﻿744 
  

  

  SEARLES 
  V. 
  WOOD 
  ON 
  THE 
  NEWER 
  

  

  Chalky 
  Clay 
  (cZ) 
  shown 
  in 
  fig. 
  XL., 
  the 
  line 
  of 
  which 
  figure 
  crosses 
  this 
  channel 
  to 
  

   the 
  south 
  of 
  fig. 
  VII. 
  ; 
  and 
  it 
  shows 
  how 
  the 
  ice 
  entering 
  this 
  channel 
  and 
  con- 
  

   stricted 
  by 
  these 
  two 
  islands 
  issued 
  by 
  it 
  to 
  the 
  North 
  Sea. 
  The 
  patch 
  of 
  Chalky 
  

   Clay 
  shown 
  in 
  fig. 
  XL. 
  being 
  above 
  the 
  level 
  to 
  which 
  from 
  emergence 
  the 
  sea- 
  

   line 
  in 
  this 
  part 
  had 
  then 
  fallen, 
  the 
  sea 
  on 
  re-entering 
  this 
  channel 
  as 
  the 
  ice 
  

   receded 
  did 
  not 
  reach 
  it, 
  and 
  it 
  has 
  therefore 
  no 
  gravel 
  over 
  it 
  ; 
  but 
  part 
  of 
  

   the 
  same 
  clay 
  in 
  fig. 
  VII. 
  being 
  below 
  that 
  level, 
  the 
  sea 
  covered 
  this 
  part 
  with 
  

   the 
  gravel 
  e, 
  as 
  shown 
  in 
  that 
  figure. 
  The 
  ice 
  also 
  passed 
  round 
  the 
  western 
  

   side 
  of 
  Danbury 
  Hill, 
  against 
  the 
  lower 
  part 
  of 
  which 
  also, 
  but 
  beyond 
  the 
  

   limit 
  of 
  fig. 
  XL., 
  it 
  has 
  laid 
  the 
  Chalky 
  Clay 
  ; 
  and 
  mounting 
  the 
  rest 
  of 
  the 
  island, 
  

   shown 
  as 
  extending 
  through 
  the 
  centre 
  of 
  Sheet 
  1, 
  of 
  which 
  Danbury 
  Hill 
  was 
  the 
  

   eastern 
  promontory, 
  it 
  has 
  covered 
  much 
  of 
  it 
  with 
  its 
  moraine 
  of 
  Chalky 
  Clay 
  up 
  

   to 
  the 
  broken 
  line 
  which 
  in 
  Map 
  8 
  denotes 
  the 
  southern 
  limit 
  of 
  that 
  clav, 
  illus- 
  

   trated 
  by 
  fig. 
  VI. 
  

  

  The 
  delineations 
  of 
  the 
  gravels 
  c, 
  e, 
  /, 
  and^ 
  are, 
  in 
  Sheets 
  7 
  and 
  46, 
  taken 
  from 
  

   the 
  Geological 
  Survey 
  Maps 
  (published 
  and 
  unpublished), 
  as 
  well 
  as 
  the 
  line 
  

   showing 
  the 
  limit 
  of 
  the 
  Chalky 
  Clay 
  there* 
  ; 
  but 
  in 
  the 
  other 
  sheets 
  these 
  are 
  

   all 
  taken 
  from 
  my 
  own 
  field-work. 
  In 
  Sheet 
  47 
  much 
  of 
  the 
  gravel 
  shown 
  

   (except 
  at 
  the 
  south-east 
  extremity) 
  is 
  covered 
  up 
  by 
  the 
  Chalky 
  Clay, 
  and 
  being 
  

   exposed 
  along 
  the 
  valley-edges 
  and 
  cut 
  out 
  of 
  the 
  valley-centres, 
  it 
  for 
  the 
  most 
  

   part 
  forms 
  a 
  fringe 
  to 
  the 
  Chalky 
  Clay 
  along 
  the 
  valley-sides, 
  but 
  is 
  intermitting 
  

   in 
  places. 
  

  

  The 
  numbered 
  divisions 
  in 
  all 
  the 
  maps 
  are 
  those 
  of 
  the 
  one-inch 
  scale 
  

   Ordnance 
  sheets 
  ; 
  but 
  by 
  inadvertence 
  the 
  number 
  13 
  was 
  inserted 
  in 
  two 
  divi- 
  

   sions 
  o'i 
  Map 
  1, 
  that 
  which 
  is 
  next 
  to 
  12 
  on 
  the 
  left 
  hand 
  being 
  No. 
  14. 
  I 
  find 
  

   also 
  that 
  two 
  or 
  three 
  of 
  the 
  small 
  islands 
  shown 
  in 
  the 
  south-east 
  of 
  Sheet 
  54 
  

   of 
  Map 
  No. 
  2 
  should 
  have 
  been 
  omitted, 
  their 
  elevation 
  being 
  below 
  that 
  which 
  

   would 
  correspond 
  with 
  the 
  stage 
  in 
  the 
  emergence 
  intended 
  to 
  be 
  represented. 
  

