﻿200 
  

  

  TROT. 
  E. 
  HULL 
  OX 
  A 
  PROPOSED 
  

  

  20. 
  On 
  a 
  Proposed 
  Devono-Silurian^ 
  Formation. 
  By 
  Professor 
  

   Edward 
  Hull, 
  LL.D., 
  F.R.S., 
  F.G.S., 
  &c, 
  Director 
  of 
  the 
  Geo- 
  

   logical 
  Survey 
  of 
  Ireland. 
  (Read 
  January 
  11, 
  1882.) 
  

  

  The 
  beds 
  which 
  I 
  propose 
  to 
  group 
  under 
  the 
  above 
  title 
  are 
  found 
  

   at 
  various 
  parts 
  of 
  the 
  British 
  Isles, 
  and 
  only 
  to 
  a 
  slight 
  extent, 
  if 
  

   at 
  all, 
  in 
  Belgium 
  and 
  France 
  *. 
  The 
  formation 
  is 
  therefore 
  emi- 
  

   nently 
  British, 
  and 
  goes 
  by 
  various 
  local 
  names 
  where 
  it 
  occurs. 
  

   But 
  it 
  seems 
  desirable 
  that 
  the 
  relations 
  of 
  these 
  detached 
  groups 
  to 
  

   each 
  other 
  should 
  be 
  more 
  clearly 
  defined 
  than 
  has 
  hitherto 
  been 
  

   done 
  — 
  and 
  also 
  that 
  one 
  definite 
  term 
  should 
  be 
  applied 
  to 
  designa- 
  

   nate 
  them, 
  such 
  as 
  that 
  I 
  have 
  ventured 
  to 
  place 
  at 
  the 
  head 
  of 
  this 
  

   paper 
  f. 
  

  

  I 
  shall 
  commence 
  by 
  the 
  admission 
  that 
  the 
  coining 
  of 
  new 
  names 
  

   is 
  objectionable, 
  and 
  is 
  not 
  agreeable 
  to 
  my 
  own 
  inclinations. 
  But 
  

   in 
  this 
  case, 
  at 
  least, 
  it 
  seems 
  unavoidable, 
  because, 
  where 
  there 
  

   are 
  several 
  competitors 
  for 
  the 
  honour 
  of 
  giving 
  a 
  name 
  to 
  a 
  large 
  

   and 
  distinguished 
  family 
  of 
  rocks, 
  with 
  apparently 
  equal 
  claims, 
  the 
  

   simplest 
  solution 
  of 
  the 
  difficulty 
  of 
  choice 
  seems 
  to 
  be 
  to 
  select 
  a 
  

   name 
  which 
  belongs 
  to 
  none 
  of 
  the 
  candidates, 
  but 
  which 
  will 
  

   serve 
  to 
  designate 
  the 
  social 
  standing 
  of 
  them 
  all. 
  The 
  term 
  " 
  De- 
  

   vono-Silurian," 
  as 
  it 
  seems 
  to 
  me, 
  meets 
  the 
  case, 
  as 
  it 
  indicates 
  

   that 
  the 
  disconnected 
  groups 
  of 
  strata 
  which 
  I 
  propose 
  to 
  include 
  

   under 
  it 
  lie 
  at 
  the 
  margin 
  of 
  the 
  two 
  great 
  formations 
  — 
  the 
  Devo- 
  

   nian 
  on 
  the 
  one 
  hand 
  and 
  the 
  Silurian 
  on 
  the 
  other. 
  They 
  form, 
  in 
  

   fact, 
  the 
  connecting 
  links 
  between 
  the 
  two 
  series, 
  though 
  generally 
  

   found 
  dissociated 
  from 
  one 
  or 
  other 
  of 
  their 
  neighbouring 
  formations. 
  

  

  I 
  shall 
  commence 
  by 
  indicating 
  the 
  British 
  localities 
  for 
  repre- 
  

   sentatives 
  of 
  the 
  Devono-Silurian 
  formation, 
  and 
  give 
  at 
  the 
  same 
  

   time 
  a 
  description 
  of 
  their 
  characters 
  and 
  stratigraphical 
  position. 
  

   Fortunately, 
  this 
  need 
  only 
  be 
  brief, 
  as 
  each 
  locality 
  has 
  already 
  

   received 
  no 
  small 
  amount 
  of 
  attention 
  from 
  previous 
  writers. 
  

  

  Only 
  one 
  Old 
  Red 
  Sandstone. 
  — 
  Let 
  me 
  here 
  clear 
  the 
  ground 
  for 
  

   my 
  proposal 
  by 
  endeavouring 
  to 
  dispel 
  from 
  the 
  minds 
  of 
  British 
  

   geologists 
  the 
  idea 
  that 
  there 
  are 
  two 
  formations 
  entitled 
  to 
  be 
  called 
  

   respectively 
  " 
  Upper" 
  and 
  "Lower" 
  Old 
  Bed 
  Sandstone. 
  Until 
  

   recently 
  I 
  was 
  myself 
  under 
  this 
  impression 
  ; 
  and 
  the 
  doctrine 
  being 
  

   upheld 
  by 
  many 
  high 
  authorities, 
  I 
  clung 
  to 
  it 
  tenaciously 
  till 
  I 
  

   went 
  through 
  the 
  process 
  of 
  disenchantment 
  which 
  was 
  brought 
  

   about 
  by 
  my 
  visits 
  to 
  Belgium 
  and 
  Devonshire 
  in 
  1879. 
  The 
  re- 
  

   sults 
  of 
  these 
  visits 
  have 
  already 
  been 
  published 
  J 
  ; 
  and 
  not 
  the 
  least 
  

   important 
  to 
  myself 
  was 
  that 
  by 
  which 
  I 
  discovered 
  that 
  there 
  is 
  

  

  * 
  Postea, 
  p. 
  203. 
  — 
  It 
  is 
  possible 
  that 
  in 
  America 
  these 
  beds 
  may 
  be 
  repre- 
  

   sented 
  by 
  the 
  lower 
  portion 
  of 
  the 
  "G-aspe 
  Sandstones 
  " 
  with 
  plants. 
  

  

  t 
  This 
  term 
  I 
  adopted 
  when 
  drawing 
  up 
  Tables 
  of 
  the 
  Devonian 
  and 
  Car- 
  

   boniferous 
  sj-stems 
  for 
  the 
  British 
  Committee 
  of 
  the 
  International 
  Geological 
  

   Congress, 
  to 
  be 
  held 
  at 
  Bologna 
  this 
  year. 
  

  

  } 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  May 
  1880, 
  p. 
  255. 
  

  

  