After  a  long  period  of  submergence  the  country
gradually  rose  again,  and  the  evidence  of  this  I  will
prove  chiefly  from  what  I  know  of  North  Wales,
although  I  could  easily  do  the  same  by  taking  you
to  the  Highlands  of  Scotland.
I  shall  take  the  Pass  of  Llanberis  as  an  example,  for
there  we  have  all  the  ordinary  proofs  of  the  valley
having  been  filled  with  glacier-ice.  First,  then,  after
the  great  glacial  epoch,  the  country  to  a  great  extent
sunk  below  the  water,  and  the  drift  was  deposited,  and
more  or  less  filled  many  of  the  valleys  of  Wales.  When


Decline  of  the  Glaciers.  1 1 1

the  land  had  risen  again  to  a  considerable  height,  the
glaciers  increased  in  size,  although  they  never  reached
the  immense  magnitude  which  they  attained  at  the
earlier  portion  of  the  icy  epoch.  Still,  they  became
so  large,  that  such  a  valley  as  the  Pass  of  Llanberis
was  a  second  time  occupied  by  ice,  and  the  result  was,
that  the  glacier  ploughed  out  the  drift  and  loose  rub-
bish, that  more  or  less  covered  the  valley.  Other
cases  of  the  same  kind  could  easily  be  given,  while,
on  the  other  hand,  in  many  valleys  you  find  the  drift
still  remaining.  By  degrees,  however,  as  we  approach
nearer  our  own  days,  for  unknown  reasons,  the  climate
slowly  ameliorated,  and  the  glaciers  began  to  decline,
till  becoming  less  and  less,  they  crept  up  and  up ;  and
here  and  there,  as  they  died  away,  they  left  their  ter-
minal and  lateral  moraines,  still  in  some  cases  as  well
denned  as  moraines  in  lands  where  glaciers  now  exist.
