8 4  PROCEEDINGS  OE  THE  GEOLOGICAL  SOCIETY.  [May  1 893, 
to  Moel  Tryfaen.  These  gravels  occur  on  the  eastern  slope  of  the 
ridge  of  Carboniferous  rocks,  here  represented  by  Millstone  Grit, 
which  forms  the  western  boundary  of  the  Shropshire  and  Cheshire 
plain.  The  main  mass  of  the  gravels  at  Gloppa  is  comprised  in  a 
ridge  of  eskers,  about  1000  yards  long  and  ranging  from  900  to 
1160  feet  above  sea-level.  The  beds  present  the  appearance  of  having 
been  abruptly  cut  off  on  the  north-eastern  slope,  the  greatest  depth 
exposed  being  about  60  feet.  The  upper  layers  seem  to  be  sufficiently 
argillaceous  to  have  prevented  the  percolation  of  water,  and  the 
gravels  themselves  are  in  places  much  contorted  and  current-bedded. 
Among  the  boulders  are  granites  like  those  of  Eskdale,  Criffel,  etc., 
felspathic  traps,  Silurian  grits  and  argillites,  Carboniferous  rocks, 
Liassic  shale,  and  Chalk  flints.  England,  Ireland,  Scotland,  and 
Wales  seem  to  have  been  requisitioned  in  order  to  find  materials  for 
this  curious  deposit.  The  shells  are  often  broken,  rolled,  and  striated, 
but  the  bulk  of  them  are  in  fairly  good  condition,  so  that  many 
species  of  varying  bathymetrical  range  have  been  determined.  The 
fauna  is  like  that  of  Moel  Tryfaen,  and,  as  there  is  a  considerable 
mixture  of  species  belonging  to  various  depths,  such  an  assemblage 
cannot  be  regarded  as  having  lived  contemporaneously  on  the  spot 
where  the  deposit  occurs.  A  large  proportion  of  the  shells  belong 
to  species  frequenting  a  sandy  bottom,  and  different  from  those 
which  might  be  expected  on  a  steep,  rocky  coast  such  as  would 
here  be  exposed  to  the  sea  by  submergence.  The  highest  point  for 
marine  shells  at  Gloppa  is  1120  feet.  A  similar  gravel  occurs  on 
Selattyn  Hill,  two  miles  to  the  north  along  the  Millstone  Grit  ridge, 
at  a  height  reaching  to  1300  feet,  but  hitherto  no  shells  have  been 
found  here,  the  exposure  being  small. 
More  recently  Mr.  Mellard  Eeade  has  again  drawn  attention  to 
some  facts  in  connexion  with  the  shell-sands  on  Moel  Tryfaen, 
which  have  evidently  been  sorted  by  water.  He  points  out  that 
they  are  in  fact  overlain  by  typical  4  till  ’  composed  of  local  rocks 
with  a  small  percentage  of  clay  :  whereas  the  sands  and  gravels  are 
full  of  erratics,  including  rocks  from  Scotland  and  elsewhere.  He 
still  adheres  apparently  to  the  hypothesis  of  submergence  to  an 
extent  of  at  least  1400  feet. 
There  are  other  geologists  of  eminence  who  likewise  maintain 
these  views,  though  in  the  case  of  the  high-level  shell-gravels  it  is 
now  generally  admitted  that  these  are  not  original  marine  deposits. 
The  believers  in  the  Great  Submergence  would  ascribe  such  accumu¬ 
lations  to  the  action  of  floating  ice  transported  by  the  waves  and 
