Dr Daubcny on the Volcmioes qf Auvergne. SOS 
The recent limestone beds already noticed, merely cover the 
granite in the bottom and on the sides of the valleys, attain- 
ing only the comparatively moderate elevation of the hill Ger- 
govia, where they are capped with basalt ; but not seen as we 
ascend the loftier mountains to the N. W. of Clermont, w^here 
the fundamental granite, wherever it is concealed, is covered by 
a description of rocks of quite a different character. 
These rocks constitute a chain of eminences which rise con- 
siderably above the elevated granitic platform on which they 
rest, and extend at intervals over a space of above eight leagues 
from north to south ; from whence the rocks v/hich compose 
them may often be traced a considerable way into the valleys 
contiguous. Above sixty of these eminences might, I believe, 
be enumerated within the boundary marked out; but as their 
number renders selection necessary, we shall simply notice such 
as are most remarkable, beginning with that of Volvic near 
Riom, — the lava of which furnishes a considerable part of the 
building-stone used in that neighbourhood, and, in spite of its 
porous character, is exceedingly durable*. 
The lava which covers the valley of Volvic, extending nearly 
to the town of Riom, may be traced up the sides, and to the 
summit of the Puy de la Nugere to the west of it, whilst not a 
vestige is to be seen at a similar elevation on any of the hills to 
the east. The fact, therefore, of its having descended in a liquid 
form from above the mountain, and that at a period subsequent 
to that of any of the great revolutions which have changed the 
face of our planet, is demonstrated by the exactness with which 
the stream of lava has accommodated its course to the slope of 
the valley ; and that its fluidity was owing to heat, is evident 
enough from its porous texture and semi- vitreous aspect ; so 
that its connexion with volcanoes now in activity seems suffi- 
ciently apparent. 
On the summit of the Puy de Nugere, is a regular bason- 
shaped concavity, broken away on the side, down which the 
lava has taken its course, and notwithstanding the changes which 
time has effected in its form, still retaining sufficient marks of 
* Its dark and sombre character adds much to the religious gloom of the Ca- 
thedral of Clermont. 
