42 mallkt: geology of darjiling and western duaes. 



All that can be done is to divide the less from the more altered strata 

 on the large scale, and it must be remembered that this is merely a 

 provisional separation of convenience, as there is no evidence of any 

 stratigraphical break. The same difficulties were experienced by 

 Mr. H. B. Medlicott in the north-western Himalayas/* by whom at 

 least a portion of the metamorphic rocks were shown to be on the horizon 

 of some groups of his slate and limestone series. 



The slates appear to be faulted against the gneiss in the Little 

 Eangit and on the Takvor spur; and the fault may extend to the 

 eastward. I nowhere, however, elsewhere observed any indications of 

 faulting along the junction, nor of pseudo-faulting, from deposition of 

 one series against a steep pre-existing cliff of the older rocks. It is 

 beyond dispute that the Daling beds do underlie the gneiss, and it is, 

 I consider, equally certain that they do so normally and not from inver- 

 sion. The latter hypothesis would involve nothing less than the com- 

 plete inversion of all the pre-tertiary rocks over the greater part, if not 

 the whole, of the Darjiling district. It would imply in fact that inver- 

 sion is, so to speak, the normal order of things ; for the facts cannot be 

 explained by mere local inversion along the lines of contact. Such super- 

 position of fully metamorphosed rocks on those in a less highly altered 

 condition is a phenomenon by no means confined to the Darjiling hills. 

 It has been described by Mr. Medlicott f as the usual order of things in 

 the north-western Himalayas, amongst the strata of his Himalayan 

 series, with which, there can be little doubt, the slate and gneiss rocks 

 of Darjilinsr correspond more or less completely J. 



* Vol. Ill, pt. 2, and Panjab Gazetteer, article Geology. 



f Vol. Ill, pt. 2, and Panjah Gazetteer, article Geology. 



J In this connection I would refer to Mr. R. Mallet's recent paper on volcanic 

 energy (Philosophical Transactions of the Royal Society, vol. 163, page 147), in which the 

 author shows (page 168) that if several horizontal beds or layers of rock, of different 

 compressibilities, be subjected to tangential pressure, the work of compression will be greatest 

 in the layers of least compressibility, and consequently the beat evolved greatest also- If the 

 upper of two layers be the less compressible, it will be the hotter, and we may therefore reason- 

 ably conclude, the more highly metamorphosed, if the elevation of temperature be sufficient 

 to induce such action. The extent to which the Himalayan rocks have been subjected to 

 tangential pressure is abundantly shown by their disturbed and folded condition, 



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