the Last Town in China 113 
slopes were stately crimson spikes of Epzlobzum, with an 
occasional white-flowered specimen. 
It was dusk before we found a convenient camping- 
ground by a small stream. Everything was sodden, we 
were still some distance from the pass, and there was no 
prospect of getting a good fire or having anything hot 
to drink for some time. However, we put up the tents, 
tethered the ponies, and did what we could with the damp 
firewood. 
Next morning, leaving the men in camp, I climbed to 
the top of the pass, which crosses the Mekong-Yang-tze 
watershed at 15,800 feet, and from there ascended the ridge, 
which runs south-west towards Pei-ma-shan. A great 
plateau country covered with dwarf rhododendron spread 
away to the south towards the snow mountains, which were 
entirely obscured, and in the shelter of the screes vegetation 
extended to about 18,000 feet, where various primulas, 
saxifrages, and Meconopsis speciosa grew scattered amongst 
the rock fragments. 
On the other flank of the pass, however, bare screes 
faced the south, the belt of dwarf rhododendron ending a 
few hundred feet above the pass, while above towered 
the curiously fretted limestone buttresses of the divide. 
Throughout the day a keen wind blew down from the 
plateau bringing showers and mist, sometimes in the form 
of a drizzle, sometimes in storms of chilly rain. 
The valley facing A-tun-tsi which we had ascended 
owes its elevated tree-limit (15,000 feet) and the presence 
of such trees as the larch, to the local down-valley rain- 
bearing wind which drenches the valley almost every day 
throughout the summer, while the A-tun-tsi valley itself is 
swept by the direct up-valley wind from the Mekong. In 
the mountains here were many signs of previous glaciation 
—stair-way structure in the valleys, piles of angular scree 
material having the appearance of moraines at the valley 
heads, and a curious plateau structure at the foot of the 
peaks dominating the valleys, across which the collecting 
streams wandered independently, sometimes forming small 
lakes, before joining to dash down the stair-way. But 
the well-defined rock basins to be described later were 
wanting. 
W. T. 8 
