﻿ON" 
  THE 
  BAGSHOT 
  BEDS 
  AND 
  THEIR 
  STRATIGRAPHY. 
  033 
  

  

  39. 
  Notes 
  on 
  the 
  Bagshot 
  Beds 
  and 
  their 
  Stratigraphy. 
  

   By 
  H. 
  G. 
  Lyons, 
  Esq., 
  R.E., 
  E.G.S. 
  (Read 
  June 
  19, 
  1889.) 
  

  

  [Plate 
  XXI.] 
  

  

  Since 
  the 
  publication 
  in 
  the 
  Quarterly 
  Journal 
  of 
  the 
  Society 
  (Q. 
  J. 
  

   G. 
  S. 
  xliii. 
  p. 
  431) 
  of 
  a 
  paper 
  on 
  the 
  London 
  Clay 
  and 
  Bagshot 
  

   Beds 
  of 
  Aldershot, 
  I 
  have 
  made 
  a 
  number 
  of 
  observations 
  on 
  these 
  

   beds 
  as 
  they 
  occur 
  in 
  the 
  area 
  between 
  Aldershot 
  and 
  Ascot. 
  These 
  

   observations 
  I 
  would 
  now 
  place 
  at 
  the 
  disposal 
  of 
  other 
  workers, 
  

   as 
  I 
  shall 
  have 
  no 
  further 
  opportunities 
  of 
  making 
  use 
  of 
  them, 
  and 
  

   I 
  would 
  also 
  shortly 
  refer 
  to 
  the 
  results 
  to 
  which 
  they 
  seem 
  to 
  me 
  

   to 
  lead. 
  

  

  In 
  my 
  previous 
  paper, 
  referred 
  to 
  above, 
  I 
  only 
  discussed 
  the 
  beds 
  

   at 
  their 
  southern 
  outcrop 
  over 
  an 
  area 
  about 
  5 
  miles 
  from 
  E. 
  to 
  ~W. 
  

   by 
  2 
  miles 
  from 
  N. 
  to 
  S., 
  and 
  showed 
  that 
  within 
  this 
  area 
  the 
  

   Bagshot 
  and 
  London-Clay 
  strata 
  remained 
  of 
  constant 
  thickness 
  and 
  

   dipped 
  at 
  an 
  angle 
  of 
  about 
  2|° 
  northwards. 
  

  

  t 
  Over 
  so 
  small 
  an 
  area 
  it 
  was 
  easy 
  to 
  obtain 
  sections 
  which 
  would 
  

   show 
  what 
  was 
  required, 
  and 
  at 
  the 
  same 
  time 
  of 
  a 
  length 
  short 
  

   enough 
  to 
  avoid 
  the 
  necessity 
  of 
  any 
  great 
  exaggeration 
  of 
  the 
  vertical 
  

   scale 
  in 
  order 
  to 
  show 
  the 
  details. 
  But 
  now 
  that 
  the 
  area 
  under 
  

   consideration 
  is 
  some 
  15 
  miles 
  square, 
  the 
  difficulty 
  becomes 
  greater 
  

   when 
  a 
  consideration 
  of 
  the 
  effect 
  upon 
  this 
  area 
  of 
  the 
  Hog's 
  Back 
  

   monocline 
  is 
  attempted 
  ; 
  however, 
  as 
  there 
  is 
  in 
  the 
  case 
  of 
  the 
  60 
  

   feet 
  of 
  strata 
  grouped 
  as 
  Middle 
  Bagshot 
  a 
  series 
  of 
  nearly 
  constant 
  

   thickness 
  over 
  the 
  area, 
  it 
  occurred 
  to 
  me 
  that 
  if 
  the 
  attempt 
  was 
  

   made 
  to 
  contour 
  the 
  surface 
  of 
  this 
  bed 
  from 
  the 
  various 
  known 
  

   altitudes 
  of 
  the 
  outcrops, 
  from 
  its 
  positions 
  in 
  well-sections, 
  and, 
  

   in 
  some 
  cases, 
  from 
  its 
  restored 
  positions, 
  where 
  it 
  has 
  been 
  removed 
  

   by 
  erosion, 
  the 
  result 
  might 
  very 
  probably 
  give 
  the 
  form 
  into 
  which 
  

   the 
  beds 
  had 
  been 
  pushed 
  by 
  the 
  different 
  small 
  flexures 
  which 
  there 
  

   might 
  be, 
  and 
  which 
  were 
  too 
  slight 
  to 
  be 
  seen 
  in 
  sections 
  of 
  any 
  

   length. 
  Of 
  course 
  it 
  is 
  not 
  for 
  a 
  moment 
  contended 
  that 
  this 
  con- 
  

   touring 
  can 
  produce 
  accurately 
  the 
  form 
  of 
  the 
  surface 
  ; 
  but 
  it 
  seems 
  

   to 
  me 
  that 
  it 
  may 
  be 
  possible 
  thus 
  to 
  group 
  the 
  different 
  altitudes 
  so 
  as 
  

   to 
  show 
  more 
  clearly 
  their 
  relations 
  to 
  one 
  another, 
  and 
  to 
  accentuate 
  

   rather 
  more 
  those 
  slight 
  and 
  gradual 
  rolls 
  by 
  which 
  these 
  beds 
  have 
  

   been 
  affected 
  and 
  which, 
  though 
  insignificant 
  in 
  themselves, 
  do, 
  if 
  

   unnoticed, 
  increase 
  the 
  difficulties 
  of 
  correlating 
  strata 
  even 
  in 
  so 
  

   small 
  an 
  area. 
  

  

  First, 
  taking 
  the 
  country 
  round 
  Swinley 
  Park, 
  we 
  have 
  the 
  pebble- 
  

   bed 
  at 
  the 
  top 
  of 
  the 
  Middle 
  Bagshot 
  recorded 
  at 
  * 
  Red 
  Lodge 
  at 
  

   300' 
  f 
  O.D., 
  observed 
  on 
  the 
  road 
  to 
  the 
  west 
  at 
  290', 
  in 
  Swinley 
  

  

  * 
  Dr, 
  Irving, 
  Q. 
  J. 
  Gk 
  S. 
  vol. 
  xliv. 
  p. 
  165. 
  

  

  t 
  Heights 
  shown 
  thus 
  (300') 
  are 
  heights 
  above 
  Ordnance 
  Datum; 
  thick- 
  

   nesses 
  have 
  the 
  word 
  "feet" 
  in 
  full. 
  

  

  