262 The Land of Deep Corrosions 
beating against these mountainous barriers, deluges them 
one after the other till the Salween-Mekong divide is 
reached. And then comes a change. 
North of Lat. 28° this ridge rises abruptly from a mode- 
rate elevation to the stupendous peaks of K‘a-gur-pu, and 
thence continues northwards into Tibet to the conspicuous 
snowy range of Ta-miu; and the important point is that, 
from K‘a-gur-pu northwards, the height of this range 
becomes a vital factor in the distribution of climate. 
In like manner, both the Salween-Irrawaddy divide to 
the west, as I observed from above the Salween, and the 
Mekong-Yang-tze divide to the east, which I crossed by 
three passes, receive a sudden considerable uplift in about 
the same latitude. 
The effect of this is extraordinary. The Salween- 
Mekong watershed itself, on account of the overwhelming 
height of K‘a-gur-pu, still receives a very big rainfall for 
some distance north of the rain-screen at any rate, but by 
the time the winds have crossed this great range, they have 
been robbed of nearly all their moisture, and the Mekong- 
Yang-tze divide, instead of being clothed with dense forests 
and waving meadows of alpine flowers, presents vast 
stretches of barren scree, towering pillars of naked lime- 
stone, grim rocky ridges, and an aspect so drear and bleak 
that the scenery appals one. The snow-line stands at an 
enormous elevation—little less than 19,000 feet I think, and 
consequently the passes, high though they be, are open most 
of the year. 
The passes over the Salween-Mekong divide are con- 
siderably lower, but owing to the far heavier rainfall which 
this receives in the neighbourhood of K ‘a-gur-pu, are open 
no longer than those on the next watershed to the east. 
The Sie-la above Tsu-kou for example, which is about 
14,000 feet, was under deep snow when we crossed it in 
June, and was almost impassable when we crossed during 
the second week of November. It could hardly have been 
clear before the end of June, by which time the Doker-la 
somewhat further north was just clear, and snow was cer- 
tainly falling there again in October. The main pass above 
Londre, situated between the two passes mentioned above— 
the Chun-tsung-la as it is called—is barely 13,000 feet high, 
