﻿SUBDIVISIONS 
  OF 
  THE 
  SPEETON 
  CLAY. 
  601 
  

  

  taining 
  a 
  larger 
  proportion 
  of 
  lime. 
  They 
  are 
  occasionally, 
  but 
  not 
  

   usually, 
  fossiliferous. 
  

  

  The 
  measurement 
  of 
  the 
  beds 
  in 
  fig. 
  G 
  above 
  the 
  asterisk, 
  

   having 
  been 
  made 
  only 
  in 
  the 
  great 
  slip 
  of 
  Black 
  Cliff, 
  is 
  somewhat 
  

   doubtful. 
  The 
  clays 
  seem 
  to 
  be 
  in 
  sequence, 
  but 
  I 
  could 
  not 
  identify 
  

   them 
  in 
  the 
  Speeton 
  Beck 
  Ridge, 
  where, 
  however, 
  the 
  beds 
  above 
  

   a 
  certain 
  level 
  are 
  much 
  disturbed 
  and 
  seem 
  as 
  though 
  they 
  may 
  at 
  

   some 
  period 
  have 
  been 
  forced 
  forward 
  bodily 
  by 
  an 
  enormous 
  

   foundering 
  of 
  the 
  chalk, 
  being 
  for 
  some 
  distance 
  nearly 
  vertical, 
  

   and 
  then 
  curving 
  over 
  in 
  a 
  large 
  fold. 
  In 
  this 
  fold 
  on 
  Speeton 
  

   Beck 
  Ridge 
  the 
  " 
  Cement-beds," 
  which 
  Judd 
  places 
  at 
  the 
  base 
  of 
  

   his 
  Upper 
  Neocomian, 
  are 
  fairly 
  well 
  exposed, 
  and 
  the 
  section 
  given 
  

   in 
  fig. 
  7, 
  w 
  T 
  hich 
  will 
  serve 
  to 
  show 
  their 
  character, 
  has 
  been 
  mea- 
  

   sured 
  across 
  them, 
  If 
  there 
  be 
  any 
  interval 
  between 
  the 
  bottom 
  of 
  

   this 
  section 
  and 
  the 
  top 
  of 
  the 
  last, 
  I 
  do 
  not 
  think 
  it 
  can 
  exceed 
  

   from 
  20 
  to 
  30 
  feet. 
  

  

  Judd, 
  enjoying, 
  no 
  doubt, 
  exceptional 
  facilities 
  during 
  the 
  working 
  

   of 
  the 
  seam, 
  gives 
  a 
  long 
  list 
  of 
  fossils 
  from 
  these 
  " 
  Cement-beds," 
  

   and 
  correlates 
  them 
  with 
  the 
  Lower 
  Greensand 
  and 
  Atherfield 
  Clay 
  

   of 
  the 
  south 
  of 
  England. 
  He 
  moreover 
  maps 
  these 
  beds 
  and 
  the 
  

   beds 
  above 
  them 
  in 
  the 
  great 
  slip 
  of 
  Black 
  Cliff, 
  and 
  states 
  that 
  they 
  

   may 
  be 
  well 
  studied 
  there. 
  But 
  the 
  pale 
  clay 
  with 
  nodules 
  which 
  

   is 
  now 
  prominent 
  in 
  this 
  part 
  of 
  the 
  section 
  (the 
  Echinospatangus- 
  

   bed) 
  belongs, 
  as 
  I 
  have 
  shown, 
  to 
  a 
  much 
  lower 
  horizon, 
  nor 
  is 
  it 
  

   likely 
  that 
  there 
  has 
  been 
  any 
  radical 
  change 
  here 
  during 
  the 
  last 
  

   twenty 
  years. 
  There 
  is 
  indeed 
  a 
  much 
  higher 
  band 
  of 
  large 
  pale 
  

   fossiliferous 
  septaria 
  in 
  dark 
  clay 
  (shown 
  in 
  fig. 
  6) 
  occasionally 
  

   slightly 
  exposed 
  near 
  the 
  southern 
  end 
  of 
  the 
  slip, 
  which 
  may 
  

   possibly 
  represent 
  the 
  " 
  Cement-beds," 
  but 
  of 
  this 
  I 
  am 
  doubtful. 
  

   If 
  any 
  of 
  the 
  fossils 
  of 
  the 
  above-mentioned 
  list 
  were 
  collected 
  from 
  

   the 
  slip, 
  there 
  has 
  almost 
  certainly 
  been 
  a 
  mingling 
  of 
  the 
  faunas 
  of 
  

   two 
  distinct 
  horizons. 
  For 
  this 
  reason 
  I 
  suspect 
  the 
  authenticity 
  in 
  

   the 
  "Cement-bed" 
  list 
  of 
  Amm. 
  marginatus, 
  A. 
  rotula, 
  A. 
  JS 
  T 
  isus, 
  

   TrocJius 
  pulclierrimus, 
  fnoceramus 
  venustulus, 
  and 
  a 
  few 
  other 
  

   species. 
  

  

  South 
  of 
  Speeton 
  Gap, 
  beds 
  of 
  dark 
  clay 
  and 
  banded 
  clay 
  with 
  

   nodules 
  may 
  be 
  observed 
  between 
  the 
  slips 
  of 
  chalk, 
  and 
  similar 
  

   beds 
  are 
  occasionally 
  visible 
  in 
  limited 
  exposures 
  on 
  the 
  foreshore 
  

   as 
  far 
  as 
  the 
  broken 
  ground 
  extends. 
  These 
  clays, 
  which 
  show 
  

   here 
  and 
  there 
  brilliant 
  pyrites 
  in 
  groups 
  of 
  fine 
  cubical 
  crystals, 
  

   contain 
  the 
  same 
  species 
  of 
  Belemnites 
  as 
  the 
  cement-beds, 
  and 
  seem 
  

   to 
  have 
  in 
  general 
  the 
  same 
  fauna. 
  

  

  There 
  is 
  a 
  remarkable 
  scarcity 
  of 
  Ammonites 
  throughout 
  the 
  

   zone. 
  

  

  In 
  the 
  following 
  list 
  are 
  recorded 
  the 
  species 
  obtained 
  by 
  me 
  from 
  

   the 
  zone 
  of 
  Bel. 
  semicanaliculatus 
  ?. 
  Pending 
  the 
  completion 
  of 
  the 
  

   section, 
  I 
  have 
  not 
  attempted 
  to 
  indicate 
  the 
  vertical 
  distribution. 
  

  

  