8 
KXPLANATJON OF PLATE 1. 
Craters. 
Our section represents three cases of Volcanic craters ; 
the most simple (i. 5.) rising through Granite, or stratified 
rocks, at the bottom of the sea, and accumulating craters, 
which, like those of Lipari and Stromboli, Sabrina, and 
Graham Islands, are occasionally formed in various parts 
of the ocean.* The second case is that of volcanos, 
which, like Etna and Vesuvius, are still in action on the 
dry land, (i. 1. to i. 4.) The third is that of extinct vol- 
canos, like those in Auvergne, (h^. h-.) which, although 
there exist no historical records as to the period of their 
last eruptions, shew by the perfect condition of their cra- 
ters, that they have been formed since the latest of those 
aqueous inundations, that have affected the Basalts and 
Tertiary strata, through which they have burst forth. 
One great difference between the more ancient Basaltic 
eruptions and those of the Lava and Trachyte of existing 
volcanos, is that the emission of the former, probably taking 
place under the pressure of deep water, was not accompa- 
nied by the formation of any permanent craters. 
In both cases, the fissures through some of which these 
Eruptions may have issued, are abundantly apparent under 
the upward passage of the Lava through fractures in the solid 
Granite. 
At Graveneire, near Clermont, a stream of Lava still retains the 
exact form, in which it issued through a fissure in the side of a 
mountain of Granite, and overflowed the subjacent valley. Most 
accurate representations of this, and many similar productions of 
Volcanic Eruptions from the Granite of this District may he seen 
in Mr. Poulett Scrope’s inimitable Panoramic Views of the Vol- 
canic formations of Central France. 
* Within the last few years, the Volcanic Cones of Sabrina in the 
Atlantic, and of Graham Island in the Mediterranean, have risen 
suddenly in the sea and been soon levelled and dispersed by the 
Waves. 
