ECCEXK PERIOD. [Ch. XIX. 



of the period under consideration, and shall then proceed to 

 show that there arc in the same country volcanic rocks of 

 much newer date, sonic of which appear to be referrible to the 

 Miocene era. 



Volcanic rocks associated with Lacustrine inAuvergne. The 

 first locality to which we shall call the reader's attention is Pont 

 clu Chateau near derm on tj where a section is seen in a preci- 

 pice on the right bank of the river Allier *. Beds of volcanic tuff 

 alternate with a fresh-water limestone, which is in some places 

 pure, but in others spotted with fragments of volcanic matter, 

 as if it were deposited while showers of sand and scoria? -were 

 projected from a neighbouring- vent -J-. This limestone contains 

 the Ili'lix Ramondi and other shells of Eocene species. It is 

 immaterial to our present argument whether the volcanic sand 

 was showered down from above, or drifted to the spot by a 

 river, for the latter opinion must presuppose the country to 

 have been covered with volcanic ejections during the Eocene 

 period. 



Another example occurs in the Puy cle Marmont, near 

 V eyres, where a fresh-water marl alternates with volcanic tuff 

 containing Eocene shells. The tuff or breccia in this locality 

 is precisely such as is known to result from volcanic ashes 

 falling into water, and subsiding together with ejected frag- 

 ments of marl and other stratified rocks. These tuffs and 

 marls are highly inclined, and traversed by a thick vein of 

 basalt which, as it rises in the hill, divides into two branches. 



Geryoma. The hill of Gergovia near Clcrmont affords a 

 third example. We agree with MM. Dufrenoy and Jobert 

 that there is no alternation here of lava and fresh-water strata, 

 in the manner supposed by some other observers J; but the 

 position and contents of some of the mil's prove them to have 

 been derived from volcanic eruptions which occurred during 

 the deposition of the Eocene formations. 



* Tins place, and all the others in Auvcr^nt 1 . mentioned in this chapter, were 

 examined by the author, in company with Mr. Murcliison, in 182S. 



} See Scrope's Central France, p. -1. J Scrope ; ibid. p. 7, 



