﻿PLIOCENE 
  PKKIOD 
  IN 
  ENGLAND. 
  

  

  073 
  

  

  it 
  (and 
  in 
  which 
  Mr. 
  Skertchly 
  has 
  found 
  palaeolithic 
  implements), 
  

   is 
  between 
  200 
  and 
  300 
  feet 
  lower 
  in 
  elevation 
  than 
  the 
  highest 
  

   patch 
  of 
  gravel 
  attributed 
  by 
  Mr. 
  Penning 
  to 
  this 
  river, 
  coming 
  into 
  

   existence 
  after 
  the 
  Chalky 
  Clay, 
  though 
  that 
  patch 
  is 
  hardly 
  twenty 
  

   miles 
  S.S.W. 
  of 
  it 
  ; 
  and 
  I 
  fail 
  to 
  see 
  how 
  this 
  river-denudation, 
  

   altering 
  altogether 
  the 
  drainage 
  within 
  the 
  Cam 
  system, 
  and 
  con- 
  

   verting 
  river- 
  bottoms 
  into 
  hills 
  which 
  separate 
  the 
  old 
  stream 
  into 
  

   distinct 
  rivers, 
  could 
  have 
  taken 
  place 
  after 
  the 
  Lark 
  valley 
  (to 
  the 
  

   drainage 
  of 
  which 
  the 
  Mildenhall 
  brickearth 
  was 
  due, 
  as 
  that 
  of 
  

   Brandon 
  is 
  to 
  the 
  drainage 
  of 
  the 
  Little-Ouse 
  valley) 
  had 
  acquired 
  its 
  

   present 
  form, 
  and 
  this 
  brickearth 
  been 
  overwhelmed 
  with 
  the 
  Chalky 
  

   Clay 
  — 
  as 
  I 
  also 
  cannot 
  believe 
  the 
  postulate 
  of 
  Mr. 
  Jukes-Browne, 
  

   that 
  a 
  river 
  can 
  convert 
  the 
  centre 
  of 
  its 
  bed 
  into 
  a 
  hill. 
  More- 
  

   over, 
  how 
  can 
  such 
  an 
  enormous 
  excavation 
  by 
  river-agency 
  have 
  

   thus 
  taken 
  place 
  in 
  the 
  Cam 
  system, 
  when 
  the 
  valley 
  of 
  the 
  Stort, 
  

   which 
  is 
  divided 
  from 
  it 
  by 
  this 
  parting 
  of 
  less 
  than 
  300 
  feet 
  eleva- 
  

   tion, 
  has, 
  like 
  the 
  valley 
  of 
  the 
  Lea, 
  and 
  all 
  the 
  valleys 
  of 
  Essex. 
  

   Suffolk, 
  and 
  Norfolk, 
  undergone 
  no 
  material 
  denudation 
  since 
  the 
  ice 
  

   of 
  the 
  Chalky 
  Clay 
  deserted 
  them, 
  as 
  is 
  shown 
  by 
  the 
  plunge 
  of 
  the 
  

   Chalky 
  Clay 
  into 
  them, 
  which 
  I 
  described 
  in 
  the 
  first 
  part 
  of 
  this 
  

   memoir 
  ? 
  

  

  On 
  the 
  other 
  hand, 
  the 
  whole 
  of 
  the 
  phenomena 
  appear 
  to 
  me 
  to 
  

   be 
  consistent 
  and 
  mutually 
  supporting 
  in 
  the 
  way 
  in 
  which 
  I 
  have 
  

   traced 
  the 
  case 
  through 
  this 
  memoir*; 
  for, 
  at 
  the 
  time 
  when 
  this 
  

   brickearth 
  accumulated, 
  Norfolk 
  and 
  Suffolk 
  had, 
  owing 
  to 
  the 
  

   decrease 
  of 
  original 
  depression 
  in 
  that 
  direction, 
  emerged, 
  and 
  the 
  

   ice 
  had 
  retreated 
  from 
  those 
  counties 
  and 
  the 
  counties 
  to 
  the 
  south 
  

