1873.] DREW UPPER-INDUS BASIN. 459 



nant, some strip of narrow terrace, which shows that the stream 

 had formerly accumulated alluvium up to that level ; and where, 

 from the nature of the rock or other cause, there is any wide open- 

 ing in the valley, there occur spreads of alluvium, plateaux, often 

 high above the stream. I do not find in the various valleys any 

 thing like a constant height to which the alluvium may occur, 

 nor do I think it likely that there has been everywhere one 

 thickness up to which it accumulated : this must have depended on 

 the fall of the stream, which itself must have been varied by the 

 character of the material it had to deal with in different parts of its 

 course and the amount of water flowing in the different branches. 



In determining these facts, one must be careful not to confuse the 

 deposits of the side fan-producing streams with those of the larger 

 river ; for a fan, when denuded back, may well, at first sight, give 

 one the impression of a former great vertical accumulation of allu- 

 vium of the river, whereas really it has no such relationship with 

 that river as for its altitude to imply that. With careful attention 

 it is always possible to separate the different kinds of alluvium if 

 the falls of the two streams are markedly different — the alluvial ter- 

 race, which may be but a narrow strip or may be a wide spread of 

 the larger valley, and the fan of the branch one, which, even after 

 the wreck it has undergone through various forms of denudation, 

 will show the slightly curved surface of the low cone-form in 

 which it accumulated. If the fall of the two streams at their junc- 

 tion was about the same, the two alluviums will have formed one 

 general plateau, and the relation of both streams to the height 

 of it may be considered together. 



Varying from the above causes as they do, the alluvial plateaux 

 show themselves at such heights above their streams as 150 feet 

 and 250 feet commonly, 300 and 400 feet also not being rare. 

 It should, too, be remarked that above the highest remaining por- 

 tion of alluvium there may have been at any given spot a yet 

 higher level, which was destroyed in the first recommencing of down- 

 ward denudation. 



We will now add further instances of alluvium by which to test 

 the above generalizations. We will go to some of the branches of 

 the Shayok river — that great tributary of the Indus which drains 

 a large mountain-area on the north-east of it. 



At Khardong, two marches from Leh on the road to*Nubra, is a 

 remarkable instance of a deep-cut alluvium. The village stands on 

 the narrow remaining portion of a high alluvial plateau, composed 

 of debris of various sizes, even of large blocks. This was formed on 

 a slope of some degrees ; it has been cut into by ravines, which 

 show something like 800 feet of it in steep cliffs ; in one part is an 

 isolated rock that had been enclosed in the alluvium, and has since 

 been freed from it, except that a few beds are still adhering to its 

 sides. The road descends on a stony slope to the bottom of the 

 ravine, and keeps between the high alluvial cliffs, which shut out 

 the view of the mountains, although these at no great distance 

 bound the alluvial terraces. 



