218 
MIOCENE PERIOD. 
[Ch. XVI. 
then inhabiting the country were buried. The trachytic 
breccia cl was then superimposed ; this breccia is an aggregate 
of shapeless and angular fragments of trachyte, cemented by 
volcanic tuff and pumice, resembling some of the breccias 
which enter into the composition of the neighbouring extinct 
volcano of Mont Dor in Auvergne, or those which are found 
in Etna. Upon this rests another alluvium c, which also con- 
tains the bones of Miocene species, and this is covered by 
another enormous mass of tufaceous breccia. We suppose the 
breccias to have resulted from the sudden rush of large bodies 
of water down the sides of an elevated volcano at its moments 
of eruption, when snow perhaps was melted by lava. Such 
floods occur in Iceland, sweeping away loose blocks of lava 
and ejections surrounding the crater, and then strewing the 
plains with fragments of igneous rocks, enveloped in mud or 
' moya.' The abrupt escarpment presented by the above- 
described beds, b, c, d, e, towards the valley of the Couze, must 
have been caused by subsequent erosion, whereby a large por- 
tion of those masses has been carried away % 
In the alluviums c and e, MM. Croizet, Jobert, Chabriol, and 
Bouillet have discovered the remains of about forty species 
of extinct mammalia, the greater part of which are peculiar 
as yet to this locality ; but some of them characteristic of the 
Miocene period, being common to the faluns of Touraine, and 
associated in other localities with marine Miocene strata. 
Among these species may be enumerated Mastodon minor 
and M. arvernensis, Hippopotamus major, Rhinoceros lep- 
torhinus and Tapir arvernensis. The Elephas primigenius, a 
species common to so many tertiary periods, is also stated to 
accompany the rest. In some cases the remains are not suf- 
ficiently characteristic to indicate the exact species, but the 
following genera can be determined: the boar, horse, ox, 
hysena (two species), felis (three or four species), bear (three 
* For an account of the position and age of the volcanic breccias of Mont 
Perrier and Boulade, see Lyell and Murchison on the beds of Mont Perrier, Ed. 
Jfew Phil. Journ., July, 1829, p. 15. 
