OF THE MALVERN HILLS. 



487 



may have been brought about by the faulting of rocks in which 

 there may have been once a persistently uniform strike, is, however, 

 a possibility not unworthy of consideration*. On the other hand, 

 the arguments in favour of the divisional planes being old planes of 

 bedding appear to rest on the parallelism of the foliation to the 

 divisional planes, on the seeming inters tratification of rocks which 

 exhibit no foliation, on the marked differences in texture shown by 

 adjacent bands or beds, and also on the differences which occur in 

 their respective mineral constitution. If we assume these rocks to 

 be metamorphosed sediments, it follows that they were originally 

 bedded, but it does not necessarily follow that they were all sub- 

 sequently affected by cleavage ; and we do not therefore seem 

 justified in the inference that the foliation in this case is parallel to 

 structural planes which may have existed, to the exclusion of the 

 possibility that it may be parallel to others which, if the rocks be 

 metamorphosed sediments, we feel assured did exist t. 



The reference of cases of more or less advanced metamorphism, 

 and the accompanying phenomenon of foliation, to the shearing or 

 creeping movement of one rock-mass over another, may induce many 

 to search in the Malvern range for evidences of disturbance other 

 than those already mapped as faults. Pending the result of such 

 inquiries, it seems better to leave one's mind in a receptive state 

 than to crowd it with opinions of questionable value. 



In the meanwhile strikes and dips indicate the directions and 

 inclinations of structural planes ; but whether those planes denote an 

 original stratification is an open question and one upon which it 

 seems unsafe to express any decided opinion. 



The upheavals and plications which the older rocks have undergone 

 render it more than likely that in many instances the steeply 

 inclined planes of foliation do actually agree with steeply and 

 similarly inclined planes of original stratification in rocks in which 

 cleavage has not been induced, at least to some extent and along 

 parallel portions of folds. On the other hand, the facts recorded by 

 good and competent observers show that in a great number of cases 

 unanswerable proof exists that often, over wide areas, the .planes of 

 foliation agree with planes of cleavage, and do not in any way 

 correspond with planes of original stratification. 



Interbedded lavas and other eruptive rocks are also frequently 

 present in most of the older formations, and it is therefore needful 

 to remember this in accounting for some of the more strongly 

 marked lithological differences in contiguous bands. 



* The foliation was developed in the range before the faults were formed, 

 since the faults cause marked changes in the direction of foliation. In de- 

 scribing the old ridge of the Malvern Hills as an axis of elevation, we are 

 probably expressing merely a partial truth, since the ridge is, most likely, only 

 an upcast portion of an axis of elevation, disrupted by north and south 

 fissures. 



t The late David Forbes considered that the direction of foliation agreed in 

 all cases with the planes of least resistance, whether planes of stratification or 

 cleavage, or, in eruptive rocks, with " strias of fusion." (" The Structure of Hock 

 Masses," Popular Science Eeview, vol. x. p. 236.) 



