Yol.  49.]  ROLLED  STONES  AT  HIGH  LEVELS  IN  JERSEY.  529 
on  the  southern  and  south-eastern  shores  of  the  island,  if  not  else¬ 
where,  there  is  a  blue  clay  under  the  sand,  lying  on  the  brick-clay 
below.  In  many  places  it  is  merely  a  few  inches  beneath  the  surface, 
very  sandy,  and  only  a  few  inches  thick,  hut  sometimes  it  is  covered 
with  some  feet  of  sand  and  shingle,  and  is  a  stiff  plastic  clay.  For 
example,  in  the  harbour  of  St.  Helier,  about  25  feet  below  spring- 
tide  high-water  mark,  there  is  a  bed  of  stiff  blue  clay,  4  feet  thick, 
under  4  feet  of  sand  and  shingle,  resting  on  14  feet  of  brick-clay, 
with  angular  rock-fragments  at  its  base.  It  is  evident  that  this 
clay  must  have  been  formed  when  the  land  stood  at  a  higher  level 
than  now. 
The  question  of  the  mode  of  deposition  and  spread  of  the  hricJs- 
clay,  brick-earth,  or  loess,  with  its  contained  rock-fragments,  is  a 
difficult  one.  There  seems  to  be  no  doubt  that  this  took  place 
while  the  island  was  submerged,  or  during  emergence.  But  the 
action  of  ordinary  water-power  would  hardly  account  for  the  situa¬ 
tion  and  position  of  many  of  the  fragments  embedded  in  it — some 
occurring  in  long  lines  or  layers,  and  some  of  them  standing  up  on 
edge  as  if  they  had  been  dropped  into  it  while  it  was  forming. 
The  mass  of  stones  studding  it  on  the  slopes  is  susceptible  of  more 
easy  explanation. 
On  March  9th  of  the  present  year  Prof .  Prestwich  read  an  important 
paper  before  the  Royal  Society,1  in  which  he  brought  forward  a 
mass  of  observations  from  various  parts  of  Western  Europe  and  the 
Mediterranean  coasts  in  support  of  his  theory  that  the  ‘  rubble- 
drift,’  etc.,  had  been  spread  out  by  the  rush  of  water  off  suddenly 
rising  land  after  a  short  submergence.  With  regard  to  the  Channel 
Islands,  he  said  that  the  high  grounds  there  are  often  covered  by 
loam  or  loess,  which,  he  thinks,  was  deposited  from  turbid  sea-waters 
during  submergence,  while  the  ‘  head  ’  results  from  the  surface- 
debris,  together  with  a  portion  of  the  previously-deposited  sediment 
swept  off  by  divergent  currents  during  upheaval. 
In  the  case  of  Jersey,  the  submergence  during  which  the  raised 
beach  at  South  Hill  was  formed  was  at  least  long  enough  to  wear 
and  smooth  the  hard  granite  above  it,  and  the  beaches  at  lower 
levels  seem  to  show  that  there  were  pauses  of  some  duration  in  the 
subsidence  or  elevation,  probably  the  latter.  Even  if  we  suppose  a 
second  short  submergence  and  sudden  upheaval,  during  which  the 
brick-clay  was  deposited,  the  beach  at  Anne  Port  at  the  top  of  the 
clay,  the  layer  of  rounded  pebbles  in  it,  and  in  the  cutting  at  South 
Hill,  as  well  as  that  in  the  railway-cutting,  seem  to  indicate  that 
beaches  were  formed  after  some  of  the  clay  had  been  deposited.  A 
succession  of  sudden  upheavals  may,  however,  have  taken  place, 
with  intervals  of  some  duration  between  them.  The  theory  of  its 
being  deposited  by  the  tumultuous  rush  of  water  off  a  violently- 
uplifted  surface  would  certainly  explain  most  of  the  peculiarities  of 
the  clay  and  its  contents. 
1  ‘  On  the  Evidences  of  a  Submergence  of  Western  Europe,  etc.’  Proc.  Roy. 
Soc.  vol.  liii.  p.  80. 
2n  2 
