,Ch. X.] ON THE PRIMARY ROCKS. 199 



those which are interstratified with the gneiss and mica-slate 

 of Norway and Sweden, and with the talc-schists of the 

 Higher Alps, and similar formations ? It is true, these are 

 of much greater extent, and the smaller beds are generally 

 more regularly disposed in their alternations with the schistose 

 rocks ; but this is no criterion on which to found a distinc- 

 tion, for if in those countries where the large masses of granite 

 occur in central rounded patches, the smaller ones have the 

 form of beds, possessing considerable uniformity with the 

 containing strata, it is not surprising that where the main 

 masses themselves appear to be stratified, that the lesser ones 

 should exhibit the same characteristics in a higher degree. 

 Indeed, the apparent perplexity of such a constitution of the 

 primary districts is diminished, since we have learnt that 

 even the granitic masses of Ireland and Cornwall are com- 

 posed of an accumulated series of layers or beds, having a dis- 

 position to determinate bearings both in strike and dip ; 

 which is confirmed, if any farther evidence be necessary, by 

 the fact just mentioned, that these beds sometimes extend far 

 beyond the limits of the granite ; and, when in the slate, bear 

 the same relations thereto, as those granitic beds which seem 

 to be wholly enveloped in the primary strata. 



Some have argued from the arrangement of the granitic 

 rocks in the northern part of Europe, that they are, in these 

 cases, stratified ; others are of opinion, that, like the trap and 

 volcanic rocks, they have been intruded between the beds of 

 slate, and consolidated in this position. We shall not, in this 

 place, enter into an examination of either supposition : our 

 only object by these remarks, and by the details in the pre- 

 ceding chapters, is to induce a conviction, if possible, that all 

 the granitic masses, whatever may be their form or position 

 among the slates, are of the same nature, as are likewise the 

 individual rocks of which such granitic groups are composed. 



It may perhaps be conceded, that all granitic rocks are 

 analogous in composition, structure, and mode of formation ; 

 but that they belong to different epochs. But by so doing, 