  

  Discussion. 
  

  

  Dr. 
  Gwyn 
  Jeffreys 
  considered 
  Corbimla 
  fluminalis 
  essentially 
  

   a 
  freshwater 
  species, 
  and 
  that 
  where, 
  as 
  at 
  Kelsea 
  Hill, 
  it 
  was 
  

   found 
  mixed 
  with 
  marine 
  shells, 
  the 
  fact 
  must 
  be 
  accounted 
  for 
  

   by 
  the 
  freshwater 
  shells 
  having 
  been 
  washed 
  into 
  the 
  sea. 
  He 
  

  

  * 
  The 
  only 
  departure 
  made 
  by 
  me 
  from 
  the 
  survey 
  representation 
  (in 
  which 
  

   the 
  gravel 
  /is 
  shown 
  by 
  a 
  different 
  colour 
  from 
  c 
  and 
  c) 
  is 
  in 
  giving 
  # 
  distinct 
  

   from 
  / 
  by 
  elevation, 
  the 
  gravel 
  shown 
  by 
  me 
  under 
  the 
  dottings 
  respectively 
  

   indicating 
  the 
  gravels 
  / 
  and 
  a 
  being 
  shown 
  in 
  the 
  Survey 
  Map 
  as 
  one. 
  There 
  

   are 
  also 
  a 
  group 
  of 
  gravels 
  shown 
  in 
  the 
  Survey 
  Map 
  under 
  a 
  separate 
  colour 
  

   as 
  "pebble 
  gravel." 
  These 
  (which 
  are 
  omitted 
  from 
  Map 
  3) 
  rest 
  on 
  the 
  islands 
  

   shown 
  in 
  that 
  map 
  on 
  the 
  east 
  side 
  of 
  the 
  Colne 
  Channel 
  ; 
  and 
  that 
  gravel 
  which 
  

   is 
  comprised 
  in 
  Prof. 
  Hughes's 
  section 
  at 
  page 
  678, 
  and 
  called 
  by 
  him 
  " 
  Pebble 
  

   gravel 
  of 
  the 
  Higher 
  Plain," 
  is 
  part 
  of 
  these. 
  Most 
  of 
  this 
  gravel 
  is, 
  like 
  that 
  in 
  

   Prof. 
  Hughes's 
  section, 
  the 
  earlier 
  part 
  of 
  the 
  gravel 
  c, 
  Avhich 
  had 
  emerged 
  before 
  

   the 
  ice 
  of 
  the 
  Chalky 
  Clay 
  reached 
  it, 
  and 
  though 
  composed 
  chiefly 
  of 
  kidney- 
  

   shaped 
  flint 
  pebbles, 
  derived 
  from 
  the 
  bed 
  VIII. 
  of 
  my 
  figures, 
  contains 
  a 
  large 
  

   proportion 
  of 
  quartz 
  and 
  quartzite 
  pebbles 
  also 
  ; 
  but 
  some 
  of 
  what 
  is 
  thus 
  

   shown 
  is, 
  I 
  think, 
  not 
  that 
  gravel 
  but 
  bed 
  VIII., 
  which 
  I 
  am 
  quite 
  clear 
  is 
  not 
  

   of 
  Newer 
  Pliocene 
  age 
  at 
  all, 
  and, 
  I 
  think, 
  probably 
  oldest 
  Pliocene 
  (Diestian), 
  

   i. 
  e. 
  the 
  shingle 
  equivalent 
  of 
  the 
  Lenham 
  and 
  Paddlesworth 
  sands 
  ; 
  and 
  in 
  this 
  

   nearly 
  every 
  pebble 
  is 
  of 
  flint. 
  To 
  keep 
  in 
  accord 
  with 
  the 
  Geological 
  Survey 
  Map, 
  

   I 
  have 
  shown 
  in 
  Map 
  3 
  the 
  patch 
  of 
  gravel 
  c 
  at 
  Finchley 
  ; 
  but 
  in 
  my 
  opinion 
  this, 
  

   like 
  most 
  of 
  that 
  coloured 
  as 
  pebble 
  gravel, 
  is 
  the 
  earlier 
  part 
  of 
  c, 
  which 
  had 
  

   emerged 
  at 
  the 
  time 
  represented 
  by 
  Map 
  3, 
  and 
  had 
  the 
  Chalky 
  Clay 
  laid 
  upon 
  

   it 
  terrestrially 
  ; 
  so 
  that 
  in 
  order 
  to 
  show 
  correctly 
  the 
  geographical 
  conditions 
  of 
  

   the 
  time, 
  it 
  should, 
  I 
  consider, 
  be 
  omitted 
  from 
  that 
  map, 
  and 
  the 
  black 
  tint 
  

   representing 
  the 
  island 
  of 
  Hampstead 
  and 
  Highgate 
  Hill 
  extended 
  so 
  as 
  to 
  

   include 
  this 
  part 
  of 
  the 
  gravel 
  and 
  into 
  connexion 
  with 
  the 
  black 
  tint 
  to 
  the 
  

   north 
  of 
  it. 
  

  

  