342 



PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



[Apr. 1, 



which induced the change. Julpigoree, where the alteration took 

 place, is 200 feet above the level of the river at its mouth, and it 

 flows for the first forty or fifty miles with a fall of 3 feet per mile ; for 

 a like distance further on the fall is 2 feet, and the slope gradually 

 sinks to 6 inches, or it may be less ; but nowhere is it a depositing 

 river or, consequently, influenced by back-waters ; and it therefore 

 appears to have been merely an accident which caused the change, 

 though being so, it is as likely to go back any day as to remain in 

 its present position. 



10. Retrocession of the Junctions of tributary Streams iviih main 

 Rivers. — There still remains one class of phenomena to which I must 

 direct attention before concluding, namely, the shifting upwards of 

 all the mouths of the tributaries of the Ganges along the main 

 stream. This is, perhaps, the most generally interesting of the 

 alterations that are taking place, not only from the magnitude of the 

 changes it superinduces, but because of its forming the best chrono- 

 metric scale for estimating the extension of the delta and the recent 

 sequence of events. 



Although I am not aware that they have been anywhere alluded 

 to before, the causes that lead to the changes appear to be tolerably 

 obvious when pointed out. 



In order, however, to make myself perfectly understood, let me 

 first refer to what I said about secular elevation in an early part of 

 this paper, and then assume two hypothetical cases, which I trust 

 will make the matter quite clear. 



First let me assume hypothetically that the Ganges, from Allahabad 

 to Rajmahal, was a perfectly horizontal canal or arm of the sea, run- 

 ning due east and west. It is evident that the slope formed by the 

 rivers bringing down detritus from the hills on the north and south 

 would dip north and south — but their plains would equally be hori- 

 zontal in a direction east and west — and consequently that all the 



Figs. 3-6. — Diagrams illustrating the Junctions of tributary Streams 



with Main Rivers. 



FiR. 3. 



