226 The Last of the Mekong 
parting to move so far eastwards that its crest now hangs 
right over the Mekong. Such a beheading of one of the 
great rivers of Tibet can only take place south of latitude 
28°, for north of this parallel are the arid regions where the 
rainfall is practically the same in all the deep valleys. But 
here the change is surely being effected, and the tropical 
rainfall of the Salween valley is gradually strangling to 
death the ever-shrinking Mekong, flowing in its rainless 
gorge. 
Spread out at our feet was a green valley where small 
villages, surrounded by cultivated fields, peeped from 
amongst clumps of trees; here and there shone the white 
walls of a temple, and in the distance Lao-wau caught the 
sunshine and glistened indistinctly. Beyond the valley rose 
another range of mountains, completely shutting out any 
view of the Salween, and still further away appeared the 
black and jagged crest of the ridge which separates the 
Salween from the Shweli. 
On this side the country does not fall away abruptly to 
the Salween, as it does to the Mekong on the east, but is 
more cut up into hill and dale by the mountain streams 
which, flowing in broad valleys, run for some distance north 
and south before turning westwards to break through the 
secondary ranges so created, and join the main river. The 
heavy rainfall leaves its mark on the topography of the 
country, which is much diversified, the broad valleys being 
further characterised by their gently rounded form and the 
smoothing away of abrupt inequalities on the ridges by 
masses of vegetation. There were here none of those hard 
lines so typical of the Mekong scenery. 
A steep descent, at first down well-laid steps, presently 
deteriorating into a narrow and slippery path through pine 
forests similar to those above the Mekong, brought us into 
the valley, where we stopped for lunch at a tiny village. 
Here camellias were to be seen in flower, besides several 
other shrubs, and one or two betel-palms rose high above 
the thatched roofs, so that we were certainly approaching 
a region of mild winters, though immediately above us 
frowned the rugged cliffs of the divide we had just crossed, 
and it had been by no means warm up there on the pass. 
Following the stream westwards through the gap it had 
