﻿384 
  C. 
  J. 
  A. 
  MEYER 
  ON 
  THE 
  CRETACEOUS 
  ROCKS 
  OE 
  

  

  The 
  base-bed 
  of 
  the 
  Chalk 
  Marl 
  (bed 
  13) 
  with 
  its 
  phosphatic 
  

   nodules, 
  which 
  is 
  fairly 
  represented 
  in 
  the 
  Beer-Head 
  district, 
  is 
  

   also 
  traceable 
  more 
  or 
  less 
  continuously 
  to 
  the 
  eastward. 
  Some- 
  

   times, 
  indeed, 
  it 
  almost 
  merges 
  into 
  the 
  Chloritic 
  Marl 
  ; 
  yet 
  even 
  then 
  

   it 
  is 
  always 
  traceable. 
  Its 
  upper 
  bed, 
  however 
  (bed 
  14), 
  and 
  the 
  

   succeeding 
  representatives 
  of 
  the 
  Lower 
  and 
  Upper 
  Chalk 
  (beds 
  15 
  

   to 
  20) 
  are, 
  on 
  account 
  of 
  their 
  local 
  peculiarities 
  of 
  structure, 
  far 
  

   from 
  easy 
  to 
  correlate 
  with 
  the 
  thicker 
  masses 
  to 
  the 
  eastward. 
  

   This 
  difficulty 
  of 
  correlation 
  is 
  also 
  increased 
  considerably 
  by 
  the 
  

   present 
  ambiguity 
  of 
  the 
  terms 
  Upper 
  and 
  Lower 
  Chalk. 
  The 
  term 
  

   Upper 
  Chalk, 
  in 
  its 
  ordinary, 
  text-book 
  acceptation, 
  appears 
  hitherto 
  

   to 
  have 
  signified 
  chalk 
  with 
  flints. 
  And 
  this 
  acceptation 
  of 
  the 
  term 
  

   would 
  have 
  been 
  perhaps 
  as 
  good 
  as 
  any 
  other 
  if 
  flints 
  occurred 
  only 
  

   above 
  a 
  given 
  horizon. 
  That 
  such 
  is 
  not 
  the 
  case 
  is 
  sufficiently 
  

   evident. 
  The 
  chalk 
  of 
  Yorkshire, 
  for 
  example, 
  contains 
  flints 
  on 
  a 
  

   lower 
  geological 
  horizon 
  than 
  that 
  of 
  Sussex 
  or 
  of 
  Hampshire. 
  

   Now 
  it 
  is 
  evident, 
  as 
  shown 
  by 
  its 
  fossils, 
  that 
  the 
  chalk 
  of 
  the 
  

   Dorset 
  and 
  Devon 
  sections 
  contains 
  flints 
  at 
  an 
  exceptionally 
  low 
  

   geological 
  horizon. 
  Mr. 
  Whitaker, 
  in 
  a 
  recent 
  communication 
  to 
  

   the 
  Geological 
  Society 
  (Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxvii.) 
  has 
  

   pointed 
  out 
  this 
  fact 
  very 
  clearly 
  where 
  (pp. 
  95 
  & 
  96) 
  he 
  refers 
  to 
  

   the 
  presence 
  of 
  flints 
  in 
  the 
  Chalk 
  Marl 
  itself. 
  It 
  is 
  clear, 
  therefore, 
  

   that 
  the 
  beds 
  above 
  the 
  Chalk 
  Marl 
  in 
  the 
  Devon 
  sections 
  are, 
  from 
  

   their 
  exceptional 
  character, 
  exceedingly 
  difficult 
  to 
  correlate 
  with 
  

   their 
  true 
  equivalents 
  to 
  the 
  eastward. 
  

  

  Taking 
  bed 
  13 
  as 
  the 
  true 
  base-bed 
  of 
  the 
  Chalk 
  Marl, 
  bed 
  14 
  must 
  

   at 
  the 
  least 
  be 
  added 
  to 
  that 
  division. 
  

  

  Beds 
  15 
  and 
  16, 
  which 
  include 
  the 
  Beer 
  Stone, 
  will 
  then 
  fall 
  in 
  the 
  

   Lower 
  Chalk. 
  And 
  in 
  this 
  point 
  I 
  fully 
  agree 
  with 
  Mr. 
  "Whitaker. 
  

   But 
  I 
  believe 
  the 
  lower 
  part 
  of 
  the 
  chalk 
  with 
  flints 
  (beds 
  17 
  and 
  

   part 
  of 
  18) 
  of 
  the 
  Beer 
  section 
  to 
  be 
  also 
  Lower 
  Chalk, 
  as 
  compared 
  

   with 
  that 
  of 
  Surrey 
  and 
  the 
  Isle 
  of 
  Wight, 
  and 
  that, 
  as 
  above 
  

   stated, 
  the 
  flints 
  are 
  here 
  below 
  tbeir 
  ordinary 
  level 
  *. 
  It 
  is 
  bed 
  17 
  

   which 
  caps 
  the 
  cliffs 
  to 
  east 
  and 
  west 
  of 
  Branscombe, 
  and 
  which, 
  by 
  

   a 
  partial 
  thinning- 
  out 
  of 
  the 
  intermediate 
  strata, 
  is 
  brought 
  down 
  in 
  

   places 
  so 
  nearly 
  on 
  the 
  Upper 
  Greensand. 
  

  

  The 
  succeeding 
  portions 
  of 
  the 
  chalk 
  of 
  the 
  Beer 
  district 
  (beds 
  

   18-20) 
  I 
  have 
  had 
  too 
  little 
  opportunity 
  of 
  studying 
  to 
  describe 
  

   with 
  confidence. 
  I 
  may 
  say, 
  however, 
  that 
  the 
  zones 
  of 
  fossils 
  are 
  

   fairly 
  marked, 
  and 
  that 
  these 
  appear 
  to 
  indicate 
  the 
  presence 
  of 
  a 
  

   considerable 
  portion 
  of 
  the 
  higher 
  chalk. 
  

  

  On 
  comparing 
  the 
  Devon 
  cretaceous 
  system 
  with 
  that 
  of 
  the 
  north- 
  

   east 
  of 
  Ireland 
  as 
  described 
  by 
  Mr. 
  Ralph 
  Tate 
  (Quart. 
  Journ. 
  Geol. 
  

   Soc. 
  vol. 
  xxi. 
  p. 
  15), 
  one 
  can 
  hardly 
  resist 
  the 
  supposition 
  that 
  the 
  two 
  

   series 
  were 
  originally 
  connected. 
  There 
  is 
  at 
  the 
  same 
  time, 
  however, 
  

   so 
  marked 
  a 
  difference 
  in 
  the 
  distribution 
  of 
  their 
  respective 
  faunas, 
  

   that 
  one 
  must 
  question 
  either 
  their 
  former 
  actual 
  connexion 
  or 
  the 
  

   horizons 
  at 
  present 
  assigned 
  to 
  the 
  Irish 
  strata. 
  

  

  * 
  Vide 
  a 
  paper 
  on 
  the 
  Surrey 
  Chalk, 
  by 
  Caleb 
  Evans, 
  Esq., 
  E.G-.S. 
  (Proc. 
  

   Geologists' 
  Association 
  for 
  1870). 
  

  

  