Tol.  49.] 
THE  GEOLOGY  OF  THE  NEW  HEBRIDES. 
227 
17.  Geological  Hotes  on  certain  Islands  in  the  Hew  Hebrides. 
By  Lieut.  G.  C.  Frederick,  B.H.  (Communicated  by 
Sir  Archibald  Geikie,  D.Sc.,  For.Sec.B.S.,  Y.P.G.S.  Bead 
February  22nd,  1893.) 
[Abridged.] 
So  far  as  can  be  judged  at  present  from  the  soundings  obtained,  it 
appears  that  the  Hew  Hebrides  are  probably  situated  on  a  bank 
lying  from  350  to  400  fathoms  below  the  surface  of  the  ocean  and 
running  in  a  H.H.W.  and  S.S.E.  direction,  with  a  deep  valley  between 
it  and  Hew  Caledonia.  The  only  soundings  obtained  between 
these  two  groups  are  2375  and  2730  fathoms  respectively,  the 
former  within  a  short  distance  of  the  Hew  Hebrides. 
1.  Tanna . — On  the  east  side  of  this  island  is  situated  a  volcano 
which  has  been  in  constant  activity  for  many  years,  and  on  ascend¬ 
ing  its  sides  one  is  struck  by  the  fact  that  so  little  lava  is  to  be 
seen.  The  cone  itself,  which  rises  to  a  height  of  nearly  1000  feet 
above  the  sea,  appears  to  be  formed  entirely  of  more  or  less  fine 
ash,  and  there  are  no  signs  of  any  lava-flow. 
In  Hovember  1890  the  crater  appeared  to  be  about  300  feet  deep, 
and  was  split  into  two  nearly  equal  parts  by  a  kind  of  rocky  wall 
or  partition  which  rose  to  a  height  of  about  100  feet  from  the 
bottom. 
There  were  five  fire-holes,  three  on  one  side  and  two  on  the 
other  side  of  the  partition,  where  the  molten  materials  were  bubbling 
and  pulsating  with  a  subdued  roaring  sound ;  but  every  few 
minutes  a  tremendous  explosion  took  place,  throwing’  up  the 
molten  scoriae,  etc.,  to  heights  varying  from  100  to  300  feet 
above  the  summit  of  the  crater. 
Clouds  of  sulphurous  fumes  arose  from  the  surface  of  the  crater, 
many  yards  back  from  the  lip,  whenever  these  explosions  took  place, 
as  if  forced  up  through  the  porous  material  by  the  violence  of  the 
outburst. 
2.  Efate  Island  is  about  24  miles  long  and  18  miles  broad.  It 
is  chiefly  made  up  of  coral-limestone.  The  north-western  portion 
of  the  island  is  the  most  elevated,  rising  into  mountains  and  ridges 
to  a  height  of  2203  feet,  and  thence  sloping  down  in  long  spurs 
to  the  south-eastward,  where  the  land  assumes  the  features  of  a 
plateau  some  200  or  300  feet  in  height,  in  which  are  carved 
deep,  narrow  valleys,  with  steep,  and  in  many  places  almost  perpen¬ 
dicular  sides. 
In  some  parts  natural  terraces  appear  to  rise  one  above  the  other, 
denoting  distinct  periods  of  upheaval ;  this  is  most  noticeable  in 
the  vicinity  of  Havannah  Harbour. 
Coral  was  found  in  Efate  Island  at  the  remarkable  height  of 
1500  feet  above  sea-level. 
Lying  off  the  northern  coast  of  Efate  are  several  smaller  islands, 
Q  2 
