9° 
PROCEEDINGS  OF  THE  GEOLOGICAL  SOCIETY.  [May  1 893, 
With  the  ice  filling  up  the  bed  of  the  North  Sea  to  the  extent 
indicated  by  the  Basement  Clay,  and  this  ice  not  of  local  origin  (for 
it  is  clear  that  the  Yorkshire  Wolds  added  nothing  to  it,  and  were 
not  entirely  submerged  by  it),  there  must  have  been  a  time  when  the 
great  ice-sheet  rested  with  its  flank  upon  this  coast-line  while  the 
main  current  swept  southwards,  following  the  deepest  part  of  the 
sea-bottom.  At  the  time  of  its  greatest  extension  the  ice  seems 
to  have  been  500  or  600  feet  thick  at  Speeton,  and  a  thin  flange 
from  the  top  of  the  glacier  probably  passed  over  the  edge  of 
the  cliff  there  during  the  deposition  of  the  Basement  Clay.  So 
long  as  the  edge  of  the  ice  was  advancing  no  very  great  accumu¬ 
lation  of  material  could  well  take  place  at  its  margin,  but  as  soon 
as  its  growth  was  arrested  and  it  began  to  decline  there  must 
have  been  a  considerable  deposition  in  this  quarter.  It  is  to  the 
washings  of  such  morainic  material  at  the  margin  of  the  ice  that 
Mr.  Lamplugh  ascribes  the  origin  of  the  ‘  Intermediate  Series  ’  of 
Flamborough  and  of  the  northern  part  of  Holderness.  In  the  neigh¬ 
bourhood  of  the  Humber  there  may  have  been  some  difference 
of  origin,  and  possibly  the  sea  was  not  entirely  excluded  from  the  old 
bay,  where  in  some  places  it  might  have  laved  the  edge  of  the 
glacier.  Whilst  the  ‘  Intermediate  Series  ’  was  being  formed  at 
the  edge  of  the  ice  during  a  period  of  slow  recession,  following  a 
long  pause,  the  formation  of  Boulder-clay  was  still  being  carried  on 
over  the  area  covered  by  the  glacier,  and  thus,  he  says,  originated 
the  Purple  Clay  of  Holderness.  These  b§ds  he  is  inclined  to 
correlate  with  the  Contorted  Drift  and  Middle  Glacial  gravels  of 
Norfolk. 
With  regard  to  the  Upper  Boulder-clay,  he  considers  that  as 
the  ice  in  the  North  Sea  gradually  diminished  in  volume,  so  the 
products  of  the  Teesdale  glacier  were  able  to  make  themselves  more 
and  more  felt.  When  the  ice,  from  want  of  renewal,  gradually 
melted  away,  there  resulted  a  stony  and  earthy  residuum,  and  the 
Upper  Boulder-clay  is  in  part  the  result  of  this  action.  The  Hessle 
Clay  of  Messrs.  Wood  and  Borne,  which  they  describe  as  a  mantle 
covering  everything,  had  a  similar  origin  in  Holderness. 
Such  is  a  brief  outline  of  Mr.  Lamplugh’s  views  on  the  Glacial 
deposits  of  East  Yorkshire.  We  seem  to  recognize  in  this  Upper 
Boulder-clay,  charged  as  it  is  with  debris  of  Carboniferous  origin, 
something  analogous  to  the  Upper  Pennine  Boulder-clay  of  Deeley, 
where  the  indigenous  glaciers  were  beginning  to  re-assert  themselves. 
If  this  is  so,  the  Author  can  scarcely  be  correct  in  regarding  the 
