ASSOCIATED METAJIORPJIIC HOCKS OF THE LAKE-DISTRICT. 23 



beneath the rocks in connexion with which it now occurs, and in- 

 truded into its present position, or by metamorphism in situ? 

 If A, or even D, be contrasted with C, the difference in composition 

 is at once seen to be striking, especially with regard to the relative 

 proportions of silica and of ferrous oxide. On the other hand, 

 when C is contrasted with E, the general correspondence is well 

 marked. The same applies also to B — a considerable divergence 

 between it and A or D, and a marked correspondence between 

 it and E. Hence we may infer that, in so far as these few 

 analyses represent the average composition of the rocks, it is 

 quite possible that both the quartz felsite and the syenitic granite 

 may be due to the extreme metamorphism in situ, of beds of the 

 volcanic series. And, further, the presence of bands of Skiddaw 

 slate, interstratified with volcanic ash or trap, might tend to modify 

 the result, some bands of slate (probably the black shaly bands) not 

 yielding themselves readily to the change, and therefore remaining 

 as such, and others, more highly silicated, such as the example from 

 How Gill, becoming likewise transformed into the crystalline rock, 

 though, perhaps, less decidedly so. "We have already seen what 

 evidence there is in the field to support the view that these felsitic 

 and syenitic rocks represent or take the place of beds of the volcanic 

 and Skiddaw series ; and I am inclined to think that the evidence of 

 chemical composition goes some way towards strengthening that view. 



That these masses of St. John's and of Buttermere were probably 

 consolidated at a very considerable depth has already been shown 

 in the first part of this memoir, when dealing with the evidence of 

 the liquid-cavities in the quartz ; and it becomes a question how far 

 metamorphism, carried on thus deeply, may be accompanied by an 

 introduction of an additional amount of silica from below. 



Finally, I would by no means wish to assert that no part of the 

 masses in question is intrusive. 'With regard to that of St. John's, 

 occupying only a small area, it may perhaps be so, any intrusive 

 appearance which the rock may now have being probably the result 

 of the subsequent faulting (see map, fig. 1, p. 13). But in the case of 

 so large an area as that of the Buttermere and Ennerdale rocks, it is 

 most probable that, even if we suppose the whole mass to be due to 

 the metamorphism of beds of the volcanic and Skiddaw series, some 

 measure of intrusion among and absorption of overlying beds may 

 have taken place over certain tracts. 



The comparatively large percentage due to " loss on ignition " in 

 A and B represents carbon and water in the following proportions : — 



A. B. 



\Vater 1-704 -752 



Carbonaceous matter .... -361 *797 



2-065 1-549 



2. Rocks of Carrock Fell. — I have had analyses made of typical 

 samples of (F) spherulitic felsite of Carrock Fell, and (G) hyper- 