   of 
  them, 
  but 
  still 
  continued 
  over 
  parts 
  of 
  Sheets 
  69 
  and 
  70, 
  and 
  

   thence 
  northwards. 
  The 
  drainage 
  from 
  West 
  Suffolk, 
  while 
  thus 
  

   emerging, 
  flowed 
  into 
  the 
  low 
  country 
  of 
  Sheet 
  51, 
  whence, 
  by 
  the 
  

   increment 
  of 
  depression 
  westwards, 
  it 
  escaped 
  in 
  that 
  direction, 
  if 
  

   any 
  of 
  the 
  partings 
  separating 
  the 
  Wash 
  rivers 
  from 
  those 
  of 
  the 
  

   Thames 
  or 
  Severn 
  systems 
  continued 
  then 
  submerged 
  — 
  and 
  if 
  not, 
  by 
  

   that 
  part 
  of 
  Sheet 
  09 
  to 
  which 
  the 
  ice 
  did 
  not 
  reach 
  ; 
  and 
  from 
  this 
  

   drainage 
  the 
  Mildenhall 
  brickearth 
  originated. 
  A 
  temporary 
  ad- 
  

   vance 
  of 
  the 
  ice 
  in 
  this 
  receded 
  position 
  (as 
  stated 
  at 
  p. 
  499 
  of 
  the 
  

   first 
  part 
  of 
  this 
  memoir) 
  then 
  took 
  place'!', 
  which 
  covered 
  this 
  

  

  * 
  Except 
  that 
  in 
  the 
  first 
  pai't 
  of 
  this 
  memoir 
  I 
  referred 
  the 
  transit 
  of 
  the 
  

   Lincolnshire 
  red 
  and 
  hard 
  white 
  chalk 
  into 
  the 
  gravel 
  of 
  the 
  Trent 
  system 
  to 
  

   the 
  time 
  when 
  the 
  excavation 
  of 
  the 
  Steeping 
  valley 
  was 
  effected 
  by 
  the 
  effluent 
  

   water 
  of 
  the 
  ice 
  of 
  the 
  Chalky 
  Clay, 
  after 
  its 
  retreat 
  to 
  the 
  Lincolnshire 
  Wold. 
  

   As, 
  however, 
  the 
  transit 
  of 
  this 
  chalk 
  must 
  have 
  been 
  either 
  when 
  the 
  water- 
  

   parting 
  between 
  the 
  Avon 
  and 
  Welland 
  was 
  submerged, 
  or 
  else 
  when 
  it 
  was 
  

   overridden 
  by 
  the 
  ice, 
  I 
  see 
  now 
  that 
  it 
  preceded 
  the 
  excavation 
  of 
  the 
  Steeping 
  

   valley, 
  and 
  that 
  this 
  chalk 
  must 
  have 
  been 
  dropped 
  by 
  floes 
  that 
  took 
  it 
  up 
  from 
  

   banks 
  of 
  the 
  moraine 
  which 
  was 
  carried 
  by 
  the 
  ice 
  into 
  the 
  Avon 
  valley 
  at 
  the 
  

   time 
  of 
  its 
  greatest 
  extension 
  in 
  that 
  direction 
  (as 
  represented 
  by 
  the 
  delineation 
  

   of 
  the 
  Chalky 
  Clay 
  in 
  Map 
  1), 
  when 
  it 
  issued 
  into 
  the 
  sea 
  over 
  the 
  Severn 
  system 
  

   by 
  way 
  of 
  the 
  valleys 
  of 
  the 
  Welland 
  and 
  Avon. 
  

  

  t 
  Such 
  an 
  advance 
  is 
  conceivable 
  to 
  me 
  without 
  resort 
  to 
  any 
  oscillation 
  of 
  

   climate, 
  by 
  supposing 
  that 
  the 
  recovery 
  from 
  the 
  Western 
  depression 
  gained 
  

   upon 
  the 
  gradual 
  diminution 
  of 
  the 
  ice, 
  which 
  was 
  taking 
  place 
  by 
  the 
  wane 
  

  

  