﻿LAND 
  PLANTS 
  FROM 
  THE 
  PEN-Y-GLOG 
  SLATE- 
  QUARRY, 
  N. 
  WALES. 
  97 
  

  

  8. 
  Additional 
  Notes 
  on 
  the 
  Land 
  Plants 
  from 
  the 
  Pen-y-glog 
  

   Slate-quarry 
  near 
  Corwen, 
  North 
  Wales. 
  By 
  Henry 
  Hicks, 
  

   Esq., 
  M.D., 
  F.G.S. 
  (Read 
  November 
  16, 
  1881.) 
  

  

  [Plate 
  III.] 
  

  

  In 
  my 
  former 
  paper, 
  read 
  before 
  the 
  Geological 
  Society 
  in 
  May 
  1881, 
  1 
  

   mentioned 
  that, 
  in 
  addition 
  to 
  the 
  plant-remains 
  from 
  the 
  Pen-y-glog 
  

   grits 
  and 
  shales 
  chiefly 
  referred 
  to 
  in 
  that 
  paper, 
  I 
  had 
  also 
  ob- 
  

   tained 
  some 
  evidence 
  of 
  a 
  still 
  earlier 
  flora 
  in 
  the 
  underlying 
  slates. 
  

   Since 
  then 
  I 
  have 
  revisited 
  the 
  slate-quarry 
  ; 
  and 
  with 
  the 
  kind 
  as- 
  

   sistance 
  of 
  Mr. 
  Phillips, 
  the 
  manager 
  of 
  the 
  quarry, 
  I 
  have 
  secured 
  

   specimens 
  which 
  prove 
  beyond 
  doubt 
  that 
  fragments 
  of 
  land-plants 
  

   occur 
  in 
  tolerable 
  abundance 
  at 
  several 
  horizons 
  to 
  the 
  very 
  base 
  of 
  

   the 
  quarry. 
  In 
  consequence 
  of 
  the 
  slaty 
  cleavage 
  and 
  the 
  difficulty 
  

   therefore 
  of 
  obtaining 
  bedding-surfaces, 
  large 
  specimens 
  can 
  seldom 
  

   be 
  found. 
  All 
  the 
  specimens 
  are 
  in 
  a 
  mineralized 
  condition, 
  the 
  

   larger 
  ones 
  in 
  the 
  form 
  of 
  anthracite 
  with 
  a 
  bright 
  glassy 
  fracture. 
  

   The 
  anthracite 
  is 
  very 
  hard 
  ; 
  and 
  there 
  is 
  often 
  a 
  thickness 
  of 
  from 
  

   T 
  \ 
  to 
  -i- 
  of 
  an 
  inch 
  remaining 
  as 
  the 
  result 
  of 
  the 
  decomposition 
  of 
  a 
  

   fragment 
  of 
  the 
  plant*. 
  

  

  The 
  smaller 
  stems 
  and 
  branches 
  show 
  little 
  more 
  than 
  a 
  carbo- 
  

   naceous 
  film. 
  A 
  light 
  fibrous 
  mineral, 
  a 
  hydrated 
  magnesian 
  sili- 
  

   cate, 
  now 
  spreads 
  more 
  or 
  less 
  over 
  the 
  surfaces 
  of 
  most 
  of 
  the 
  speci- 
  

   mens 
  and 
  fills 
  up 
  also 
  the 
  fractures. 
  The 
  anthracite, 
  though 
  so 
  pure, 
  

   appears 
  here 
  to 
  have 
  been 
  the 
  result 
  of 
  the 
  slow 
  decomposition 
  of 
  one 
  

   plant, 
  accompanied 
  by 
  pressure 
  only. 
  The 
  conversion 
  could 
  not 
  

   have 
  been 
  the 
  result 
  of 
  heat, 
  as 
  there 
  is 
  no 
  evidence 
  in 
  the 
  rocks 
  or 
  

   the 
  associated 
  fossils 
  of 
  their 
  having 
  been 
  subjected 
  to 
  a 
  high 
  tem- 
  

   perature. 
  This 
  fact 
  may, 
  I 
  think, 
  throw 
  some 
  light 
  on 
  the 
  way 
  

   vegetable 
  matter 
  may, 
  in 
  many 
  cases, 
  have 
  been 
  converted 
  into 
  

   anthracite. 
  I 
  have 
  shown 
  most 
  of 
  the 
  specimens 
  to 
  Mr. 
  Carruthers 
  ; 
  

   and 
  he 
  has 
  kindly 
  written 
  me 
  a 
  note 
  in 
  which 
  he 
  says 
  that 
  " 
  it 
  is 
  

  

  * 
  Mr. 
  T. 
  Davies, 
  F.G.S., 
  has 
  kindly 
  examined 
  the 
  anthracite 
  ; 
  and 
  he 
  says 
  as 
  

   follows 
  : 
  — 
  

  

  " 
  Your 
  coal 
  is 
  a 
  true 
  anthracite. 
  Heated 
  in 
  a 
  test-tube 
  to 
  a 
  red 
  heat 
  it 
  de- 
  

   crepitates 
  slightly, 
  but 
  gives 
  off 
  no 
  appreciable 
  quantity 
  of 
  gas; 
  nor 
  does 
  it 
  seem 
  

   to 
  be 
  affected 
  in 
  any 
  way 
  whatever 
  by 
  prolonging 
  the 
  heating. 
  After 
  four 
  hours' 
  

   subjection 
  to 
  a 
  bright 
  red 
  heat, 
  I 
  obtained 
  05 
  per 
  cent, 
  of 
  ash 
  ; 
  as 
  you 
  will 
  see, 
  

   this 
  is 
  considerably 
  below 
  that 
  given 
  for 
  some 
  of 
  the 
  anthracites 
  of 
  Pennsyl- 
  

   vania, 
  though 
  it 
  is 
  not 
  improbable 
  that 
  some 
  of 
  the 
  compact 
  kinds 
  of 
  this 
  

   (Penns.) 
  coal, 
  which 
  are 
  regarded 
  as 
  quite 
  unfit 
  for 
  fuel, 
  may 
  contain 
  as 
  small 
  

   a 
  quantity. 
  I 
  recollect 
  reading 
  in 
  the 
  Comptes 
  Reudus 
  in 
  1867, 
  a 
  notice 
  of 
  some 
  

   anthracite, 
  analyzed 
  by 
  M. 
  Daubree, 
  which 
  contained 
  the 
  following 
  : 
  — 
  

  

  Carbon 
  976 
  

  

  Hydrogen 
  0*7 
  

  

  Oxygen 
  1*7 
  

  

  1000 
  

   You 
  see 
  here 
  is 
  no 
  room 
  left 
  for 
  ash." 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  149. 
  n 
  

  

  