KHASI HILLS. 171 



would seem to bear out Captain Strachey's views that the elevation of 

 the Himalaya ranges, or at least of a great portion of those ranges, had 

 taken place previously to the deposition of the numraulitic rocks, and 

 that, in fact, these ranges formed the land from the shores of which the 

 nummulitic sea extended Southwards with a very gradually inclined 

 bottom. But what then are the representatives or parallel of these 

 nummulitic beds in the more central part of India ? Can the group 

 to which I have already elsewhere (a) given the name Mahadeva 

 be in this position ? And may not the irregularly developed beds of 

 limestone, which are found accompanying those sandstones, be the 

 faint representatives of this widely extended and largely developed 

 nummulitic limestone ? The solution of this question must be left for 

 further and more extended research. 



Again, in connexion with the occurrence of an upper group resting 

 upon the true nummulitic rocks, in all known localities, extending from 

 Arabia and Persia on the West, to Burmah on the East, this upper group 

 being characterized generally by the presence of gypsum and of petroleum 

 (the " gypsiferous series" of Loftus (b), I would allude to the occurrence 

 of petroleum springs in the vicinity of Ch.erra, and also further to the 

 East near Cachar as an additional proof of the remarkable constancy 

 in general character and detail, which this important group of rocks 

 presents over such a widely-extended area. 



Physical Geogeaphy. — Some of the striking peculiarities in outhne 

 and general character of these hills have been already alluded to, and 

 nave been illustrated in the sketches which accompany this report. 



The curiously flat-topped plateaux of the range forming long swelling 

 grassy plains, marked here and there by small outstanding hillocks, which 

 scarcely interfere with the general level, cannot fail to suggest the idea of 

 long continued denuding forces acting at tolerably fixed levels. Of these 

 plateaux or terraces, a remarkable one is that on which the station of 



fa] Jour, Aeiat. Soc. Beng.il, Vol. XXV. p. 252. (b) Qufu-. Jour. Geol. Soc. London, Vol. XI. p. 2.04-27O. 



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