﻿BED 
  OP 
  ABTGTJLAK 
  DEIPT. 
  131 
  

  

  angular. 
  There 
  is 
  also 
  a 
  bed 
  of 
  chalk-rubble, 
  in 
  which 
  are 
  angular 
  

   fragments 
  of 
  soft 
  chalk. 
  

  

  All 
  the 
  fragments 
  of 
  flint, 
  on 
  the 
  other 
  hand, 
  even 
  the 
  smallest 
  (and 
  

   there 
  are 
  few 
  more 
  than 
  2 
  or 
  3 
  inches 
  in 
  length), 
  are 
  perfectly 
  sharp 
  

   and 
  angular, 
  and 
  are 
  generally 
  not 
  discoloured. 
  Some, 
  however, 
  

   are 
  slightly 
  whitened. 
  The 
  chalk 
  debris 
  predominates 
  at 
  the 
  north 
  

   end 
  of 
  the 
  cutting, 
  and 
  the 
  flint 
  debris 
  at 
  the 
  south 
  end. 
  

  

  Few 
  bones 
  were 
  found, 
  except 
  at 
  the 
  first 
  place. 
  They 
  did 
  not 
  

   seem 
  confined 
  to 
  one 
  bed, 
  though 
  most 
  of 
  them 
  were 
  found 
  in 
  the 
  

   lower 
  part 
  of 
  the 
  deposit. 
  

  

  There 
  is 
  no 
  trace 
  in 
  any 
  part 
  of 
  this 
  section 
  of 
  stream- 
  or 
  river- 
  

   action. 
  With 
  few 
  exceptions, 
  where 
  the 
  rubble 
  forms 
  a 
  soft 
  con- 
  

   crete, 
  the 
  whole 
  mass 
  is 
  loose 
  and 
  incoherent 
  like 
  so 
  much 
  shingle. 
  

   This 
  condition 
  continues 
  to 
  the 
  very 
  base 
  of 
  the 
  section 
  without 
  

   difference, 
  except 
  that 
  the 
  rubble 
  is 
  there 
  rather 
  coarser 
  and 
  more 
  

   coloured. 
  Few 
  of 
  the 
  beds 
  were 
  continuous 
  for 
  the 
  whole 
  distance. 
  

   They 
  generally 
  formed 
  lenticular 
  masses 
  of 
  greater 
  or 
  less 
  extent. 
  

   It 
  was 
  in 
  an 
  intercalated 
  mass 
  of 
  white 
  marl, 
  or 
  chalk 
  paste, 
  at 
  the 
  

   south 
  end 
  of 
  the 
  Chilton 
  cutting, 
  and 
  at 
  a 
  depth 
  of 
  from 
  8 
  to 
  12 
  feet 
  

   from 
  the 
  surface, 
  that 
  almost 
  all 
  the 
  shells 
  were 
  obtained 
  ; 
  but 
  even 
  

   there 
  they 
  were 
  far 
  from 
  abundant. 
  They 
  consist 
  essentially 
  of 
  land 
  

   shells 
  ; 
  the 
  two 
  exceptions 
  are 
  so 
  rare 
  that 
  they 
  only 
  prove 
  the 
  

   rule 
  ; 
  for 
  Planorbis 
  alhus, 
  which 
  lives 
  on 
  water-plants 
  and 
  fre- 
  

   quents 
  marshes, 
  can 
  pass 
  over 
  land 
  surfaces, 
  while 
  the 
  Limncea 
  

   truncatula 
  " 
  is 
  nearly 
  amphibious, 
  being 
  more 
  frequently 
  met 
  with 
  

   out 
  of 
  the 
  water 
  than 
  in 
  it 
  ; 
  it 
  is 
  also 
  found 
  in 
  very 
  elevated 
  spots"*. 
  

   Dr. 
  Gwyn 
  Jeffreys, 
  who 
  has 
  kindly 
  examined 
  the 
  collection, 
  tells 
  me 
  

   that 
  the 
  species 
  present 
  no 
  peculiar 
  variations. 
  

  

  The 
  following 
  are 
  the 
  species 
  found 
  in 
  bed 
  6. 
  In 
  order 
  to 
  show 
  

   their 
  relative 
  abundance, 
  I 
  have 
  given 
  the 
  total 
  number 
  obtained 
  

   during 
  some 
  days' 
  search 
  : 
  — 
  

  

  No. 
  of 
  No. 
  of 
  

  

  specimens. 
  specimens, 
  

  

  Pupa 
  marginata, 
  Drap. 
  ... 
  226 
  Succinea 
  oblonga, 
  Drap 
  11 
  

  

  Helix 
  hispida, 
  Linn 
  53 
  Limnsea 
  truncatula, 
  Mull. 
  3 
  

  

  Limax 
  agrestis, 
  Linn 
  1 
  Planorbis 
  albus, 
  Mull, 
  (young) 
  ... 
  1 
  

  

  I 
  met 
  with 
  no 
  fragments 
  of 
  wood, 
  except 
  one 
  derived 
  probably 
  

   from 
  Tertiary 
  strata. 
  

  

  A 
  short 
  distance 
  further 
  the 
  chalk 
  rose 
  rather 
  abruptly 
  to 
  the 
  

   surface 
  ; 
  but 
  the 
  drift 
  reappeared 
  a 
  quarter 
  of 
  a 
  mile 
  further 
  on* 
  

   occupying 
  a 
  small 
  shallow 
  hollow, 
  in 
  which 
  it 
  presented 
  no 
  new 
  

   features, 
  and 
  where 
  no 
  organic 
  remains 
  were 
  met 
  with. 
  As 
  a 
  

   whole, 
  the 
  drift 
  becomes 
  coarser 
  and 
  more 
  flinty 
  as 
  it 
  trends 
  to 
  this 
  

   end. 
  

  

  The 
  level 
  of 
  the 
  base 
  of 
  this 
  drift 
  at 
  its 
  northern 
  extremity 
  is 
  

   290 
  feet, 
  and 
  of 
  its 
  top 
  at 
  its 
  southern 
  end 
  407 
  feet 
  above 
  the 
  sea^ 
  

   level, 
  — 
  the 
  level 
  of 
  the 
  Thames 
  at 
  its 
  nearest 
  point 
  (Moulsford) 
  

   being 
  about 
  140 
  feet, 
  and 
  that 
  of 
  the 
  Gault 
  plain 
  below 
  Didcot 
  

   about 
  160 
  feet 
  above 
  the 
  sea-level. 
  

  

  * 
  Jeffreys, 
  ' 
  British 
  Oonchology,' 
  vol. 
  i. 
  p. 
  83. 
  

  

  