712 
SIE  CHAELES  LTELL  ON  THE  STEECTEEE  OF  LAVAS 
red  colour  are  to  be  seen  at  the  contact  of  the  lava  of  1669,  Tvith  ground  which  before 
that  year  was  highly  cultivated 
The  cliflF  of  Aci  Eeale  above  mentioned  and  represented  in  the  accompanymg  rough 
sketch  (fig.  1),  for  which  I am  indebted  to  the  kindness  of  my  friend  Dr.  Caklo  Gem- 
MELLAEO,  is  about  500  feet  high.  It  runs  parallel  to  the  sea  for  some  distance  north 
South.  Fig.  1. — Cliff  a/nd  coast  at  Aci  Reale. 
Aci  Reale.  Nonh. 
A.  Upper  part  of  tlie  road  called  the  Scalazza, 
B.  Bastione  del  Tocco. 
C.  Lava-current  which  descends  the  cliff  to  the  Grotto  delle  Palomhe. 
D.  Grotto  deUe  Palomhe. 
and  south  of  Aci.  Seen  from  a boat,  the  lava-currents  appear  horizontal,  because  the 
section  is  transverse  to  their  dip.  They  are,  however,  in  reality  inclined  at  angles  varying 
from  4°  to  7°  seaward.  Below  the  letter  A (fig.  1)  a zigzag  road  called  the  Scalazza. 
partly  built  on  arches,  leads  down  from  the  town  to  the  tillage  of  La  Scala.  At  the 
end  of  the  second  turn  of  this  road,  and  about  150  feet  below  the  summit  of  the  plat- 
form (B,  fig.  1),  is  a part  of  the  fortification  called  the  Bastione  del  Tocco,  where  an  inden- 
tation occurs  in  the  face  of  the  clitf,  probably  made  originally  by  the  sea  at  the  time 
when  the  precipice  was  undermined  by  the  waves.  This  indentation  afibrds  the  geolo- 
gist a rare  opportunity  of  seeing  a longitudinal  section  of  one  of  the  lavas,  the  upper- 
most of  the  whole  series  at  this  point,  exposed  in  the  direction  of  its  coiu’se  from  west 
to  east.  It  consists  of  a powerful  current  dipping  east  or  towards  the  sea  at  angles 
varying  from  23°  to  29°,  and  exposed  for  a length  of  80  feet  in  the  garden  of  one 
Giuseppe  Torrisi.  The  mass  has  aU  the  usual  characters  of  an  Etnean  lava-cui-rent. 
displaying  an  upper  and  lower  bed  of  scoriae  (A  1 and  5,  fig.  2)  with  an  intermediate 
stony  portion  (A  2,  3,  4),  which  in  this  instance  is  more  than  usually  thick  and  compact. 
The  upper  scoriaceous  crust  (A  1,  fig.  2)  is  about  12  feet  thick,  below  which  comes  the 
stony  portion  (A  2,  3,  4)  20  feet  thick,  having  a dip  of  from  23°  to  29°,  and  dmded 
into  three  beds,  each  about  6 or  7 feet  thick,  the  lowest  becoming  at  its  base  fii'st  cel- 
lular, and  then  vesicular  and  scoriaceous.  The  rock  is  a compact  grey  dolerite  nith 
numerous  crystals  of  felspar,  and  some  of  augite  mth  a small  quantity  of  olhine.  The 
