﻿550 
  mr, 
  t. 
  roberts 
  on 
  the 
  upper 
  

  

  3. 
  The 
  Clays 
  above 
  the 
  Oxford 
  Clay, 
  

   (a) 
  General 
  Description. 
  

  

  Overlying 
  the 
  Oxford 
  Clay, 
  with 
  its 
  pyritized 
  Ammonites, 
  is 
  a 
  

   series 
  of 
  clays 
  varying 
  somewhat 
  in 
  their 
  lithological 
  character 
  as 
  

   well 
  as 
  in 
  their 
  fossils. 
  The 
  clays 
  up 
  to 
  the 
  summit 
  of 
  what 
  has 
  

   been 
  mapped 
  as 
  Lower 
  Kimeridge 
  may 
  be 
  conveniently 
  divided 
  into 
  

   four 
  zones. 
  The 
  lowest 
  of 
  these 
  is 
  made 
  up 
  of 
  black 
  clays, 
  which 
  

   usually 
  contain 
  numerous 
  well-developed 
  crystals 
  of 
  selenite. 
  The 
  

   fossils 
  are, 
  as 
  a 
  rule, 
  not 
  abundant, 
  but 
  it 
  will 
  be 
  seen 
  that 
  they 
  

   differ 
  from 
  those 
  in 
  the 
  clays 
  above 
  and 
  below, 
  although 
  several 
  

   species 
  are 
  common 
  to 
  all 
  three. 
  

  

  The 
  black 
  clays 
  were 
  nowhere 
  seen 
  immediately 
  overlying 
  the 
  

   Oxford 
  Clay, 
  but 
  they 
  are 
  found 
  in 
  several 
  places 
  to 
  the 
  east 
  of 
  

   what 
  is 
  regarded 
  as 
  the 
  uppermost 
  zone 
  of 
  the 
  Oxford 
  Clay 
  (zone 
  of 
  

   cordati 
  Ammonites). 
  They 
  are 
  easily 
  distinguished 
  from 
  the 
  latter 
  

   by 
  their 
  darker 
  colour, 
  and 
  by 
  their 
  fossils 
  never 
  being 
  pyritized. 
  

  

  The 
  most 
  southerly 
  point 
  at 
  which 
  these 
  clays 
  were 
  seen 
  is 
  in 
  a 
  

   brickyard 
  west 
  of 
  Hawkstead 
  Hall, 
  where 
  there 
  is 
  exposed 
  17 
  

   feet 
  of 
  black 
  clays 
  containing 
  numerous 
  crystals 
  of 
  selenite, 
  either 
  

   scattered 
  through 
  the 
  clays 
  or 
  aggregated 
  in 
  masses 
  held 
  together 
  

   by 
  a 
  yellowish 
  ferruginous 
  material. 
  The 
  clays 
  here 
  were 
  unfos- 
  

   siliferous, 
  but 
  in 
  the 
  layer 
  of 
  septarian 
  nodules 
  which 
  occurs 
  in 
  

   the 
  upper 
  part 
  of 
  the 
  section, 
  Ammonites 
  eoccavatus, 
  Sow., 
  was 
  

   not 
  uncommon. 
  Prof. 
  Blake 
  also 
  records 
  from 
  this 
  pit 
  Ostrea 
  del- 
  

   toidea 
  and 
  Belemnites 
  nitidus 
  *. 
  

  

  About 
  half 
  a 
  mile 
  south-east 
  of 
  the 
  village 
  of 
  Bardney 
  (at 
  " 
  C 
  " 
  

   in 
  " 
  Bardney 
  Common 
  " 
  on 
  Survey 
  Map) 
  is 
  a 
  brickyard 
  in 
  which 
  are 
  

   black 
  shaly 
  clays 
  with 
  minute 
  crystals 
  of 
  selenite. 
  The 
  following 
  

   fossils 
  are 
  fairly 
  common 
  here 
  : 
  — 
  

  

  Belemnites 
  abbreviates, 
  Mill. 
  

  

  nitidus, 
  Dollf. 
  

  

  Gryphaea 
  dilatata, 
  Sow. 
  

  

  In 
  addition 
  to 
  which 
  the 
  following 
  are 
  recorded 
  in 
  the 
  Survey 
  

   Memoir 
  f 
  : 
  — 
  

  

  Thracia 
  depressa, 
  Sow. 
  

   Cucullaea 
  longipunctata, 
  Blake. 
  

   Astarte 
  supracorallina, 
  d'Orb. 
  

  

  In 
  the 
  Jermyn 
  Street 
  Museum 
  are 
  some 
  badly-preserved 
  Am- 
  

   monites 
  from 
  this 
  locality, 
  some 
  of 
  which 
  appear 
  to 
  belong 
  to 
  

  

  Ammonites 
  vertebralis, 
  Sow. 
  

   cawtonensis, 
  Bl. 
  cf 
  H. 
  

  

  Further 
  north, 
  Prof. 
  Blake 
  mentions 
  X 
  that 
  in 
  a 
  well-sinking 
  on 
  

   the 
  Bishop's-Bridge 
  road, 
  about 
  1| 
  mile 
  west 
  of 
  the 
  Market-Easen 
  

   pits, 
  black 
  clays 
  were 
  met 
  with 
  in 
  which 
  Belemnites 
  nitidus 
  and 
  

   Gryphaea 
  dilatata 
  were 
  plentiful, 
  together 
  with 
  some 
  reptilian 
  remains 
  

   and 
  Disci 
  na 
  Humphriesiana. 
  

  

  * 
  Op. 
  cit. 
  p. 
  209. 
  t 
  P. 
  79. 
  j 
  Op. 
  cit. 
  p. 
  209. 
  

  

  