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SIE  CHAELES  LTELL  ON  THE  STEHCTHEE  OF  LAVAS 
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Highly  inclined  modem  Lava  near  the  Montagnuola  736 
Eecapitulation  of  Part  1 737 
Pakt  II. 
ON  THE  STEUCTHEE  AND  POSITION  OF  THE  OLDEE  VOLCANIC 
EOCKS  OF  MOUNT  ETNA,  AS  SEEN  IN  THE  VAL  DEL  BOVE, 
AND  ON  THE  PEOOFS  OF  A DOUBLE  AXIS  OF  EEUPTION  ...  738 
Proofs  of  a double  axis — cones  of  Trifoglietto  and  of  Mongibello  738 
Comparison  of  the  twofold  axis  of  Etna  with  that  of  Madeira  744 
Want  of  continuity  of  the  older  and  modern  parts  of  Mount  Etna,  and  truncation 
of  the  summit  745 
Elliptical  crater,  and  question  as  to  three  centres  of  eruption  discussed 746 
Hypothesis  of  upheaval  by  injection  or  the  formation  of  dikes,  and  on  the  incbna- 
tion  of  old  lavas  in  the  cliffs  of  the  Val  del  Bove  748 
Supposed  frequent  injection  of  lava  in  beds  parallel  to  strata  of  tuff  considered  ...  751 
Evidence  of  pseudo-paraUelisin  and  want  of  uniform  thickness  of  the  beds  forming 
the  escarpments  of  the  Val  del  Bove  753 
Analogous  form  and  arrangement  of  ancient  and  modern  lavas  756 
Flexures  and  arches  in  ancient  lavas  758 
Dikes  in  the  Val  del  Bove  759 
Lateral  cones  of  Etna  760 
Eecapitulation  of  Part  II 761 
Paet  III. 
ON  THE  EELATION  OF  THE  VOLCANIC  EOCKS  OF  MOUNT 
ETNA  TO  THE  ASSOCIATED  ALLUVIAL  AND  TEETIAEY  DE- 
POSITS, WITH  EEMAEKS  ON  THE  THEOET  OF  “ CEATEES 
OF  ELEVATION”  762 
Origin  of  the  Val  del  Bove,  and  how  far  due  to  aqueous  erosion  762 
Alluvium  of  Giarre  763 
Val  del  Tripodo,  and  proofs  of  aqueous  erosion  anterior  to  the  Val  del  Bove...  764 
Section  of  alluvium  and  basaltic  lava  between  Giarre  and  La  Macchia  767 
Hypothesis  of  a series  of  subsidences  and  lateral  explosions  in  the  Val  del  Bove  768 
Flood  of  1755  in  the  Val  del  Bove 770 
Gradual  rise  of  the  sea-coast  and  inland  sea-cliffs  at  the  eastern  base  of  Etna...  772 
Alluvium  of  the  northern,  south-western,  and  southern  base  of  Etna 773 
Volcanic  eruptions  in  the  alluvial  plain  of  the  Simeto  774 
Upraised  fluviatile  and  marine  deposits  of  the  old  estuary  of  the  Simeto  775 
Ancient  tulfs  of  Fasano,  near  Catania,  with  leaves  of  terrestrial  plants 776 
