WHICH  HAVE  CONSOLIDATED  ON  STEEP  SLOPES. 
747 
west  of  the  great  cone  (see  Map,  Plate  L.);  but  my  friend,  Signor  Gaetano  G.  Gemmellaro, 
ha«  had  the  kindness  to  explore  it  at  my  request,  and  has  communicated  to  me  for 
publication  an  account  of  it,  in  a letter  dated  Catania,  October  18,  1868,  in  which  he 
rephes  fully  to  the  numerous  questions  I had  put  to  him.  He  found  the  eastern  rem- 
nant of  the  old  crater-wall  (that  lying  east  of  the  lava  of  1809)  almost  concealed  under 
recent  volcanic  sand  and  fine  scoriae,  to  such  an  extent  that  it  was  extremely  difficult  to 
determine  even  the  site  of  the  ruins  which  S.  von  Waltershausen  discovered  many  years 
ago.  But  the  other  fragment  which  lies  to  the  west  of  the  recent  lava  of  1838,  “is 
still,”  says  Signor  Gemmellaro,  “ clearly  exposed  to  view,  forming  for  1100  paces  an  arc 
of  a circle  round  the  present  axis  of  Etna ; its  mean  height  11  metres,  or  36  English  feet. 
It  is  composed  of  alternations  of  lavas  and  fragmentary  materials,  or  scorise,  sand,  and 
lapilh,  its  upper  margin  broken  and  serrated.  The  lavas,  except  the  bottom  bed,  which 
is  nearly  6 feet  thick,  are  thin  but  compact,  the  upper  beds,  however,  becoming  more 
cellular.  All  the  lavas  are  inclined  steeply  to  the  north  at  an  angle  of  31°,  the  average 
of  many  measurements.  Most  of  them  are  continuous  from  one  end  to  the  other  of  the 
elliptical  crater,  but  some  of  them  thin  out  in  their  extension  from  east  to  west.  They 
are  not  strictly  parallel,  but  present  slight  undulations.  Several  dikes  occur,  of  which 
two  especially  are  conspicuous.  The  principal  one  is  3 metres  wide,  of  a reddish  colour 
and  schistose  fracture,  and  decomposing  rapidly.  It  does  not  reach  the  upper  part  of 
the  precipice,  but  terminates  about  half-way  up.  The  direction  of  both  dikes  is  nearly 
north  and  south,  or  exactly  towards  the  centre  of  the  present  axis  of  Etna.  The 
smaller  one  has  the  same  structure  as  the  larger,  but  its  thickness  is  much  less.” 
In  conclusion.  Signor  Gaetano  believes  “ this  elliptical  crater  of  Baron  S.  von  Walters- 
hausen to  be  a fragment  of  the  ancient  cone  of  the  actual  axis  of  Etna,  destroyed  by 
earthquakes  and  the  explosive  force  of  gases  during  one  or  many  eruptions;  also  that 
the  epoch  of  that  catastrophe  may  not  be  very  remote,  geologically  speaking ; for  in  the 
works  of  Recupero,  Ferrara,  and  Alessi,  we  find, — 1st,  that  Seneca  reminds  Lucilius 
that  Mount  Etna  had  in  his  time  lost  so  much  of  its  height  that  it  could  be  no  longer 
seen  by  boatmen  from  certain  points  whence  it  was  previously  visible;  2ndly,  Ugone 
Falcando,  referring  to  Filotes,  relates  that  the  lofty  summit  of  Etna  had  fallen  in,  in 
1179,  in  the  time  of  William  the  Eleventh ; also  that  it  was  destroyed,  for  the  third  time, 
in  the  reign  of  Frederick  the  Eleventh,  in  the  year  1329,  as  Fazzello  relates.  More- 
over, that  it  was  engulfed,  for  the  fourth  time,  in  the  year  1444,  according  to  the  autho- 
rity of  the  same  writer,  and  of  Filotes  and  Carrera  ; and  finally,  in  the  year  1669,  nearly 
the  whole  top  of  the  mountain  fell  in^.” 
If  within  the  last  2000  years  such  revolutions  have  been  witnessed  in  the  upper  region 
of  Mongibello,  it  may  well  be  supposed  to  have  experienced  a far  greater  transmutation 
by  the  reiterated  catastrophes  of  the  ten  or  twenty  thousand  years  which  immediately 
preceded  the  historical  period,  during  which  time  there  may  have  been,  within  the  area 
of  the  highest  platform,  several  summits  blown  off,  and  several  deep  craters  formed  and 
* Alessi,  Storia  critica  dell’  eruz.  dell’  Etna,  p.  149. 
