﻿W. 
  WHTTAKER 
  ON 
  THANET 
  BEDS 
  AND 
  CRAG 
  AT 
  SUDBURY. 
  401 
  

  

  31. 
  On 
  the 
  Occurrence 
  of 
  Thanex 
  Beds 
  and 
  of 
  Crag 
  at 
  Sudbury, 
  

   Suffolk. 
  By 
  William 
  Whitaker, 
  B.A. 
  (LoncL), 
  F.G.S., 
  of 
  the 
  

   Geological 
  Survey 
  of 
  England. 
  (Bead 
  June 
  10, 
  1874.) 
  

  

  (Communicated 
  by 
  permission 
  of 
  the 
  Director-General 
  of 
  the 
  Geological 
  Surveys 
  

   of 
  the 
  United 
  Kingdom.) 
  

  

  1. 
  Thanet 
  Beds. 
  

  

  The 
  newer 
  Tertiary 
  deposits 
  of 
  the 
  Eastern 
  Counties 
  have 
  had 
  such 
  • 
  

   a 
  power 
  of 
  fascination 
  over 
  geologists 
  that 
  the 
  older 
  beds 
  have 
  been 
  

   left 
  almost 
  unnoticed 
  : 
  indeed 
  since 
  the 
  description 
  of 
  a 
  few 
  sections 
  

   in 
  Mr. 
  Prestwich's 
  essays 
  on 
  the 
  Lower 
  London 
  Tertiaries, 
  which 
  

   have 
  now 
  been 
  published 
  20 
  years 
  and 
  more, 
  I 
  know 
  of 
  but 
  one 
  

   paper 
  (and 
  this 
  probably 
  known 
  to 
  very 
  few 
  geologists)* 
  that 
  gives 
  

   us 
  any 
  information 
  about 
  that 
  series 
  in 
  the 
  district 
  in 
  question, 
  

   whereas 
  the 
  number 
  of 
  papers 
  that 
  treat 
  of 
  Crag 
  and 
  Drift 
  is 
  

   legion. 
  It 
  has 
  therefore 
  been 
  an 
  agreeable 
  surprise 
  to 
  me 
  to 
  find, 
  

   in 
  the 
  course 
  of 
  my 
  Geological 
  Survey 
  work, 
  that 
  there 
  are 
  fine 
  

   sections 
  of 
  the 
  older 
  Tertiary 
  beds 
  in 
  Suffolk 
  and 
  the 
  neighbouring 
  

   part 
  of 
  Essex 
  ; 
  and 
  it 
  was 
  with 
  some 
  astonishment 
  that 
  I 
  saw 
  one 
  

   of 
  the 
  finest 
  sets 
  of 
  sections 
  in 
  the 
  London 
  Basin 
  round 
  the 
  town 
  of 
  

   Sudbury, 
  on 
  the 
  border 
  of 
  those 
  two 
  counties. 
  

  

  These 
  sections 
  convinced 
  me 
  that 
  the 
  lowest 
  member 
  of 
  the 
  Lower 
  

   London 
  Tertiaries, 
  the 
  Thanet 
  Beds, 
  crops 
  out 
  along 
  part 
  of 
  the 
  

   northern 
  edge 
  of 
  the 
  Tertiary 
  district, 
  an 
  occurrence 
  of 
  which 
  I 
  had 
  

   a 
  very 
  slight 
  suspicion 
  from 
  other 
  sections 
  near 
  Ipswich. 
  

  

  Mr. 
  Prestwich 
  has, 
  indeed, 
  doubtfully 
  referred 
  some 
  of 
  the 
  sands 
  

   of 
  the 
  northern 
  outcrop 
  to 
  this 
  division, 
  though 
  without 
  describing 
  

   any 
  section 
  ; 
  but 
  he 
  does 
  not 
  notice 
  the 
  particular 
  part 
  where 
  it 
  is 
  

   now 
  to 
  be 
  seen 
  in 
  many 
  large 
  and 
  clear 
  pits, 
  and 
  the 
  following 
  notes 
  

   are 
  all 
  that 
  can 
  be 
  gleaned 
  from 
  his 
  elaborate 
  papers 
  : 
  — 
  

  

  " 
  In 
  north 
  Essex 
  the 
  zone 
  of 
  outcrop 
  of 
  these 
  sands 
  usually 
  occurs 
  

   on 
  the 
  slope 
  of 
  hills, 
  and 
  they 
  therefore 
  form 
  a 
  very 
  narrow 
  belt, 
  

   which 
  is 
  further 
  frequently 
  so 
  obscured 
  by 
  drift 
  that 
  they 
  do 
  not 
  

   constitute 
  any 
  marked 
  feature 
  in 
  the 
  district. 
  Owing 
  to 
  this 
  cause 
  

   and 
  the 
  want 
  of 
  sections, 
  their 
  structure 
  there 
  remains 
  uncertain. 
  

   Their 
  thickness 
  may 
  be 
  from 
  30 
  to 
  50 
  feet 
  " 
  f 
  ; 
  and 
  in 
  a 
  foot-note 
  is 
  

   added 
  the 
  remark 
  that 
  the 
  Thanet 
  Sands, 
  if 
  present, 
  probably 
  com- 
  

   mence 
  (on 
  the 
  west) 
  somewhere 
  near 
  Bishop's 
  Stortford. 
  Again, 
  

   in 
  a 
  later 
  paper, 
  " 
  I 
  am 
  doubtful 
  whether 
  the 
  Thanet 
  Sands 
  range 
  

   thus 
  far 
  north. 
  If 
  they 
  do, 
  they 
  must 
  be 
  represented 
  by 
  the 
  bed 
  of 
  

   sand 
  which 
  is 
  to 
  be 
  seen 
  reposing 
  on 
  the 
  Chalk 
  in 
  a 
  few 
  pits 
  be- 
  

   tween 
  Bishop 
  Stortford 
  and 
  Newport 
  "J. 
  

  

  Since 
  the 
  above 
  was 
  written 
  a 
  great 
  improvement 
  in 
  the 
  matter 
  

   of 
  sections 
  has 
  taken 
  place, 
  so 
  that 
  I 
  have 
  had 
  the 
  advantage 
  of 
  

  

  * 
  J. 
  B. 
  Pbear, 
  " 
  On 
  the 
  Geology 
  of 
  some 
  parts 
  of 
  Suffolk, 
  particularly 
  of 
  the 
  

   Valley 
  of 
  the 
  Gipping," 
  Trans. 
  Camb. 
  Phil. 
  Soc. 
  ix. 
  p. 
  431 
  (1856). 
  

  

  t 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  viii. 
  p. 
  241 
  (1852). 
  | 
  Ibid. 
  vol. 
  x. 
  p. 
  92 
  (1854). 
  

  

  