Dr. Irving — The Malvern Crydallines. 457 



what rounded (as the quartzes are known to be in quartz-porphyry 

 from abrasion in a viscous "flowing" magma), and arranged in 

 linear series, reminding one of a loose string of beads. The rock 

 has at the same time become distinctly fissile under the hammer in 

 the direction of the foliation.' Kneading-out or stretching-out rather 

 than crushing-out seems to have been the order of things in such 

 cases. This description applies to the "shear-zones" of Dr. Callaway. 

 Good examples are seen in the Gullet Quarry (south end of Swinyard 

 Hill), in the quarry south of the Wych Pass (where larger masses 

 of felspathic material are di'awn out into slabs), in all the three 

 quarries at West Malvern,^ and at North Malvern above the reservoir, 

 where they bear no relation whatever in their orientation to the 

 crush-planes exposed in the quarries below. The differential move- 

 ment in such cases, so far as each plane of shear is concerned, seems 

 to have been but slight ; no more, in fact, than could be referred to 

 unequal contraction of adjacent portions of the rock-mass during the 

 later stage of consolidation. In some cases, as in the quarry above 

 the church at West Malvern, such a foliated zone occurs on both 

 sides of a divisional plane, as if the shearing had been produced by 

 sliding along a shrinkage-crack, while the mass on either side of it 

 (in this case a very felspathic variety of diorite or a biotite-granite) 

 was still in a pasty condition. 



Diorite-gneiss would seem to result from the segregation of 

 minerals in the course of their development ; and its conversion 

 locally into " diorite-schist " (amphibolite) to differential movement 

 ^rior to final consolidation of the materials. The idea suggested itself 

 to the author when Dr. Callaway's paper was read at the Geological 

 Society in 1889, and certainly seems to work yery well in the field. 



(ii.) Gneissose (fiaserig) structures. This kind of alternation of 

 more basic and more acid layers, giving the rock at times a very 

 stratiform character, may be most easily explained as due to original 

 veining, accompanied possibly in some instances by some differential 

 movement prior to complete solidification. This simulation of 

 bedding is most conspicuous about the central parts of the range, as 

 at Wind's Point, in the Hereford Beacon, and in the quaiTies by 

 the roadside at Little Malvern; but at the latter place the rock again 

 puts on its more massive structure in the quarry half-way up the 

 flank of the hill.^ On the ridge of Swinyard's Hill also this slabby 

 structure of alternating hornblendic and felspathic layers may be 

 observed. Various degrees of deformation of these layers (especially 



1 It appears to have become a rock of the Araphibolite-type of continental writers 

 (rasp. " felspar-ampMbolite " or "diorite-scbist "). See Credner {op. cit. p. Ill), 

 also Kalkowsky, "Elemente der Lithologie" (Heidelberg, 1886), p. 209. 



2 At the north end of the village is a disused quarry, which does not seem to be 

 noticed by recent writers. In a certain broad zone of the rock exposed there, the 

 structure here under consideration is splendidly shown. 



^ Here, however, the diorite is intersected by felsite dykes. It is interesting to 

 note this injection of felsite into the more banded and more massive portions of the 

 same broad orographic zone of the Malvern chain, pointing to community of age in 

 the two. It is curious also to see how this was overlooked by earlier writers, when 

 they wrote so confidently about these gneissose portions of the crystalline massif 

 as bedded sedimentaries. (See e.gf. Symouds " Old Stones," pp. 18, 19.) 



