734 
SIE  CHAELES  LTELL  OX  THE  STErCTHEE  OE  LAVAS 
form,  by  which  one  may  ascend  to  the  flanks  and  summit  of  Zoccolaro.  The  best  section 
occurs  at  the  height  of  about  60  feet  above  the  bottom  of  the  ravine,  opposite  a dike 
which  traverses  the  older  lavas  on  the  left  or  north  side  of  the  Cava  Secca.  The  inclina- 
tion of  the  lava  augments  higher  up  the  slope  to  40°,  and  the  stony  layer  decreases  to  a 
thickness  of  6 inches ; but  this  occurs  very  near  the  edge,  and  it  is  probably  thicker  in 
the  middle  of  the  current,  which  is  at  least  130  feet  wide.  At  the  same  place  the  lower 
scoriae  are  3 feet  thick,  and  are  seen  to  rest  on  a red,  burnt  tufi".  On  approaching  the 
top  of  the  pass,  there  is  no  longer  any  lateral  section  of  the  inclined  lava  to  be  seen,  for 
it  is  there  overflowed  for  a considerable  space  by  a more  modem  current,  viz.  that  of 
1792,  the  course  of  which  is  laid  down  in  S.  vov  Waltekshausev’s  map  (see  Plate 
XLIX.). 
The  Cava  Secca,  therefore,  afibrds  us  an  instance  of  a lava  having  a central  continuous 
layer  as  compact  as  are  most  of  the  beds  of  older  date  in  the  Val  del  Bove,  and  that  layer 
is  inclined  at  angles  of  26°,  30°,  and  40°,  and  is  partially  covered  by  a newer  lava  (that  of 
1792)  in  one  part  of  its  course,  where  both  currents  slope  at  an  angle  of  26°. 
Stee]ply  inclined  com/pact  lava  of  modern  date  below  the  Cisterna  {b.  Map,  Plate  L.). 
The  next  remarkable  instance  of  a steeply  inclined  continuous  sheet  of  compact  modern 
lava  to  which  I shall  advert,  occurs  at  a point  5000  feet  higher  than  that  last  mentioned, 
or  near  the  top  of  the  great  precipice  at  the  head  of  the  Val  del  Bove,  not  far  below  the 
Cisterna.  Its  lower  termination  may  be  seen  just  above  that  upper  part  of  the  Serra 
Giannicola  to  which  S.  von  Walteeshausen  has  given  the  name  of  Teatro  Piccolo  (at 
the  point  b.  Map,  Plate  L.).  Its  dip  is  between  30°  and  35°  East,  and  in  some  parts  38°; 
Eig.  12. — Modern  inclined  lava  between  the  Cisterna  and  the  Teatro  Piccolo,  or  upper  part  of  Giannicola 
(see  h,  Map,  Plate  L.). 
its  upper  crust  of  scorise  (C  1,  flg.  12)  is  about  5 feet,  the  central  stony  mass  (C  2)  7 feet, 
and  the  lower  scoriae  (C  3)  7 feet  thick.  The  whole  is  flnely  exposed  to  view,  the  rain 
and  melted  snow  having  washed  away  the  subjacent  scoriae  from  both  sides  of  the  current. 
