﻿PLIOCENE 
  PEKIOD 
  IN 
  ENGLAND. 
  695 
  

  

  of 
  Clacton 
  Cliff 
  in 
  the 
  ' 
  Geological 
  Magazine 
  ' 
  for 
  1868, 
  p. 
  214, 
  is 
  

   substantially 
  the 
  same 
  as 
  that 
  subsequent 
  thereto 
  which 
  is 
  in 
  the 
  

   Geological 
  Survey 
  memoir 
  for 
  quarter-sheet 
  48 
  S.W. 
  ; 
  but 
  I 
  have 
  

   reduced 
  fig. 
  XXIV. 
  from 
  the 
  figure 
  in 
  that 
  memoir. 
  

  

  On 
  the 
  opposite 
  side 
  of 
  the 
  Thames 
  estuary, 
  at 
  Chislet 
  in 
  the 
  val- 
  

   ley 
  of 
  the 
  Kentish 
  Stour 
  (north 
  centre 
  of 
  Sheet 
  3), 
  the 
  remains 
  of 
  

   the 
  Cyrena 
  are 
  described 
  by 
  Prof. 
  Prestwich 
  * 
  as 
  occurring 
  with 
  

   other 
  freshwater 
  shells 
  in 
  a 
  bed 
  of 
  sand 
  from 
  20 
  to 
  30 
  feet 
  above 
  

   0. 
  D., 
  intermixed 
  with 
  valves 
  of 
  a 
  marine 
  Cirriped, 
  and 
  with 
  (ac- 
  

   cording 
  to 
  Prof. 
  T. 
  R. 
  Jones) 
  a 
  brackish-water 
  Entomostracan 
  found 
  

   in 
  the 
  (7?/mi«-formation 
  at 
  Grays, 
  and 
  a 
  brackish-water 
  Eoraminifer. 
  

   This 
  sand 
  at 
  Chislet 
  is 
  described 
  by 
  Prof. 
  Prestwich 
  as 
  overlain 
  by 
  a 
  

   mass 
  of 
  gravel, 
  rubble, 
  and 
  brickearth, 
  from 
  3 
  to 
  8 
  feet 
  thick, 
  which 
  

   may 
  correspond 
  to 
  the 
  bed 
  Xo. 
  4 
  of 
  Clacton, 
  or 
  be 
  the 
  terrestrial 
  forma- 
  

   tion 
  y 
  described 
  in 
  Stage 
  YII. 
  There 
  is 
  thus 
  at 
  about 
  equidistant 
  

   points 
  from 
  Grays 
  evidence 
  of 
  the 
  propinquity 
  of 
  the 
  sea 
  towards 
  

   the 
  latter 
  part 
  of 
  the 
  formation 
  on 
  the 
  south 
  side 
  of 
  the 
  Thames 
  

   estuary, 
  and 
  of 
  its 
  actual 
  presence 
  on 
  the 
  north 
  side. 
  

  

  At 
  Grays 
  the 
  gravel-bed 
  Xo. 
  1, 
  forming 
  the 
  basement 
  part 
  of 
  the 
  

   formation, 
  is 
  overlain 
  and 
  overlapped 
  by 
  laminated 
  brickearth 
  

   with 
  sandy 
  seams 
  (bed 
  2), 
  and 
  this 
  again 
  by 
  a 
  considerable 
  thick- 
  

   ness 
  of 
  false-bedded 
  yellow 
  sand 
  (bed 
  3), 
  into 
  which 
  it 
  passes 
  by 
  

   alternations 
  of 
  either 
  bed, 
  and 
  in 
  the 
  lower 
  part 
  of 
  which, 
  as 
  

   well 
  as 
  in 
  bed 
  2, 
  the 
  Cyrena 
  abounds 
  in 
  association 
  with 
  freshwater 
  

   shells 
  only 
  f 
  ; 
  but 
  the 
  change 
  to 
  this 
  sand, 
  and 
  the 
  false-bedded 
  cha- 
  

   racter 
  of 
  it 
  at 
  Grays, 
  seem 
  to 
  show 
  that 
  tidal 
  action 
  in 
  a 
  decided 
  form 
  

   extended 
  now, 
  by 
  reason 
  of 
  the 
  incressing 
  depression, 
  up 
  to 
  that 
  place. 
  

