316  ME.  H.  W.  MONCKTON  ON  BOULDERS  AND  [Aug.  1 893, 
Drift  pebbles  and  boulders,  all  are  probably  newer  than  that 
formation  ;  and  if  the  Thames  ever  flowed  south  of  Bowsey  Hill,  I 
should  expect  to  find  Glacial  Gravel  material  in  the  area  between 
Maidenhead  and  Sonning. 
I  have  already  described  the  patches  of  Southern  Drift  shown  on 
the  left  of  fig.  2.1  In  the  low  ground  between  them  and  Ashley 
Hill  there  is  a  patch  of  gravel  in  which  I  have  seen  many  small 
pits,  and  I  once  found  a  pebble  of  reddish-brown  quartzite  on 
a  heap  of  gravel  in  one  of  them ;  but  with  that  exception  every¬ 
thing  may  well  have  come  from  the  Southern  Drift  or  Tertiary 
pebble-beds — in  short,  it  is  a  gravel  of  the  Binfield  Brook.  About 
Warfield  and  Winkfield  there  are  patches  of  a  gravel  which  is,  so  far 
as  I  have  seen,  of  the  same  character  as  the  last.  Pits  are,  how¬ 
ever,  scarce,  and  pebbles  of  Glacial  Gravel  character  are  seen  here 
and  there  on  the  surface  of  the  ground.  I  think  it  nevertheless 
probable  that  Thames  Gravel  may  have  been  brought  from  time  to 
time  for  mending  the  roads  about  here ;  therefore  such  pebbles  are 
of  little  value  as  evidence. 
There  is  a  small  gravel-pit  a  little  west  of  Warfield  Church ; 
there  the  gravel  consists  of  Southern  Drift  materials  and  flint- 
pebbles.  Lower  Greensand  fragments  are  very  abundant,  and  this 
is  also  the  case  in  the  pits  by  the  Binfield  Brook.  I  have  thus 
failed  to  find  any  evidence  of  the  existence  of  Thames  Gravel 
between  Ashley  Hill  and  Easthampstead  Plain,  and  I  therefore 
think  it  most  probable  that  even  before  the  Glacial  Gravel  was 
deposited  the  Thames  flowed  in  its  present  direction  by  Wargrave, 
Bisham,  and  Cookham  to  Maidenhead. 
Till.  Weybridge,  Kingston,  and  Wimbledon. 
Below  Maidenhead  the  river  flows  in  a  southerly  direction,  and 
though  material  from  the  Northern  Drift  is  found  in  the  more 
recent  gravels  (these,  on  the  south  of  the  river,  are  generally  less 
than  50  feet  above  Ordnance  datum),  I  have  not  found  any  in  the 
gravels  at  higher  levels.  Thus  the  hills  above  Egham,  260  feet  O.D., 
are  capped  by  gravel  derived  almost  entirely  from  Tertiary  pebble- 
beds,  and  the  same  may  be  said  of  St.  Ann’s  Hill,  near  Chertsey, 
220  feet  O.D.  Near  Portnall  Park  (about  230  feet  O.D.)  there  is 
an  outlying  patch  of  the  Southern  Drift  in  which  Lower  Greensand 
fragments  are  very  abundant,2  and  the  gravels  at  about  100  feet  O.D. 
near  Virginia  Water  Station  are  composed  of  materials  from  pebble- 
beds  and  Southern  Drift.  There  are  several  pits,  but  I  have  never 
1  Quart.  Journ.  Geol.  Soc.  vol.  xlviii.  (1892)  pp.  33-36.  The  diagram  now 
given  will  serve  to  illustrate  the  relation  of  the  drift  on  Easthampstead  Plain 
to  that  at  Coppid  Beach  Lane,  and  will  also  elucidate  the  argument  at  p.  40 
of  the  same  paper  as  to  unequal  elevation  having  taken  place  since  the  deposition 
of  the  hill-gravels. 
2  This  locality  may  he  added  to  the  list  of  gravels  with  abundance  of  Lower 
Greensand  fragments,  given  at  p.  36  of  my  paper  in  vol.  xlviii.  of  this  Journal ; 
the  gravel -pits  were  shown  to  me  by  Mr.  B-.  De  Salis,  F.G.S. 
