86  PEOCEEDINGS  OE  THE  GEOLOGICAL  SOCIETY.  [May  1 893, 
day  to  justify  Messrs.  Peach  and  Horne’s  conception  of  the  west 
coast  of  Scotland  during  the  extreme  glaciation  of  our  islands.  In 
modern  Greenland  there  is  a  strip  of  ice-free  land,  broader  on  the 
west  than  on  the  east  coast,  and  possessed  of  a  fairly  abundant 
fauna  and  flora ;  and  this  strip  is  continuous,  except  where  glaciers 
actually  enter  the  sea.  The  recent  researches  of  Lieut.  Peary  tend 
to  show  that  such  a  strip  of  ice-free  land  extends  even  to  the  hitherto 
unknown  shores  of  N orth-eastern  Greenland. 
Put  I  have  been  digressing.  The  point  for  present  consideration  is 
the  condition  of  the  shallow  Irish  Sea  and  of  the  glaciers  that  flowed 
into  it  during  the  great  glaciation.  If  we  accept  the  main  conclusions 
of  Mr.  Kilroe,  we  may  readily  admit  that  the  North  Channel  leading 
into  the  Irish  Sea  was  blocked  by  the  Scottish  ice -flow  passing  over 
Ulster  and  Northern  Connaught,  and  that  this  flow  even  controlled 
for  a  time  the  glacial  system  of  North-western  Ireland.  This  central 
snow-field  of  Ireland  is  represented  as  having  its  axis  on  the  con¬ 
fines  of  the  northern  and  the  western  province  in  a  district  which 
is  elevated,  but  by  no  means  lofty  ;  from  this  axis  the  striae  indicate 
a  regular  movement  of  the  ice  in  a  south-easterly  direction  towards 
the  Irish  Sea.  The  most  direct  flow  into  the  Irish  Sea  would  arise 
out  of  the  glaciers  that  descended  from  the  southern  uplands  of 
Scotland  in  Galloway  and  Dumfries-shire,  a  limited  area  certainly, 
and  only  of  moderate  elevation,  but  possibly  overridden  at  times 
by  more  northern  ice.  Lastly  there  was  the  Lake  District  ice 
streaming  in  from  the  north-east.  The  outlet  for  these  masses  of  ice 
must  have  been  in  a  southerly  direction. 
Granting  these  premises,  which  do  not  seem  unreasonable  in  the 
light  of  modern  investigation,  although  a  few  years  ago  we  might 
have  hesitated  to  accept  them,  there  must  have  been  a  stupendous 
crush,  the  result  of  contending  glaciers,  in  the  shallow  basin  of  the 
Irish  Sea.  Some  authors  assert  that  this  sea  was  filled  from  side  to 
side  by  an  ice-stream  fully  2000  feet  thick,  and  the  heights  at  which 
striae  occur  in  the  Isle  of  Man  are  adduced  in  favour  of  this  hypo¬ 
thesis.  The  power  of  ice  to  thrust  rocks  uphill  is  also  said  to  be 
exemplified  in  that  island,  where  boulders  of  granite  from  Granite 
Mountain  have  been  carried  to  the  summit  of  South  Barule,  a  rise 
of  over  800  feet  in  a  mile  and  a  half.  The  comparatively  low 
watershed  of  the  Irish  and  South  Scottish  glacier-systems,  which 
are  supposed  mainly  to  have  fed  this  mass,  appears  to  be  the  principal 
difficulty  in  assigning  such  a  thickness  as  2000  feet  to  the  ice  of 
the  Irish  Sea.  We  may,  however,  believe  that  in  an  area  of 
excessive  precipitation  a  very  considerable  thickness  of  ice  did 
