﻿THAKET 
  BEDS 
  AND 
  CRAG 
  AT 
  ST7DBURY, 
  SUEEOLK. 
  403 
  

  

  river, 
  laying 
  bare 
  the 
  set 
  of 
  beds 
  shown 
  in 
  the 
  figure, 
  drawn 
  on 
  the 
  

   same 
  scale 
  as 
  various 
  analogous 
  figures 
  in 
  the 
  Memoir 
  on 
  the 
  

   London 
  Basin*. 
  

  

  No 
  fossils 
  have 
  been 
  found 
  in 
  the 
  beds 
  that 
  I 
  have 
  classed 
  as 
  

   Thanet 
  Sand, 
  except 
  some 
  pieces 
  of 
  Foraminifera, 
  by 
  Dr. 
  Holden 
  ; 
  

   the 
  reasons 
  for 
  this 
  classification 
  are 
  purely 
  lithological, 
  and 
  as 
  

   follows 
  : 
  — 
  

  

  1. 
  The 
  likeness 
  of 
  the 
  sand, 
  in 
  fineness, 
  compactness, 
  and 
  colour 
  

   to 
  that 
  which 
  occurs 
  in 
  the 
  same 
  position 
  in 
  "West 
  Kent. 
  

  

  2. 
  The 
  persistence 
  of 
  these 
  characters 
  in 
  all 
  the 
  sections, 
  and 
  the 
  

   absence 
  of 
  false-bedding 
  of 
  pebbles 
  and 
  of 
  red-mottling, 
  tending 
  to 
  

   show 
  that 
  the 
  sand 
  belongs 
  to 
  tbe 
  Thanet 
  Beds 
  rather 
  than 
  to 
  the 
  

   more 
  varying 
  Reading 
  Series. 
  

  

  3. 
  The 
  fact 
  that 
  the 
  greensand 
  at 
  the 
  bottom 
  is 
  like 
  the 
  " 
  base- 
  

   bed 
  " 
  of 
  the 
  Thanet 
  Sand 
  ; 
  and 
  the 
  occurrence 
  immediately 
  beneath 
  

   it 
  of 
  a 
  layer 
  of 
  tabular 
  flint, 
  as 
  is 
  very 
  usual 
  where 
  that 
  bed 
  caps 
  

   the 
  Chalk. 
  

  

  "Westward 
  from 
  Sudbury 
  I 
  have 
  traced 
  this 
  sand 
  for 
  more 
  than 
  

   three 
  miles 
  ; 
  but 
  eastward 
  it 
  is 
  soon 
  hidden 
  by 
  Drift, 
  after 
  being 
  

   shown 
  in 
  many 
  sections 
  on 
  the 
  outskirts 
  of 
  the 
  town. 
  The 
  green- 
  

   sand 
  over 
  the 
  Chalk, 
  near 
  Ipswich, 
  is 
  much 
  like 
  that 
  at 
  Sudbury 
  ; 
  

   so 
  perhaps 
  the 
  progress 
  of 
  the 
  Geological 
  Survey 
  may 
  establish 
  the 
  

   occurrence 
  of 
  the 
  Thanet 
  Beds 
  in 
  that 
  direction. 
  

  

  In 
  the 
  northern 
  band 
  here 
  noticed 
  this 
  division 
  seems 
  to 
  be 
  pre- 
  

   sent 
  at 
  the 
  expense 
  of 
  the 
  overlying 
  Beading 
  Beds, 
  which 
  are 
  re- 
  

   markably 
  thin 
  at 
  Sudbury; 
  and 
  this 
  outcrop 
  most 
  likely 
  joins 
  on 
  

   underground 
  to 
  that 
  in 
  South 
  Essex 
  and 
  Kent, 
  many 
  of 
  the 
  deep 
  wells 
  

   in 
  the 
  tract 
  between 
  seeming 
  to 
  pass 
  through 
  the 
  Thanet 
  Sand. 
  

  

  2. 
  Crag. 
  

  

  The 
  pits 
  that 
  give 
  evidence 
  of 
  the 
  occurrence 
  of 
  Crag 
  have 
  been 
  

   opened 
  only 
  during 
  the 
  last 
  few 
  years, 
  and 
  are 
  all 
  on 
  the 
  left, 
  or 
  

   Suffolk, 
  side 
  of 
  the 
  Stour, 
  at 
  the 
  northern 
  and 
  eastern 
  edge 
  of 
  Sud- 
  

   bury, 
  the 
  three 
  best 
  sections 
  being 
  close 
  together, 
  on 
  the 
  hill 
  within 
  

   a 
  quarter 
  of 
  a 
  mile 
  N.E. 
  of 
  St. 
  Peter's 
  Church. 
  

  

  The 
  general 
  section 
  of 
  these 
  is 
  as 
  follows 
  : 
  — 
  

  

  A 
  small 
  patch 
  of 
  Drift. 
  

  

  Crag. 
  Ferruginous 
  dark 
  reddish 
  -brown 
  sand, 
  -with 
  layers 
  of 
  ironstone, 
  slightly 
  

   false-bedded 
  ; 
  in 
  parts 
  a 
  light-coloured 
  grit 
  with 
  broken 
  shells 
  ; 
  

   thin 
  layers 
  of 
  flint-pebbles, 
  phosphatic 
  nodules, 
  and 
  phosphatized 
  

   bones 
  in 
  the 
  lower 
  part 
  ; 
  and 
  at 
  the 
  bottom 
  a 
  marked 
  bed 
  of 
  the 
  same, 
  

   up 
  to 
  a 
  foot 
  or 
  more 
  thick. 
  The 
  whole 
  as 
  much 
  as 
  10 
  feet 
  in 
  a 
  hol- 
  

   low, 
  elsewhere 
  as 
  much 
  as 
  7 
  feet. 
  

  

  Thanet 
  Sand 
  ; 
  the 
  lower 
  pinkish 
  bed, 
  and 
  the 
  green 
  base-bed. 
  

  

  Chalk. 
  

  

  In 
  the 
  furthest 
  pit, 
  Mr. 
  "Webb's, 
  the 
  shells 
  are 
  mostly 
  broken 
  up, 
  

  

  and 
  many 
  specimens 
  of 
  Purpura 
  lapillus, 
  var. 
  crispata, 
  with 
  one 
  

  

  valve 
  of 
  a 
  small 
  Anomia 
  ephijppiurn, 
  were 
  all 
  that 
  could 
  be 
  found 
  in 
  

  

  any 
  thing 
  like 
  a 
  perfect 
  state 
  ; 
  but 
  in 
  the 
  nearest 
  pit, 
  Mr. 
  Harding's, 
  

  

  * 
  Memoirs 
  of 
  the 
  Geological 
  Survey, 
  iv. 
  (1872). 
  

  

  