﻿PLIOCENE 
  PEEIOD 
  IN 
  ENGLAND. 
  727 
  

  

  the 
  others 
  ; 
  and 
  therefore 
  the 
  objection, 
  if 
  applicable 
  to 
  some, 
  becomes 
  

   applicable 
  to 
  all. 
  

  

  The 
  accumulation, 
  moreover, 
  though 
  thick 
  in 
  hollows 
  such 
  as 
  the 
  

   cliffs, 
  or 
  beneath 
  a 
  steep 
  slope 
  as 
  a 
  talus, 
  is 
  not 
  shown 
  in 
  Mr. 
  Prest- 
  

   wich's 
  sections 
  at 
  all 
  distributed 
  generally 
  as 
  a 
  marine 
  deposit 
  would 
  

   be 
  ; 
  and 
  without 
  dwelling 
  upon 
  the 
  gradual 
  way 
  in 
  which 
  any 
  sub- 
  

   mergence, 
  however 
  rapid, 
  geologically 
  speaking, 
  would 
  first 
  fill 
  the 
  

   valleys, 
  and, 
  after 
  planing 
  off 
  all 
  preexisting 
  cliffs 
  in 
  yielding 
  strata, 
  

   rise 
  from 
  level 
  to 
  level, 
  it 
  seems 
  a 
  far 
  less 
  demand 
  to 
  make 
  on 
  our 
  

   reason 
  to 
  suggest 
  that 
  the 
  presence 
  of 
  fragments 
  of 
  the 
  Middle 
  Pur- 
  

   beck 
  in 
  this 
  accumulation 
  may 
  be 
  explained 
  either 
  by 
  patches 
  of 
  

   that 
  formation 
  in 
  situ 
  being 
  overlooked 
  or 
  concealed 
  from 
  view, 
  or 
  

   else 
  by 
  their 
  having 
  been 
  altogether 
  removed 
  by 
  the 
  agency 
  which 
  

   introduced 
  the 
  fragments 
  into 
  this 
  accumulation, 
  than 
  to 
  explain 
  the 
  

   case 
  by 
  resort 
  to 
  a 
  great 
  submergence, 
  which 
  is 
  diametrically 
  in 
  

   contradiction 
  to 
  all 
  the 
  phenomena 
  traced 
  in 
  this 
  memoir, 
  and, 
  as 
  it 
  

   seems 
  to 
  me, 
  irreconcilable 
  with 
  the 
  presence 
  of 
  seams 
  of 
  loam 
  

   containing 
  tender 
  land-shells 
  intercalated 
  in 
  this 
  accumulation. 
  

  

  On 
  the 
  other 
  hand, 
  all 
  the 
  features 
  displayed 
  by 
  the 
  sections 
  of 
  

   the 
  Portland 
  and 
  Weymouth 
  district, 
  by 
  which 
  Prof. 
  Prestwich 
  has, 
  

   with 
  his 
  well-known 
  accuracy, 
  illustrated 
  his 
  account, 
  appear 
  to 
  me, 
  

   when 
  properly 
  interpreted, 
  to 
  be 
  precisely 
  in 
  accordance 
  with 
  all 
  

   that 
  I 
  have 
  traced 
  in 
  this 
  memoir. 
  

  

  Resuming 
  now 
  my 
  examination 
  of 
  the 
  evidences 
  of 
  the 
  minor 
  

   glaciation 
  in 
  the 
  South 
  of 
  England, 
  I 
  proceed 
  with 
  the 
  gravel 
  g. 
  

   This 
  1 
  have 
  shown 
  by 
  a 
  tint 
  of 
  more 
  open 
  dots 
  in 
  the 
  Map 
  3, 
  and 
  it 
  

   agrees 
  in 
  level 
  with 
  the 
  position 
  of 
  the 
  country 
  at 
  the 
  time 
  when, 
  

   by 
  a 
  pause 
  in 
  the 
  rise 
  from 
  the 
  C?/>v»«-redepression, 
  the 
  buried 
  

   cliffs 
  and 
  the 
  clay-gravel 
  with 
  great 
  blocks, 
  showu 
  in 
  fig. 
  XLII. 
  by 
  the 
  

   letter 
  G, 
  came 
  into 
  existence. 
  Mr. 
  Codrington 
  has 
  correlated 
  this 
  

   marine 
  gravel 
  G 
  with 
  the 
  river-gravel 
  of 
  lowest 
  elevation 
  of 
  the 
  

   Hampshire 
  valleys, 
  when 
  these 
  existed 
  under 
  a 
  geographical 
  ar- 
  

   rangement 
  which 
  has 
  been 
  to 
  a 
  great 
  degree 
  obliterated 
  by 
  the 
  

   cutting 
  back 
  of 
  the 
  Solent 
  cliffs 
  ; 
  and 
  in 
  this 
  I 
  quite 
  agree 
  with 
  

   him 
  : 
  merely 
  adding 
  that 
  I 
  think 
  it 
  likely 
  that 
  this 
  alteration 
  may 
  

   have 
  been 
  induced 
  by 
  those 
  disturbances 
  which 
  I 
  have 
  shown 
  in 
  the 
  

   case 
  of 
  the 
  Thames 
  valley 
  to 
  have 
  been 
  renewed 
  after 
  the 
  formation 
  

   of 
  the 
  gravel 
  g 
  there. 
  It 
  was 
  during 
  this 
  pause 
  in 
  the 
  rise 
  there- 
  

   fore 
  that 
  the 
  Thames 
  valley 
  became 
  stationary 
  at 
  a 
  point 
  which 
  

   allowed 
  the 
  Thames 
  water 
  during 
  flood 
  to 
  rise 
  to 
  a 
  level 
  which 
  

   seems 
  to 
  be 
  everywhere 
  between 
  25 
  and 
  30 
  feet 
  above 
  that 
  of 
  the 
  

   present 
  river. 
  At 
  Grays 
  and 
  Dartford 
  the 
  gravel 
  g, 
  which 
  repre- 
  

   sents 
  this 
  flood-level, 
  does 
  not 
  extend 
  higher 
  than 
  about 
  30 
  feet 
  above 
  

   0. 
  D. 
  At 
  Ilford 
  (see 
  figs. 
  XXY. 
  and 
  XXVI.) 
  it 
  ceases 
  between 
  the 
  

   levels 
  of 
  30 
  and 
  40 
  feet 
  above 
  O. 
  D. 
  ; 
  for 
  while 
  it 
  covers 
  the 
  Cyrena- 
  

   formation 
  in 
  the 
  Uphall 
  field 
  up 
  to 
  30, 
  no 
  sign 
  of 
  it 
  appears 
  in 
  the 
  

   London-road 
  field, 
  which 
  (except 
  where 
  the 
  surface 
  has 
  been 
  lowered 
  

   by 
  excavation 
  for 
  bricks) 
  is 
  above 
  40 
  feet 
  elevation 
  ; 
  and 
  in 
  lieu 
  of 
  

   it 
  the 
  (Tymia-brickearth 
  (bed 
  (p 
  2) 
  is 
  covered 
  by 
  the 
  terrestrial 
  

   formation, 
  y, 
  already 
  described 
  as 
  originating 
  from 
  the 
  freezing 
  and 
  

  

  