Chap. IV.] nahun and sivalik groups. 105 



might be possible, only by fossil evidence, to disconnect the bed 6 from 

 the overlying series and to connect it with those at e. 



The only view that can be taken of the section differs in no essential 

 particular from the case I have just supposed in explanation of the 

 doubtful identification. There is no evidence, such as I have been able to 

 show in the case of the Subathu group, that the Nahun rocks were entirely 

 removed from the present area of the next younger group ; on the contrary, 

 we see some cases of distinct, though limited, overlap along the boundary 

 of the two, and there is no kind of improbability in the appearance of 

 the underlying rocks at any point of the disturbed area to the south of 

 this general boundary. Thus, then, the confirmation of Colonel Cautley's 

 identification would in no way affect the establishment of a younger 

 group, distinct from that of Nahun, typically developed in the Sivalik 

 hills, and the chief depository of the Sivalik fossils ; it would only be 

 the detection of a reappearance of the older group, due to- upheaval and 

 denudation, beneath the newer one at the south base of the Sivalik hills. 

 Should the fact be established, it will afford an admirable illustration of 

 the great assistance of palseontological evidence in the elucidation of strati- 

 graphical phenomena ; and, on the other hand, the stratigraphical facts 

 would warrant the expectation of some distinction between the fossils of 

 the two groups ; no such distinction has as yet been suspected by the 

 authors of the "Fauna Sivalensis." 



There is one more suggestion I would offer for the benefit of any 

 future explorer, who may be fortunate enough to re-discover the fossil- 

 iferous deposit north of Nahun : — to examine whether it may not be 

 local, an outlying remnant of some swamp-deposit on the shore of the 

 ancient Sivalik estuary, lake, or sea. 



This moot point of identification is of much importance, as bearing 



Bearinguponthetheory u P on the most interesting problem in physical 



of disturbance. geology, — the manner of upheaval and disturbance. 



We will see that the rocks of the Nahun group exhibit a greater gene- 



o 



