the Formation of Rocks. 183 



increased their dimensions beside, and over one another, in all 

 directions. We have also to take into consideration the quan- 

 tity of water which must have been required for the solution, 

 and of which we are totally ignorant as to where it has gone^ 

 unless we adopt the idea to which Werner was inclined, that 

 the largest portion of it has been transported to another heavenly 

 body. 



On the other hand, there are important arguments opposed to 

 the Plutonic theory. Such, for example, is the behaviour in the 

 fireof those mineralswhich constitute the component partsof Plu- 

 tonic mountain- rocks. How are we to explain the occurrence 

 of various minerals in compound stony masses, when we find 

 easily or difficultly fusible, or apparently infusible substances, 

 not only lying next one another, but very frequently imbedded 

 in, or penetrating one another, so that their simultaneous origin 

 cannot be doubted ? How is such a relation to be explained 

 if the whole had been melted together into a homogeneous 

 mass ? It is true that, in furnaces, crystals resembling minerals 

 have been formed, but a compound like granite has never been 

 thus produced. Had granite been fused, the quartz would have 

 crystallized first of all, and long afterwards the crystals of fel- 

 spar and mica would have been formed, according to the very 

 different degrees of fusibility and solidifying power of these 

 three substances. But how, under these circumstances, could 

 they have been blended with one another as we now find them, 

 and as they also occur with other minerals, which are partly 

 more refractory than quartz, and partly more easily fusible than 

 felspar and mica ? In my opinion, this is altogether impos- 

 sible ; and, on this circumstance alone, apart from all other 

 grounds of objection, I think that the elevation theory must be 

 regarded as untenable. To this is also to be added the consi- 

 deration, that, in granite and similar rocks, no trace has hither- 

 to been found of a vitreous substance, which we sliould expect 

 if they were products of fire. 



What stood chiefly in the way of the Neptunian theory, was 

 the assumption that all rocks had been dissolved in water, a 

 supposition which cannot be conceded by chemistry. This opi- 

 nion found support, more especially in the crystalline nature of 

 the mountain-rocks, and particularly of the older ones, which 



