﻿SUBDIVISIONS 
  OP 
  THE 
  SPEETON 
  CLAY. 
  607 
  

  

  We 
  can 
  easily 
  trace 
  in 
  the 
  Bed 
  Chalk 
  itself 
  the 
  effect 
  of 
  the 
  

   deepening 
  waters, 
  at 
  Speeton 
  as 
  elsewhere, 
  as 
  Hill's* 
  recent 
  re- 
  

   searches 
  so 
  admirably 
  show, 
  and 
  in 
  the 
  same 
  bed 
  we 
  find 
  clear 
  

   proof 
  of 
  the 
  greater 
  comparative 
  depth 
  of 
  the 
  sea 
  at 
  Speeton 
  than 
  

   further 
  west. 
  Gradually, 
  however, 
  as 
  the 
  land 
  sank, 
  the 
  effect 
  

   of 
  this 
  difference 
  of 
  level 
  became 
  less 
  apparent, 
  until 
  a 
  wide 
  ocean 
  

   without 
  local 
  conditions 
  spread 
  once 
  more 
  over 
  the 
  Eastern 
  Counties, 
  

   and 
  deposited 
  a 
  winding-sheet 
  of 
  chalk 
  indiscriminately 
  over 
  every- 
  

   thing. 
  

  

  Thus 
  the 
  Speeton 
  clays 
  seem 
  to 
  have 
  been 
  deposited 
  not 
  far 
  from 
  

   the 
  western 
  edge 
  of 
  an 
  ocean 
  which 
  probably 
  stretched 
  eastward, 
  as 
  

   Judcl 
  t 
  has 
  suggested, 
  over 
  the 
  northern 
  part 
  of 
  Central 
  Europe, 
  

  

  Could 
  we 
  see, 
  then, 
  a 
  continuous 
  section 
  east 
  and 
  west 
  across 
  the 
  

   Wolds, 
  I 
  should 
  expect 
  to 
  find 
  a 
  westward 
  thinning 
  of 
  the 
  deposits 
  

   as 
  a 
  whole, 
  culminating 
  probably 
  in 
  the 
  complete 
  disappearance, 
  

   first 
  of 
  the 
  upper 
  beds, 
  and 
  finally 
  of 
  the 
  lower 
  beds 
  also, 
  for 
  in 
  

   approaching 
  the 
  elevated 
  area 
  such 
  portions 
  of 
  the 
  series 
  as 
  were 
  

   deposited 
  there 
  before 
  the 
  elevation 
  reached 
  its 
  maximum 
  would 
  

   afterwards 
  be 
  partially 
  or 
  wholly 
  removed. 
  The 
  clays 
  of 
  Speeton 
  

   might 
  also 
  be 
  expected 
  to 
  give 
  place 
  to 
  beds 
  of 
  rougher 
  material 
  as 
  

   they 
  approached 
  the 
  western 
  coast-line. 
  

  

  It 
  is 
  much 
  to 
  be 
  regretted 
  that 
  we 
  can 
  now 
  obtain 
  no 
  direct 
  

   information 
  regarding 
  the 
  actual 
  conditions 
  in 
  the 
  western 
  area, 
  

   the 
  inland 
  pits 
  mentioned 
  by 
  Judd 
  having 
  long 
  been 
  closed 
  and 
  

   overgrown. 
  

  

  As 
  proof 
  of 
  the 
  extended 
  period 
  covered 
  by 
  the 
  clays, 
  and 
  as 
  

   favouring 
  the 
  view 
  of 
  a 
  gradual 
  passage 
  into 
  the 
  Upper 
  Cretaceous, 
  

   it 
  is 
  important 
  to 
  note 
  the 
  occurrence, 
  especially 
  in 
  the 
  upper 
  portion 
  

   of 
  the 
  Speeton 
  section, 
  of 
  several 
  species 
  known 
  in 
  the 
  Gault, 
  and 
  

   these 
  are 
  nearly 
  all 
  species 
  which 
  are 
  either 
  confined 
  to 
  the 
  Lower 
  

   Gault 
  or 
  range 
  through 
  both 
  divisions. 
  

  

  Thus, 
  if 
  I 
  read 
  the 
  Speeton 
  section 
  aright, 
  we 
  have, 
  in 
  the 
  lower 
  

   portion, 
  in 
  the 
  clays 
  of 
  the 
  zone 
  of 
  Bel. 
  lateralis, 
  beds 
  which 
  mark 
  

   the 
  passage 
  from 
  Jurassic 
  to 
  Lower 
  Cretaceous 
  or 
  Neocomian 
  ; 
  and 
  

   in 
  the 
  upper 
  part, 
  in 
  the 
  marls 
  below 
  the 
  Red 
  Chalk, 
  a 
  similar 
  pas- 
  

   sage 
  into 
  the 
  Upper 
  Cretaceous, 
  and 
  an 
  unbroken 
  sequence 
  between. 
  

   And 
  if 
  this 
  be 
  so, 
  then 
  these 
  clays 
  must 
  necessarily 
  bridge 
  over 
  the 
  

   period 
  of 
  the 
  formation 
  of 
  the 
  Portlandian, 
  Purbeck, 
  and 
  Wealden 
  

   beds, 
  as 
  well 
  as 
  of 
  the 
  Lower 
  Greensand, 
  in 
  the 
  south 
  of 
  England. 
  

   It 
  is 
  not, 
  however, 
  in 
  these 
  southern 
  beds, 
  where 
  the 
  marine 
  history 
  

   of 
  the 
  Jurassic 
  period 
  has 
  been 
  abruptly 
  cut 
  short, 
  and 
  the 
  opening 
  

   chapters 
  of 
  the 
  Cretaceous 
  replaced 
  by 
  a 
  story 
  of 
  freshwater 
  and 
  

   estuarine 
  conditions, 
  that 
  we 
  ought 
  to 
  look 
  for 
  the 
  equivalents 
  and 
  

   analogues 
  of 
  the 
  Speeton 
  beds 
  ; 
  but 
  rather 
  in 
  those 
  localities, 
  whether 
  

   at 
  home 
  or 
  abroad, 
  where 
  that 
  history 
  has 
  been 
  given 
  complete 
  and 
  

   in 
  a 
  similar 
  manner. 
  Nor, 
  as 
  it 
  seems 
  to 
  me, 
  should 
  we 
  be 
  bound 
  to 
  

   adopt 
  as 
  the 
  exact 
  limits 
  of 
  a 
  period 
  the 
  lines 
  drawn 
  where 
  the 
  

   conditions 
  have 
  been 
  local 
  and 
  incomplete, 
  but 
  rather 
  strive 
  to 
  define 
  

   them 
  more 
  exactly 
  in 
  an 
  area 
  of 
  better 
  development. 
  

  

  * 
  Quart, 
  Journ. 
  G-eol. 
  Soc. 
  vol. 
  xliv. 
  p. 
  320. 
  t 
  Ibid. 
  vol. 
  xxvi. 
  p. 
  346. 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  180. 
  2 
  t 
  

  

  