Yol.  49.]  RAISED  REACHES  AND  ROLLED  STORES  IN  JERSEY. 
523 
38.  On  Baised  Beaches  and  Bolled  Stores  at  High  Levels  in 
Jersey.  By  Andrew  Dunlop,  M.D.,  L.G.S.  (Bead  June  7th, 
1893.) 
[Abridged.] 
.The  valuable  paper  of  Prof.  Prestwich  on  ‘  The  Baised  Beaches, 
and  ‘  Head  ’  or  Bubble-drift,  of  the  South  of  England,’  1  which  has 
thrown  so  much  light  on  the  Quaternary  geology  of  that  area,  is 
especially  interesting  to  me.  for  in  Jersey  there  are  well-marked 
post-Glacial  deposits  which  have  hitherto  received  little  attention 
from  geologists.  The  brick-clay  or  brick-earth,  which  covers  so 
much  of  the  island,  I  have  already  described,2  and  I  am  now  desirous 
of  directing  attention  to  the  higher  raised  beaches,  and  to  other 
evidences  of  alteration  in  the  height  of  the  land,  more  especiallj’  of 
considerable  and  probably  long-continued  subsidence. 
Several  writers  have  already  described  or  mentioned  the  low-level 
raised  beach,  found  in  places  all  round  the  island — as,  for  example, 
Mr.  Trevelyan,3  Lieut.  Helson,4 5  Prof.  Prestwich,0  and  Lather 
Houry.6  The  last-named  geologist,  however,  seems  to  doubt  its 
being  a  raised  beach  in  the  proper  sense  of  the  term.  Mr.  T.  W. 
Danby,  on  the  authority  of  the  late  Dr.  M.  Bull,  mentions7  a  raised 
beach  on  the  west  coast  of  the  island,  said  to  be  about  100  feet 
above  the  level  of  the  present  beach ;  and  in  Latham  and  Ansted’s 
work  on  the  Channel  Islands8  it  is  stated  that  a  raised  beach  about 
30  feet  above  the  present  mean  level  of  the  sea  was  laid  bare  during 
the  construction  of  Port  Begent. 
The  most  elevated  raised  beach  which  I  have  as  yet  observed  is 
that  on  the  top  of  the  southern  part  of  the  hill  on  'which  Fort 
Begent  is  built,  a  hill  formerly  known,  I  believe,  by  the  name  of 
‘  Mont  de  la  Yille.’  This  hill,  a  detached,  outlying  mass  of  horn- 
blendic  granite,  towers  above  the  harbour  of  St.  Helier  to  the  height 
of  170  or  more  feet  above  equinoctial  spring- tide  high-water  mark. 
The  southern  portion  of  it — South  Hill — partly  separated  by  a  slight 
depression  from  the  main  mass  on  which  the  fort  stands,  rises  about 
135  feet  above  spring- tide  high  water,  or  155  feet  above  mean  tide 
at  its  highest  part.  The  whole  hill  forms  an  oblong  about  200 
yards  wide,  the  main  part  of  it  being  some  500  yards,  and  South 
Hill  about  250  yards  in  length. 
1  Quart.  Journ.  Geol.  Soc.  vol.  xlviii.  (1892)  p.  263. 
2  ‘  On  the  Jersey  Brick-Clay,’  ibid.  vol.  xlv.  (1889)  p.  118. 
3  ‘  Indications  of  Recent  Elevations  in  the  Islands  of  Guernsey  and  Jersey  ’ 
Proc.  Geol.  Soc.  vol.  ii.  p.  577,  Nov.  1837. 
4  ‘  Geol.  Survey  of  the  Island  of  Jersey,’  Quart.  Journ.  Sci.,  Lit.,  &  Art 
n.  s.  vol.  vi.  (1830)  p.  359. 
5  ‘  Geology,’  vol.  ii.  (1888)  p.  518. 
6  ‘  Geologie  de  Jersey,’  1886,  pp.  159  et  seq. 
7  ‘  Elevation  and  Subsidence  of  Land  in  Jersey,’  Geol.  Mag.  for  1876,  p.  144. 
8  ‘  The  Channel  Islands,’  1862,  p.  280. 
