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are placed in strata on each other, like the layers 
of the mountains of secondary formation. 
These strata, similar to those observed on the 
brink of the ancient crater of Vesuvius at the 
Somma, appear to be the result of successive 
overflowings. They are formed of vitrified lava, 
of a porphyry with base of osidian, and of pitch- 
stone. For ages past, the peak of Tenerifie, 
the perpendicular height of which is more than 
nineteen hundred toises, has acted only by late- 
ral eruptions. The last of these eruptions is 
that of Chahorra, which took place in 1798. 
On beholding in the plain of Retama the enor- 
mous quantity of substances thrown out by the 
peak, we are astonished at the smallness of the 
crater, from which we suppose that so much 
ashes, pumice stone, and blocks of volcanic vi- 
trified matter, have issued ; but Mr. Cordier, who 
has made the longest residence of any mine- 
ralogist in the island of Tenerilfe, has furnished 
the important observation, that the present cra- 
ter, the caldera of the piton, is not the principal 
opening of the volcano. This learned traveller 
found on the northern declivity of the peak a 
funnel of enormous dimensions, which appears to 
have acted the principal part in the ancient 
eruptions of the volcano of Tenerilfe. 
