1873.] DREW — -UPPER-INDUS BASIN. 461 



the extent of the advance. There would be a tendency of the sur- 

 face of the alluvium to assume a waved form ; but this would pro- 

 bably soon be counteracted by the levelling effect of denudation by 

 the stream and further deposition. If after doing this the glacier 

 definitely retreated, the disturbance of the beds would be completely 

 hidden until further changes exposed it in section. To the above 

 cause I attribute both the curvature seen in this Changchenmo allu- 

 vium and the straight false-bedding-like slope of the beds (at such 

 angles as 30°) in proximity to curvature, of the Tsarap and its 

 branches. The slopes seen may be but parts of a long curve ; or the 

 action of the glacier may have been in some cases more an under- 

 prising and tilting one than I have described it. 



Another example of alluvial terraces is shown in the sketch, 

 fig. 7. Here is a cliff of the alluvium of a branch of the Chang- 

 chenmo river (that leading down from Masinuk Pass) which is 

 about 120 feet high, and very regular and persistent ; the slope of 

 the surface of the terrace down the direction of the valley is 1^-°. 

 It is instructive to trace from this sketch that, although the river 

 has cut down to such a depth in its own alluvium, the fans behind 

 have not been cut into by their streams. At the time I passed them 

 (in the month of August) they were, indeed, dry, but there were 

 marks of shallow watercourses on them : it is clear the water did 

 not come down in volume enough to reach the edge of the alluvium 

 cliff and cut a notch, and cut back a gully for itself, as has occurred 

 in so many other instances. 



In the Tainyar valley, down which another tributary of the 

 Shayok flows, the sides of the ravine are great cliffs, showing at first 

 350 feet of alluvium, continuing from the top of the cliff down to 

 the present level of the stream. Some beds are coarse and contain 

 boulders; some are of fine gravel. The strata slope down the 

 valley at an angle of 2° or 3°, the present stream-bed having a 

 rather greater fall than that. Further down the cliffs get higher, 

 and a still greater thickness of deposit is shown in section ; but here 

 come on lacustrine beds, the description of which I defer ; and as 

 what deposits I have seen on the Shayok itself are either lacustrine 

 or closely connected with lacustrine ones, I shall now pass to the 

 alluvium of the Indus proper. 



"Where the Indus enters Ladakh from Chinese Tibet, it is flowing 

 towards the north-west through a flat alluvial plain at an elevation 

 of about 13,700 feet above the sea. This flat, which lies between 

 mountains of 19,000 and 20,000 feet high, has a width of about two 

 miles, and continues like that for a length of some five-and-twenty 

 miles. It is so regular in slope that when one stands on it the 

 horizon of the curvature of the earth can be seen in both directions, 

 both up and down the valley. The river flows gently, winding 

 through the flat at the rate of two miles an hour. After this it bends 

 suddenly to the south-west, and traverses a range of granite 

 mountains, and then nearly regains the north-westerly direction ; 

 flowing still over alluvium in the same gentle manner, it traverses 

 another twenty-five miles beyond the distance first mentioned. 



VOL. XXIX. PART I. 2 H » 



