﻿ON 
  A 
  PECTTLIAB 
  BED 
  OP 
  ANGULAR 
  DRIFT. 
  127 
  

  

  13. 
  On 
  a 
  peculiar 
  Bed 
  of 
  Angular 
  Driet 
  on 
  the 
  Lower-chalk 
  high 
  

   Plain 
  between 
  Upton 
  and 
  Chilton. 
  By 
  Prof. 
  J. 
  Prestwich, 
  

   F.K.S., 
  F.G.S., 
  &c. 
  (Bead 
  February 
  8, 
  1882.) 
  

  

  In 
  making 
  the 
  new 
  line 
  of 
  railway 
  from 
  Didcot 
  to 
  Newbury 
  some 
  

   sections 
  of 
  considerable 
  interest 
  were 
  laid 
  open 
  between 
  the 
  main 
  

   Great 
  Western 
  line 
  and 
  the 
  village 
  of 
  Chilton. 
  For 
  the 
  first 
  three 
  

   miles 
  from 
  Didcot 
  the 
  railway 
  passes 
  over 
  the 
  Upper 
  Greensand, 
  

   the 
  lower 
  part 
  of 
  which 
  here 
  consists 
  of 
  compact 
  beds 
  of 
  greenish 
  

   sandstone, 
  and 
  the 
  upper 
  part 
  of 
  beds 
  of 
  a 
  light-coloured 
  greensand, 
  

   together 
  probably 
  more 
  than 
  100 
  feet 
  thick. 
  Beyond 
  these, 
  at 
  

   Upton, 
  the 
  Chalk 
  without 
  flints 
  rises 
  in 
  a 
  range 
  of 
  hills 
  running 
  

   east 
  and 
  west, 
  through 
  which 
  the 
  line 
  is 
  carried, 
  exposing 
  a 
  fine 
  

   section, 
  a 
  mile 
  in 
  length, 
  of 
  drift, 
  Chalk-marl, 
  and 
  Lower 
  Chalk* 
  

   (see 
  section 
  fig. 
  1). 
  

  

  The 
  point, 
  however, 
  of 
  more 
  particular 
  interest 
  is 
  the 
  great 
  bed 
  of 
  

   drift 
  indenting 
  the 
  chalk. 
  It 
  sets 
  in 
  one 
  third 
  of 
  a 
  mile 
  south 
  of 
  

   Upton, 
  and 
  extends 
  to 
  a 
  short 
  distance 
  beyond 
  Chilton, 
  a 
  length 
  of 
  

   about 
  1 
  J 
  mile. 
  It 
  is 
  a 
  drift 
  of 
  a 
  character 
  so 
  abnormal 
  in 
  this 
  dis- 
  

   trict 
  that 
  it 
  deserves 
  a 
  short 
  separate 
  record. 
  The 
  tract 
  it 
  occupies 
  

   forms 
  part 
  of 
  the 
  flat 
  plain 
  which 
  here 
  extends 
  with 
  a 
  width 
  of 
  

   about 
  two 
  miles 
  from 
  the 
  foot 
  of 
  the 
  escarpment 
  of 
  the 
  Upper 
  Chalk 
  

   with 
  flints, 
  near 
  East 
  Ilsley, 
  to 
  the 
  edge 
  of 
  the 
  lesser 
  escarpment 
  of 
  

   the 
  Lower 
  Chalk 
  without 
  flints 
  at 
  Upton, 
  above 
  referred 
  to 
  (see 
  

   section 
  fig. 
  2). 
  A 
  small 
  transverse 
  valley 
  here 
  runs 
  through 
  these 
  

   Lower-Chalk 
  hills 
  ; 
  but, 
  though 
  a 
  line 
  of 
  drainage, 
  it 
  is 
  without 
  any 
  

   permanent 
  brook 
  or 
  stream, 
  nor 
  was 
  there 
  any 
  distinct 
  appearance 
  

   in 
  the 
  railway-cutting 
  (which 
  at 
  Upton 
  was 
  carried 
  up 
  this 
  small 
  

   valley) 
  of 
  there 
  having 
  been 
  a 
  stream 
  here 
  in 
  former 
  times. 
  

  

  In 
  the 
  first 
  cutting 
  the 
  Lower 
  Chalk 
  rises 
  bare 
  to 
  the 
  height 
  of 
  

   27 
  feet. 
  The 
  next 
  cutting, 
  which 
  is 
  from 
  10 
  to 
  20 
  feet 
  deep, 
  is 
  

   through 
  a 
  white 
  chalk 
  rubble, 
  fine 
  and 
  marly 
  at 
  base, 
  coarser 
  and 
  

   with 
  a 
  few 
  small 
  angular 
  fragments 
  of 
  flints 
  at 
  top. 
  A 
  little 
  way 
  

   beyond, 
  the 
  chalk 
  comes 
  up 
  again 
  through 
  the 
  drift, 
  is 
  again 
  

   replaced 
  by 
  the 
  drift, 
  and 
  again 
  the 
  hard 
  grey 
  chalk 
  rises 
  abruptly 
  

   to 
  the 
  surface 
  in 
  a 
  cutting 
  35 
  feet 
  deep. 
  Thus 
  far 
  the 
  diift 
  is 
  very 
  

   fine, 
  more 
  like 
  decomposed 
  Lower 
  Chalk, 
  and 
  no 
  organic 
  remains 
  

   were 
  found 
  in 
  it 
  in 
  this 
  part 
  of 
  the 
  cutting. 
  

  

  Beyond, 
  the 
  characters 
  begin 
  to 
  change 
  ; 
  the 
  drift 
  becomes 
  more 
  

   coloured 
  and 
  somewhat 
  coarser, 
  and 
  occasionally 
  small 
  boulders 
  and 
  

   bones 
  were 
  met 
  with. 
  A 
  great 
  number 
  of 
  bones 
  were 
  found 
  to- 
  

   gether 
  about 
  two 
  thirds 
  down 
  in 
  this 
  rubble 
  drift 
  about 
  midway 
  in 
  

   the 
  Chilton 
  cutting, 
  at 
  the 
  point 
  marked 
  A 
  (see 
  figs. 
  1 
  and 
  3, 
  p. 
  129). 
  

   A 
  short 
  distance 
  further 
  southward 
  an 
  intercalated 
  darker 
  clay 
  bed 
  

  

  * 
  Very 
  few 
  fossils 
  had 
  hitherto 
  been 
  obtained 
  from 
  the 
  Lower 
  Chalk 
  of 
  the 
  

   Didcot 
  district 
  ; 
  but 
  in 
  this 
  cutting 
  they 
  were, 
  in 
  places, 
  abundant, 
  especially 
  

   Ammonites 
  varians. 
  Altogether 
  we 
  obtained 
  35 
  species 
  from 
  the 
  Lower 
  Chalk, 
  

   and 
  23 
  species 
  from 
  the 
  Upper 
  Greensand, 
  for 
  the 
  Oxford 
  Museum. 
  

  

  