C. Lyell on the Formation of Volcanic Cones. 215 
the assumed law, such an inclined position of the beds must have - 
~ been acquired subsequently to their origin. 
ter giving a brief sketch of the controversy respecting “Cra- 
ters of Elevation,” the author describes the results of his recent =~ 
"visit (October, 1857) to Mount Etna, in company with Signor 
etano G. Gemmellaro, and his discovery there of modern lavas, 
some of known date, which have formed continuous beds of 
_ Compact stone on slopes of 15°, 86°, 38°, and, in the case of the ~~ 
_ lava of 1852, more than 40°. The thickness of these tabular 
_ layers varies from 14 foot to 26 feet; and their plains of stratifi- 
_ Cation are parallel to those of the overlying and underlying 
h form part of the same currents. The most striking 
— Scoriz whic 
examples of this phenomenon were met with—Ist, at Aci Reale; 
Adly, in the ravine called the Cava Grande near Milo, where a 
section of the lava of 1689 is obtained; 3dly, in the precipice at 
the head of the Val di Calanna, in the lava of 1852-63; and 
4thly, at a great height above the sea near the base of the 
] 
a 
ich, called 
ie jagens which encrust the steep slope at 
; and it is shown 
ccessive C 
pea é 
