466 ORIGIN OP ERUPTIVE AND PRIMARY ROOKS. 



line rocks, which occur, on the one hand, as undoubted primitive, 

 and on the other as newer products, make it advisable to class- 

 both together under the common name of the cryptogenous form- 

 ations, or also of the stratified silicate formations." 



" Many, perhaps even the most of the geologists of the present 

 day, are of the opinion that the strata of the primitive formation 

 are very ancient metamorphic sedimentary strata. Until convinc- 

 ing proofs are adduce! in support of this view, it may however, 

 only be excused as an attempt to bring incomprehensible pheno- 

 mena into unison, at least hypothetically, with comprehensible 

 appearances. 'Whereupon,' asks Humboldt, 'do the oldest sedimen- 

 tary rocks rest, if gneiss and mica-schist are only to be regarded 

 as altered sedimentaay strata V Cosmos, i., p. 299." 



It is very evident from the foregoing, that Naumann leans to 

 the opinion that the primitive formation is the result of the first 

 process of solidification which the fluid globe underwent. He 

 refrains from declaring himself in favor of this idea, principally on 

 the grounds mentioned in another chapter of his " Lehrbuch," a 

 translation of which has already been given in this Journal.* 

 These grounds are the foliated texture of gneiss and its associated 

 rocks, and the highly inclined position of their strata. The first 

 of these phenomena I have already attempted to account for. We 

 shall, in the course of the following remarks, endeavour to ascer- 

 tain whether the almost vertical position of the primitive strata is 

 also capable of being explained. 



la regarding gneiss as an igneous rock, there are, of course, the 

 same difficulties arising from its mineralogical composition, to be 

 explained away, as in the case of granite, but these we intend to 

 postpone ^considering, until we come to speak of the protrusion of 

 the latter rock. The same mode of explanation adopted in the 

 case of gneiss, would of course require to be resorted to in the 

 case of the schistose rocks associated with it, especially such as 

 mica-schist and hornblende slate. We must not suppose thai the 

 latter rock was formed from the same zone of igneous material as 

 the gneiss, but on the contrary, that it is the product of some of 

 the lower zones, brought up to the newly formed crust by cosmical 

 influences, and consolidated on the inner part of the same, sub. 

 ject, of course, to the same influences during its solidification as 

 we have supposed in the case of gneiss, We thus suppose that 

 the first stage of the consolidation of the globe consisted in the 



* Vol. vH, p. 254. 



