﻿6*74 
  SEARLES 
  V. 
  WOOD 
  ON 
  THE 
  NEWER 
  

  

  brickearth 
  with 
  chalky 
  clay 
  ; 
  and 
  it 
  was 
  while 
  thus 
  advanced, 
  but 
  

   when 
  the 
  partings 
  of 
  the 
  Wash 
  valleys 
  from 
  the 
  valleys 
  of 
  the 
  Thames 
  

   and 
  Severn 
  systems 
  had 
  fully 
  emerged, 
  that 
  the 
  effluent 
  water 
  from 
  it, 
  

   as 
  well 
  as 
  drainage 
  from 
  the 
  emerged 
  land 
  beyond 
  its 
  limit, 
  which 
  it 
  

   clammed 
  up, 
  gave 
  rise 
  to 
  the 
  lake-like 
  water 
  thus 
  described. 
  It 
  seems 
  

   to 
  me, 
  therefore, 
  that 
  the 
  freshwater 
  bed 
  in 
  Casewick 
  cutting 
  and 
  

   the 
  brickearth 
  intercalated 
  in 
  the 
  Chalky 
  Clay 
  in 
  West 
  Suffolk 
  are 
  

   nearly 
  coeval, 
  both 
  having 
  arisen 
  on 
  places 
  which, 
  when 
  the 
  ice 
  of 
  

   the 
  Chakly 
  Clay 
  was 
  at 
  its 
  greatest 
  extension, 
  were 
  deeply 
  buried 
  

   under 
  it, 
  but 
  which 
  were 
  vacated 
  by 
  its 
  retreat 
  to 
  Sheet 
  69 
  — 
  the 
  one 
  

   of 
  them 
  having 
  been 
  overwhelmed 
  by 
  the 
  ice 
  during 
  its 
  temporary 
  

   readvance, 
  and 
  the 
  other 
  by 
  the 
  water- 
  rise 
  which 
  was 
  the 
  consequence 
  

   of 
  that 
  readvance. 
  

  

  To 
  render 
  my 
  views 
  intelligible, 
  I 
  give 
  the 
  little 
  Map 
  (No. 
  6, 
  

   PI. 
  XX 
  YI.) 
  to 
  represent 
  what 
  I 
  conceive 
  to 
  be 
  the 
  conditions 
  of 
  the 
  

   country 
  at 
  this 
  time. 
  It 
  comprises 
  the 
  same 
  Ordnance 
  sheets 
  as 
  the 
  

   Map 
  Xo. 
  2 
  given 
  in 
  the 
  plate 
  to 
  the 
  first 
  part 
  of 
  this 
  memoir 
  ; 
  but 
  the 
  

   vscale 
  being 
  only 
  half 
  of 
  that 
  (linear), 
  the 
  rivers 
  which 
  are 
  delineated 
  in 
  

   Xo. 
  2 
  are 
  omitted 
  from 
  it, 
  except 
  the 
  Trent, 
  the 
  Avons 
  of 
  Warwick- 
  

   shire 
  and 
  Somersetshire, 
  and 
  the 
  Thames. 
  The 
  Map 
  Xo. 
  2, 
  accompany- 
  

   ing 
  the 
  first 
  part 
  of 
  this 
  memoir, 
  represents 
  the 
  condition 
  to 
  which 
  

   the 
  area 
  comprised 
  in 
  it 
  had 
  been 
  brought 
  by 
  from 
  200 
  to 
  250 
  feet 
  

   of 
  emergence 
  from 
  the 
  maximum 
  depression 
  described 
  in 
  Stage 
  II., 
  

   and 
  before 
  the 
  ice 
  of 
  the 
  Chalky 
  Clay 
  reached 
  its 
  greatest 
  extension 
  

   (that 
  extension 
  being 
  represented 
  by 
  the 
  limit 
  shown 
  by 
  the 
  line 
  in 
  

   Map 
  4 
  in 
  the 
  present, 
  and 
  by 
  the 
  distribution 
  of 
  that 
  clay 
  delineated 
  

   in 
  Map 
  1 
  of 
  the 
  previous 
  part 
  of 
  the 
  memoir); 
  and 
  in 
  it 
  the 
  water- 
  

   partings 
  between 
  the 
  Wash 
  rivers 
  and 
  those 
  of 
  the 
  Thames 
  and 
  

   Severn 
  systems 
  are 
  shown 
  as 
  still 
  submerged, 
  for 
  they 
  were 
  parts 
  

   of 
  the 
  channels 
  or 
  fiords 
  by 
  which 
  this 
  ice 
  issued 
  to 
  the 
  western 
  

   sea. 
  The 
  Map 
  0, 
  on 
  the 
  contrary, 
  shows 
  these 
  vater-partings 
  all 
  

   emerged, 
  and 
  the 
  land 
  area 
  as 
  extended 
  in 
  proportion 
  to 
  the 
  increased 
  

   emergence, 
  regard 
  being 
  had 
  to 
  the 
  original 
  increment 
  of 
  southerly 
  

   and 
  great 
  westerly 
  depression. 
  The 
  ice 
  having 
  retreated 
  not 
  merely 
  

   from 
  the 
  plateaux 
  of 
  East 
  Xorfolk 
  and 
  East 
  Suffolk, 
  but 
  also 
  from 
  

   the 
  valleys 
  of 
  that 
  region, 
  which 
  had 
  now 
  all 
  emerged 
  to 
  something 
  

   above 
  their 
  present 
  level, 
  as 
  well 
  as 
  from 
  the 
  various 
  other 
  issues 
  

   described 
  in 
  the 
  first 
  part 
  of 
  this 
  memoir 
  except 
  that 
  of 
  the 
  Trent, 
  

   is 
  represented 
  as 
  still 
  extending 
  over 
  the 
  low 
  ground 
  of 
  the 
  Fen 
  

   country 
  into 
  the 
  north 
  of 
  Sheet 
  51, 
  its 
  extremity 
  overwhelming 
  the 
  

   brickearth 
  of 
  the 
  Lark 
  and 
  Little-Ouse 
  valleys, 
  and 
  causing 
  the 
  water 
  

   in 
  the 
  valleys 
  of 
  the 
  Welland, 
  Xen, 
  Great 
  Ouse, 
  and 
  Cam, 
  thus 
  

   blocked 
  up 
  by 
  it, 
  to 
  rise 
  and 
  overflow 
  the 
  low 
  water-partings 
  which 
  

   divide 
  tributaries 
  of 
  these 
  respective 
  systems, 
  such 
  as 
  that 
  of 
  Case- 
  

  

  of 
  the 
  glaciation 
  ; 
  so 
  that 
  the 
  issue 
  of 
  the 
  ice 
  to 
  the 
  sea 
  by 
  the 
  Trent 
  valley 
  

   ( 
  which 
  of 
  all 
  the 
  issues 
  by 
  which 
  it 
  passed 
  to 
  the 
  sea 
  was 
  the 
  one 
  that 
  the 
  ice 
  last 
  

   retreated 
  from) 
  was 
  checked, 
  and 
  the 
  area 
  of 
  the 
  i 
  dand 
  ice 
  in 
  consequence 
  pro- 
  

   portionally 
  extended, 
  thus 
  causing 
  the 
  part 
  of 
  it 
  covering 
  the 
  Wash 
  to 
  advance 
  

   over 
  Sheet 
  65 
  into 
  51, 
  as 
  shown 
  in 
  Map 
  6, 
  PI. 
  XXVI. 
  

  

  

  