62 BALL : GEOLOGY OF THE RAJMEHAL HILLS. 



In consequence of this tendency of the trap rocks to conceal the sedimentary 

 deposits, it is very possible that, some thin beds, especially if only of local occurrence, 

 may have escaped notice entirely. 



Towards the south, many of these beds between the trap-flows thin out and 

 disappear, and although some (such as No. 4 in general section ) may be traced almost 

 to the southern extremity of the hills, they become much thinner there. 



Indeed, owing to the peculiar nature of the ground, it cannot be asserted that there 

 is absolute continuity. The sections of the upper beds are, however, fewer and less 

 exposed in the south than in the north, as the whole series there dip more abruptly, 

 and at a shorter distance beneath the Gangetic alluvium. Yet it seems a clearly 

 established fact, that there is an almost total absence of intertrappean beds in the south- 

 ern portion of the Rajmehal hills. This portion lying south of the Brahmini, and 

 stretching to a few miles north of Suri, is known as the Ramgurh hills. It is highly 

 probable that the whole of the lower portion of the trap series is here very much 

 reduced in thickness, or, perhaps, altogether wanting, as in one locality a small group 

 of beds similar to those of No. 4 in the general section ' white beds' seem to rest 

 directly on the subtrappean sandstones, while another thin run of similar beds occurs 

 above the lowest trap-flow in that place. In the neighbourhood of the Brahmini, on 

 the Dubrajpur and Mohwagarhi hills, a bed (about 30 feet thick) of coarse ferruginous 

 sandstone occurs above the lowest flow of trap. This would seem (perhaps) to corre- 

 spond with No. 10 of the section, as seen in the north-west of the hills, although it is 

 much coarser and more ferruginous. 



But this bed is also wanting in the Eamgarh hills, or in the most southerly part 

 of the range. 



All these circumstances unite to prove that there is no constant sequence of 

 beds, and shew that while the area, considered as a whole, presented similar features 

 at the same time, still the conditions varied in adjoining portions of that area, and 

 that, as might be anticipated from the nature of the deposits, volcanic flows were 

 taking place in some places, while clays and mud were being deposited in others at 

 the same time. 



Of these mechanical deposits a very brief description will suffice. 



The uppermost seen in the Rajmehal hills (No. 2 of the general section above) 

 occurs only locally in the high range south-east of Meghi village, and again near 

 a village called Itari, north-east of Murrero. 



It is a white quartz grit, locally ferruginous (slightly), never more than 4 or 5 feet 

 in thickness, and generally altered by the overlying trap to a dense quartzite, and 

 sometimes so completely as to have become a perfect hornstone, So far as seen, this 

 bed is quite unfossiliferous. 



This, as we have said, was the highest bed seen, but scattered upon the summits 

 of the hills in several places, and occasionally lower down, pieces of excessively hard 

 ( 216 ) 



