WHICH  HAVE  CONSOLIDATED  ON  STEEP  SLOPES. 
771 
affirms  is  never  more  than  4 feet  deep  (some  chasms  we  presume  excepted),  were  melted 
in  one  instant,  which  no  current  of  lava  could  accomplish,  it  would  not  have  supplied 
such  a volume  of  water.  He  came  therefore  to  the  somewhat  startling  conclusion,  that 
the  water  was  vomited  forth  by  the  crater  itself,  and  was  driven  out  from  some  reservoir 
in  the  interior  of  Etna*. 
It  seems  to  me  very  unlikely  that  the  Canon,  who  was  on  the  ground  within  three 
months  of  the  date  of  the  catastrophe,  should  have  been  mistaken  in  regard  to  the  region 
of  the  mountain  whence  the  waters  came.  His  conclusions  on  that  head  seem  to  have 
been  legitimately  deduced  from  the  fact,  that  the  wreck  of  the  inundation  was  traceable 
continuously  from  the  sea-shore  at  Eiposto  up  to  the  highest  cone  or  its  neighbourhood. 
[I  am  therefore  inclined  to  suspect  that  at  the  time  of  the  eruption  of  1755  there  was 
upon  the  summit  of  Etna  not  only  the  winter’s  snow  of  that  year,  but  many  older  layers 
of  ice,  alternating  with  volcanic  sand  and  lava,  at  the  foot  or  in  the  flanks  of  the  cone, 
which  were  suddenly  melted  by  the  permeation  through  them  of  hot  vapours,  and  the 
injection  into  them  of  melted  matter.  I stated  in  the  first  edition  of  my  ‘ Principles  of 
Geology,’  that  during  my  visit  to  Etna  in  1828,  I ascertained  the  existence  of  a glacier 
under  lava  near  the  Casa  Inglese,  on  the  S.E.  side,  near  the  base  of  the  cone,  and  that 
it  had  been  quarried  during  the  previous  summer,  affording  a supply  of  ice  to  the  Cata- 
nians.  On  returning  thirty  years  afterwards  (September  1858),  I found  the  same  ice,  a 
mass  of  unknown  extent  and  thickness,  still  unmelted.  It  had  been  quarried  only  five 
years  before  to  the  depth  of  4 feet  on  the  very  same  spot.  My  guide  told  me  that  he 
had  seen  this  mass  of  solid  ice,  the  bottom  of  which  they  did  not  reach,  and  that  it  was 
overlaid  by  10  feet  of  sand,  and  the  sand  again  by  lava. 
If  glaciers  may  thus  endure  for  a series  of  years  under  ’^^olcanic  sand  and  lava,  the  store 
of  water  which  Recupeeo  speculated  upon  as  contained  somewhere  in  the  interior  of 
the  mountain,  seems  sufficiently  accounted  for.  I am  also  now  disposed  to  attach  more 
importance  than  when  I first  wrote  on  this  subject f,  to  the  tales  of  the  mountaineers, 
which  Recupeeo  thought  worth  recording.  They  related  to  him  that  the  water  was 
boiling,  that  it  was  as  salt  as  the  sea,  and  that  it  brought  down  with  it  sea-shells  to  the 
coast.  Now  it  will  be  seen  that  the  hypothesis  above  suggested  would  very  naturally 
account  for  the  water  being  hot,  and  it  may  have  been  impregnated  with  saline  matter 
exhaled  from  fumeroles  on  the  sides  of  the  cone  or  from  the  crater  itself  during  the 
eruption ; and  these  exhalations,  without  giving  to  it  the  composition  of  sea-water,  may 
have  taken  away  its  freshness.  As  to  the  story  of  the  marine  shells,  if  the  flood,  after 
issuing  from  the  Val  del  Bove,  cut  deeply  through  the  superficial  lava  or  the  alluvium 
between  Milo  and  Giarre,  it  may  possibly  have  reached  a bed  of  subjacent  newer  plio- 
cene clay  at  the  height  of  1000  or  1200  feet  above  the  sea,  washing  out  of  it  a great 
number  of  fossil  shells  of  li\4ng  species,  strong  enough  to  bear  transportation  as  far  as 
Riposto.  But  as  the  tertiary  strata  do  not  crop  out  anywhere  at  present  in  the  region 
here  alluded  to,  many  of  my  geological  readers  will  think  it  safer  to  ascribe  this  part  of 
* Eecvpeeo,  Storia  dell’  Etna,  p.  85.  -f  Principles  of  Geology,  3rd  edition,  vol.  ii.  p.  123. 
