﻿REV. 
  W. 
  DOWNES 
  ON 
  THE 
  BLACKDOWN 
  BEDS. 
  79 
  

  

  Correlation 
  of 
  the 
  Blaclcdown 
  Beds 
  iviili 
  other 
  Localities. 
  

  

  Mr. 
  Meyer, 
  referring 
  to 
  Mr. 
  Ralph 
  Tate's 
  description 
  of 
  the 
  Cre- 
  

   taceous 
  rocks 
  of 
  the 
  jSTorth-east 
  of 
  Ireland 
  (Quart. 
  Journ. 
  Geol. 
  Soc. 
  

   vol. 
  xxi. 
  p. 
  15), 
  says 
  that 
  of 
  the 
  three 
  zones 
  of 
  Tate 
  " 
  the 
  lowest, 
  or 
  

   ' 
  Glauconitic 
  sands 
  ' 
  . 
  . 
  . 
  apparently 
  represents 
  to 
  some 
  extent 
  " 
  

   his 
  " 
  beds 
  1 
  to 
  3 
  of 
  the 
  Devon 
  sections," 
  i. 
  e. 
  1 
  to 
  3 
  of 
  Meyer. 
  

  

  Prof. 
  Duncan, 
  referring 
  to 
  the 
  coral 
  fauna, 
  which 
  occurs 
  high 
  up 
  

   in 
  the 
  series, 
  and 
  which 
  is 
  chiefly 
  found 
  at 
  Haldon, 
  and 
  is 
  but 
  barely 
  

   represented 
  at 
  Blackdown, 
  says 
  of 
  this 
  zone, 
  that 
  " 
  the 
  fauna 
  is 
  a 
  

   poor 
  representation 
  of 
  that 
  of 
  Gosau; 
  but 
  the 
  facies 
  is 
  the 
  same." 
  

   MM. 
  Briart 
  et 
  Cornet 
  have 
  no 
  hesitation 
  in 
  asserting 
  the 
  iden- 
  

   tity 
  of 
  the 
  Blackdown 
  beds 
  with 
  the 
  Meule 
  de 
  Bracquegnies. 
  The 
  

   argument 
  is 
  based 
  on 
  the 
  proportion 
  of 
  fossil 
  species 
  common 
  to 
  the 
  

   two 
  localities. 
  Out 
  of 
  93 
  species 
  referred 
  by 
  them 
  in 
  1870 
  to 
  the 
  

   Meule, 
  42 
  are 
  found 
  at 
  Blackdown, 
  3 
  only 
  in 
  the 
  English 
  Gault, 
  

   while 
  8, 
  13, 
  and 
  5 
  respectively 
  are 
  found 
  at 
  Rouen, 
  Sarthe, 
  and 
  

   in 
  the 
  Tourtia 
  of 
  Tournai 
  and 
  Montignies-sur-Roc, 
  leaving 
  a 
  re- 
  

   mainder 
  of 
  22 
  not 
  compared. 
  

  

  In 
  the 
  Geological 
  Magazine, 
  1881, 
  p. 
  431, 
  I 
  read 
  that 
  MM. 
  Bri- 
  

   art 
  et 
  Cornet 
  had 
  at 
  that 
  date 
  raised 
  the 
  number 
  of 
  species 
  from 
  the 
  

   Meule 
  to 
  120. 
  How 
  far 
  this 
  may 
  affect 
  the 
  proportion 
  of 
  fossils 
  

   common 
  to 
  Blackdown 
  I 
  do 
  not 
  know 
  ; 
  but 
  taking 
  their 
  original 
  

   comparison, 
  we 
  have 
  42 
  out 
  of 
  93 
  species 
  common 
  to 
  the 
  two 
  local- 
  

   ities 
  — 
  that 
  is 
  to 
  say, 
  less 
  than 
  half. 
  I 
  should 
  scarcely 
  have 
  thought 
  

   that 
  this 
  fact 
  alone 
  would 
  warrant 
  the 
  conclusion, 
  " 
  ces 
  resultats 
  ne 
  

   peuvent 
  laisser 
  aucun 
  doute 
  sur 
  1'identite 
  de 
  la 
  meule 
  avec 
  les 
  

   couches 
  si 
  remarquables 
  de 
  Blackdown." 
  

  

  Mr. 
  Meyer, 
  writing 
  in 
  reference 
  to 
  this 
  subject 
  in 
  1879, 
  says 
  : 
  — 
  

   " 
  The 
  fossils 
  of 
  the 
  Meule 
  de 
  Bracquegnies, 
  so 
  many 
  of 
  which 
  are 
  

   referred 
  by 
  MM. 
  Briart 
  et 
  Cornet 
  to 
  Blackdown 
  species, 
  differ 
  in 
  

   such 
  points 
  as 
  bring 
  them 
  nearer 
  to 
  the 
  Chlori 
  tic 
  -Marl 
  fauna; 
  and 
  

   they 
  are, 
  moreover, 
  associated 
  with 
  Chloritic-Marl 
  species 
  ; 
  and 
  for 
  

   this 
  reason 
  I 
  fancy 
  our 
  Blackdown 
  fossils 
  are 
  older 
  than 
  their 
  

   supposed 
  Belgian 
  equivalents 
  " 
  *. 
  

  

  To 
  this 
  I 
  would 
  add 
  that 
  the 
  very 
  small 
  number 
  in 
  common 
  with 
  

   the 
  English 
  Gault 
  (3 
  only) 
  is 
  remarkable, 
  seeing 
  that 
  the 
  Blackdown 
  

   fauna 
  has 
  been 
  supposed 
  to 
  contain 
  a 
  very 
  large 
  proportion 
  of 
  Gault 
  

   formsf. 
  

  

  I 
  observe 
  also 
  that 
  the 
  beds 
  above 
  the 
  Meule, 
  five 
  in 
  number, 
  

   which 
  separate 
  it 
  from 
  the 
  Chalk, 
  are, 
  according 
  to 
  MM. 
  Briart 
  et 
  

   Cornet's 
  section, 
  all 
  marly, 
  and 
  that 
  bed 
  J" 
  immediately 
  above 
  the 
  

   Meule 
  contains 
  Pecten 
  asper, 
  which 
  apparently 
  does 
  not 
  occur 
  in 
  the 
  

   Meule 
  itself 
  %. 
  

  

  I 
  am 
  not 
  aware 
  that 
  a 
  detailed 
  comparison 
  of 
  the 
  Blackdown 
  beds 
  

  

  * 
  Extract 
  from 
  letter, 
  by 
  permission. 
  

  

  f 
  Mr. 
  J. 
  S. 
  Gardner 
  tells 
  me 
  that 
  the 
  species 
  supposed 
  to 
  be 
  common 
  to 
  the 
  

   two 
  localities 
  are 
  very 
  often 
  not 
  strictly 
  identical, 
  

   i 
  Plate 
  i., 
  Mem. 
  Cour. 
  torn. 
  34. 
  

  

  