﻿204 
  PKOF. 
  E. 
  HULL 
  OX 
  A 
  TEOrOSED 
  

  

  (c) 
  South 
  Wales, 
  Hereford, 
  Src. 
  {Welsh 
  Borders). 
  — 
  The 
  beds 
  re- 
  

   ferable 
  to 
  this 
  group 
  in 
  the 
  district 
  north 
  of 
  the 
  Severn 
  and 
  border- 
  

   ing 
  the 
  Wye, 
  in 
  which 
  Murchison 
  first 
  established 
  his 
  Upper 
  Silurian 
  

   divisions, 
  may 
  be 
  supposed 
  to 
  embrace 
  all 
  those 
  lying 
  above 
  the 
  

   Upper 
  Ludlow 
  Bone-bed 
  extending 
  into 
  the 
  lower 
  beds 
  of 
  the 
  so-called 
  

   " 
  Old 
  Eed 
  Sandstone." 
  The 
  Down 
  ton 
  Sandstone 
  and 
  rocks 
  of 
  the 
  

   ridge 
  of 
  the 
  Trichrag 
  may 
  be 
  included 
  in 
  this 
  series. 
  

  

  The 
  formation 
  is 
  here 
  thin 
  and 
  unimportant 
  as 
  compared 
  with 
  its 
  

   representatives 
  in 
  Ireland 
  and 
  Scotland, 
  owing 
  probably 
  to 
  the 
  shal- 
  

   low 
  state 
  of 
  the 
  sea-bed 
  over 
  which 
  it 
  was 
  formed, 
  as 
  shown 
  by 
  the 
  

   contents 
  of 
  the 
  Upper 
  Ludlow 
  Bone-bed 
  itself. 
  

  

  It 
  is 
  in 
  this 
  district 
  alone 
  that 
  we 
  have 
  an 
  uninterrupted 
  and 
  con- 
  

   formable 
  succession, 
  from 
  the 
  Upper 
  Silurian 
  series 
  into 
  the 
  repre- 
  

   sentatives 
  of 
  the 
  Devonian, 
  visibly 
  displayed 
  ; 
  and 
  here 
  we 
  are 
  met 
  

   by 
  another 
  source 
  of 
  confusion 
  in 
  our 
  geological 
  nomenclature, 
  

   because 
  these 
  representatives 
  of 
  the 
  Devonian 
  series 
  are 
  also 
  called 
  

   " 
  Old 
  Red 
  Sandstone," 
  a 
  name 
  which 
  has 
  been 
  applied 
  to 
  them 
  

   mainly 
  in 
  consequence 
  of 
  their 
  prevalent 
  red 
  colouring, 
  but 
  also 
  

   from 
  the 
  idea 
  that 
  they 
  represent 
  the 
  " 
  (Lower) 
  Old 
  Red 
  Sandstone 
  " 
  

   of 
  other 
  districts. 
  Thus 
  it 
  comes 
  to 
  pass 
  that 
  in 
  the 
  British 
  Isles 
  we 
  

   have 
  been 
  accustomed 
  to 
  call 
  three 
  sets 
  of 
  strata, 
  occupying 
  three 
  

   distinct 
  geological 
  horizons, 
  by 
  the 
  favourite 
  name 
  of 
  "Old 
  Red 
  

   Sandstone." 
  Let 
  me 
  here 
  name 
  them 
  once 
  and 
  for 
  all 
  : 
  — 
  

  

  1st. 
  The 
  (Upper) 
  Old 
  Red 
  Sandstone, 
  representing, 
  in 
  fact, 
  the 
  

   Upper 
  Devonian 
  series 
  in 
  part. 
  

  

  2nd. 
  "The 
  Old 
  Red 
  Sandstone" 
  of 
  Hereford 
  and 
  South 
  Wales, 
  

   representing 
  the 
  Middle 
  and 
  Lower 
  Devonian 
  beds 
  of 
  Devon- 
  

   shire 
  and 
  the 
  continent. 
  

  

  3rd. 
  " 
  The 
  (Lower) 
  Old 
  Red 
  Sandstone 
  " 
  of 
  Scotland 
  and 
  parts 
  of 
  

   Ireland, 
  representing 
  the 
  Passage-beds 
  into 
  the 
  Upper 
  Silurian 
  

   series, 
  or, 
  as 
  I 
  now 
  propose 
  to 
  call 
  them, 
  the 
  Devono-Silurian 
  

   beds. 
  

  

  Now, 
  as 
  I 
  have 
  shown 
  above, 
  it 
  is 
  only 
  to 
  the 
  first 
  of 
  these 
  that 
  

   the 
  name 
  " 
  Old 
  Red 
  Sandstone 
  " 
  can 
  be 
  properly 
  applied. 
  The 
  " 
  Old 
  

   Red 
  Sandstone 
  " 
  (so 
  called) 
  of 
  Hereford 
  and 
  South 
  Wales 
  really 
  

   represents 
  all 
  the 
  beds 
  which 
  in 
  Devonshire 
  lie 
  between 
  the 
  " 
  Pick- 
  

   well-Down 
  Sandstone 
  " 
  and 
  the 
  " 
  Fprcland 
  Grits 
  and 
  Slates." 
  And 
  

   here 
  I 
  must 
  express 
  my 
  regret 
  that 
  I 
  cannot 
  concur 
  in 
  the 
  views 
  of 
  

   those 
  who 
  regard 
  the 
  so-called 
  " 
  Old 
  Red 
  Sandstone 
  " 
  of 
  Hereford 
  

   &c. 
  as 
  a 
  lake 
  deposit. 
  Professor 
  Geikie 
  considers 
  these 
  beds 
  to 
  

   have 
  been 
  deposited 
  in 
  one 
  of 
  his 
  lakes 
  of 
  the 
  Old- 
  Red 
  period, 
  

   namely 
  " 
  the 
  Welsh 
  Lake, 
  bounded 
  on 
  the 
  north 
  and 
  west 
  by 
  the 
  

   Cambrian 
  and 
  Silurian 
  rising 
  grounds, 
  but 
  its 
  eastern 
  and 
  southern 
  

   extension 
  obscured 
  by 
  later 
  formations 
  " 
  *. 
  I 
  have 
  already 
  ex- 
  

   pressed 
  an 
  opinion 
  that 
  these 
  beds 
  were 
  deposited, 
  not 
  in 
  the 
  bed 
  of 
  

   a 
  lake, 
  but 
  in 
  that 
  of 
  an 
  estuary, 
  bounded 
  (as 
  Professor 
  Geikie 
  

   states) 
  on 
  the 
  north 
  and 
  west 
  by 
  Cambrian 
  and 
  Silurian 
  rising 
  

  

  *' 
  Trans. 
  Roy. 
  Soc. 
  Edinburgh, 
  vol. 
  xx\dii. 
  

  

  