300 EXPERIMENTS ON METAIIORPHISM AND 



the Pyrenees * &c. We meet with these analogies still more strongly 

 characterized in the metalliferous deposits, which appear to be also a 

 product of like origin, and although the greater part of them contain 

 numerous mineral species often distributed in a very unequal manner 

 in different parts of the same vein, the nature of the gangues, as well 

 as that of the metals, which can be mined Avith profit, show they are 

 generally grouped in systems. These systems sometimes embrace 

 entire regions, especially on the continents whose geological structure 

 is not parcelled out like that of Western Europe; as, for instance, the 

 argentiferous groups of Mexico, the great auriferous bands of the 

 Alleghanies and Brazil, the stanniferous zone of Malaya. 



The same fact is well known of volcanoes. If there are any that 

 are isolated, the greater part constitute a series, as de Buch long 

 ago demonstrated, when he compared them to vents which had been 

 formed on a line of the same great fault. As to earthquakes, we 

 shall only mention them to associate them with volcanoes, to which 

 they seem so intimately related. 



The families of thermal springs, of metalliferous veins, of volcanoes 

 with their earthquakes, occupy extents quite comparable to those 

 which we have established for regional metamorphism, the seat of 

 which occupies entire countries. As with all these families, the met- 

 amorphic formationst are exclusively confined to regions where dis- 

 locations have taken place. 



On the one hand, in effect, the oldest stratified formations of Russia 

 and Southern Sweden, as well as those of North America, which have 

 preserved their primitive horizontal position, are not sensibly trans- 

 formed. On the other hand, the recent formations, but whose strati- 

 fication is very much disturbed, such as the Jurassic and cretaceous 

 beds of the Alps, the Apennine mountains, and Tuscany, have, on 

 the contrary, been entirely modified, even where there are only a 

 few eruptive masses. The phyllades are but the first term of much 

 deeper transformations ; so they are never found outside of zones 

 which have been more or less dislocated. 



It is, then, difficult not to see, in these different kinds of phenomena 

 of which I have just spoken, the manifestations of one and the same 

 agent, whose seat extends beneath entire countries. This essential 

 agent is water, aided by heat of different intensities, with which are 

 joined, as secondary causes, the emanations which accompany it. 

 For volcanoes the thing is evident ; for metalliferous veins there can 

 hardly be any doubt, especially after the labors of Elie de Beau- 

 mont and the experiments of de Scnarmont; and with regard to 

 metamorphism we think that our assertion has become extremely 

 probable. Thus we think that water acts without cessation in the 

 lower regions of the earth, after having there acquired a temperature 



"-■ Longscliamp remarked that ia the enth-e length of this chain, which is more than 

 sixty miles, there are more than one hundred and fifty springs, all of the same kind, and 

 only differing within very narrow limits by the proportion of their elements. — {Memmr 

 read at the Acadmy of Sciences, August 12, 1833.) 



t At the least, those that are posterior to the silurian formation. 