   Being 
  not 
  only 
  some 
  miles 
  higher 
  up, 
  but 
  also 
  apparently 
  the 
  deposit 
  

   of 
  a 
  tributary 
  of 
  the 
  Thames, 
  the 
  division 
  of 
  this 
  sand 
  Xo. 
  3 
  from 
  

   the 
  laminated 
  brickearth 
  Xo. 
  2 
  is 
  less 
  marked, 
  and 
  the 
  sand 
  of 
  less 
  

   thickness, 
  in 
  the 
  Crayford 
  and 
  Dartford-heath 
  portions 
  of 
  the 
  for- 
  

   mation, 
  shown 
  in 
  figs. 
  XXI. 
  and 
  XXII., 
  while 
  I 
  am 
  not 
  clear 
  that 
  

   Xo. 
  4 
  is 
  present 
  there, 
  or 
  whether 
  what 
  is 
  represented 
  as 
  such 
  in 
  

   fig. 
  XXI. 
  may 
  not 
  be 
  the 
  bed 
  y 
  described 
  in 
  the 
  sequel 
  : 
  but 
  at 
  

   Ilford 
  the 
  sand 
  Xo. 
  3 
  is 
  very 
  distinguishable 
  from 
  the 
  brickearth 
  

   Xo. 
  2. 
  It 
  is, 
  however, 
  but 
  little 
  false-bedded, 
  and 
  contains, 
  so 
  far 
  

   as 
  I 
  am 
  aware, 
  only 
  freshwater 
  organisms. 
  

  

  At 
  Grays 
  Xo. 
  4 
  reaches 
  a 
  higher 
  elevation 
  than 
  Xo. 
  3, 
  and 
  is 
  

   proportionately 
  more 
  transgressive 
  ; 
  so 
  that 
  I 
  have 
  found 
  patches 
  

   of 
  it 
  on 
  the 
  chalk 
  of 
  Stifford 
  quarry 
  a 
  mile 
  to 
  the 
  north 
  of 
  fig. 
  XXIII., 
  

   and 
  on 
  the 
  gravel 
  / 
  opposite 
  the 
  " 
  Inn" 
  at 
  Stifford 
  (at 
  between 
  80 
  

   and 
  90 
  feet 
  above 
  0. 
  D.), 
  which 
  have 
  escaped 
  the 
  general 
  denuda- 
  

   tion 
  of 
  this 
  formation 
  presently 
  referred 
  to, 
  as 
  I 
  have 
  found 
  it 
  on 
  

   this 
  gravel 
  in 
  various 
  parts 
  of 
  Essex. 
  On 
  the 
  top 
  of 
  the 
  chalk-quarry 
  

   shown 
  in 
  fig. 
  XXIII. 
  the 
  transgression 
  of 
  Xo. 
  4 
  over 
  Xo. 
  3 
  was, 
  

   when 
  I 
  drew 
  it 
  in 
  1865, 
  actually 
  visible 
  in 
  section, 
  the 
  two 
  occupying 
  

  

  * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xi. 
  p. 
  111. 
  

  

  t 
  Although 
  TJnio 
  tumidus 
  swarms 
  at 
  Grays, 
  I 
  could 
  never 
  find 
  U. 
  littoralis 
  

   there, 
  Sir 
  Chas. 
  Lyell, 
  however, 
  sent 
  my 
  father 
  some 
  specimens 
  of 
  it 
  which 
  he 
  

   had 
  found 
  there 
  many 
  years 
  ago. 
  

  

  