C. Lyell on the Formation of Volcanic Cones. 217 
‘portion of a cone, traceable af intervals around the borders of an 
elevated platform between 9,000 and 10,000 feet high. These 
remains bear the same relation to the highest and active cone, 
nearly in the centre of the platform, which Somma bears to 
Vesuvius. The manner in which the north and south escarp- 
ments of the Val del Bove diminish in altitude as they trend 
the great lateral valley had no existence till after the time whet 
Mongibello had attained its fullest development and height, —__ 
The double axis of Etna is then compared to the twofold axis | 
ong, attains at one point a height of 6000 feet. Parallel to it, 
at t 
n attem e proportional amount 
of inclination which may be due to upheaval in those parts of 
few intercalated lavas, are inclined at 
agglomerate and beds of ‘ 
Seen inclined at angles exceeding 40°. l 
| me believed to be exceptionable = to loca 
ee. ‘may have an intimate connection Pi 
fissures, ohn a an width, filled with lava, for such dikes are. 
_ ‘Much more frequent near the original 
eastward from the high platform, is appealed to as showing that 
may 
; 
* 
be oR island of Madeira, as inferred from observations made in _ 
centres of eruption than at s 
