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MR.  H.  W.  MONCKTON  ON  BOULDERS  AND 
[Aug.  1893, 
IV.  Sonning-. 
East  of  Beading  we  come  to  tlie  gravel- capped  plateau  between 
Earley  and  Sonning  which  overlooks  the  Thames  Yalley  on  the  north 
and  west,  and  that  of  the  Loddon  on  the  south  and  east.  This 
plateau  is  at  a  higher  level  than  the  tract  of  country  through  which 
the  Great  Western  Railway  runs  till  it  crosses  the  Thames  at 
Maidenhead.  There  is  a  pit,  about  205  feet  O.D.,  close  to  the  bridge 
where  the  London  and  Eeading  road  crosses  the  Sonning  cutting  on 
that  railway.  The  gravel  is  9  feet  or  more  thick,  roughly  and 
indistinctly  stratified.  It  is  very  ferruginous  in  places,  and  is  com¬ 
posed  of  the  following  materials  : — 
(a)  Flints  forming  the  main  part  of  the  gravel ;  all  waterworn,  but  some  of 
irregular  shapes.  I  noted  one  flint,  11  inches  long  and  not  much  rolled 
or  waterworn,  near  the  top  of  the  gravel.  It  must  have  been  derived 
from  the  Chalk  of  the  neighbourhood,  i.  e.  from  the  north  or  west,  and 
not  from  the  older  gravels  of  the  south. 
( b )  Flint-pebbles. 
(e)  Quartz. 
( d )  Eed  and  brown  quartzites  and  brown  sandstone  abundant,  no  doubt 
from  the  Glacial  Gravel.  I  noted  one  red  quartzite  (which  measured 
4  X  X  2  inches)  3  feet  below  the  surface  of  the  ground. 
(e)  Small  pebbles  of  ironstone,  like  those  in  the  Glacial  Gravel  at  Tilehurst. 
(/')  Lower  Greensand  fragments,  from  the  Southern  Drift,  small  but  numerous. 
Clearly  there  is  here  a  mingling  of  Thames  and  Loddon  gravels, 
the  Loddon  draining  a  Southern  Drift-gravel  country.  On  this 
plateau,  near  Eulmershe,  I  found  one  or  two  pebbles  of  a  Glacial 
Gravel  character,  and  I  believe  that  is  the  southern  limit  of  their 
distribution  at  this  point. 
North-east  of  this  plateau  there  is  a  pit  by  the  high  road,  3J  miles 
from  Eeading,  about  170  feet  O.D.  It  is,  as  one  would  expect,  in 
a  Thames  gravel.  Northern  Drift  pebbles  abound,  and  I  could  find 
in  it  no  Lower  Greensand  fragments.  On  the  Loddon  side  of  the 
plateau  we  find,  as  we  should  expect,  if  my  view  be  the  right  one, 
gravel  composed  of  materials  from  the  south — debris  of  Southern 
Drift  or  Tertiary  pebble-beds — in  other  words,  Loddon  gravels. 
There  are  pits  at  Hurst,  126  feet  O.D. ;  half  a  mile  west  of  Bill 
Hill,  128  feet  O.D. ;  near  Berrygrove  Farm,  150  feet  O.D. ;  and  at 
Wokingham,  227  feet  O.D.,  in  none  of  which  have  I  found  Northern 
Drift  pebbles. 
V.  Bisham  and  Cooxham. 
Within  the  great  bend  of  the  Thames  between  Wargrave  and 
Maidenhead  are  several  gravel-capped  hills,  and  on  one  of  them 
above  Bisham  there  is  a  patch  of  Glacial  Gravels  at  351  feet  O.D., 
which  is  shown  at  the  right  end  of  the  diagram,  fig.  2.  It  is 
mapped  4  Pebble  Gravel  ’  on  sheet  7  of  the  Geological  Survey  Map. 
There  is  the  following  section  in  a  gravel-pit,  close  to  the  eastern 
fence  of  the  wood  by  the  Hockett : — 
feet.  in. 
1.  Surface-bed  full  of  stones  up  to . 1  6 
2.  Brown,  rather  earthy  sand,  with  scattered  stones,  and.  in 
one  place  a  patch  of  mottled  clay,  variable  up  to .  3  0 
3.  Gravel  .  6  6 
4.  Yellow  sand. 
