﻿192 
  W. 
  X0PLEY 
  ON 
  AREAS 
  OJ? 
  APPARENT 
  UPHEAVAL. 
  

  

  but 
  even 
  after 
  making 
  every 
  allowance 
  for 
  this, 
  we 
  are 
  still 
  compelled 
  

   to 
  admit 
  that 
  the 
  dip 
  of 
  the 
  higher 
  Cretaceous 
  beds 
  is 
  partly 
  due 
  to 
  

   thinning 
  of 
  the 
  underlying 
  Neocomian 
  beds. 
  

  

  The 
  main 
  line 
  of 
  watershed 
  of 
  the 
  Weald 
  runs 
  from 
  near 
  Pair- 
  

   light 
  westwards 
  along, 
  or 
  near 
  to, 
  the 
  main 
  anticlinal 
  line, 
  as 
  far 
  as 
  

   the 
  western 
  extremity 
  of 
  the 
  Hastings 
  beds, 
  near 
  Horsham 
  ; 
  it 
  then 
  

   turns 
  northwards 
  over 
  the 
  Weald 
  Clay, 
  and 
  goes 
  over 
  the 
  top 
  of 
  

   Leith 
  Hill, 
  on 
  the 
  Lower 
  Greensand 
  range. 
  The 
  top 
  of 
  the 
  Weald 
  

   Clay 
  attains 
  its 
  maximum 
  height 
  at 
  Leith 
  Hill, 
  where 
  it 
  is 
  about 
  

   750 
  feet 
  above 
  the 
  sea. 
  If 
  the 
  Weald 
  Clay 
  here 
  had 
  only 
  the 
  thick- 
  

   ness 
  which 
  it 
  is 
  known 
  to 
  have 
  further 
  east, 
  it 
  would 
  be 
  necessary 
  

   to 
  assume 
  that 
  the 
  main 
  Wealden 
  anticlinal, 
  or 
  the 
  line 
  along 
  

   which 
  the 
  lower 
  beds 
  attain 
  their 
  greatest 
  elevation, 
  passes 
  under 
  

   Leith 
  Hill 
  ; 
  in 
  which 
  case 
  the 
  main 
  anticlinal 
  and 
  the 
  main 
  line 
  

   of 
  watershed 
  would 
  coincide, 
  as 
  they 
  usually 
  do. 
  From 
  an 
  exa- 
  

   mination 
  of 
  railway-cuttings 
  between 
  Dorking 
  and 
  Horsham, 
  it 
  is 
  

   now 
  certain 
  that 
  the 
  Weald 
  Clay 
  must 
  be 
  of 
  unusual 
  thickness 
  there, 
  

   probably 
  not 
  much 
  under 
  1000 
  feet. 
  

  

  The 
  result 
  of 
  this 
  is, 
  that 
  if 
  we 
  consider 
  only 
  the 
  base 
  of 
  the 
  

   Weald 
  Clay, 
  we 
  see 
  that 
  the 
  main 
  anticlinal 
  lies 
  near 
  Horsham, 
  

   where 
  we 
  should 
  expect 
  to 
  find 
  it 
  ; 
  if 
  we 
  consider 
  only 
  the 
  top 
  of 
  

   the 
  Weald 
  Clay 
  (or 
  the 
  base 
  of 
  the 
  Lower 
  Greensand), 
  we 
  see 
  that 
  

   the 
  main 
  anticlinal 
  lies 
  under 
  Leith 
  Hill. 
  

  

  Mr. 
  Beckles 
  some 
  years 
  back 
  published 
  some 
  notes 
  in 
  the 
  Journal 
  

   of 
  this 
  Society 
  upon 
  the 
  Lowest 
  strata 
  of 
  the 
  cliffs 
  at 
  Hastings*. 
  

   He 
  there 
  describes 
  a 
  set 
  of 
  beds, 
  the 
  highest 
  member 
  of 
  which 
  is 
  a 
  

   peculiar 
  sandstone, 
  which, 
  when 
  exposed 
  in 
  large 
  masses 
  on 
  the 
  

   shore 
  has 
  the 
  appearance 
  of 
  a 
  pavement 
  ; 
  hence 
  it 
  has 
  been 
  called 
  

   the 
  " 
  Tessellated 
  Sandstone." 
  At 
  several 
  places 
  between 
  Hastings 
  

   and 
  Cliff 
  End 
  sandstone 
  of 
  this 
  character 
  is 
  seen, 
  which 
  by 
  

   Mr. 
  Beckles 
  is 
  believed 
  to 
  be 
  the 
  same 
  bed 
  ; 
  but 
  this 
  lies 
  at 
  very 
  

   different 
  depths 
  below 
  the 
  base 
  of 
  the 
  Ashdown 
  Sand. 
  Either, 
  

   then, 
  Mr. 
  Beckles 
  is 
  mistaken 
  as 
  to 
  the 
  position 
  of 
  these 
  sandstone 
  

   beds, 
  or 
  the 
  beds 
  between 
  them 
  and 
  the 
  base 
  of 
  the 
  Ashdown 
  sand 
  

   thicken 
  out 
  enormously 
  in 
  a 
  comparatively 
  short 
  distance. 
  This 
  

   thickening 
  would 
  occur 
  just 
  where 
  the 
  anticlinal 
  comes 
  ; 
  in 
  fact 
  the 
  

   " 
  Eairlight 
  anticlinal," 
  which 
  is 
  assumed 
  to 
  have 
  affected 
  the 
  Ash- 
  

   down 
  Sand 
  and 
  overlying 
  beds, 
  would 
  be 
  largely 
  accounted 
  for 
  by 
  

   this 
  thickening. 
  For 
  this 
  reason, 
  and 
  also 
  because 
  the 
  " 
  tessellated 
  

   sandstone 
  " 
  cannot 
  be 
  continuously 
  traced, 
  I 
  have 
  always 
  thought 
  that 
  

   Mr. 
  Beckles 
  was 
  mistaken 
  in 
  the 
  matter 
  ; 
  but 
  the 
  numerous 
  instances 
  

   which 
  we 
  have 
  considered 
  of 
  dips 
  and 
  anticlinals 
  being 
  produced 
  by 
  

   thickening 
  of 
  underlying 
  strata, 
  certainly 
  very 
  much 
  weakens 
  one 
  of 
  

   the 
  arguments 
  against 
  Mr. 
  Beckles's 
  viewf- 
  

  

  * 
  Vol. 
  xii. 
  p. 
  288. 
  

  

  t 
  Mr. 
  A. 
  Tylor 
  has 
  remarked 
  upon 
  the 
  thinning 
  of 
  the 
  lowest 
  Wealden 
  beds 
  

   of 
  the 
  Sussex 
  coast. 
  In 
  describing 
  a 
  section 
  of 
  the 
  coast, 
  which 
  is 
  given 
  in 
  the 
  

   paper, 
  he 
  says 
  : 
  — 
  " 
  The 
  passage 
  of 
  some 
  beds 
  of 
  sand-rock 
  into 
  clay 
  is 
  well 
  shown 
  

  

  on 
  the 
  east 
  of 
  Hastings 
  ; 
  and 
  the 
  thinning 
  of 
  the 
  Castle 
  Rock 
  on 
  the 
  same 
  

  

  line 
  is 
  also 
  shown. 
  The 
  bearings 
  of 
  the 
  same 
  strata 
  to 
  the 
  west, 
  through 
  St. 
  Leo- 
  

  

  