300 On the relative Age of the 



the system of which Ventoux forms a part, none of the species 

 of sedimentary formation are horizontal, the whole four being 

 raised. When Ventoux rose, therefore, the alluvial formation 

 itself had already been deposited. 



In commencing this article, I announced, however singular it 

 must have appeared, that the relative antiquity of the different 

 chains of the European mountains had been discovered. We 

 now see that M. de Beaumont's observations have even done 

 more, since we have been able to compare the age of the forma- 

 tion of the mountains with that of the various sedimentary de- 

 positcs. 



I have already called the attention of the reader to the un- 

 known but necessary causes, which have induced variations so 

 abrupt in the nature of the deposites formed by the waters at 

 the surface of the globe. M. de Beaumont's investigation per- 

 mits us to add to what had been conjectured respecting the nature 

 of these revolutions, some positive notions which arc as follows : 



The sedimentary formations seem, by their nature and the 

 regular disposition of their beds, to have been deposited in times 

 of tranquillity. Each of these formations being characterized 

 by a |")eculiar system of organized beings, vegetable and animal, 

 it was indispensable to suppose that between the periods of tran- 

 quillity corresponding to the precipitation of two of these super- 

 imposed formations, a great physical revolution had taken place 

 upon the globe. We now know that these revolutions have 

 consisted of, or at least have been characterized by, the uprais- 

 ing of a system of mountains. The two first raisings pointed 

 out by M. de Beaumont not being by any means the greatest 

 among the four which he has succeeded in classifying, it will be 

 seen that it cannot be said that, in growing old, the globe be- 

 comes less liable to undergo these catastrophes, and that the 

 present |x.>riod of tranquillity may not terminate, like the prece- 

 ding, by the sudden irruption of some immense chain of moun- 

 tains. 



Since it remains established that the mountains have not 

 emerged from the globe at the same epochs, it were natural to 

 examine if the contemporaneous mountains do not present some 

 relations of position between each other, This inquiry could 



