710 
SIE  CHAELES  LTELL  OX  THE  STErCTUEE  OE  LAVAS 
remembered  to  have  seen  when  I visited  Etna  in  1828  among  the  old  lavas  and  dikes  of 
the  Val  del  Bove.  Hence  I was  led  to  inquire  whether  these  transported  masses,  some 
angular,  others  rounded,  the  larger  ones  often  more  than  5,  and  in  some  cases  9 feet 
in  diameter,  might  not,  together  with  the  associated  sand  and  gravel,  bear  testimony  to 
the  gradual  excavation  by  aqueous  erosion  of  that  vast  crateriform  cavity  which  forms 
the  principal  feature  of  the  eastern  flank  of  Etna. 
No  small  portion  of  the  alluvial  deposit,  particularly  where  the  thickness  of  the  mass 
and  size  of  the  blocks  are  most  conspicuous,  hes  exactly  opposite  the  Val  del  Bove,  in 
the  low  region  to  which  the  few  torrents  which  still  drain  it  in  the  rainy  season  cany 
down  their  tribute  of  sand  and  boulders.  The  area  occupied  by  the  old  alluvium  is 
accurately  laid  down  on  the  great  map  which  accompanies  Baron  S.  vox  Waltees- 
HAUSEx’s  splendid  work,  now  in  the  course  of  publication,  entitled  ‘ Atlas  von  Etna,’  to 
which  I shall  often  have  occasion  to  refer  in  the  sequel.  A reduced  copy  of  the  map 
accompanying  that  valuable  monograph  is  given,  with  the  author’s  kind  permission,  as 
one  of  the  illustrations  of  this  memou’  (Plate  XLIX.).  The  nature  and  geological  age  of 
the  alluvium  will  be  more  fully  discussed  wEen  I treat  of  the  probable  origin  of  the 
Val  del  Bove. 
Another  feature  which  arrests  the  geological  traveller’s  attention  as  he  passes  along 
the  coast  at  the  base  of  the  great  volcano,  is  a series  of  terraces  Avhich  terminate 
abruptly  in  escarpments  facing  eastwards  and  resembling  sea-chfis.  This  character  in 
the  physical  geography  of  the  country  prevails  throughout  the  fertile  region,  extending 
for  more  than  twenty  miles  north  of  the  city  of  Catania  and  three  or  more  miles  west 
from  the  sea  to  a height  of  1000  feet  and  more  above  it,  and  is  equally  observable, 
wliether  the  country  consists  of  marine  tertiary  clay  with  associated  basaltic  rocks,  as  at 
Trezza,  Aci  Gastello  and  Catira,  or  is  composed  of  lavas  of  subaerial  origm,  as  at  Aci 
Beale,  or  of  the  alluvium  already  alluded  to,  as  at  S.  Leonardello.  The  ancient  chffs 
are  often  from  300  to  600  feet  in  height ; some  of  them  two  or  three  miles  inland, 
others,  as  in  the  case  of  Aci  Beale,  having  their  base  still  washed  by  the  waves. 
Beasons  will  be  given  in  the  sequel  for  concluding  that  this  Ime  of  coast  has  been 
gradually  upraised  and  made  to  emerge  in  comparatively  modern  times ; and  it  will  be 
shown,  among  other  proofs,  that  littoral  shells  of  recent  marine  species  are  met  vflth 
here  and  there  on  the  surface,  as  high  as  40  feet  or  more  above  the  sea-level,  in  a Besh 
state  and  retaining  much  of  their  original  colour.  A similar  upheaval  prevailing  for  a 
much  longer  period,  and  affecting  somewhat  uniformly  considerable  areas,  has  canied 
upwards  the  whole  of  the  adjoining  land,  perhaps  the  w’hole  mass  of  Etna  and  much  of 
the  surrounding  non-volcanic  territory,  raising  it  bodily  a thousand  or  more  feet  above 
its  former  level,  and  giving  rise  to  those  ancient  inland  cliffs  above  alluded  to. 
When  we  try  to  determine  the  relative  age  of  the  various  geological  monuments 
connected  with  these  movements,  Ave  And  the  task  more  comphcated  than  where  Ave 
have  simply  to  deal  with  rocks  of  subaqueous  origin,  such  as  haA  e been  slowly  uplifted 
and  made  gradually  to  rise  out  of  the  sea.  For  beside  the  successive  rise  and  denuda- 
