458 J)r. Irving — The Malvern Crystallmes. 



those of a more basic chai'actei') may be seen ; and in places — as in 

 Eushy Valley above Great Malvern, and in the Raggedstone quarry 

 — the basic minerals have been more completely pulverised and 

 rendered incoherent by the grinding action to which they have been 

 subjected between the harder and more rigid felspathic masses. 

 This was observed to be especially the case where the stratiform 

 structure of the rock had suffered considerable contortion against 

 massive intrusive dykes of basic rock/ and is, therefore, one of the 

 phases of deformation which may be with some certainty referred to 

 dynamic action since the consolidation of the whole mass. Where 

 this seems to have been excessive, some mica has made its appearance 

 in the felspathic distorted bands of the rock, probably at the expense 

 of the original felspar. 



(iii.) PhyJlolithic rocks approximating in various degrees to true 

 schists. These seem to be very local in their development. 



(a.) Hornblende-schists, In some of these the deformation of the 

 hornblende crystals is the chief feature ; and it seems probable that 

 this mineral deformation, without any conspicuous shearing-move- 

 ment, has occurred since the mass became fairly solid, and as a 

 result of static rather than dynamic forces. It seems to occur in the 

 more massive portions of the diorite, even where the rock-mass as a 

 whole assumes a stratiform character, as in the large quarry at 

 Wind's Point and in the quarries at Little Malvern. Something of 

 this sort of crumpling was observed also in the more basic rocks 

 extensively quarried at the Hollybush Pass. 



In other cases distinct parallel planes of foliation, with marked 

 differentiation of the minerals are seen, and lenticular plates of 

 quartz are common, sometimes a quarter of an inch or more in 

 thickness. This structure is well seen in the larger of the two old 

 quarries at the south end of Raggedstone Hill, in the crags on the 

 ridge south of the Wych, and in the crags near the ridge nearly half 

 a mile north of the Wych above Rock Villa. Observations in the 

 field make it difficult to resist the conclusion that these local develop- 

 ments of an apparently perfect schist are directly related to the 

 greater resisting-power of the already consolidated felspathic masses 

 contiguous to them, with which, in every case, so far as the writer's 

 observations go, they are in close relation, either alternating with 

 such masses (as in the crags mentioned), or the schistosity (as in the 

 Raggedstone Quarry) being most definite and perfect in close 

 contiguity with massive quartzo-felspathic veins, and gradually 

 dying away into the undeformed hornblendic mass. The deficiency 

 of felspar — if not the entire absence of that mineral — seems to be 

 accounted for by its previous concentration in the adjoining felspathic 

 veins ; while the flattening out of the quartz has taken place in such 



1 On the top of the crag referred to {Ante p. 454) on the south side of Rushy 

 Valley the granite becomes flaggy close to the junction-planes, as if from shearing, 

 while the dolerite on the other side of the junction-plane is crushed to a breccia. In 

 another crag lower down the gneissose granite is bent round against a massive 

 dolerite. Good examples of this gneissose structure may be seen by the footpath, 

 halfway up the hill. 



