216 On the Antiquity of the Voleanos of Auvergne. | April, 
long series of igneous formations which we witness in Auvergne, 
it sinks almost into insignificance by the side of that period of 
incalculable duration which must have elapsed since the globe 
became first fitted for the maintenance of organic life. 
And this leads me to another point of some general interest — 
namely, that volcanic action, notwithstanding its long continuance 
in one district, shifts its ground from time to time, so as probably in 
the course of years to visit in succession every region of the globe. 
Before the close of the Eocene period, when the volcanos of 
Auvergne first came into activity, those of the Hebrides, of the North 
of Ireland, and of parts of Scotland had become extinct, and yet we 
have reason to believe that these last were for the most part contem- 
poraneous with the chalk, and do not date back so far as the Oolite. 
That they are entirely burnt out, may be inferred from the 
absence, throughout the whole space comprised within their several 
areas, of thermal springs, and of the severer forms at least of earth- 
quake, which cannot be said of Auvergne; for the latter volcanos, 
though, as I believe, not in activity smce the earliest periods of 
history, still give evidence of smouldering internal fire in their 
warm springs, evolutions of carbonic acid gas, and in occasionally 
recurring earthquakes of considerable intensity. 
It would be easy to point out volcanic regions of still greater 
antiquity in other parts of the globe, which became extinct 
even before the igneous operations in the Hebrides, &., had 
commenced ; but it may be most to the purpose to note that in the 
highly vulcanized region of Southern Italy, the Apennine lime- 
stone, there so abundant, and of an age corresponding to the Jura 
or Oolite, exhibits no proof of igneous action having extended back 
so far as the period at which their beds were deposited. 
From these considerations it may be inferred, that every portion 
of the globe is destined at one time or another to become the theatre 
of similar catastrophes. 
Perhaps in some future time a chain of burning mountains may 
show itself along the coasts of Scandinavia; perhaps Australia may 
hereafter experience some of those underground convulsions which 
are now so rife amongst the islands of the Pacific. 
And if so, what an impression is conveyed to the mind as to the 
length of time which must have elapsed since the planet we inhabit 
was first called into existence, or, indeed, even as to the number of 
years which have rolled on since the commencement of organic life. 
For from the period occupied by one only of these epochs, that 
which has been pointed out in Auvergne, we may form some slight 
estimate of the remainder, and the aggregate certainly presents an 
idea of past time which it is difficult for our limited faculties fully 
to realize. 
