218 MIOCENE PERIOD. 



[Ch.XVL 



then inhabiting the country were buried. The trachytic 

 breccia d 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 9 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, 

 hyaena (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. 

 New Phil, Journ., July, 1829, p. 15. 



