﻿STRATA 
  OF 
  THE 
  HAMPSHIRE 
  BASIN. 
  463 
  

  

  To 
  this 
  proposed 
  classification 
  exception 
  has 
  been 
  taken 
  by 
  various 
  

   critics, 
  on 
  very 
  different 
  and 
  often 
  qnite 
  opposite 
  grounds. 
  Many 
  

   esteemed 
  continental 
  correspondents, 
  who 
  entirely 
  agree 
  with 
  me 
  as 
  

   to 
  the 
  order 
  of 
  succession 
  of 
  the 
  strata, 
  point 
  out 
  that 
  in 
  the 
  Paris 
  

   basin 
  the 
  zone 
  of 
  Cerithium 
  concavum 
  appears 
  to 
  be 
  simply 
  an 
  upper 
  

   and 
  subordinate 
  member 
  of 
  the 
  Bartonian 
  ; 
  they 
  argue, 
  therefore, 
  

   that 
  the 
  line 
  of 
  separation 
  between 
  the 
  Eocene 
  and 
  Oligocene 
  should 
  

   be 
  drawn 
  at 
  the 
  base 
  of 
  the 
  Brockenhurst 
  series, 
  thus 
  including 
  the 
  

   Headon 
  Clays 
  and 
  Sands 
  in 
  the 
  Bartonian 
  or 
  Upper 
  Eocene. 
  My 
  

   reason 
  for 
  not, 
  in 
  the 
  first 
  instance, 
  adopting 
  this 
  line 
  as 
  the 
  limit 
  of 
  

   the 
  Eocene 
  and 
  Oligocene 
  was 
  the 
  great 
  inconvenience 
  which 
  would 
  

   result 
  from 
  breaking 
  up 
  our 
  fluvio-marine 
  series 
  into 
  two 
  portions, 
  

   and 
  grouping 
  one 
  with 
  the 
  Eocene 
  and 
  the 
  other 
  with 
  the 
  Oligocene. 
  

   It 
  is 
  true 
  that 
  the 
  interesting 
  observation 
  made 
  by 
  Messrs. 
  Keeping 
  

   and 
  Tawney, 
  that 
  at 
  "\Yhitecliff 
  Bay 
  an 
  actual 
  unconformity 
  appears 
  

   to 
  exist 
  at 
  this 
  horizon, 
  lends 
  some 
  support 
  to 
  the 
  view 
  that 
  this 
  

   is 
  the 
  line 
  of 
  demarcation 
  between 
  the 
  two 
  great 
  series 
  ; 
  and, 
  in 
  

   order 
  to 
  prevent 
  the 
  inconvenience 
  of 
  adopting 
  different 
  limits 
  

   between 
  the 
  great 
  geological 
  divisions 
  in 
  this 
  country 
  and 
  on 
  the 
  

   continent, 
  it 
  may 
  be 
  advisable 
  to 
  waive 
  the 
  objection 
  to 
  breaking 
  up 
  

   what 
  appears 
  to 
  be, 
  locally, 
  a 
  natural 
  grouping 
  of 
  the 
  strata. 
  

  

  But 
  other 
  critics, 
  while 
  agreeing 
  with 
  M. 
  von 
  Konen, 
  Dr. 
  Duncan, 
  

   and 
  myself 
  as 
  to 
  the 
  Lower-Oligocene 
  age 
  of 
  the 
  Brockenhurst 
  beds, 
  

   maintain 
  that 
  I 
  have 
  altogether 
  misunderstood 
  the 
  order 
  of 
  succession 
  

   of 
  the 
  strata*. 
  They 
  assert 
  that 
  the 
  Brockenhurst 
  beds 
  do 
  not 
  

   overlie 
  the 
  Headon 
  group, 
  but 
  lie 
  in 
  the 
  midst 
  of 
  it, 
  forming 
  a 
  base- 
  

   ment 
  bed 
  to 
  the 
  so-called 
  " 
  Middle 
  Headon 
  series." 
  To 
  the 
  very 
  

   obvious 
  objection 
  that 
  this 
  places 
  what 
  nearly 
  all 
  continental 
  palaeon- 
  

   tologists 
  regard 
  as 
  an 
  Upper 
  Eocene 
  fauna 
  below 
  one 
  belonging 
  to 
  

   the 
  Lower 
  Oligocene, 
  one 
  of 
  the 
  authors 
  has 
  replied 
  by 
  asserting 
  that 
  

   the 
  name 
  of 
  the 
  zone 
  of 
  Cerithium 
  concavum 
  is 
  properly 
  applicable 
  

   only 
  to 
  the 
  sands 
  at 
  the 
  base 
  of 
  the 
  Headon 
  series, 
  and 
  not 
  to 
  the 
  

   overlying 
  clays 
  f 
  . 
  More 
  matured 
  study 
  of 
  the 
  question, 
  however, 
  

   appears 
  to 
  have 
  led 
  Mr. 
  Tawney 
  to 
  greatly 
  modify 
  his 
  views 
  on 
  

   the 
  whole 
  question 
  ; 
  for 
  in 
  a 
  later 
  memoir 
  we 
  find 
  him 
  maintaining 
  

   that 
  the 
  term 
  Oligocene 
  " 
  is 
  less 
  applicable 
  to 
  the 
  English 
  Ter- 
  

   tiaries 
  than 
  the 
  older 
  and 
  more 
  classical 
  division 
  into 
  Eocene 
  &c," 
  

   and, 
  again, 
  "the 
  break 
  between 
  Oligocene 
  and 
  Eocene 
  is 
  an 
  unnatural 
  

   one, 
  and 
  the 
  introduction 
  of 
  the 
  term 
  in 
  our 
  opinion 
  obscures 
  the 
  

   affinities 
  between 
  the 
  members 
  of 
  the 
  English 
  series" 
  %. 
  

  

  In 
  the 
  same 
  paper 
  this 
  author 
  abandons 
  his 
  former 
  views 
  as 
  to 
  

   the 
  English 
  representatives 
  of 
  the 
  zone 
  of 
  Cerithium 
  concavum, 
  and 
  

   states 
  that 
  the 
  Headon 
  Sands 
  are 
  characterized 
  by 
  the 
  Cerithium 
  

   pleurotomoides, 
  Desh., 
  while 
  he 
  now 
  admits 
  that 
  Cerithium 
  concavum 
  

   is 
  especially 
  abundant 
  in 
  the 
  overlying 
  clays. 
  With 
  the 
  great 
  

  

  * 
  " 
  On 
  the 
  Beds 
  of 
  Headon 
  Hill 
  and 
  Colwell 
  Bay 
  in 
  the 
  Isle 
  of 
  Wight," 
  by 
  

   H. 
  Keeping 
  and 
  E. 
  B. 
  Tawney, 
  Quart. 
  Journ. 
  Greol. 
  Soc. 
  vol. 
  xxxvii. 
  (1881) 
  

   p. 
  85. 
  

  

  t 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxvii. 
  (1881) 
  p. 
  127. 
  

  

  \ 
  Proceedings 
  of 
  the 
  Cambridge 
  Philosophical 
  Society, 
  vol. 
  iv. 
  p. 
  147, 
  note. 
  

  

  