50 DOMAIN I. SIDEROUS. 



the surface of the globe presents : it is posterior 

 to the entire excavation of the valleys, since it 

 occupies their bottoms. 



" 2d. Basalts. The volcanic productions of 

 the second kind, are basalts, which, under the 

 form of sheets, tables, peaks, cover the elevated 

 parts of the ancient soil, or constitute the sum- 

 mit of some mountains and isolated eminences ; 

 they are also observed on almost all the skirts of 

 Mont Dor and Cantal ; they are evidently only 

 the remains and patches of different currents, 

 which have spread over the country; they pre- 

 sent the same mineralogical characters as the 

 basalts of other countries, Saxony, &c. ; they 

 contain the same substances ; they equally in- 

 cline to a prismatic division ; they cover without 

 distinction all kinds of rocks, and are never 

 covered by them, &c. 



" A volcanic origin cannot be denied to these 

 basalts. The perfect resemblance between their 

 paste and that of some parts of currents of lava 

 which are found in the neighbourhood, and 

 which have come from a crater still existing, is 

 already a very strong presumption; but they 

 present other infallible marks of this origin. 

 1. In following step by step certain masses of 

 basalt which are near Mont Dor and Cantal, 

 and supplying by the imagination what has vi* 



