266 



THE WONDERS OF GEOLOGY. Lect. III. 



cannot be doubted that shoals of fishes may at the same 

 time have been enveloped in the volcanic matter at the 

 bottom of the sea, and become compressed and preserved ; 

 and when the mud which envelopes them is consolidated, 

 and the bed of the Mediterranean elevated above the 

 waters, these fishes may resemble the ichthyolites of Monte 

 Bolca.* 



46. Tertiary volcanoes of France. — In the former 

 lecture I alluded to volcanic action as still in activity, and 

 as having been equally energetic in more ancient periods ; 

 and there is abundant proof, that during the immense lapse 

 of time comprehended between the earliest and the latest of 

 the tertiary formations, the internal fires of our globe were 

 not dormant. We have already had occasion to remark 

 how rarely the former geographical relations of a country 

 are preserved, and that though we may be able to pronounce 

 with certainty that this spot was once dry land, — that 

 yonder flowed a river, — that here is the bed of an ancient 

 sea, — yet we can seldom determine the limits of the one, or 

 trace the boundaries of the other. But there is one re- 

 markable exception — a district, where the most striking 

 geological revolutions have taken place, and yet the area 

 of those changes still maintains its ancient physical geo- 

 graphy — that district is Auvergne, a province in central 

 France. 



Nearly a century since, two French academicians, MM. 

 Guettard and Malesherbes, on their return from an explo- 

 ration of Vesuvius, arrived at Montelimart, a small town 

 on the left banks of the Rhone, where Faujas St. Fond, a 

 distinguished naturalist, was sojourning. These savans 

 were struck with the remarkable character of the pavements 

 of the streets, which were formed of short joints of basaltic 

 columns, placed perpendicularly in the ground ; and upon 

 inquiry they found the stones had been obtained from the 



* See Lecture VIII. 



