ON THE FORMATION OF CRYSTALLINE ROCKS. 303 



ducts. Bj a true metamorphic action the water of this primitive 

 ocean first caused the structure proper to these melted masses to dis- 

 appear by penetrating them, and afterwards formed, as in our tubes, 

 crystallized minerals by means of the very principles which had 

 caused it to dissolve them. These matters formed or suspended in 

 the midst of the liquid, would be precipitated to its bottom with 

 variable characters in the deposit, in proportion as the heat of the 

 liquid diminished. Are these different periods of chemical decompo- 

 sition and recomposition, in which the wet way intervenes under those 

 extreme conditions which touch so nearly on the dry way, the era of 

 the formation of granite and of the schistose rocks which are alto- 

 gether azoic and crystallized ? We cannot afiSrm it absolutely, but 

 ■we must presume so, especially if we consider that on this hypothe- 

 sis there have been formed two series of products, the one entirely 

 massive, the other presenting traces of sedimentary origin, and which 

 connect themselves one with the other in an insensible manner. This, 

 in effect, is what exists in nature with regard to granite and gneiss. 



In concluding I will remark, that if there has ever been a time 

 "when rocks were exclusively under the dominion of the dry way, they 

 have passed under the regime of the wet way at an epoch much more 

 remote than has until lately been supposed. We can hardly find now 

 on the globe rocks to which we can assign with entire certainty a 

 formation exclusively due to the dry way, without any concurrence 

 of water. There is, however, an example which shows us what rocks 

 of such a kind might be, and it is furnished us by the aerolites. These 

 bodies in effect do not offer in their essential constitution either water 

 or hydrated combinations. Is it not singular that, formed of silicates 

 of the same bases as those of our globe, they have never presented 

 either quartz, mica, or granite, but bodies which we do not meet with 

 on the crust of the earth, such as metallic iron and metallic phosphu- 

 rets and carburets ? The existence of these bodies appears wholly to 

 protest against the presence of water. Is not this a new motive, al- 

 though a little far-fetched it is true, for believing in the impotence 

 of heat alone to produce granite ? 



According to the hypothesis which we have just mentioned, the 

 first deposits of the sea would have remained a long time in a soft 

 state eminently favorable to the production of the schistose structure. 

 The lamellas of these rocks, as well as of those of the more recent 

 metamorphic formations, have in general a position near the vertical, 

 even outside of mountain chains in countries like Sweden, the Li- 

 mousin, and Moravia, the outlines of which present nothing peculiar. 

 From what we have said above on the production of a lamellar struc- 

 ture, the lateral pressures to which it appears to owe its origin must 

 have acted almost horizontally. They were probably of the same na- 

 ture as the compression which afterwards gave rise, in more solid 

 stratified formations, to those difi"erent foldings and convolutions Avhich 

 characterize mountain chains. Thus, as tlie fibrous structure of iron 

 shows the mechanical action that it has undergone, so these more an- 

 cient formations appear even then to have testified to the force of 



