﻿84 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 18. 



period, because it is manifest, that, since it occurred, there have been 

 considerable changes, in one of which the gravel and debris alluded to 

 were spread over the tops of the broken and eroded strata (see fig. 2, b) . 

 The fissure at Vichy was therefore probably produced at the period of 

 the emission of the domites, trachytes, and earlier basalts, which, as 

 volcanic outbursts, have little reference to the existing geography of 

 the region. I can now, however, say no more in respect to the earlier 

 volcanic operations of Central France, except to connect them in my 

 mind's eye with the fracture along which the waters of Vichy were 

 first evolved. The full explanation of this subject would require a 

 long memoir, and much more attention than I have paid to the sub- 

 ject. I will conclude, therefore, for the present, with pointing out, that 

 the fracture of the Celestins, and the line on which the thermal waters 

 of Vichy issue, being from S.S.E. to N.N.W., is parallel not only to 

 the depression in which the Allier there flows (probably also a fis- 

 sure *), but also to the major axis of the Forez, with its old deposits 

 and porphyritic rocks. 



* A minor issue of mineral springs, apparently parallel to the fissure at "Vichy, 

 occurs on the opposite bank of the Allier. 



