00 Dr Daubeny on the Volcanoes of Auvergne. 
obtained, although its altitude is considerable, exceeding consi- 
derably 4000 feet. The Puy de Dome is of a conical form, 
and remarkable for the distinctness of its outline, rising abrupt- 
ly from the midst of a sort of amphitheatre of volcanic rocks, 
which it considerably overtops, but which, by a little stretch of 
the imagination, may be supposed to have constituted the crater 
from which this central mass was projected. However this may 
be, the mineral ogical clwacters of the mountain are such as dif- 
fer entirely from those of the hills on either side of it. The 
Puy de Dome seems to consist almost entirely of a rock with a 
felspar base, having crystals of glassy felspar and of augite dis- 
seminated through it, frequently containing plates of mica, and 
more rarely fragments of quartz. In some cases, the different 
ingredients are so intimately blended, that the aggregate might 
be mistaken for a whitish sandstone until carefully examined. 
The most extraordinary circumstance is, that the rock in ques- 
tion is confined to this hill, and two or three in its immediate 
vicinity, which, though they all present some modifications of 
aspect, still possess sufficient of a common character to be refe- 
rable to the same class. They are all conical, all detached, and 
have surrounding them hills of a volcanic nature, which bear not 
the slightest analogy to them in appearance. I shall refer to 
M. Montlosier, and the other writers who have described them, 
for an account of the Grand and Petit Cliersou and tlie Sarcouy, 
and shall confine myself to some remarks on the Puy Chopine, 
the most extraordinary, certainly, for the assemblage of rocks of 
which it is made up. 
This mountain, which is situated to the N, W. of Clermont, 
about half way between that city and the village of Pont Gi- 
baud, has long puzzled geologists, from the singular confusion 
and anomalous structure of the rocks which compose it. Owing, 
indeed, to the quantity of debris which covers every where its 
sides, where not concealed by vegetation, it is difficult to deter- 
mine with precision the position they occupy, or the relations 
they bear to each other. On climbing to its summit, I found 
in situ^ that porphyritic felspar rock, which, from its occurrence 
at the Puy de Dome has obtained the name of Domite, unal- 
tered granite, and a conglomerate with a granite base, rocks 
which seem to be related to each other. Lower down, I obser- 
