Yd.  49.]  ANNIVERSARY  ADDRESS  OF  THE  PRESIDENT.  85 
currents  of  the  sea.  A  younger  and  more  numerous  school  of 
geologists  consider  that  they  are  the  result  of  the  action  of  glacier- 
ice,  which  has  actually  thrust  a  portion  of  the  bed  of  the  sea  uphill, 
into  positions  where  the  materials  have  been  roughly  assorted  in 
the  streams  and  lakelets  resulting  at  various  times  from  the  thawing 
of  such  ice.  This  is  a  considerable  demand  upon  the  credence  of  the 
older  race  of  geologists,  essentially  and  rightly  a  conservative  body  of 
men.  One  may  venture  to  say  that  it  is  the  dynamical  question  which 
has  been  the  chief  obstacle  to  the  general  acceptance  of  this  view ; 
if  that  part  of  the  problem  could  be  satisfactorily  solved,  we  should 
accept  with  thankfulness  an  explanation  which  does  away  with  the 
necessity  for  belief  in  the  Great  Submergence  and  all  the  incongruities 
which  that  belief  involves.  Certainly,  there  is  yet  a  third  explana¬ 
tion  to  which  I  may  make  a  passing  allusion,  viz.  the  possibility 
of  that  Great  Mood  which  is  to  relieve  us  from  the  Glacial  Night¬ 
mare,  and  thus  enable  us  to  get  rid  of  our  difficulties.  Lyell,  in  one 
of  his  letters,1  as  some  of  you  may  remember,  speaks  of  a  tour  in 
Wales,  where  “  a  certain  Trimmer  ”  had  found  near  Snowdon  6  crag  y 
shells  at  the  height  of  1000  feet,  “  which  Buckland  and  he  convey 
thither  by  the  Deluge.”  This,  I  presume,  alludes  to  Moel  Tryfaen, 
and  it  is  significant  that  the  writers  spoke  of  these  remains  as 
4  crag  ’  shells.  The  Great  Mood  seems  to  be  a  kind  of  revival  of  the 
Noachian  Deluge. 
In  order  to  satisfy  ourselves  as  to  the  necessary  vis-a-tergo  required 
by  the  ice-thrust  hypothesis,  we  must  take  into  consideration  the 
possible  condition  of  the  Irish  Sea  towards  the  period  of  intense 
glaciation.  Some  notion  of  this  state  of  things  may  be  furnished  by 
studying  Mr.  Kilroe’s  paper  on  the  direction  of  the  ice-flow  in  the 
North  of  Ireland  and  the  accompanying  map.  It  may  be  objected 
that  the  conclusions  of  this  paper  are  based  mainly  on  the  direction 
of  the  striae,  and  especially  that  portions  of  the  map  represent  what 
may  possibly  be  regarded  as  an  exaggerated  aspect  of  the  case,  more 
particularly  in  the  direction  of  the  Atlantic.  Messrs.  Peach  and 
Horne,  whom  the  Author  follows,  extend  the  margin  of  their  Atlantic 
ice-sheet  to  the  edge  of  the  200-fathom  line,  a  distance  of  about  80 
miles  from  North-western  Ireland  and  the  Hebrides,  although  this 
is  a  moderate  distance  compared  with  Dr.  CrolTs  estimate.  As  we 
are  frequently  told  that  if  we  want  to  study  the  phenomena  of  the 
Glacial  Period  we  should  go  to  Greenland,  I  would  merely  remark 
that  there  is  nothing  taking  place  in  that  country  at  the  present 
1  ‘Life  of  Sir  Charles  Lyell,’  vol.  i.  p.  319. 
