METAMORPHICS. 169 



a cleaved slaty rock belonging to the metamorphic series. 

 This observation was of much importance ; for, as the 

 direction of the planes of cleavage is the same as that of 

 -the lamination, viz. north and south and vertical, it is 

 evident that the foliation in this case corresponds with 

 pre-existing cleavage. It is also supported by nume- 

 rous instances observable in the slaty rocks of the 

 higher part of the pass and elsewhere, in which the 

 character of the planes of division is intermediate 

 between foliation and cleavage.^ It is, therefore, highly 

 probable, that the high dip, approaching verticality, met 

 with on the highlands is normal, and that the low dips 

 at the base of the hills are due to subsequent disturbance. 

 This disturbance may be of late date, and synchronous 

 with that which has affected the volcanic beds of the 

 coast, which will be described in a subsequent section. 



■' In a report on the geology of the lower Nerbudda valley in the western 

 part of the Indian peninsula (Mem. Geol. Survey of India, vol. vi. p. 193), I 

 have shown the strong probabilities which exist in favour of gneissic lamina- 

 tion corresponding with pre-existing cleavage whenever the dip is high and 

 the strike constant over large areas. In the Nerbudda area the probability 

 of the direction being due to cleavage was shown by independent evidence. 

 The metamorphics of Abyssinia offer another instance to the same effect, and 

 the rule may be universal. It will be of considerable geological importance 

 if this be established by further observations ; for if, as some of our best 

 geologists believe, lamination in metamorphic rocks may owe its direction to 

 either bedding or cleavage, according as the one or the other was the ruling 

 structure in the rock before metamorphism, the regularity and dip of the 

 lamination will afford a test as to which of the two the present direction of the 

 lamination planes should be ascribed, 



