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THE OROGRAPHY OF WESTERN TIBET ACCORDING TO DREW.   173

of the monsoon is also in accordance with the general view of the time. As a

matter of fact the influence of the monsoon is felt much further north of the Himalaya than formerly believed.

From FREDERIC DREw's excellent work I must, for the sake of completeness, insert a few quotations.' He discusses in a most able way some of the geological questions regarding the western parts of our system:

»Cunningham, in his book on Ladakh, speaks of the 'Kailas Range' as extending in one unbroken chain from the source of the Indus to the junction of the Shayok, the name being taken from a peak on it near Mansarawar Lake, and he calls the great ridge behind Leh, between the Indus and the Shayok, by the same name, 'Kailas or Gangri Range'. It will be seen that I have not used this name in my map nor elsewhere; in this I follow Col. H. Strachey, who does not connect by its name this last ridge (which I have called 'Leh Range', though on the maps I have put no name to it) with any of the chains to the east or south-east of the part we have now reached . . . We are now (at Dora) where the unbroken continuation of the Leh Range ceases. That long line of granite mountain, which began at the Indus and Shayok junction, and has, up to here, extended from north-west to south-east for 220 miles, in that direction ends, and the Indus Valley occurs. Immediately beyond the river, between the Indus and the Hanle stream, occur again granite mountains, which, geologically, are a continuation of the others, and indeed lie in the same line with them. So that it would not be alien to the methods of geological description to say, that the Indus here cuts through the granite range; the range being taken to extend from the Indus and Shayok junction to the neighbourhood of Hanle at all events — how much farther to the south-east I know not. Now to the north-east of all this is a distinct line of mountain, of which Sajum Station, 20 021 feet, is one of the summits; this, according to Cunningham, would be part of the Kailas Range; here this range also is of granite, though farther east its composition changes; the line of it runs north-westward, overlapping the line of the Leh Range; the granite of the two ranges is in part continuous and in part separated, as regards the surface, by some shale and limestone; in the line of the occurrence of these last rocks is the depression separating the two ridges; the highest part of this depression is the Tsaka Pass, about 1200 feet above the Indus Valley, but nearly 5 00o feet below the hill summits, on either side; the rise to this is a gentle ascent of 3°; the Pass divides the Upper Indus Valley from the Pangkong drainage-basin. According to General Cunningham's nomenclature this Pass is a depression in the Kailas Range. According to the plan of description just followed by me the Tsaka Pass is a neck connecting two ridges, the Leh Range on the south-west and this other on the north-east . . . About NE from Dora the northern mountain-ridge changes in point of composition from granite to a more or less altered shale; the line of it is continued more to the east than before, while in the line of its original direction are some more hills which are joined to the other ridge by a neck called on the survey map 'Chang Pass'; this Pass is practically the boundary of Chinese Tibet in that direction; in the Indus Valley the boundary will be a day or two's march beyond Dora.»

The Leh Range of which Drew said he did not know how far it proceeded to the east, is the same which Burrard calls the Ladak range and continues the

c-   whole way to the Dihang bend of the Brahmaputra.

I The Jummoo und Kashmir Territories. A geographical account. London 1875, p. 312 et seq.