GENERAL DESCRIPTION OF AREA AND ROCKS. 7 



two in the plains, joins the Ganges above Rampur Bolia. All the 

 remainder of the Darjiling hills is drained by the Tista and its tribu- 

 taries, except the extreme eastern end, where the superfluous water is 

 carried off by the Jaldoka. These rivers eventually reach the Brahma- 

 putra south-east and east of Rangpur. Thus the Singalela ridge forms 

 at the present time the watershed between the Ganges and the Brahma- 

 putra. The Mahanaddi and the Tista flow into the plains in the 

 debatable ground where, under sub-deltaic conditions, a constant struggle 

 is going on between the Ganges and the Brahmaputra, as they approach 

 each other from the west and from the east, across the great plains to 

 the south of the mountain range. Early in this century the Tista 

 was tributary to the Ganges. 



Here, as elsewhere in the outer Himalayas, lakes are very uncommon 



and of insignificant dimensions. There is one 

 Lakes. 



such about six miles south-west of Hope Town, 



and another, called Rom Tal, on the Ramthi naddi, some miles east of 



the Tista. The latter presents some features of interest. As measured 



on the map, it is 550 yards long and about 200 broad. For 30 or 40 



yards from each bank in the upper part of the lake, dead stumps of 



trees (which are evidently in situ, and not large branches of sunken 



drift wood), appear above the surface of the water, indicating that the lake, 



if not formed, has at least increased considerably in depth, within the 



time that such timber can remain under and above water without 



falling to pieces. Charred piles below water are known to be capable of 



resisting decay for centuries, but trees in the above condition would no 



doubt rot much sooner. Towards the lower end vertical precipices rise 



from the lake, and here the water seems to be much deeper ; too deep 



to allow of any stumps appearing above the surface. For more than 



a quarter of a mile above the lake there is a delta of slate shingle, which 



yearly encroaches on and diminishes the area of the water. The Lepchas 



have a tradition that three or four generations ago the whole of this 



( 7 ) 



