GEOLOGICAL NOTES ON ASSAM. 37 



thousand. If the conglomerate at Mawbelurkar be continuous with that 

 in a corresponding' position in the Cherra section^ (as the coal there must^ 

 I suppose^ be taken to represent the nummulitic coal,) I would almost 

 despair of any traceable strati graphical boundary being discoverable, and 

 would look rather for a blending of the faunae. I could see no pretext for 

 separating the conglomerate at Mawbelurkar from the coal sandstone 

 Hint of the desired immediately associated with it. The only sugges- 

 boundary. ^ioj^ j ^an make to relieve the difficulty is, that the 



conglomerate of Mawbelurkar may not be the same as the conglomerate 

 resting on the metamorphic rocks at Cherra. If this notion be correct, the 

 much sought for boundary might be found by tracing the younger conglo- 

 merate into the Cherra section. A possible representative of it does occur 

 there. The sandstone forming the plateau of Cherra station, though not 

 different in kind from others above and below it, is the most massive band 

 among the upper strata, and at or towards the base of it, on both the 

 sections I examined below the station, I found it to be conglomeratic. 

 In connection with the suggestion I have just made regarding 

 the stratigraphical demarcation of the nummulitic 



Possible identity of tbe 

 Shillong rocks with tbe and the cretaccous strata, and with the relation of 

 cretaceous, 



the trap to the strata of both periods, I consi- 

 dered the possible identity of the altered sandstone of Shillong and the 

 conglomerate which so constantly accompanies it with the cretaceous rocks 

 of Cherra. The lithological aspects are compatible, and perhaps even 

 the conditions of disturbance. The less reconcilable features are, the 

 distinct superposition of the Cherra beds to the stratified trap^ of the 

 southern sections, and the close proximity in the valley just below Cherra 

 itself to the east of a trap like that of the Kalapani to the undisturbed 

 and unaltered cretaceous rocks. 



* The connection of this 'stratified trap' with the more crystalline trappean rocks 

 seen to the north has yet to be shown. — T. 0. 



, ( 423 ) 



