﻿SUBDIVISIONS 
  OF 
  THE 
  SPEETON 
  CLAY. 
  603 
  

  

  physical 
  characteristics 
  of 
  the 
  Speeton 
  Clay, 
  contain 
  a 
  fauna 
  very 
  

   closely 
  allied 
  to 
  that 
  of 
  the 
  Red 
  Chalk 
  ; 
  and 
  that 
  these 
  beds 
  are 
  far 
  

   too 
  thick 
  to 
  be 
  explained 
  * 
  as 
  the 
  result 
  of 
  a 
  " 
  working 
  up 
  " 
  of 
  the 
  

   underlying 
  clays 
  into 
  the 
  base 
  of 
  the 
  Red 
  Chalk. 
  

  

  Fragments 
  of 
  these 
  beds 
  may 
  occasionally 
  be 
  found 
  among 
  the 
  

   slipped 
  ground 
  under 
  the 
  chalk 
  escarpment 
  ; 
  and 
  recently 
  the 
  sea, 
  

   having 
  effected 
  a 
  considerable 
  removal 
  of 
  chalk-debris 
  in 
  the 
  cliff- 
  

   foot 
  south 
  of 
  the 
  Gap, 
  has 
  revealed 
  in 
  three 
  different 
  places 
  large 
  

   masses 
  of 
  the 
  beds. 
  These, 
  though 
  not 
  actually 
  in 
  place, 
  have 
  

   slipped 
  in 
  such 
  masses 
  as 
  to 
  show 
  very 
  well 
  the 
  character 
  and 
  fossils 
  

   of 
  the 
  deposits, 
  and 
  also 
  to 
  some 
  extent 
  their 
  sequence. 
  

  

  The 
  first 
  of 
  these 
  slips 
  is 
  at 
  present 
  f 
  to 
  be 
  seen 
  at 
  the 
  cliff-foot 
  

   about 
  200 
  yards 
  from 
  Speeton 
  Beck. 
  At 
  this 
  place 
  the 
  beds 
  are 
  

   much 
  shattered, 
  having 
  probably 
  slipped 
  for 
  some 
  distance 
  ; 
  but 
  it 
  is 
  

   still 
  easy 
  to 
  trace 
  several 
  distiuct 
  beds 
  and 
  to 
  collect 
  a 
  fauna 
  rather 
  

   numerous 
  individually, 
  though 
  not 
  specifically. 
  The 
  beds 
  consist 
  of 
  

   brown, 
  grey, 
  dull 
  red, 
  and 
  brilliantly 
  variegated 
  marly 
  clay 
  and 
  shale. 
  

  

  A 
  short 
  distance 
  further 
  south 
  there 
  is 
  another 
  similar, 
  though 
  

   smaller, 
  exposure 
  ; 
  and 
  beyond 
  this, 
  about 
  350 
  yards 
  from 
  Speeton 
  

   Gap, 
  the 
  most 
  extensive 
  and 
  important 
  of 
  the 
  disclosures 
  has 
  been 
  

   made. 
  At 
  this 
  ixla.ce 
  the 
  beds 
  may 
  be 
  traced 
  for 
  fully 
  20 
  yards 
  

   along 
  the 
  cliff-foot, 
  rising 
  in 
  one 
  place 
  a 
  few 
  feet 
  above 
  high-water 
  

   mark, 
  and 
  though 
  they 
  are 
  undoubtedly 
  slipped, 
  they 
  are 
  probably 
  

   not 
  so 
  very 
  far 
  from 
  their 
  original 
  position, 
  as 
  the 
  base 
  of 
  the 
  Red 
  

   Chalk 
  cannot 
  here 
  lie 
  much 
  above 
  sea-level. 
  The 
  sequence 
  of 
  the 
  

   beds 
  is 
  well 
  preserved, 
  and 
  they 
  are 
  clearly 
  in 
  the 
  order 
  of 
  their 
  

   deposition. 
  They 
  rest 
  on 
  black 
  clay 
  in 
  which 
  fossils 
  are 
  very 
  rare 
  — 
  

   the 
  only 
  recognizable 
  fossil 
  I 
  have 
  found 
  being 
  a 
  fragment 
  of 
  Bel.semi- 
  

   canaliadatus 
  ? 
  — 
  and 
  seem 
  to 
  do 
  so 
  naturally, 
  and 
  not 
  by 
  reason 
  of 
  the 
  

   slipping 
  ; 
  but 
  the 
  state 
  of 
  the 
  section 
  prevents 
  one 
  speaking 
  positively 
  

   on 
  this 
  point. 
  The 
  section 
  observed 
  is 
  shown 
  in 
  fig. 
  8. 
  

  

  In 
  this 
  section 
  the 
  green 
  and 
  yellow 
  gritty 
  bed 
  with 
  nodules 
  

   forms 
  a 
  very 
  striking 
  and 
  distinct 
  horizon, 
  and 
  might 
  be 
  thought 
  to 
  

   mark 
  a 
  break 
  in 
  the 
  series. 
  It 
  exhibits 
  many 
  peculiar 
  features, 
  

   being 
  full 
  of 
  nodules 
  that 
  look 
  as 
  though 
  thejr 
  might 
  be 
  derivatives, 
  

   and 
  frequently 
  present 
  a 
  curiously 
  pitted 
  and 
  partially 
  decomposed 
  

   surface, 
  as 
  if 
  through 
  erosion. 
  These 
  are 
  often 
  coated 
  thickly 
  with 
  

   gritty 
  green 
  matter 
  (probably 
  glauconite 
  ), 
  and 
  sometimes 
  form 
  a 
  

   centre 
  from 
  which 
  springs 
  a 
  mass 
  of 
  radiating 
  crystals 
  (selenite) 
  

   which 
  completely 
  surrounds 
  the 
  nodule 
  in 
  a 
  layer 
  from 
  an 
  inch 
  to 
  

   three 
  inches 
  thick. 
  But 
  the 
  variegated 
  marly 
  clays 
  extend 
  below 
  

   this 
  nodular 
  bed, 
  and 
  do 
  so 
  regularly, 
  without 
  any 
  appearance 
  of 
  

   erosion 
  or 
  unconformity; 
  and 
  though, 
  as 
  I 
  have 
  said, 
  one 
  could 
  not 
  

   say 
  positively 
  that 
  there 
  is 
  an 
  actual 
  passage 
  from 
  them 
  to 
  the 
  black 
  

   clay 
  with 
  Bel. 
  semicanaliculatus 
  ? 
  on 
  which 
  they 
  rest, 
  the 
  evidence 
  

   is 
  all 
  in 
  favour 
  of 
  their 
  doing 
  so. 
  Both 
  beds 
  contain 
  similar 
  small 
  

   brown-coated 
  " 
  potato-nodules," 
  and 
  otherwise 
  " 
  fraternize 
  " 
  in 
  cha- 
  

   racter,, 
  as 
  one 
  might 
  say. 
  

  

  Somewhat 
  analogous 
  is 
  the 
  evidence 
  above 
  this 
  gritty 
  and 
  nodular 
  

  

  * 
  W. 
  Hill, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xliy. 
  p. 
  338. 
  t 
  January 
  1889. 
  

  

  