266 The Land of Deep Corrosious 
features and such a diverse flora as that we have seen on the 
Mekong-Yangtze divide, much more will this be the case in 
the deep gutters which separate ridge from ridge, since it is 
here that the effect of the rain-screen makes itself felt in its 
fullest intensity. 
The positions of the great snowy ranges correspond so 
exactly with the change from a region of summer rains to 
arid desert that it is impossible to doubt that it is the 
peculiar topographical features of the country which account 
for the extraordinary climatic conditions, more particularly 
their startling changes. 
West of T‘sam-p‘u-t‘ong rises the great snow mountain of 
Ke-ni-ch‘un-pu, separating the Salween from the headwaters 
of the ’Nmai-kha, and at the same time abruptly putting an 
end to the Salween jungles by depriving them of their vital 
rainfall. 
To the east, between the Salween and the Mekong, rises 
the still more remarkable K ‘a-gur-pu, which is, as we have 
seen, continued northwards in a chain of high peaks to 
Ta-miu in Tibet. 
Eastwards again we have a nameless snow mountain 
between the Mekong and the Yang-tze, continued, not 
northwards, but southwards by the snowy peaks of Pei-ma- 
shan, though it is only the scanty precipitation on this 
stupendous ridge which prevents many other peaks from 
being clad with eternal snow. 
The really important rain-screen, then, is the K ‘a-gur-pu 
masstf, since it is owing to the presence of this overwhelming 
mountain, which divides with Ke-ni-ch‘un-pu the lion’s 
share of the rains on this, the eastern limit of the monsoon, 
that the Mekong-Yang-tze watershed is entirely changed in 
character. 
South of T‘sam-p‘u-t‘ong there is no really big barrier 
west of the Salween ; ridge beyond ridge there is still, right 
away to the plains of Assam, but not one of them is 
sufficiently high to screen the country beyond from the 
effects of the monsoon and seriously affect the rainfall in 
the Salween valley. 
But the Mekong rift is so extraordinarily narrow that 
the rains seem to pass right over it and precipitate them- 
selves on the mountains and plains further east, so that this 
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