Metamorphic Changes of Rocks, <^c. 119 



M. Fournet attributes to water in a state of incandescence, a 

 very powerful dissolving and penetrating influence in effecting 

 those modifications which are so extensive that they may almost 

 be denominated complete transformations ; and, in fact, it was 

 quite necessary that he should admit, in a liquid so abundant 

 ^nd so common, a condition which was altogether extraordinary, 

 ere it could effect transformations which, in the existing state of 

 nature, appear to us as anomalous and astonishing as incandes- 

 cent water itself. 



Many of these views concerning the transformation of rocks 

 by the agency of powerful geological operations, whether more 

 actively, or more slow and gradually, have been proposed by 

 different geologists, but in a manner which appears much more 

 hypothetical, since they were not supported either upon ade- 

 quate observations or upon chemical data. It may almost be 

 asserted that the ideas concerning the transformation and pass- 

 ing of one rock into another, belongs to that class which sug- 

 gests itself to every one ; but they have rarely been based upon 

 a critical and serious examination, and when the proof is de- 

 manded, nothing but the most vague generalities are almost in- 

 variably supplied. It is thus that both Hutton and Playfair 

 have endeavoured to explain the formation of granite rocks by 

 the solidification, through means of the high internal tempera- 

 ture of the earth, of the sediment conveyed by the course of 

 waters to the bottom of the sea. Sir James Hall suggested that 

 fusion under high pressure might account for the formation of 

 certain rocks in which the gaseous elements were still retained. 

 Dr MacCulloch, and more recently M. Virlet, have since prose- 

 cuted the same subject. The first learned geologist, ingenious 

 observer, and able chemist, made and published in his work on 

 the Scottish Isles, and in papers in the Transactions of the 

 Geological Society, observations concerning the attraction, and 

 the mechanical, and likewise the chemical transformation of 

 rocks, which, being nearly of the same character as those con- 

 tended for by M. Fournet, strongly support the results deduced 

 by this latter gentleman, and prove, by the agreement in the 

 facts and the explanations, that these are not cjuite so hypothe- 

 tical as we might be led to suppose. 



But the previously collected facts which led to tlic admission 



