12 MEDLICOTTj SHILLONG PLATEAU. 



of both rocks, with consequent crushing in of the beds immediately 

 above the excavation. The great extent to which this action has oper- 

 ated, and the remarkable superficial features resulting therefrom, have 

 been fully described in previous accounts. As far as the strata extend 

 in this region the same band of nummulitic rocks rests upon the same 

 band of cretaceous beds. The two are quite parallel. No change or 

 displacement seems to have affected the lower group prior to the depo- 

 sition of the upper ; they are conformable.* 



The limestone at Cherra Piinji is quite isolated on the cretaceous 

 sandstone. It is at once apparent that the hills to the north of the 

 station of about the same height as the limestone hill are formed on 

 the prolongation of the nummulitic strata ; and one is much surprised 

 by the total absence of the striking scarp so common along the base 

 of the southern hill. It. would be possible to explain this by the 

 peculiar process of denudation that has operated so extensively in this 

 region — the underground removal of the limestone and the crushing 

 down of the superincumbent sandstones ; but this removal and conceal- 

 ment of the limestone has no doubt been greatly facilitated by the 

 much reduced thickness of this rock to the north. Some four miles to 

 the north, the nearest point at which I have seen a fair section of its 

 outcrop, the band of limestone is reduced to four or five feet. I believe 

 that this change takes place very rapidly to the north of the - present 

 limestone hill at Cherra. 



* Few terms in our vocabulary need regulating more than tlie word conformability. 

 Tbere are, I doubt not, observers who would at once pronounce this junction unconform- 

 able : the limestone beds are regular and steady J the sandstone is very much the reverse j 

 the surface of an individual bed is often very uneven ; the beds are thick, irregular, and 

 overlapping each other ; there are frequently sudden rises, much steeper than the slope 

 of the general surface, produced by local banks of the sandstone. But these features are 

 all such as could be accounted for by the original conditions of deposition, implying no 

 disturbance or denudation of the older group ; and this is the sense I would attach to the 

 word conformable. Any more geometrical definition would deprive the term of its prac- 

 tical signification : a total change of deposits has its own distinct signification. 



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