THE DRAINAGE AREA OF LAVAR-TSANGPO. 327
through the latter is a road to the S.W. passing a little lake, Tsi-nguri-tso. To the S. 60° W. is Lavar-naglep, a great valley to which all the source branches of the Lavar-tsangpo run clown. From Kyangyang-la the road descends in sand to Lavardemar on the Lavar-tsangpo and at a height of 5 048 m.
The road to Camp 444, at 4 949 m, follows the Lavar-tsangpo, which carried about r cub. m, thus being much smaller than the Sumdang-tsangpo. A little red mountain to the north, belonging to the range of Kyangyang-la, is called Tsa-mogri, indicating the existence of rock salt. Targo-tsiri is a valley from the left or south with a brook of V2 cub. m of water per second, coming from the snowy mountains in its upper part; such mountains are also seen in the upper part of Targo-nakta. Higher up, east of Camp 443 is a tributary to the Lavar-tsangpo, called Chirimarmo. Two small hills on the northern side of the valley are called Cham-ngota and Dung-ri. From the left or south enters the brook of Chu-sän, coming, as the name shows, from a hot spring. The valley of Lavar-tsangpo is very broad and open; its soil is partly grass-covered, partly gravel.
In order to reach Ding-la the road slowly diverges from the Lavar-tsangpo, going straight west and crossing the vegetation belt along the river and the left side erosion terrace; then it gradually ascends the scree of gravel at the northern foot of the Ding-la range. Several small transverse valleys run down to the Lavar-tsangpo. Higher up there are several old moraines of gravel and blocks of gray granite. Tugyen-gerko is one of the transverse valleys; opposite it, at the northern side of the Lavar-tsangpo, is a tributary called Lungmar. From the next southern tributary, Ganglung-ringmo, comes a brook. Tsalung is the next. In the background of all these small valleys, snowy heights are visible belonging to the crest of the Ding-la range. From the slope west of Tsalung we notice the very broad and level valley of the Lavar-tsangpo stretching far to the north. To the N. 8o° W. are a couple of small peaks belonging to a range situated between the Lavar-tsangpo and Aong-tsangpo; N. 60° W. is a left tributary called Raa-taong; to the N.W. is the valley Lungnak and south of it a light low mountain called Su-kamruk; N. 23° W. is a place called Tokchung; to the N.N.W. is the junction of the valleys of Aongtsangpo and Lavar-tsangpo, and in the same direction Tok-marpo and Aong-dunker; to the N. 5° W. is seen a little salt lake, Damrap-tso, which must be close west of Lavar-tsangpo. The plain itself has the name Tsabsang-tanga; N. 8° E. is a low peak with some snow, and near it the valley Shaglung; N. 18° E. Pago-la; N. 23° E. the valley Lungchen, and N. 33° E. the valley Yülo, both right tributaries of the Lavar-tsangpo.
After having crossed another two or three deep-cut ravines, the road enters the more considerable valley from Ding-la, where Camp 445 has a height of 5 196 m. From here the direction of the road becomes straight south. The valley is deep and narrow, and the road has to climb the left side slopes, covered with gravel. The crest rising at the right side of the valley has some patches of eternal snow.
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