Ch. XIX.] 
AGE OF AUVERGNE VOLCANOS. 
269 
those of ante-diluvian and those of post-diluvian origin. To 
the former they attribute such hills of sand and scoria? as 
exhibit on their surface evident signs of aqueous denudation ; 
to the latter, such as betray no marks of having been exposed 
to such aqueous action. According to this classification almost 
all the minor cones of Central France must be called post- 
diluvian ; although, if we receive this term in its ordinary 
acceptation as denoting posteriority of date to the Noachian 
deluge, we are forced to suppose that all the volcanic eruptions 
occurred within a period of little more than twenty centuries, 
or between the era of the flood, which happened about 4000 
years ago, and the earliest historical records handed down 
to us respecting the former state of Central France. Dr. 
Daubeny has justly observed, that had any of these French 
volcanos been in a state of activity in the age of Julius Caesar, 
that general, who encamped upon the plains of Auvergne., and 
laid siege to its principal city, (Gergovia, near Clermont,) 
could hardly have failed to notice them. Had there been 
even any record of their existence in the time of Pliny or 
Sidonius Apollinaris, the one would scarcely have omitted 
to make mention of it in his Natural History, nor the other to 
introduce some allusion to it among the descriptions of this 
his native province. This poet's residence was on the borders 
of the Lake Aidat, which owed its very existence to the dam- 
ming up of a river by one of the most modern lava cur- 
rents*. 
The ruins of several Roman bridges and of the Roman 
baths at Royat confirm the conclusion that no sensible 
alteration has taken place in the physical geography of the 
district, not even in the chasms excavated through the newest 
lavas since ages historically remote. We have no data at 
present for presuming that any one of the Auvergne cones has 
been produced within the last 4000 or 5000 years; and the 
* Daubeny on Volcanos, p. 14, 
