 
  and 
  Loch 
  Scridain 
  — 
  in 
  Morvern, 
  Ardnamurchan 
  

   and 
  the 
  islands 
  of 
  Eigg 
  and 
  Canna 
  — 
  -and 
  in 
  Skye, 
  at 
  Talisker, 
  Scori- 
  

   breck, 
  Portree, 
  Camiskianevig, 
  Loch 
  Grisornish 
  and 
  other 
  points. 
  

   Attempts 
  to 
  work 
  these 
  masses 
  of 
  coal 
  and 
  lignite 
  have 
  been 
  made 
  

   at 
  various 
  times, 
  especially 
  at 
  the 
  Giant's 
  Causeway 
  in 
  Antrim, 
  at 
  

   Carsaig 
  in 
  Mull, 
  and 
  at 
  Portree 
  in 
  Skye. 
  In 
  the 
  case 
  of 
  the 
  last-men- 
  

   tioned 
  locality 
  500 
  or 
  600 
  tons 
  of 
  fuel 
  is 
  said 
  to 
  have 
  been 
  obtained 
  ; 
  

   but, 
  as 
  might 
  be 
  anticipated, 
  the 
  deposits 
  have 
  been 
  found 
  to 
  be 
  too 
  

   irregular 
  in 
  thickness 
  and 
  inconstant 
  in 
  character 
  to 
  repay 
  the 
  cost 
  

   of 
  extensive 
  operations. 
  Owing 
  to 
  the 
  high 
  price 
  of 
  coal, 
  the 
  well- 
  

   known 
  lignite 
  bed 
  at 
  the 
  Giant's 
  Causeway 
  was 
  again 
  opened 
  out 
  by 
  

   the 
  country 
  people 
  during 
  the 
  winter 
  of 
  1872 
  ; 
  and 
  I 
  thus 
  had 
  an 
  

   opportunity 
  of 
  studying 
  its 
  characters. 
  It 
  is 
  evidently 
  the 
  vestige 
  

   of 
  an 
  old 
  forest 
  overwhelmed 
  by 
  a 
  lava 
  stream. 
  At 
  its 
  base 
  is 
  an 
  

   " 
  underclay 
  " 
  formed 
  from 
  the 
  decomposition 
  of 
  the 
  older 
  lava 
  bed 
  

   on 
  which 
  it 
  rests, 
  and 
  intermingled 
  with 
  much 
  vegetable 
  matter 
  ; 
  

   the 
  substance 
  of 
  the 
  lignite 
  itself 
  is 
  made 
  up 
  of 
  great 
  masses 
  of 
  

   wood, 
  still 
  very 
  clearly 
  exhibiting 
  its 
  tissues 
  ; 
  while 
  the 
  upper 
  por- 
  

   tions 
  of 
  the 
  mass, 
  which 
  are 
  in 
  contact 
  with 
  the 
  overlying 
  lava, 
  have 
  

   been 
  converted 
  by 
  heat 
  into 
  a 
  kind 
  of 
  charcoal. 
  

  

  (3) 
  In 
  the 
  interesting 
  section 
  of 
  Ardtun 
  we 
  have 
  evidence 
  of 
  

   mud 
  streams 
  (such 
  as 
  are 
  so 
  commonly 
  formed 
  in 
  the 
  vicinity 
  of 
  

   volcanoes 
  in 
  action) 
  having 
  overwhelmed 
  and 
  buried 
  the 
  deposits 
  of 
  

   fine 
  sediment 
  with 
  leaves 
  that 
  had 
  accumulated 
  in 
  pond-like 
  

   hollows 
  of 
  an 
  old 
  land 
  surface. 
  These 
  mud 
  streams 
  have 
  evidently, 
  

   during 
  part 
  of 
  their 
  course, 
  flowed 
  over 
  a 
  disintegrated 
  surface 
  of 
  

   the 
  chalk 
  rocks 
  of 
  the 
  district, 
  and 
  have 
  thus 
  caught 
  up 
  in 
  their 
  

   mass 
  many 
  unworn 
  chalk 
  flints 
  and 
  angular 
  fragments 
  of 
  the 
  highly 
  

   indurated 
  Scottish 
  chalk*. 
  The 
  remains 
  of 
  many 
  similar 
  old 
  mud 
  

  

  Mediterranean 
  area 
  (which, 
  through 
  the 
  kindness 
  of 
  Mr. 
  Scrope, 
  I 
  have 
  been 
  

   enabled 
  to 
  make 
  since 
  this 
  paper 
  was 
  read) 
  I 
  have 
  had 
  the 
  opportunity 
  of 
  seeing 
  

   how 
  completely 
  in 
  this, 
  as 
  in 
  innumerable 
  other 
  instances, 
  the 
  products 
  of 
  still 
  

   active 
  volcanoes 
  agree 
  with 
  those 
  which 
  are 
  connected 
  with 
  vents 
  long 
  since 
  

   extinct, 
  like 
  those 
  on 
  the 
  west 
  of 
  Scotland. 
  

  

  * 
  At 
  the 
  time 
  of 
  the 
  discovery 
  and 
  description 
  of 
  the 
  interesting 
  Ardtun 
  

   beds 
  the 
  fact 
  of 
  the 
  existence 
  of 
  rocks 
  of 
  chalk 
  and 
  flint 
  in 
  situ 
  in 
  the 
  island 
  of 
  

   Mull 
  was 
  unknown. 
  The 
  angular 
  fragments 
  in 
  the 
  mud-stream 
  of 
  Ardtun, 
  

   which 
  have 
  been 
  called 
  lapilli, 
  are 
  really 
  portions 
  of 
  the 
  peculiar 
  indurated 
  

   siliceous 
  chalk 
  of 
  the 
  district, 
  as, 
  indeed, 
  seems 
  to 
  have 
  been 
  strongly 
  suspected 
  

   by 
  the 
  Duke 
  of 
  Argyll 
  at 
  the 
  time. 
  The 
  manner 
  in 
  which 
  fragments 
  of 
  rock 
  

   of 
  all 
  sizes, 
  many 
  of 
  them 
  perfectly 
  angular, 
  are 
  mingled 
  together 
  in 
  a 
  fine- 
  

   grained 
  paste, 
  seems 
  to 
  me 
  to 
  be 
  inexplicable 
  on 
  any 
  other 
  supposition 
  than 
  that 
  

  

  