72 SUB-HIMALAYAN ROCKS OF N. W. INDIA. [CHAP. II. 



It is with much diffidence that I approach such a vexed question as 



that of cleavage ; more especially as I have little 

 Cleavage. . 



or nothing to say m the matter, lor or against any 



of the proposed theories. The fact is, I have failed to observe any general 

 phenomenon of the kind. This will surprise many, as it did myself. I 

 make the statement, however, under correction, and in direct opposition to 

 a recent assertion of the contrary by observers of some repute. In a paper 

 already referred to, by the M.M. Schlagintweit, in Volume XXV. of the 

 " Journal of the Asiatic Society, Bengal," p. 118, the following passage 

 occurs : " It was observed a long time ago, that in the great mass of gray 

 schists which must be traversed before reaching the central group of the 

 Himalayas, a remarkable uniformity in the dip of apparent stratification 

 prevails. Our observations have perfectly convinced us that this is no real 

 stratification, but merely cleavage, produced, as is now generally assumed, 

 by a great tension in the interior of the highly altered rocks." If the 

 structure described in this passage can be called cleavage, I confess that I 

 am utterly ignorant of the meaning of the term, as likewise of the term 

 stratification. I could not refer to simpler examples of interstratified 

 varieties of metamorphic rocks than occur along the section through Al- 

 morah — the one alluded to in the passage just quoted. Cleavage is however 

 to be seen in the outer Himalayan rocks. The best instance I have ob- 

 served of it is at Nairn Tal : the slates quarried 

 At Naini Tal. 



on the flanks of Ohenur are true cleavage-slates. 



But even here the phenomenon is only partial ; in many sections of slaty 

 rocks at Naini Tal I failed to detect anything I could recognize as 

 regular cleavage ; and in the several places where it can be traced it does 

 not maintain a constant direction. If originally it had a common direc- 

 tion, as may perhaps be presumed, subsequent disturbance has quite 

 At Simla and Dal- obliterated it. The slates used at Simla are 

 housie < easily recognized to be merely lamination slates. 



Again, the excellent roofing slates of Dhurmsala and Dalhousie, 



