274 



EXTINCT VOLCANOES NEAR THE RHINE. 



The basaltic rocks also extend south of Clermont, into the districts 

 called the Velay and Viverrais, and cover a great portion of the soil. 

 Near Monpezat, Thueys, and Jaujac, according to M. Faujas St. 

 Fond, there are small volcanic mountains, with distinct currents of 

 lava, that appear to issue from their feet, and flow into the valleys. 

 The lower part of the lava is scoriaceous, but the upper part is hard 

 sonorous basalt, arranged in columns as perfect as those of Staffa or 

 the Giant's Causeway. We have here a decisive proof of the ig- 

 neous formation of columnar basaltic rocks. "The basaltic forma- 

 tion extends into the South of France, to the borders of the Medi- 

 terranean Sea, where, near to Adge, is the extinct volcano of Saint 

 Loup, the cellular lava of which is employed in the construction of 

 buildings on the canal of Languedoc." — Dauhuisson.^ 



There are numerous extinct volcanoes in several parts of Germa- 

 ny, particularly in some of the districts bordering the Rhine : these 

 volcanoes, like those of central France, belong to different epochs, 

 but the most recent appear to be more ancient than the earliest peri- 

 ods of authentic history. In the volcanic district of Eyfel, between 

 the Rhine and the Moselle, are scattered numerous small cones and 

 eminences some with craters, the bottoms of which are filled with 

 water, forming lakes or meres, without oudets. A German geolo- 

 gist divides these volcanoes into three classes : — 



1. Those which have lakes or meres, and have ejected nothing 



but loose fragments of rock with balls of scoriae and sand : 

 of these there are eight in that district. 



2. Those which have ejected fragments of slag, sometimes loose, 



and sometimes cemented : of these there are eight. 



3. Those which have ejected streams of lava : of these six are 



enumerated. 



According to Dr. Daubeny, who has visited these craters, the 

 currents of lava have not been satisfactorily traced to their source, 

 being sometimes buried under heaps of volcanic matter subsequently 

 ejected. These volcanoes rise through transition rocks of slate and 

 limestone. The Seven Mountains near Bonn, belong to a very re- 

 mote volcanic epoch. Those readers who intend to visit the coun- 

 tries near the Rhine, will do well to consult Dr. Daubeny's work on 

 volcanoes, in which will be found the best information respecting the 

 extinct volcanoes of Germany. 



In proportion as the surface of the earth becomes properly exam- 

 ined, our knowledge of extinct volcanoes in various countries is en- 

 larged. According to Burckhardt, there are several in Arabia : a 



*In the article "Volcano," which I wrote for Dr. Rees's Cyclopasdia, I endeav- 

 voured to collect all the most important details of volcanic phenomena then known 

 and have given an account of different experiments made on lava by Spallan- 

 zani and others, which the limits of the present volume will not allow rne to no- 

 tice. 



