OF THE MALVEKX HILLS. 



511 



With these exceptions, I am disposed to let the remainder of the 

 section (appended to Part I.) stand as it is for the present, since it 

 is merely intended to represent diagrammatic ally what may be, and 

 is based upon a ver}?- limited foundation of observed facts. 



The foliated finely-crystalline gneiss, micaceous schists, and quart- 

 zites in the south of the range appear to represent a series of altered 

 and probably once-stratified rocks, such as sandstones, and micaceous 

 and felspathic grits, and these graduate, as we pass northwards, into 

 gneissic rocks, which probably represent coarse tufts and detrital 

 deposits, composed almost wholly of materials derived from the 

 waste of plutonic rocks. These are associated with plutonic rocks 

 of similar mineral constitution, probably in some cases of a later 

 date, but still of immense antiquity. 



It may also be a point of some significance that in what is here 

 regarded as the Lower gneissic series we have hornblende in great 

 quantity ; in the Middle series the rocks become partly micaceous 

 and partly hornblendic : while in the Upper gneissic series, horn- 

 blende is almost or totally absent, and the rocks in the lower part 

 of this Upper series are very micaceous. The mica, however, becomes 

 less and less plentiful as we pass southwards, until, in the upper part 

 of this Upper series, it is present either in very small quantity or 

 disappears altogether, as in the quartzites. There is, in fact, as we 

 pass from the north to the south of the Malvern Range, a diminution 

 in the percentage of those minerals which have the greatest density. 



Although in this paper it is assumed that the rocks of the Malvern 

 Hills are partly eruptive and partly detrital, the latter showing under 

 the microscope no distinct pseudo-fluxion structure such as would be 

 expected in cases of well-marked pressure-metamorphism, yet it is 

 quite possible that the foliation in some of these rocks may be due 

 to the latter cause. 



One of the strongest arguments in favour of such an hypothesis is 

 that foliated or gneissic diorite is here and there found in contact 

 with non-foliated diorite, while gneissic quartz-syenite also occurs in 

 contact with quartz-syenite in which no foliation is discernible. 



That the mass which constitutes the main ridge of the Malvern 

 Hills has experienced repeated movements and dislocations coupled 

 with great stresses there can be no doubt. Hence there is strong 

 probability that pressure-metamorphism has had some share in de- 

 veloping the minute structural characters of these rocks. Distinct 

 evidence upon this point seems, however, as yet, to be wanting : and 

 therefore, although willing to make all due concession to the advo- 

 cates of pressure-metamorphism, on the production of sufficient 

 proofs, I am for the present disposed to hold by the opinions which 

 I have already stated, modifying them only to the extent here 

 indicated. 



There are probably many exposures of rock, south of the Worces- 

 tershire Beacon, which the limited time at my disposal prevented me 

 from visiting, nor am I sure that, among the specimens which I 

 collected, there may not be many which would present fresh points 

 of interest if examined microscopically. In those which have been 



2m 2 



