270 



THE WONDERS OF GEOLOGY. Lect. III. 



depth, and a lava current, which first falls down a steep 

 declivity, and then rolls over the plain in hilly waves of 

 black and scorified rocks. In one part of this volcanic 

 group is a circular system of cones, apparently the produce 

 of several rapidly succeeding eruptions. " The extra- 

 ordinary character of this scene impresses it for ever 

 on the memory ; for there is, perhaps, no spot, even among 

 the Phlegrsean fields of Italy, which more strikingly dis- 

 plays the characters of volcanic desolation.* Although 

 the cones are partially covered with wood and herbage, yet 

 the sides of many are still naked ; and the interior of their 

 broken craters, rugged, black, and scorified, as well as the 

 rocky floods of lava with which they have loaded the plain, 

 have a freshness of aspect, such as the products of fire 

 alone could have so long preserved, and offer a striking 

 picture of the operation of this element in all its most 

 terrible energy." f The accompanying sketches J will illus- 

 trate these remarks. 



Plate II. fig. in. A view of the environs of Clermont. 

 In front is a basaltic peak, crowned by the Castle of 

 Montrognon ; and beyond are basaltic platforms (indicated 

 by the dark lines of shade) on hills of limestone. The town 

 is seen in the plain or basin, which has been excavated by 

 diluvial agency, since the deposition of the strata which 

 form the surrounding hills. In the distance is the primary 

 escarpment, forming part of the boundary of the volcanic 

 district. 



Fig. ii. Part of the southern volcanic chain of Puys, 

 exhibiting the broken craters of Chaumont ; from the 

 bases of several the cooled lava currents still remain as 

 when they issued. Mont Dome appears in the distance. 



* Plate II. represents a part of this chain of extinct volcanic rocks ; 

 with Mont Dome in the distance. 



f Scrope's Geology of Central France. 



X The delineations are reduced from the elaborate and beautiful 

 drawings of Mr. Scrope. 



