534 



DE. C. CALLAWAY ON THE GENESIS OF THE 



most nearly related in mineral composition. A few examples are 

 here given. 



In the North Hill we have large masses of several kinds of diorite 

 penetrating each other in veins, and it is in this locality that we 

 find the diorite-gneisses, simple and duplex. 



North of the Wych the above-named diorites are intermixed with 

 granite, and here we have a variety of gneissic rocks of more com- 

 plex structure. 



Between the Wych and Swinyard's Hill there is little besides black 

 diorite and granite, and here we chiefly find the banded granite- 

 diorite-gneiss. 



Swinyard's Hill consists largely of granite, and it is in this ridge 

 that the flaggy quartzo-felspathic schists occur. 



In Midsummer Hill there are masses of coarse diorite, and the 

 gneissic rocks in association with them are certainly more allied in 

 mineral composition with this diorite than with any other igneous 

 rock of the region. 



Raggedstone Hill contains schists widely differing from any of 

 the above, and here the associated igneous rocks are felsite. 



These associations cannot be due to accident, and even if no direct 

 proof of actual conversion could be offered, they would be of weight 

 in the argument. 



Absence of Stratification. — Except * perhaps in the Raggedstone 

 Hill, I could detect no true bedding in the crystallines of the 

 Malvern Hills. The zones of igneous and foliated rock, though 

 they have a predominantly north-west strike, behave more like veins 

 than strata. Where a sufficiently large surface is exposed in plan, 

 we find the bands, whether massive or schistose, rapidly thin out. 

 For example, on the crest of the ridge about half a mile north of the 

 Wych the attenuation is usually from east to west. Fig. 3 shows a 

 part of one of the exposures in this locality. 



Age of the Rock. — I see no reason to doubt the received views as 

 to the age of the greater part of these rocks. At the south-western 

 extremity of the Raggedstone Hill, the Holly bush Sandstone rests 

 at a low angle upon the edges of nearly vertical schists. The old 

 rocks of the Salopian district afford confirmatory evidence. The 

 Uriconian conglomerate of Charlton Hill contains several varieties of 

 plutonic rocks, most of which can be matched in the Malverns, and 

 these Uriconians are themselves older than the Longmynd series f . 

 It is possible that the felsites and the schists formed from them are 

 of a younger epoch. 



Period of Metamorpliism. — The most effective pressures may have 

 acted at more than one period ; but there is no doubt that the meta- 

 morphism was substantially complete before Cambrian times, since 

 it is incredible that a force producing a strike transverse to the 

 ridge could have acted without dislocating the strike of the flanking 

 Cambrian and Silurian strata. 



* After further research I think it no longer necessary to make even this 

 slight reservation. — C. 0., July 20th. 



t Quart. Journ. Geol. Soc. vol. xlii. p. 481. 



