GENERAL GEOLOGICAL NOTES. 27 



the possibility of the measures in question having* the same age.* No 

 fossils have yet been found in the latter except vegetable remains too 

 badly preserved to allow of specific determination. Dr. Feistmantel 

 who has examined those I procured, found them all to be impressions 

 of dicotyledonous leaves, indicating a tertiary, or at earliest cretaceous 

 age. In the Khasi and Garo hills, both cretaceous and nummulitic coals 

 are known, which differ from each other markedly in their mineral 

 character. The first is " compact, splintery, with smooth conchoidal 

 fracture, and a woody sound when struck ; a fine lamination is traceable, 

 and there is commonly an irregularly prismoidal structure across the 

 bedding". It has the further peculiarity of containing numerous specks 

 and small nests of fossil resin.'' These marked characters are main- 

 tained within the region under description, at the Nambar (see note 

 p. 17). The nummulitic coal '^has constantly very much the aspect 

 of ordinary bituminous coal — the cuboidal structure and the half stony 

 sound when struck-'-'t The Upper Assam coal agrees exactly in mineral 

 character with the latter. This, no doubt, cannot be regarded as very 

 strong evidence, but it is at least suggestive. 



The general hthology of both the cretaceous and nummulitic 

 formations varies so much in the Khasi hills as to afibrd no reliable 

 means of comparing them with the Upper Assam rocks. It may be 

 remarked, however, that the small development of calcareous strata in the 

 Upper Assam measures cannot be allowed much weight as against their 

 nummulitic age. Although limestone is generally one of the most 

 important rocks amongst the Khasi nummulitics, it is entirely absent 

 from them over some areas. At Cherra, for instance, it is largely deve- 

 loped, but thins out completely to the north, and very nearly so to the 

 east in the Garo country 4 



There is, however, a notable poiut of contrast between these Assam 

 measures and the known nummulitic coals. In north-western India 

 the coal-bearing band occurs at the very base of the nummulitic group. 



* Vol. IV, p. 416. t Vol. VII, p. 175. X Vol. VII, p. 163. 



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