﻿472 
  PKOF. 
  J. 
  W. 
  JUDD 
  ON 
  THE 
  EOCENE 
  AND 
  OLIGOCENE 
  

  

  freshwater 
  and 
  terrestrial 
  origin 
  ; 
  and 
  no 
  brackish-water 
  beds 
  have 
  

   been 
  detected 
  in 
  this 
  part 
  of 
  the 
  series 
  at 
  Whitecliff 
  Bay. 
  But 
  at 
  

   Alum 
  Bay, 
  and 
  at 
  Hordwell 
  Cliff 
  on 
  the 
  opposite 
  coast 
  of 
  Hamp- 
  

   shire 
  similar 
  beds 
  of 
  clay 
  and 
  lignite 
  occur 
  attaining 
  a 
  greater 
  

   thickness 
  and 
  containing 
  bands 
  with 
  an 
  admixture 
  of 
  freshwater 
  

   and 
  marine 
  fossils, 
  the 
  latter 
  almost 
  alwaj^s 
  in 
  a 
  dwarfed 
  condition. 
  

   I 
  will 
  reserve 
  what 
  I 
  have 
  to 
  say 
  concerning 
  the 
  Headon 
  Clays 
  at 
  

   Alum 
  Bay, 
  and 
  proceed 
  to 
  point 
  out 
  the 
  characters 
  presented 
  in 
  the 
  

   equivalent 
  strata 
  at 
  Hordwell 
  Cliff. 
  

  

  These 
  strata 
  at 
  Hordwell 
  Cliff 
  have 
  attracted 
  much 
  attention 
  

   from 
  geologists, 
  owing 
  to 
  the 
  rich 
  harvest 
  of 
  mammalian 
  and 
  

   reptilian 
  remains 
  which 
  they 
  have 
  yielded 
  to 
  the 
  late 
  Mr. 
  Searles 
  

   Wood, 
  the 
  Marchioness 
  of 
  Hastings, 
  and 
  other 
  collectors. 
  Many 
  of 
  

   the 
  beds 
  have 
  received 
  local 
  names 
  from 
  fossil-collectors 
  ; 
  and 
  more 
  

   or 
  less 
  detailed 
  descriptions 
  of 
  the 
  succession 
  of 
  the 
  strata 
  have 
  been 
  

   published 
  by 
  Webster, 
  Lvcll. 
  Scarles 
  Wood, 
  the 
  Marchioness 
  of 
  

   Hastings, 
  Dr. 
  T. 
  Wright, 
  and 
  the 
  Rev. 
  0. 
  Fisher. 
  

  

  It 
  is 
  a 
  remarkable 
  fact, 
  as 
  pointed 
  out 
  by 
  the 
  late 
  Edward 
  

   Forbes 
  *, 
  that 
  the 
  published 
  descriptions 
  of 
  these 
  sections, 
  though 
  

   professing 
  to 
  give 
  the 
  most 
  minute 
  details, 
  arrived 
  at 
  by 
  measuring 
  

   down 
  the 
  beds 
  inch 
  by 
  inch, 
  differ 
  from 
  one 
  another 
  in 
  a 
  very 
  

   striking 
  manner. 
  My 
  own 
  observations 
  on 
  this 
  section, 
  carried 
  

   on 
  during 
  the 
  last 
  twenty 
  years, 
  convince 
  me 
  that 
  these 
  strata, 
  like 
  

   most 
  deposits 
  of 
  estuarine 
  origin, 
  are 
  of 
  the 
  most 
  inconstant 
  cha- 
  

   racter, 
  varying 
  in 
  thickness 
  within 
  very 
  short 
  distances. 
  Mr. 
  Cod- 
  

   rington 
  estimates 
  that 
  this 
  coast-line 
  is 
  receding, 
  in 
  consequence 
  of 
  

   the 
  action 
  of 
  the 
  sea, 
  at 
  the 
  rate 
  of 
  a 
  yard 
  per 
  annum 
  ; 
  and 
  he 
  thus 
  

   accounts 
  for 
  the 
  remarkable 
  discrepancies 
  of 
  different 
  observers 
  as 
  

   to 
  the 
  thickness 
  of 
  the 
  gravel 
  f. 
  Among 
  such 
  variable 
  strata 
  as 
  

   these 
  are, 
  the 
  section 
  exposed 
  to 
  observers 
  at 
  different 
  dates 
  may 
  

   vary 
  considerably. 
  I 
  have 
  in 
  a 
  previous 
  paper 
  pointed 
  out 
  the 
  

   impossibility 
  of 
  relying 
  upon 
  the 
  constancy 
  of 
  the 
  thin 
  beds 
  of 
  

   limestone, 
  lignite, 
  &c. 
  in 
  tracing 
  the 
  order 
  of 
  succession 
  among 
  

   these 
  estuarine 
  beds 
  ; 
  but 
  I 
  think 
  there 
  can 
  be 
  no 
  doubt 
  as 
  to 
  the 
  

   general 
  succession 
  of 
  strata 
  at 
  Hordwell 
  Cliff. 
  

  

  The 
  Headon-Hill 
  Sands, 
  which 
  at 
  Beacon 
  Cliff 
  are 
  much 
  thinner 
  

   than 
  in 
  the 
  Isle 
  of 
  Wight, 
  contain 
  an 
  admixture 
  of 
  freshwater 
  and 
  

   marine 
  shells, 
  and, 
  as 
  Mr. 
  Searles 
  Wood 
  and 
  Dr. 
  Wright 
  long 
  ago 
  

   pointed 
  out, 
  are 
  of 
  estuarine 
  origin. 
  The 
  lowest 
  bed 
  of 
  the 
  overlying 
  

   Headon-Clay 
  series 
  consists 
  of 
  green 
  and 
  blue 
  laminated 
  clays 
  with 
  

   much 
  carbonaceous 
  matter, 
  occasionally 
  passing 
  into 
  thin 
  lignite 
  

   seams. 
  This 
  bed, 
  which 
  is 
  about 
  3£ 
  feet 
  thick, 
  is 
  known 
  locally 
  as 
  

   the 
  " 
  Lignite-bed." 
  Above 
  this 
  Lignite-bed 
  there 
  is 
  found 
  a 
  series 
  

   of 
  sands 
  and 
  sandy 
  clays 
  containing 
  freshwater 
  and 
  terrestrial 
  

   remains 
  — 
  plants, 
  shells, 
  and 
  bones. 
  From 
  the 
  fact 
  that 
  these 
  beds, 
  

   which 
  are 
  about 
  twenty 
  feet 
  thick, 
  have 
  yielded 
  to 
  collectors 
  the 
  

   remains 
  of 
  Palojolotherium, 
  Palceotherium, 
  and 
  DicJiodon, 
  they 
  are 
  

   known 
  as 
  the 
  " 
  Mammalia-bed." 
  The 
  top 
  of 
  this 
  series 
  is 
  marked 
  

  

  * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  ix. 
  (1853) 
  p. 
  268. 
  

   t 
  Ibid. 
  vol. 
  xxvi. 
  (1870) 
  p. 
  532. 
  

  

  