1866.| On the Antiquity of the Volcanos of Awergne. 207 
In reply to the arguments he advanced, I observed,* that 
although some of the expressions of Sidonius and of Alcimus Avitus 
quoted might seem at first sight to refer to a volcanic eruption, yet 
the following considerations would forbid of our entertaining such 
an hypothesis. . 
1. The city of Vienne, near which the physical convulsions 
alluded to were reported to have occurred, lies nearly seventy miles 
in a direct line from the theatre of voleanic action situated round 
Clermont. 
The relative position of the city of Vienne to the nearest volcanic 
chain is shown in the accompanying diagram. 
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2. Had Sidonius ever heard of such events occurring in his own 
neighbourhood, he would scarcely have failed to refer to them, if not 
on other occasions, at least on this, in which he vividly depicts the 
alarming catastrophes that had occurred in a neighbouring province. 
3. The city of Vienne stands upon gneiss, with the great coal 
formation of St. Etienne interposed between it and the rocks of 
Auvergne, and with a range of hills of considerable elevation inter- 
vening between the two. 
4. The geology of France has been carefully, explored by the 
labours of Elie de Beaumont and others; but no notice of anything 
volcanic in the vicinity of Vienne can anywhere be found in their 
descriptions. 
5. No volcano could have burst out without leaving permanent 
traces of its occurrence in the craters and lava-streams which it 
must have produced. 
* See my work, entitled ‘Descriptions of Volcanos,’ Taylor & Francis, 
2nd ed., 1848, p. 31. 
